fixes #25697 ; {.borrow.} on iterator for distinct seq triggers internal error

Merge remote-tracking branch 'origin/devel' into pr_so_so
tests: move regression t22842 into tests/types (auto-related)
2026-08-31 10:53:40 +00:00 · 2026-04-06 16:20:22 +08:00 · 2026-04-06 16:17:43 +08:00 · 2026-04-04 13:07:55 +08:00 · 2026-04-04 12:59:32 +08:00
110 changed files with 349 additions and 2493 deletions
--- a/.github/workflows/ci_publish.yml
+++ b/.github/workflows/ci_publish.yml
@@ -60,7 +60,7 @@ jobs:
        run: nim c -r -d:release ci/action.nim

      - name: 'Comment'
-        uses: actions/github-script@v9
+        uses: actions/github-script@v8
        with:
          script: |
            const fs = require('fs');
--- a/changelog.md
+++ b/changelog.md
@@ -35,10 +35,6 @@ errors.

 - Adds a new warning `--warning:ImplicitRangeConversion` that detects downsizing implicit conversions to range types (e.g., `int -> range[0..255]` or `range[1..256] -> range[0..255]`) that could cause runtime panics. Safe conversions like `range[0..255] -> range[0..65535]` and explicit casts do not trigger warnings. `int` to `Natural` and `Positive` conversions do not trigger warnings, which can be enabled with `--warning:systemRangeConversion`.

- Procedure compatibility also checks the backend representation of the
-parameter and result types, not just their source-level shape. Use
-`--legacy:procParamTypeBackendAliases` to restore the older behavior.
-
 ## Standard library additions and changes

 [//]: # "Additions:"
@@ -64,26 +60,17 @@ parameter and result types, not just their source-level shape. Use
    - `copyDirWithPermissions` to recursively preserve attributes

 - `system.setLenUninit` now supports refc, JS and VM backends.
- `system.setLenUninit` for the `string` type. Allows setting length without initializing new memory on growth.

 - `std/parseopt` now supports multiple parser modes via a `CliMode` enum.
  Modes include `Nim` (default, fully compatible) and two new experimental modes:
  `Lax` and `Gnu` for different option parsing behaviors.

- `std/nre2` is added to replace deprecated NRE.
-
 [//]: # "Changes:"

 - `std/math` The `^` symbol now supports floating-point as exponent in addition to the Natural type.
 - `min`, `max`, and `sequtils`' `minIndex`, `maxIndex` and `minmax` for `openArray`s now accept a comparison function.
 - `system.substr` implementation now uses `copymem` (wrapped C `memcpy`) for copying data, if available at compilation.
 - `system.newStringUninit` is now considered free of side-effects allowing it to be used with `--experimental:strictFuncs`.
- `std/re` and `std/nre` are deprecated as PCRE library is obsolete.
-  Use https://github.com/nitely/nim-regex or `std/nre2`.
-  See: https://github.com/nim-lang/Nim/issues/23668.
- `std/pegs` now correctly lexes UTF-8 bytes inside bare identifier-style
-  terminals, so case-insensitive matching of non-ASCII terms (e.g. ``\i café``)
-  works without single-quoting.

 ## Language changes

--- a/compiler/ccgcalls.nim
+++ b/compiler/ccgcalls.nim
@@ -230,11 +230,11 @@ proc genOpenArraySlice(p: BProc; q: PNode; formalType, destType: PType; prepareF
  of tyString, tySequence:
    let atyp = skipTypes(a.t, abstractInst)
    if formalType.skipTypes(abstractInst).kind in {tyVar} and atyp.kind == tyString and
-        optSeqDestructors in p.config.globalOptions and not p.config.usesSso():
+        optSeqDestructors in p.config.globalOptions and not p.config.isDefined("nimsso"):
      let bra = byRefLoc(p, a)
      p.s(cpsStmts).addCallStmt(cgsymValue(p.module, "nimPrepareStrMutationV2"),
        bra)
-    if p.config.usesSso() and
+    if p.config.isDefined("nimsso") and
        skipTypes(a.t, abstractVar + abstractInst).kind == tyString:
      let strPtr = if atyp.kind in {tyVar} and not compileToCpp(p.module): ra
                   else: addrLoc(p.config, a)
@@ -296,11 +296,11 @@ proc openArrayLoc(p: BProc, formalType: PType, n: PNode; result: var Builder) =
    of tyString, tySequence:
      let ntyp = skipTypes(n.typ, abstractInst)
      if formalType.skipTypes(abstractInst).kind in {tyVar} and ntyp.kind == tyString and
-          optSeqDestructors in p.config.globalOptions and not p.config.usesSso():
+          optSeqDestructors in p.config.globalOptions and not p.config.isDefined("nimsso"):
        let bra = byRefLoc(p, a)
        p.s(cpsStmts).addCallStmt(cgsymValue(p.module, "nimPrepareStrMutationV2"),
          bra)
-      if p.config.usesSso() and
+      if p.config.isDefined("nimsso") and
          skipTypes(n.typ, abstractVar + abstractInst).kind == tyString:
        if ntyp.kind in {tyVar} and not compileToCpp(p.module):
          let ra = a.rdLoc
@@ -335,7 +335,7 @@ proc openArrayLoc(p: BProc, formalType: PType, n: PNode; result: var Builder) =
        let ra = a.rdLoc
        var t = TLoc(snippet: cDeref(ra))
        let lt = lenExpr(p, t)
-        if p.config.usesSso():
+        if p.config.isDefined("nimsso"):
          result.add(cCall(cgsymValue(p.module, "nimStrData"), ra))
          result.addArgumentSeparator()
          result.add(cCall(cgsymValue(p.module, "nimStrLen"), t.snippet))
@@ -370,7 +370,7 @@ proc expressionsNeedsTmp(p: BProc, a: TLoc): TLoc =
 proc genArgStringToCString(p: BProc, n: PNode; result: var Builder; needsTmp: bool) {.inline.} =
  var a = initLocExpr(p, n[0])
  let tmp = withTmpIfNeeded(p, a, needsTmp)
-  let ra = if p.config.usesSso(): byRefLoc(p, tmp) else: tmp.rdLoc
+  let ra = if p.config.isDefined("nimsso"): addrLoc(p.config, tmp) else: tmp.rdLoc
  result.addCall(cgsymValue(p.module, "nimToCStringConv"), ra)

 proc genArg(p: BProc, n: PNode, param: PSym; call: PNode; result: var Builder; needsTmp = false) =
--- a/compiler/ccgexprs.nim
+++ b/compiler/ccgexprs.nim
@@ -322,7 +322,7 @@ proc genOpenArrayConv(p: BProc; d: TLoc; a: TLoc; flags: TAssignmentFlags) =
        bra)
    let rd = d.rdLoc
    let la = lenExpr(p, a)
-    if p.config.usesSso():
+    if p.config.isDefined("nimsso"):
      let bra = byRefLoc(p, a)
      p.s(cpsStmts).addFieldAssignment(rd, "Field0",
        cCall(cgsymValue(p.module, "nimStrData"), bra))
@@ -963,7 +963,7 @@ proc genDeref(p: BProc, e: PNode, d: var TLoc) =

 proc cowBracket(p: BProc; n: PNode) =
  if n.kind == nkBracketExpr and optSeqDestructors in p.config.globalOptions and
-      not p.config.usesSso():
+      not p.config.isDefined("nimsso"):
    let strCandidate = n[0]
    if strCandidate.typ.skipTypes(abstractInst).kind == tyString:
      var a: TLoc = initLocExpr(p, strCandidate)
@@ -989,7 +989,7 @@ proc genAddr(p: BProc, e: PNode, d: var TLoc) =
    # bug #19497
    d.lode = e
  else:
-    let ssoStrSub = p.config.usesSso() and e[0].kind == nkBracketExpr and
+    let ssoStrSub = p.config.isDefined("nimsso") and e[0].kind == nkBracketExpr and
        e[0][0].typ.skipTypes(abstractVar).kind == tyString
    var a: TLoc = initLocExpr(p, e[0], if ssoStrSub: {lfEnforceDeref, lfPrepareForMutation} else: {})
    if e[0].kind in {nkHiddenStdConv, nkHiddenSubConv, nkConv} and not ignoreConv(e[0]):
@@ -1318,7 +1318,7 @@ proc genSeqElem(p: BProc, n, x, y: PNode, d: var TLoc) =
  if skipTypes(a.t, abstractVar).kind in {tyRef, tyPtr}:
    a.snippet = cDeref(a.snippet)

-  if p.config.usesSso() and ty.kind == tyString:
+  if p.config.isDefined("nimsso") and ty.kind == tyString:
    let bra = byRefLoc(p, a)
    if lfPrepareForMutation in d.flags:
      # Use nimStrAtMutV3 to get a mutable reference (char*) to the element.
@@ -1889,17 +1889,10 @@ proc genObjConstr(p: BProc, e: PNode, d: var TLoc) =
  var t = e.typ.skipTypes(abstractInstOwned)
  let isRef = t.kind == tyRef

-  # check if we need to construct the object in a temporary.
-  # A temp is needed when:
-  # - the constructor produces a ref (isRef)
-  # - the destination is not a writable location (d.k == locNone)
-  # - the constructed type differs from the destination type (subtype
-  #   assignments need the genAssignment path for ObjectAssignmentDefect)
-  # - the constructor's field values may alias the destination (isPartOf)
+  # check if we need to construct the object in a temporary
  var useTemp =
        isRef or
-        d.k == locNone or
-        (d.t != nil and not sameBackendType(t, d.t.skipTypes(abstractInstOwned))) or
+        (d.k notin {locTemp,locLocalVar,locGlobalVar,locParam,locField}) or
        (isPartOf(d.lode, e) != arNo)

  var tmp: TLoc = default(TLoc)
@@ -2150,7 +2143,7 @@ proc genRepr(p: BProc, e: PNode, d: var TLoc) =
      putIntoDest(p, b, e, ra & cArgumentSeparator & ra & "Len_0", a.storage)
    of tyString, tySequence:
      let la = lenExpr(p, a)
-      if p.config.usesSso() and
+      if p.config.isDefined("nimsso") and
          skipTypes(a.t, abstractVarRange).kind == tyString:
        let bra = byRefLoc(p, a)
        putIntoDest(p, b, e,
@@ -2743,7 +2736,7 @@ proc genConv(p: BProc, e: PNode, d: var TLoc) =

 proc convStrToCStr(p: BProc, n: PNode, d: var TLoc) =
  var a: TLoc = initLocExpr(p, n[0])
-  let arg = if p.config.usesSso(): byRefLoc(p, a) else: rdLoc(a)
+  let arg = if p.config.isDefined("nimsso"): addrLoc(p.config, a) else: rdLoc(a)
  putIntoDest(p, d, n,
    cgCall(p, "nimToCStringConv", arg),
    a.storage)
@@ -2816,13 +2809,13 @@ proc genWasMoved(p: BProc; n: PNode) =
    #  [addrLoc(p.config, a), getTypeDesc(p.module, a.t)])

 proc genMove(p: BProc; n: PNode; d: var TLoc) =
+  var a: TLoc = initLocExpr(p, n[1].skipAddr, {lfEnforceDeref, lfPrepareForMutation})
  if n.len == 4:
    # generated by liftdestructors:
-    var a: TLoc = initLocExpr(p, n[1].skipAddr, {lfEnforceDeref, lfPrepareForMutation})
    var src: TLoc = initLocExpr(p, n[2])
    let destVal = rdLoc(a)
    let srcVal = rdLoc(src)
-    if p.config.usesSso() and
+    if p.config.isDefined("nimsso") and
        n[1].typ.skipTypes(abstractVar).kind == tyString:
      # SmallString: destroy dst then struct-copy src; no .p field aliasing needed
      genStmts(p, n[3])
@@ -2838,16 +2831,29 @@ proc genMove(p: BProc; n: PNode; d: var TLoc) =
  else:
    if d.k == locNone: d = getTemp(p, n.typ)
    if p.config.selectedGC in {gcArc, gcAtomicArc, gcOrc, gcYrc}:
+      genAssignment(p, d, a, {})
      var op = getAttachedOp(p.module.g.graph, n.typ, attachedWasMoved)
-      if op == nil or sfOverridden notin op.flags:
-        var a: TLoc = initLocExpr(p, n[1].skipAddr, {lfEnforceDeref, lfPrepareForMutation})
-        genAssignment(p, d, a, {})
+      if op == nil:
        resetLoc(p, a)
      else:
-        n[1] = makeAddr(n[1], p.module.idgen)
-        genCall(p, n, d)
+        var b = initLocExpr(p, newSymNode(op))
+        case skipTypes(a.t, abstractVar+{tyStatic}).kind
+        of tyOpenArray, tyVarargs: # todo fixme generated `wasMoved` hooks for
+                                   # openarrays, but it probably shouldn't?
+          let ra = rdLoc(a)
+          var s: string
+          if reifiedOpenArray(a.lode):
+            if a.t.kind in {tyVar, tyLent}:
+              s = derefField(ra, "Field0") & cArgumentSeparator & derefField(ra, "Field1")
+            else:
+              s = dotField(ra, "Field0") & cArgumentSeparator & dotField(ra, "Field1")
+          else:
+            s = ra & cArgumentSeparator & ra & "Len_0"
+          p.s(cpsStmts).addCallStmt(rdLoc(b), s)
+        else:
+          let val = if p.module.compileToCpp: rdLoc(a) else: byRefLoc(p, a)
+          p.s(cpsStmts).addCallStmt(rdLoc(b), val)
    else:
-      var a: TLoc = initLocExpr(p, n[1].skipAddr, {lfEnforceDeref, lfPrepareForMutation})
      genAssignment(p, d, a, {})
      resetLoc(p, a)

@@ -2858,7 +2864,7 @@ proc genDestroy(p: BProc; n: PNode) =
    case t.kind
    of tyString:
      var a: TLoc = initLocExpr(p, arg)
-      if p.config.usesSso():
+      if p.config.isDefined("nimsso"):
        # SmallString: delegate to nimDestroyStrV1 (rc-based, handles static strings)
        p.s(cpsStmts).addCallStmt(cgsymValue(p.module, "nimDestroyStrV1"), rdLoc(a))
      else:
@@ -4230,7 +4236,7 @@ proc genBracedInit(p: BProc, n: PNode; isConst: bool; optionalType: PType; resul
      genConstObjConstr(p, n, isConst, result)
    of tyString, tyCstring:
      if optSeqDestructors in p.config.globalOptions and n.kind != nkNilLit and ty == tyString:
-        if p.config.usesSso():
+        if p.config.isDefined("nimsso"):
          genStringLiteralV3Const(p.module, n, isConst, result)
        else:
          genStringLiteralV2Const(p.module, n, isConst, result)
--- a/compiler/ccgliterals.nim
+++ b/compiler/ccgliterals.nim
@@ -22,7 +22,7 @@ template detectVersion(field, corename) =
    result = 1

 proc detectStrVersion(m: BModule): int =
-  if m.g.config.usesSso() and
+  if m.g.config.isDefined("nimsso") and
      m.g.config.selectedGC in {gcArc, gcOrc, gcYrc, gcAtomicArc, gcHooks}:
    result = 3
  else:
--- a/compiler/ccgstmts.nim
+++ b/compiler/ccgstmts.nim
@@ -230,7 +230,7 @@ proc blockLeaveActions(p: BProc, howManyTrys, howManyExcepts: int, isReturnStmt
  # Called by return and break stmts.
  # Deals with issues faced when jumping out of try/except/finally stmts.

-  var stack = newSeq[tuple[fin: PNode, inExcept: bool, isHidden: bool, label: Natural]](0)
+  var stack = newSeq[tuple[fin: PNode, inExcept: bool, label: Natural]](0)

  inc p.withinBlockLeaveActions
  for i in 1..howManyTrys:
@@ -341,9 +341,9 @@ proc genCppParamsForCtor(p: BProc; call: PNode; didGenTemp: var bool): Snippet =
          call[i][0]
        else:
          call[i]
-      if not param.typ.isCompileTimeOnly and (param.kind != nkBracketExpr or param.typ.kind in
+      if param.kind != nkBracketExpr or param.typ.kind in
        {tyRef, tyPtr, tyUncheckedArray, tyArray, tyOpenArray,
-          tyVarargs, tySequence, tyString, tyCstring, tyTuple}):
+          tyVarargs, tySequence, tyString, tyCstring, tyTuple}:
        let tempLoc = initLocExprSingleUse(p, param)
        didGenTemp = didGenTemp or tempLoc.k == locTemp
      genOtherArg(p, call, i, typ, res, argBuilder)
@@ -836,26 +836,12 @@ proc raiseExitCleanup(p: BProc, destroy: string) =
        p.s(cpsStmts).addGoto("LA" & $p.nestedTryStmts[^1].label & "_")

 proc finallyActions(p: BProc) =
-  if p.config.exc != excGoto:
-    # Walk past compiler-injected `nkHiddenTryStmt` wrappers (e.g. ARC's
-    # destructor try/finally that wraps `except T as e:` bodies) to reach
-    # the user's actual try.  We must NOT walk past a real user try whose
-    # body we are currently in, because a raise from there will be caught
-    # by that try's own except branches rather than escaping outward.
-    #
-    # If after skipping wrappers the next entry is a user try in its
-    # except branch (inExcept=true), inline its finally body before the
-    # raise propagates — without this, the C++ sibling-catch rule would
-    # cause the user's catch(...)/finally pair to be bypassed and the
-    # finally would be silently dropped.
-    for i in countdown(p.nestedTryStmts.high, 0):
-      if p.nestedTryStmts[i].isHidden:
-        continue
-      if p.nestedTryStmts[i].inExcept:
-        let finallyBlock = p.nestedTryStmts[i].fin
-        if finallyBlock != nil:
-          genSimpleBlock(p, finallyBlock[0])
-      return
+  if p.config.exc != excGoto and p.nestedTryStmts.len > 0 and p.nestedTryStmts[^1].inExcept:
+    # if the current try stmt have a finally block,
+    # we must execute it before reraising
+    let finallyBlock = p.nestedTryStmts[^1].fin
+    if finallyBlock != nil:
+      genSimpleBlock(p, finallyBlock[0])

 proc raiseInstr(p: BProc; result: var Builder) =
  if p.config.exc == excGoto:
@@ -1179,7 +1165,7 @@ proc genTryCpp(p: BProc, t: PNode, d: var TLoc) =
        throw;
      }
    } catch(...) {
-      // C++ exception occurred, not under Nim's control.
+      // C++ exception occured, not under Nim's control.
    }
    {
      /* finally: */
@@ -1199,7 +1185,7 @@ proc genTryCpp(p: BProc, t: PNode, d: var TLoc) =
  lineCg(p, cpsLocals, "std::exception_ptr T$1_;$n", [etmp])

  let fin = if t[^1].kind == nkFinally: t[^1] else: nil
-  p.nestedTryStmts.add((fin, false, t.kind == nkHiddenTryStmt, 0.Natural))
+  p.nestedTryStmts.add((fin, false, 0.Natural))

  if t.kind == nkHiddenTryStmt:
    lineCg(p, cpsStmts, "try {$n", [])
@@ -1385,7 +1371,7 @@ proc genTryCppOld(p: BProc, t: PNode, d: var TLoc) =
  genLineDir(p, t)
  cgsym(p.module, "popCurrentExceptionEx")
  let fin = if t[^1].kind == nkFinally: t[^1] else: nil
-  p.nestedTryStmts.add((fin, false, t.kind == nkHiddenTryStmt, 0.Natural))
+  p.nestedTryStmts.add((fin, false, 0.Natural))
  startBlockWith(p):
    p.s(cpsStmts).add("try {\n")
  expr(p, t[0], d)
@@ -1464,7 +1450,7 @@ proc genTryGoto(p: BProc; t: PNode; d: var TLoc) =
  let lab = p.labels
  let hasExcept = t[1].kind == nkExceptBranch
  if hasExcept: inc p.withinTryWithExcept
-  p.nestedTryStmts.add((fin, false, t.kind == nkHiddenTryStmt, Natural lab))
+  p.nestedTryStmts.add((fin, false, Natural lab))

  p.flags.incl nimErrorFlagAccessed

@@ -1670,7 +1656,7 @@ proc genTrySetjmp(p: BProc, t: PNode, d: var TLoc) =
    initElifBranch(p.s(cpsStmts), nonQuirkyIf, removeSinglePar(
      cOp(Equal, dotField(safePoint, "status"), cIntValue(0))))
  let fin = if t[^1].kind == nkFinally: t[^1] else: nil
-  p.nestedTryStmts.add((fin, quirkyExceptions, t.kind == nkHiddenTryStmt, 0.Natural))
+  p.nestedTryStmts.add((fin, quirkyExceptions, 0.Natural))
  expr(p, t[0], d)
  var quirkyIf = default(IfBuilder)
  var quirkyScope = default(ScopeBuilder)
@@ -1954,7 +1940,7 @@ proc genAsgn(p: BProc, e: PNode, fastAsgn: bool) =
  elif optFieldCheck in p.options and isDiscriminantField(e[0]):
    genLineDir(p, e)
    asgnFieldDiscriminant(p, e)
-  elif p.config.usesSso() and e[0].kind == nkBracketExpr and
+  elif p.config.isDefined("nimsso") and e[0].kind == nkBracketExpr and
      e[0][0].typ.skipTypes(abstractVar).kind == tyString:
    # nimsso: s[i] = c  →  nimStrPutV3(&s, i, c)  (handles COW internally)
    genLineDir(p, e)
--- a/compiler/cgen.nim
+++ b/compiler/cgen.nim
@@ -389,7 +389,7 @@ proc lenField(p: BProc, val: Rope): Rope {.inline.} =

 proc lenExpr(p: BProc; a: TLoc): Rope =
  if optSeqDestructors in p.config.globalOptions:
-    if p.config.usesSso() and a.lode != nil and a.t != nil and
+    if p.config.isDefined("nimsso") and a.lode != nil and a.t != nil and
        a.t.skipTypes(abstractInst).kind == tyString:
      result = cCall(cgsymValue(p.module, "nimStrLen"), rdLoc(a))
    else:
@@ -534,7 +534,7 @@ proc resetLoc(p: BProc, loc: var TLoc) =

    let atyp = skipTypes(loc.t, abstractInst)
    let rl = rdLoc(loc)
-    if typ.kind == tyString and p.config.usesSso():
+    if typ.kind == tyString and p.config.isDefined("nimsso"):
      # SmallString zero state: bytes=0 (slen=0 in low byte, all inline chars zeroed)
      if atyp.kind in {tyVar, tyLent}:
        p.s(cpsStmts).addAssignment(derefField(rl, "bytes"), cIntValue(0))
@@ -592,7 +592,7 @@ proc constructLoc(p: BProc, loc: var TLoc, isTemp = false) =
  let typ = loc.t
  if optSeqDestructors in p.config.globalOptions and skipTypes(typ, abstractInst + {tyStatic}).kind in {tyString, tySequence}:
    let rl = rdLoc(loc)
-    if skipTypes(typ, abstractInst + {tyStatic}).kind == tyString and p.config.usesSso():
+    if skipTypes(typ, abstractInst + {tyStatic}).kind == tyString and p.config.isDefined("nimsso"):
      # SmallString zero state: bytes=0 (slen=0 in low byte, all inline chars zeroed)
      p.s(cpsStmts).addFieldAssignment(rl, "bytes", cIntValue(0))
      p.s(cpsStmts).addFieldAssignment(rl, "more", NimNil)
--- a/compiler/cgendata.nim
+++ b/compiler/cgendata.nim
@@ -75,13 +75,10 @@ type
    flags*: set[TCProcFlag]
    lastLineInfo*: TLineInfo  # to avoid generating excessive 'nimln' statements
    currLineInfo*: TLineInfo  # AST codegen will make this superfluous
-    nestedTryStmts*: seq[tuple[fin: PNode, inExcept: bool, isHidden: bool, label: Natural]]
+    nestedTryStmts*: seq[tuple[fin: PNode, inExcept: bool, label: Natural]]
                              # in how many nested try statements we are
                              # (the vars must be volatile then)
-                              # `inExcept` is true when we are in the except part of a try block.
-                              # `isHidden` is true for compiler-injected `nkHiddenTryStmt` wrappers
-                              # (e.g. ARC's destructor try/finally around `except T as e:` bodies);
-                              # finallyActions walks past such wrappers to reach the user's try.
+                              # bool is true when are in the except part of a try block
    finallySafePoints*: seq[Rope]  # For correctly cleaning up exceptions when
                                   # using return in finally statements
    labels*: Natural          # for generating unique labels in the C proc
--- a/compiler/commands.nim
+++ b/compiler/commands.nim
@@ -250,7 +250,6 @@ const
  errGuiConsoleOrLibExpectedButXFound = "'gui', 'console', 'lib' or 'staticlib' expected, but '$1' found"
  errInvalidExceptionSystem = "'goto', 'setjmp', 'cpp' or 'quirky' expected, but '$1' found"
  errInvalidFeatureButXFound = Feature.toSeq.map(proc(val:Feature): string = "'$1'" % $val).join(", ") & " expected, but '$1' found"
-  errDefaultOrSsoExpectedButXFound = "'default' or 'sso' expected, but '$1' found"

 template warningOptionNoop(switch: string) =
  warningDeprecated(conf, info, "'$#' is deprecated, now a noop" % switch)
@@ -307,13 +306,6 @@ proc testCompileOptionArg*(conf: ConfigRef; switch, arg: string, info: TLineInfo
    else:
      result = false
      localError(conf, info, errInvalidExceptionSystem % arg)
-  of "strings":
-    case arg.normalize
-    of "default": result = conf.selectedStrings == stringDefault
-    of "sso": result = conf.selectedStrings == stringSso
-    else:
-      result = false
-      localError(conf, info, errDefaultOrSsoExpectedButXFound % arg)
  of "experimental":
    try:
      result = conf.features.contains parseEnum[Feature](arg)
@@ -758,17 +750,6 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
    processMemoryManagementOption(switch, arg, pass, info, conf)
  of "mm":
    processMemoryManagementOption(switch, arg, pass, info, conf)
-  of "strings":
-    expectArg(conf, switch, arg, pass, info)
-    if pass in {passCmd2, passPP}:
-      case arg.normalize
-      of "default":
-        conf.selectedStrings = stringDefault
-      of "sso":
-        conf.selectedStrings = stringSso
-        defineSymbol(conf.symbols, "nimsso")
-      else:
-        localError(conf, info, errDefaultOrSsoExpectedButXFound % arg)
  of "warnings", "w":
    if processOnOffSwitchOrList(conf, {optWarns}, arg, pass, info): listWarnings(conf)
  of "warning": processSpecificNote(arg, wWarning, pass, info, switch, conf)
@@ -930,7 +911,7 @@ proc processSwitch*(switch, arg: string, pass: TCmdLinePass, info: TLineInfo;
      if m.len == 0:
        localError(conf, info, "Cannot resolve filename: " & arg)
      else:
-        conf.implicitImports.add(if arg.startsWith(stdPrefix): arg else: m)
+        conf.implicitImports.add m
  of "include":
    expectArg(conf, switch, arg, pass, info)
    if pass in {passCmd2, passPP}:
--- a/compiler/deps.nim
+++ b/compiler/deps.nim
@@ -10,10 +10,10 @@
 ## Generate a .build.nif file for nifmake from a Nim project.
 ## This enables incremental and parallel compilation using the `m` switch.

-import std / [os, tables, sets, times, osproc]
+import std / [os, tables, sets, times, osproc, strutils]
 import options, msgs, lineinfos, pathutils

-import "../dist/nimony/src/lib" / [nifstreams, bitabs, nifreader, nifbuilder]
+import "../dist/nimony/src/lib" / [nifstreams, nifcursors, bitabs, nifreader, nifbuilder]
 import "../dist/nimony/src/gear2" / modnames

 type
@@ -79,19 +79,22 @@ proc runNifler(c: DepContext; nimFile: string): bool =
  let exitCode = execShellCmd(cmd)
  result = exitCode == 0

-proc resolveImport(c: DepContext; origin, toResolve: string): string =
-  ## Resolve an import path using the compiler's normal module lookup rules.
-  result = findModule(c.config, toResolve, origin).string
+proc resolveFile(c: DepContext; origin, toResolve: string): string =
+  ## Resolve an import path relative to origin file
+  # Handle std/ prefix
+  var path = toResolve
+  if path.startsWith("std/"):
+    path = path.substr(4)

-proc resolveInclude(c: DepContext; origin, toResolve: string): string =
-  ## Resolve an include path relative to the including file or the search paths.
+  # Try relative to origin first
  let originDir = parentDir(origin)
-  result = originDir / toResolve.addFileExt("nim")
+  result = originDir / path.addFileExt("nim")
  if fileExists(result):
    return result

+  # Try search paths
  for searchPath in c.config.searchPaths:
-    result = searchPath.string / toResolve.addFileExt("nim")
+    result = searchPath.string / path.addFileExt("nim")
    if fileExists(result):
      return result

@@ -100,7 +103,7 @@ proc resolveInclude(c: DepContext; origin, toResolve: string): string =
 proc traverseDeps(c: var DepContext; pair: FilePair; current: Node)

 proc processInclude(c: var DepContext; includePath: string; current: Node) =
-  let resolved = resolveInclude(c, current.files[current.files.len - 1].nimFile, includePath)
+  let resolved = resolveFile(c, current.files[current.files.len - 1].nimFile, includePath)
  if resolved.len == 0 or not fileExists(resolved):
    return

@@ -115,7 +118,7 @@ proc processInclude(c: var DepContext; includePath: string; current: Node) =
  discard c.includeStack.pop()

 proc processImport(c: var DepContext; importPath: string; current: Node) =
-  let resolved = resolveImport(c, current.files[0].nimFile, importPath)
+  let resolved = resolveFile(c, current.files[0].nimFile, importPath)
  if resolved.len == 0 or not fileExists(resolved):
    return

@@ -137,171 +140,6 @@ proc processImport(c: var DepContext; importPath: string; current: Node) =
    if existingIdx notin current.deps:
      current.deps.add existingIdx

-proc skipSubtree(s: var Stream; first: PackedToken) =
-  ## Consume tokens until the ParLe at `first` is balanced. Caller has
-  ## already obtained `first`.
-  if first.kind != ParLe: return
-  var depth = 1
-  while depth > 0:
-    let t = next(s)
-    if t.kind == ParLe: inc depth
-    elif t.kind == ParRi: dec depth
-    elif t.kind == EofToken: return
-
-proc evalCondExpr(c: DepContext; s: var Stream): bool =
-  ## Read exactly one condition expression from `s` and return its truth
-  ## value. Consumes tokens whether the expression is recognised or not so
-  ## the caller stays in sync. Recognises `defined(IDENT)`, the boolean
-  ## operators `not`/`and`/`or`, and the literals `true`/`false`. Anything
-  ## else (e.g. a call to an arbitrary proc) is treated as `true` — the
-  ## conservative direction, since a false negative here drops a real
-  ## dependency from the build graph.
-  let t = next(s)
-  case t.kind
-  of Ident:
-    case pool.strings[t.litId]
-    of "true": result = true
-    of "false": result = false
-    else: result = true
-  of ParLe:
-    let tag = pool.tags[t.tagId]
-    case tag
-    of "call", "cmd", "callstrlit", "infix", "prefix":
-      # First child is the head (function/operator name).
-      let head = next(s)
-      var name = ""
-      if head.kind == Ident: name = pool.strings[head.litId]
-      case name
-      of "defined":
-        let arg = next(s)
-        var sym = ""
-        if arg.kind == Ident: sym = pool.strings[arg.litId]
-        result = sym.len > 0 and isDefined(c.config, sym)
-      of "not":
-        result = not evalCondExpr(c, s)
-      of "and":
-        result = evalCondExpr(c, s)
-        if result: result = evalCondExpr(c, s)
-        else: skipSubtree(s, next(s))
-      of "or":
-        result = evalCondExpr(c, s)
-        if not result: result = evalCondExpr(c, s)
-        else: skipSubtree(s, next(s))
-      else:
-        result = true
-      # Drain whatever remains until the matching ParRi.
-      var depth = 1
-      while depth > 0:
-        let n = next(s)
-        if n.kind == ParLe: inc depth
-        elif n.kind == ParRi: dec depth
-        elif n.kind == EofToken: return
-    of "not":
-      result = not evalCondExpr(c, s)
-      var depth = 1
-      while depth > 0:
-        let n = next(s)
-        if n.kind == ParLe: inc depth
-        elif n.kind == ParRi: dec depth
-        elif n.kind == EofToken: return
-    of "and":
-      result = evalCondExpr(c, s)
-      if result: result = evalCondExpr(c, s)
-      else: skipSubtree(s, next(s))
-      # consume closing ParRi
-      var depth = 1
-      while depth > 0:
-        let n = next(s)
-        if n.kind == ParLe: inc depth
-        elif n.kind == ParRi: dec depth
-        elif n.kind == EofToken: return
-    of "or":
-      result = evalCondExpr(c, s)
-      if not result: result = evalCondExpr(c, s)
-      else: skipSubtree(s, next(s))
-      var depth = 1
-      while depth > 0:
-        let n = next(s)
-        if n.kind == ParLe: inc depth
-        elif n.kind == ParRi: dec depth
-        elif n.kind == EofToken: return
-    else:
-      skipSubtree(s, t)
-      result = true
-  else:
-    result = true
-
-proc whenMarkerHolds(c: DepContext; s: var Stream): bool =
-  ## Caller has just consumed the `(when` ParLe. Read children until the
-  ## matching `)`, AND-ing each evaluated condition.
-  result = true
-  while true:
-    # peek by reading; if it's ParRi, we're done
-    let t = next(s)
-    if t.kind == ParRi: return
-    if t.kind == EofToken: return
-    if t.kind == ParLe:
-      # Re-feed by manually evaluating the subtree starting at `t`.
-      # evalCondExpr expects to read its own opener, so handle it directly.
-      let tag = pool.tags[t.tagId]
-      case tag
-      of "call", "cmd", "callstrlit", "infix", "prefix":
-        let head = next(s)
-        var name = ""
-        if head.kind == Ident: name = pool.strings[head.litId]
-        var ok = true
-        case name
-        of "defined":
-          let arg = next(s)
-          var sym = ""
-          if arg.kind == Ident: sym = pool.strings[arg.litId]
-          ok = sym.len > 0 and isDefined(c.config, sym)
-        of "not":
-          ok = not evalCondExpr(c, s)
-        of "and":
-          ok = evalCondExpr(c, s)
-          if ok: ok = evalCondExpr(c, s)
-        of "or":
-          ok = evalCondExpr(c, s)
-          if not ok: ok = evalCondExpr(c, s)
-        else:
-          ok = true
-        # finish the subtree
-        var depth = 1
-        while depth > 0:
-          let n = next(s)
-          if n.kind == ParLe: inc depth
-          elif n.kind == ParRi: dec depth
-          elif n.kind == EofToken: return
-        if not ok: result = false
-      of "not", "and", "or":
-        # Re-emit a synthetic dispatch: rewrap by descending.
-        var ok = true
-        case tag
-        of "not":
-          ok = not evalCondExpr(c, s)
-        of "and":
-          ok = evalCondExpr(c, s)
-          if ok: ok = evalCondExpr(c, s)
-        of "or":
-          ok = evalCondExpr(c, s)
-          if not ok: ok = evalCondExpr(c, s)
-        else: discard
-        var depth = 1
-        while depth > 0:
-          let n = next(s)
-          if n.kind == ParLe: inc depth
-          elif n.kind == ParRi: dec depth
-          elif n.kind == EofToken: return
-        if not ok: result = false
-      else:
-        # Unknown — treat as true and skip.
-        skipSubtree(s, t)
-    elif t.kind == Ident:
-      let v = pool.strings[t.litId]
-      if v == "false": result = false
-      # else (true / unknown ident): keep result
-
 proc readDepsFile(c: var DepContext; pair: FilePair; current: Node) =
  ## Read a .deps.nif file and process imports/includes
  let depsPath = c.depsFile(pair)
@@ -323,27 +161,12 @@ proc readDepsFile(c: var DepContext; pair: FilePair; current: Node) =
    if t.kind == ParLe:
      let tag = pool.tags[t.tagId]
      case tag
-      of "import", "fromimport", "include":
-        # Read first child. May be a `(when COND...)` marker — parse and
-        # evaluate; if the condition is statically false, skip the import
-        # entirely. Otherwise advance past the marker and parse the path.
+      of "import", "fromimport":
+        # Read import path
        t = next(s)
-        var live = true
-        if t.kind == ParLe and pool.tags[t.tagId] == "when":
-          # whenMarkerHolds consumes everything up to and including the
-          # closing `)` of the `(when ...)` subtree.
-          live = whenMarkerHolds(c, s)
-          t = next(s)
-        if not live:
-          # Drain the rest of this import/include node.
-          var depth = 1
-          while depth > 0:
-            let n = next(s)
-            if n.kind == ParLe: inc depth
-            elif n.kind == ParRi: dec depth
-            elif n.kind == EofToken: break
-          t = next(s)
-          continue
+        # Check for "when" marker (conditional import)
+        if t.kind == Ident and pool.strings[t.litId] == "when":
+          t = next(s)  # skip it, still process the import
        # Handle path expression (could be ident, string, or infix like std/foo)
        var importPath = ""
        if t.kind == Ident:
@@ -361,11 +184,26 @@ proc readDepsFile(c: var DepContext; pair: FilePair; current: Node) =
          if t.kind == Ident:  # second part (foo)
            importPath = importPath & "/" & pool.strings[t.litId]
        if importPath.len > 0:
-          if tag == "include":
-            processInclude(c, importPath, current)
-          else:
-            processImport(c, importPath, current)
-        # Skip to end of node
+          processImport(c, importPath, current)
+        # Skip to end of import node
+        var depth = 1
+        while depth > 0:
+          t = next(s)
+          if t.kind == ParLe: inc depth
+          elif t.kind == ParRi: dec depth
+      of "include":
+        # Read include path
+        t = next(s)
+        if t.kind == Ident and pool.strings[t.litId] == "when":
+          t = next(s)  # skip conditional marker
+        var includePath = ""
+        if t.kind == Ident:
+          includePath = pool.strings[t.litId]
+        elif t.kind == StringLit:
+          includePath = pool.strings[t.litId]
+        if includePath.len > 0:
+          processInclude(c, includePath, current)
+        # Skip to end
        var depth = 1
        while depth > 0:
          t = next(s)
@@ -488,19 +326,10 @@ proc generateBuildFile(c: DepContext): string =
  let exeFile = changeFileExt(c.nodes[0].files[0].nimFile, ExeExt)
  b.addTree "do"
  b.addIdent "nim_nifc"
-  # Input: .nim file (expanded as argument)
+  # Input: .nim file (expanded as argument) and .nif file (dependency)
  b.addTree "input"
  b.addStrLit mainNif
  b.endTree()
-  # Also depend on the semmed .nif files of the main module and all its
-  # dependencies. nifmake's topological sort orders nodes by depth; without
-  # these inputs the nim_nifc node sits at depth 1 (no recognized inputs)
-  # alongside the nifler nodes and runs *before* the nim_m steps that
-  # produce the .nif files it needs to read.
-  for node in c.nodes:
-    b.addTree "input"
-    b.addStrLit c.semmedFile(node.files[0])
-    b.endTree()
  b.addTree "output"
  b.addStrLit exeFile
  b.endTree()
--- a/compiler/importer.nim
+++ b/compiler/importer.nim
@@ -13,7 +13,7 @@ import
  ast, msgs, options, idents, lookups,
  semdata, modulepaths, sigmatch, lineinfos,
  modulegraphs, wordrecg
-from std/strutils import `%`, startsWith, replace
+from std/strutils import `%`, startsWith
 from std/sequtils import addUnique
 import std/[sets, tables, intsets]

@@ -304,9 +304,9 @@ proc myImportModule(c: PContext, n: var PNode, importStmtResult: PNode): PSym =
      var prefix = ""
      if realModule.constraint != nil: prefix = realModule.constraint.strVal & "; "
      message(c.config, n.info, warnDeprecated, prefix & realModule.name.s & " is deprecated")
-    let moduleNameNorm = getModuleName(c.config, n).replace("\\", "/")
-    if belongsToStdlib(c.graph, result) and not startsWith(moduleNameNorm, stdPrefix) and
-        not startsWith(moduleNameNorm, "system/") and not startsWith(moduleNameNorm, "packages/"):
+    let moduleName = getModuleName(c.config, n)
+    if belongsToStdlib(c.graph, result) and not startsWith(moduleName, stdPrefix) and
+        not startsWith(moduleName, "system/") and not startsWith(moduleName, "packages/"):
      message(c.config, n.info, warnStdPrefix, realModule.name.s)

    proc suggestMod(n: PNode; s: PSym) =
--- a/compiler/jsgen.nim
+++ b/compiler/jsgen.nim
@@ -1544,7 +1544,7 @@ proc genSymAddr(p: PProc, n: PNode, typ: PType, r: var TCompRes) =
    r.res = s.loc.snippet
    r.address = ""
    r.typ = etyNone
-  of skVar, skLet, skResult, skTemp, skForVar:
+  of skVar, skLet, skResult:
    r.kind = resExpr
    let jsType = mapType(p):
      if typ.isNil:
--- a/compiler/lambdalifting.nim
+++ b/compiler/lambdalifting.nim
@@ -216,10 +216,6 @@ proc newAsgnStmt(le, ri: PNode, info: TLineInfo): PNode =
  result[0] = le
  result[1] = ri

-proc markInjectDestructors(s: PSym) {.inline.} =
-  backendEnsureMutable s
-  s.flagsImpl.incl sfInjectDestructors
-
 proc makeClosure*(g: ModuleGraph; idgen: IdGenerator; prc: PSym; env: PNode; info: TLineInfo): PNode =
  result = newNodeIT(nkClosure, info, prc.typ)
  result.add(newSymNode(prc))
@@ -232,7 +228,7 @@ proc makeClosure*(g: ModuleGraph; idgen: IdGenerator; prc: PSym; env: PNode; inf
  #if isClosureIterator(result.typ):
  createTypeBoundOps(g, nil, result.typ, info, idgen)
  if tfHasAsgn in result.typ.flags or optSeqDestructors in g.config.globalOptions:
-    markInjectDestructors(prc)
+    prc.incl sfInjectDestructors

 template liftingHarmful(conf: ConfigRef; owner: PSym): bool =
  ## lambda lifting can be harmful for JS-like code generators.
@@ -244,7 +240,7 @@ proc createTypeBoundOpsLL(g: ModuleGraph; refType: PType; info: TLineInfo; idgen
    createTypeBoundOps(g, nil, refType.elementType, info, idgen)
    createTypeBoundOps(g, nil, refType, info, idgen)
    if tfHasAsgn in refType.flags or optSeqDestructors in g.config.globalOptions:
-      markInjectDestructors(owner)
+      owner.incl sfInjectDestructors

 proc genCreateEnv(env: PNode): PNode =
  var c = newNodeIT(nkObjConstr, env.info, env.typ)
@@ -520,8 +516,6 @@ proc detectCapturedVars(n: PNode; owner: PSym; c: var DetectionPass) =
  of nkLambdaKinds, nkIteratorDef:
    if n.typ != nil:
      detectCapturedVars(n[namePos], owner, c)
-  of nkClosure:
-    detectCapturedVars(n[1], owner, c)
  of nkReturnStmt:
    detectCapturedVars(n[0], owner, c)
  of nkIdentDefs:
@@ -642,7 +636,7 @@ proc rawClosureCreation(owner: PSym;
        if owner.kind != skMacro:
          createTypeBoundOps(d.graph, nil, fieldAccess.typ, env.info, d.idgen)
        if tfHasAsgn in fieldAccess.typ.flags or optSeqDestructors in d.graph.config.globalOptions:
-          markInjectDestructors(owner)
+          owner.incl sfInjectDestructors

  let upField = lookupInRecord(env.typ.skipTypes({tyOwned, tyRef, tyPtr}).n, getIdent(d.graph.cache, upName))
  if upField != nil:
@@ -771,8 +765,6 @@ proc liftCapturedVars(n: PNode; owner: PSym; d: var DetectionPass;
        let oldInContainer = c.inContainer
        c.inContainer = 0
        var body = transformBody(d.graph, d.idgen, s, {})
-        if not d.processed.containsOrIncl(s.id):
-          detectCapturedVars(body, s, d)
        body = liftCapturedVars(body, s, d, c)
        if c.envVars.getOrDefault(s.id).isNil:
          s.transformedBody = body
--- a/compiler/lexer.nim
+++ b/compiler/lexer.nim
@@ -1349,7 +1349,7 @@ proc rawGetTok*(L: var Lexer, tok: var Token) =
          lexMessage(L, errGenerated, "invalid token: no whitespace between number and identifier")
    of '-':
      if L.buf[L.bufpos+1] in {'0'..'9'} and
-          (L.bufpos == 0 or L.buf[L.bufpos-1] in UnaryMinusWhitelist):
+          (L.bufpos-1 == 0 or L.buf[L.bufpos-1] in UnaryMinusWhitelist):
        # x)-23 # binary minus
        # ,-23  # unary minus
        # \n-78 # unary minus? Yes.
--- a/compiler/liftdestructors.nim
+++ b/compiler/liftdestructors.nim
@@ -592,12 +592,10 @@ proc setLenStrCall(c: var TLiftCtx; x, y: PNode): PNode =
  result = genBuiltin(c, mSetLengthStr, "setLen", x) # genAddr(g, x))
  result.add lenCall

-proc setLenSeqCall(c: var TLiftCtx; t: PType; x, y: PNode; noinit = false): PNode =
+proc setLenSeqCall(c: var TLiftCtx; t: PType; x, y: PNode): PNode =
  let lenCall = genBuiltin(c, mLengthSeq, "len", y)
  lenCall.typ = getSysType(c.g, x.info, tyInt)
-  let name = if noinit: "setLenUninit" else: "setLen"
-  let magic = if noinit: mSetLengthSeqUninit else: mSetLengthSeq
-  var op = getSysMagic(c.g, x.info, name, magic)
+  var op = getSysMagic(c.g, x.info, "setLen", mSetLengthSeq)
  op = instantiateGeneric(c, op, t, t)
  result = newTree(nkCall, newSymNode(op, x.info), x, lenCall)

@@ -645,9 +643,8 @@ proc genBulkCopySeq(c: var TLiftCtx; t: PType; body, x, y: PNode) =
 proc fillSeqOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
  case c.kind
  of attachedDup:
-    let bulkCopy = supportsCopyMem(t.elementType)
-    body.add setLenSeqCall(c, t, x, y, noinit = bulkCopy)
-    if bulkCopy:
+    body.add setLenSeqCall(c, t, x, y)
+    if supportsCopyMem(t.elementType):
      genBulkCopySeq(c, t, body, x, y)
    else:
      forallElements(c, t, body, x, y)
@@ -661,9 +658,8 @@ proc fillSeqOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
    # This is usually more efficient than a destroy/create pair.
    # For trivially copyable types, use bulk copyMem instead of element loop.
    checkSelfAssignment(c, t, body, x, y)
-    let bulkCopy = supportsCopyMem(t.elementType)
-    body.add setLenSeqCall(c, t, x, y, noinit = bulkCopy)
-    if bulkCopy:
+    body.add setLenSeqCall(c, t, x, y)
+    if supportsCopyMem(t.elementType):
      genBulkCopySeq(c, t, body, x, y)
    else:
      forallElements(c, t, body, x, y)
@@ -732,7 +728,7 @@ proc fillStrOp(c: var TLiftCtx; t: PType; body, x, y: PNode) =
  of attachedAsgn, attachedDeepCopy, attachedDup:
    body.add callCodegenProc(c.g, "nimAsgnStrV2", c.info, genAddr(c, x), y)
  of attachedSink:
-    if c.g.config.usesSso():
+    if c.g.config.isDefined("nimsso"):
      # SmallString: destroy old dst, then bit-copy src (no rc increment — this is a move).
      # No .p aliasing check needed; rc-based destroy handles COW sharing correctly.
      doAssert t.destructor != nil
--- a/compiler/nim.cfg
+++ b/compiler/nim.cfg
@@ -12,8 +12,7 @@ define:nimPreviewNonVarDestructor
 define:nimPreviewCheckedClose
 define:nimPreviewAsmSemSymbol
 define:nimPreviewCStringComparisons
-#define:nimPreviewDuplicateModuleError
-# Incompatible with Nimony's compat2.nim for now
+define:nimPreviewDuplicateModuleError

 threads:off

--- a/compiler/nim.nim
+++ b/compiler/nim.nim
@@ -121,11 +121,6 @@ proc handleCmdLine(cache: IdentCache; conf: ConfigRef) =
        conf.cmd in {cmdGendepend, cmdNifC, cmdIc, cmdM}:
      initOrcDefines(conf)

-  if conf.selectedStrings == stringSso and
-      conf.selectedGC notin {gcArc, gcOrc, gcYrc, gcAtomicArc}:
-    rawMessage(conf, errGenerated,
-      "--strings:sso requires --mm:arc, --mm:orc, --mm:yrc, or --mm:atomicArc")
-
  mainCommand(graph)
  if conf.hasHint(hintGCStats): echo(GC_getStatistics())
  #echo(GC_getStatistics())
--- a/compiler/options.nim
+++ b/compiler/options.nim
@@ -259,9 +259,6 @@ type
      ## Old transformation for closures in JS backend
    noPanicOnExcept
      ## don't panic on bare except
-    procParamTypeBackendAliases
-      ## Keep the old proc type compatibility rules that ignore backend
-      ## c type aliases.

  SymbolFilesOption* = enum
    disabledSf, writeOnlySf, readOnlySf, v2Sf, stressTest
@@ -270,10 +267,6 @@ type
    ccNone, ccGcc, ccNintendoSwitch, ccLLVM_Gcc, ccCLang, ccBcc, ccVcc,
    ccTcc, ccEnv, ccIcl, ccIcc, ccClangCl, ccHipcc, ccNvcc

-  StringsMode* = enum
-    stringDefault = "default"
-    stringSso = "sso"
-
  ExceptionSystem* = enum
    excNone,   # no exception system selected yet
    excSetjmp, # setjmp based exception handling
@@ -373,7 +366,6 @@ type
    implicitCmd*: bool # whether some flag triggered an implicit `command`
    selectedGC*: TGCMode       # the selected GC (+)
    exc*: ExceptionSystem
-    selectedStrings*: StringsMode
    hintProcessingDots*: bool # true for dots, false for filenames
    verbosity*: int            # how verbose the compiler is
    numberOfProcessors*: int   # number of processors
@@ -706,7 +698,6 @@ template quitOrRaise*(conf: ConfigRef, msg = "") =

 proc importantComments*(conf: ConfigRef): bool {.inline.} = conf.cmd in cmdDocLike + {cmdIdeTools}
 proc usesWriteBarrier*(conf: ConfigRef): bool {.inline.} = conf.selectedGC >= gcRefc
-proc usesSso*(conf: ConfigRef): bool {.inline.} = conf.selectedStrings == stringSso

 template compilationCachePresent*(conf: ConfigRef): untyped =
  false
--- a/compiler/renderer.nim
+++ b/compiler/renderer.nim
@@ -582,7 +582,6 @@ proc put(g: var TSrcGen, kind: TokType, s: string; sym: PSym = nil) =
  inc(g.lineLen, s.len)

 proc putComment(g: var TSrcGen, s: string) =
-  const SpecialWhitespace = {' ', '\t', '\r', '\n', '\0'}
  if s.len == 0: return
  var i = 0
  let hi = s.len - 1
@@ -612,12 +611,12 @@ proc putComment(g: var TSrcGen, s: string) =
      # gets too long:
      # compute length of the following word:
      var j = i
-      while j <= hi and s[j] notin SpecialWhitespace: inc(j)
+      while j <= hi and s[j] > ' ': inc(j)
      if not isCode and (g.col + (j - i) > MaxLineLen):
        put(g, tkComment, com)
        optNL(g, ind)
        com = "## "
-      while i <= hi and s[i] notin SpecialWhitespace:
+      while i <= hi and s[i] > ' ':
        com.add(s[i])
        inc(i)
  put(g, tkComment, com)
--- a/compiler/semcall.nim
+++ b/compiler/semcall.nim
@@ -131,7 +131,7 @@ proc pickBestCandidate(c: PContext, headSymbol: PNode,
  var sym = syms[0].s
  let name = sym.name
  var scope = syms[0].scope
-  c.openShadowScope
+
  if allowTypeBoundOps:
    for a in 1 ..< n.len:
      # for every already typed argument, add type bound ops
@@ -218,10 +218,6 @@ proc pickBestCandidate(c: PContext, headSymbol: PNode,
    scope = syms[nextSymIndex].scope
    inc(nextSymIndex)

-  if best.state == csMatch and best.calleeSym != nil and best.calleeSym.kind in {skTemplate, skMacro}:
-    c.closeShadowScope
-  else:
-    c.mergeShadowScope

 proc effectProblem(f, a: PType; result: var string; c: PContext) =
  if f.kind == tyProc and a.kind == tyProc:
--- a/compiler/semdata.nim
+++ b/compiler/semdata.nim
@@ -180,12 +180,9 @@ type
    sideEffects*: Table[int, seq[(TLineInfo, PSym)]] # symbol.id index
    inUncheckedAssignSection*: int
    importModuleLookup*: Table[int, seq[int]] # (module.ident.id, [module.id])
-    forwardTypeUpdates*: seq[(PSym, PType, PNode)]
-      # top-level owner, type, and type node for delayed retries inside a
-      # type section due to containing forward types
-    forwardFieldUpdates*: seq[(PType, PNode, PType)]
-      # object/tuple field definitions whose default values mention forward
-      # types and need delayed const checking
+    forwardTypeUpdates*: seq[(PType, PNode)]
+      # types that need to be updated in a type section
+      # due to containing forward types, and their corresponding nodes
    inTypeofContext*: int

    semAsgnOpr*: proc (c: PContext; n: PNode; k: TNodeKind): PNode {.nimcall.}
@@ -637,11 +634,6 @@ proc renderNotLValue*(n: PNode): string =
  elif n.kind in {nkHiddenStdConv, nkHiddenSubConv} and n.len == 2:
    result = typeToString(n.typ.skipTypes(abstractVar)) & "(" & result & ")"

-proc isSsoStringIndex*(conf: ConfigRef; n: PNode): bool =
-  result = conf.usesSso() and n.kind == nkBracketExpr and n.len >= 1 and
-      n[0].typ != nil and
-      n[0].typ.skipTypes(abstractVar + abstractInst - {tyTypeDesc}).kind == tyString
-
 proc isAssignable(c: PContext, n: PNode): TAssignableResult =
  result = parampatterns.isAssignable(c.p.owner, n)

@@ -749,7 +741,7 @@ proc replaceHookMagic*(c: PContext, n: PNode, kind: TTypeAttachedOp): PNode =
  case kind
  of attachedDestructor:
    result = n
-    let t = n[1].typ.skipTypes({tyAlias, tyVar, tySink})
+    let t = n[1].typ.skipTypes(abstractVar)
    let op = getAttachedOp(c.graph, t, attachedDestructor)
    if op != nil:
      result[0] = newSymNode(op)
@@ -761,13 +753,13 @@ proc replaceHookMagic*(c: PContext, n: PNode, kind: TTypeAttachedOp): PNode =
          result[1] = skipAddr(n[1])
  of attachedTrace:
    result = n
-    let t = n[1].typ.skipTypes({tyAlias, tyVar, tySink})
+    let t = n[1].typ.skipTypes(abstractVar)
    let op = getAttachedOp(c.graph, t, attachedTrace)
    if op != nil:
      result[0] = newSymNode(op)
  of attachedDup:
    result = n
-    let t = n[1].typ.skipTypes({tyAlias, tyVar, tySink})
+    let t = n[1].typ.skipTypes(abstractVar)
    let op = getAttachedOp(c.graph, t, attachedDup)
    if op != nil:
      result[0] = newSymNode(op)
@@ -777,26 +769,18 @@ proc replaceHookMagic*(c: PContext, n: PNode, kind: TTypeAttachedOp): PNode =
        result.add boolLit
  of attachedWasMoved:
    result = n
-    let t = n[1].typ.skipTypes({tyAlias, tyVar, tySink})
+    let t = n[1].typ.skipTypes(abstractVar)
    let op = getAttachedOp(c.graph, t, attachedWasMoved)
    if op != nil:
      result[0] = newSymNode(op)
      analyseIfAddressTakenInCall(c, result, false)
  of attachedSink:
-    result = n
-    let t = n[1].typ.skipTypes({tyAlias, tyVar, tySink})
-    let op = getAttachedOp(c.graph, t, kind)
-    if op != nil:
-      result[0] = newSymNode(op)
+    result = c.semAsgnOpr(c, n, nkSinkAsgn)
  of attachedAsgn:
-    result = n
-    let t = n[1].typ.skipTypes({tyAlias, tyVar, tySink})
-    let op = getAttachedOp(c.graph, t, kind)
-    if op != nil:
-      result[0] = newSymNode(op)
+    result = c.semAsgnOpr(c, n, nkAsgn)
  of attachedDeepCopy:
    result = n
-    let t = n[1].typ.skipTypes({tyAlias, tyVar, tySink})
+    let t = n[1].typ.skipTypes(abstractVar)
    let op = getAttachedOp(c.graph, t, kind)
    if op != nil:
      result[0] = newSymNode(op)
--- a/compiler/semexprs.nim
+++ b/compiler/semexprs.nim
@@ -652,9 +652,6 @@ proc overloadedCallOpr(c: PContext, n: PNode): PNode =
    result = semExpr(c, result, flags = {efNoUndeclared})

 proc changeType(c: PContext; n: PNode, newType: PType, check: bool) =
-  template isViewTarget(t: PType): bool =
-    t.skipTypes({tyGenericInst, tyAlias, tySink}).kind in {tyVar, tyLent}
-
  case n.kind
  of nkCurly:
    for i in 0..<n.len:
@@ -683,15 +680,12 @@ proc changeType(c: PContext; n: PNode, newType: PType, check: bool) =
          if f == nil:
            globalError(c.config, m.info, "unknown identifier: " & m.sym.name.s)
            return
-          if not isViewTarget(f.typ):
-            changeType(c, n[i][1], f.typ, check)
+          changeType(c, n[i][1], f.typ, check)
        else:
-          if not isViewTarget(tup[i]):
-            changeType(c, n[i][1], tup[i], check)
+          changeType(c, n[i][1], tup[i], check)
    else:
      for i in 0..<n.len:
-        if not isViewTarget(tup[i]):
-          changeType(c, n[i], tup[i], check)
+        changeType(c, n[i], tup[i], check)
        when false:
          var m = n[i]
          var a = newNodeIT(nkExprColonExpr, m.info, newType[i])
@@ -714,7 +708,6 @@ proc changeType(c: PContext; n: PNode, newType: PType, check: bool) =
        localError(c.config, n.info, "cannot convert '" & n.sym.name.s &
                                         "' to '" & typeNameAndDesc(newType) & "'")
  else: discard
-
  n.typ = newType

 proc arrayConstrType(c: PContext, n: PNode): PType =
@@ -970,15 +963,12 @@ proc evalAtCompileTime(c: PContext, n: PNode): PNode =
    #  echo "SUCCESS evaluated at compile time: ", call.renderTree

 proc semStaticExpr(c: PContext, n: PNode; expectedType: PType = nil): PNode =
-  let oldErrorCount = c.config.errorCounter
  inc c.inStaticContext
  openScope(c)
  let a = semExprWithType(c, n, expectedType = expectedType)
  closeScope(c)
  dec c.inStaticContext
-  if a.findUnresolvedStatic != nil or
-      c.config.errorCounter != oldErrorCount:
-    return a
+  if a.findUnresolvedStatic != nil: return a
  result = evalStaticExpr(c.module, c.idgen, c.graph, a, c.p.owner)
  if result.isNil:
    localError(c.config, n.info, errCannotInterpretNodeX % renderTree(n))
--- a/compiler/semmagic.nim
+++ b/compiler/semmagic.nim
@@ -35,9 +35,7 @@ proc semAddr(c: PContext; n: PNode): PNode =
  let x = semExprWithType(c, n)
  if x.kind == nkSym:
    x.sym.flagsImpl.incl(sfAddrTaken)
-  let aa = isAssignable(c, x)
-  if aa notin {arLValue, arLocalLValue, arAddressableConst, arLentValue} and
-     (aa != arDiscriminant or c.inUncheckedAssignSection <= 0):
+  if isAssignable(c, x) notin {arLValue, arLocalLValue, arAddressableConst, arLentValue}:
    localError(c.config, n.info, errExprHasNoAddress)
  result.add x
  result.typ = makePtrType(c, x.typ.skipTypes({tySink}))
@@ -248,13 +246,10 @@ proc evalTypeTrait(c: PContext; traitCall: PNode, operand: PType, context: PSym)
    assert operand.kind == tyTuple, $operand.kind
    result = newIntNodeT(toInt128(operand.len), traitCall, c.idgen, c.graph)
  of "distinctBase":
-    var arg = operand.skipTypes(skippedTypes)
+    var arg = operand.skipTypes({tyGenericInst})
    let rec = semConstExpr(c, traitCall[2]).intVal != 0
-    while true:
-      let distinctArg = arg.skipTypes(skippedTypes + {tyGenericInst})
-      if distinctArg.kind != tyDistinct:
-        break
-      arg = distinctArg.base.skipTypes(skippedTypes)
+    while arg.kind == tyDistinct:
+      arg = arg.base.skipTypes(skippedTypes + {tyGenericInst})
      if not rec: break
    result = getTypeDescNode(c, arg, operand.owner, traitCall.info)
  of "rangeBase":
@@ -618,9 +613,9 @@ proc magicsAfterOverloadResolution(c: PContext, n: PNode,
  of mAsgn:
    case n[0].sym.name.s
    of "=", "=copy":
-      result = replaceHookMagic(c, n, attachedAsgn)
+      result = semAsgnOpr(c, n, nkAsgn)
    of "=sink":
-      result = replaceHookMagic(c, n, attachedSink)
+      result = semAsgnOpr(c, n, nkSinkAsgn)
    else:
      result = semShallowCopy(c, n, flags)
  of mIsPartOf: result = semIsPartOf(c, n, flags)
--- a/compiler/semobjconstr.nim
+++ b/compiler/semobjconstr.nim
@@ -486,11 +486,6 @@ proc semObjConstr(c: PContext, n: PNode, flags: TExprFlags; expectedType: PType
      # we have to watch out, there are also 'owned proc' types that can be used
      # multiple times as long as they don't have closures.
      result.typ.incl tfHasOwned
-  if t.kind == tyForward and efDetermineType in flags:
-    # a forward object type does not error during determine-type analysis;
-    # it now stays unresolved long enough for the existing delayed field-default pass to resolve it after the type section finishes.
-    result.typ = t
-    return result
  if t.kind != tyObject:
    return localErrorNode(c, result, if t.kind != tyGenericBody:
      "object constructor needs an object type".dup(addTypeNodeDeclaredLoc(c.config, t))
--- a/compiler/sempass2.nim
+++ b/compiler/sempass2.nim
@@ -809,10 +809,6 @@ proc trackOperandForIndirectCall(tracked: PEffects, n: PNode, formals: PType; ar
        markSideEffect(tracked, a, n.info)
  let paramType = if formals != nil and argIndex < formals.signatureLen: formals[argIndex] else: nil
  if paramType != nil and paramType.kind in {tyVar}:
-    let arg = n.skipAddr()
-    if isSsoStringIndex(tracked.config, arg):
-      localError(tracked.config, arg.info,
-        "expression '$1' is immutable, not 'var'" % renderNotLValue(arg))
    invalidateFacts(tracked.guards, n)
    if n.kind == nkSym and isLocalSym(tracked, n.sym):
      makeVolatile(tracked, n.sym)
@@ -1168,7 +1164,7 @@ proc trackCall(tracked: PEffects; n: PNode) =
    var (isHook, opKind) = findHookKind(a.sym.name.s)
    if isHook:
      # rebind type bounds operations after createTypeBoundOps call
-      let t = n[1].typ.skipTypes({tyAlias, tyVar, tySink})
+      let t = n[1].typ.skipTypes({tyAlias, tyVar})
      if a.sym != getAttachedOp(tracked.graph, t, opKind):
        createTypeBoundOps(tracked, t, n.info, explicit = true)
        # replace builtin hooks with lifted ones
--- a/compiler/semstmts.nim
+++ b/compiler/semstmts.nim
@@ -1808,35 +1808,15 @@ proc checkForMetaFields(c: PContext; n: PNode; hasError: var bool) =
    internalAssert c.config, false

 proc typeSectionFinalPass(c: PContext, n: PNode) =
-  # each top level type needs to be processed, each epoch should reify at least one
-  var remainingOwners = initIntSet()
-  for (owner, _, _) in c.forwardTypeUpdates:
-    remainingOwners.incl owner.id
-  
-  while c.forwardTypeUpdates.len > 0:
-    let pending = move c.forwardTypeUpdates
-    var madeProgress = false
-
-    for (owner, typ, typeNode) in pending:
-      # types that need to be updated due to containing forward types
-      # and their corresponding type nodes
-      # for example generic invocations of forward types end up here
-      var reified = semTypeNode(c, typeNode, nil)
-      assert reified != nil
-      assignType(typ, reified)
-      typ.itemId = reified.itemId  # same id
-      if containsForwardType(typ):
-        c.forwardTypeUpdates.add (owner, typ, typeNode)
-      elif not remainingOwners.missingOrExcl(owner.id):
-        madeProgress = true
-    
-    if not madeProgress:
-      # can't error here unfortunately
-      break
-
-  for (owner, field, expectedType) in c.forwardFieldUpdates:
-    semDelayedFieldDefault(c, owner, expectedType, field)
-  c.forwardFieldUpdates = @[]
+  for (typ, typeNode) in c.forwardTypeUpdates:
+    # types that need to be updated due to containing forward types
+    # and their corresponding type nodes
+    # for example generic invocations of forward types end up here
+    var reified = semTypeNode(c, typeNode, nil)
+    assert reified != nil
+    assignType(typ, reified)
+    typ.itemId = reified.itemId     # same id
+  c.forwardTypeUpdates = @[]
  for i in 0..<n.len:
    var a = n[i]
    if a.kind == nkCommentStmt: continue
@@ -2936,15 +2916,13 @@ proc semPragmaBlock(c: PContext, n: PNode; expectedType: PType = nil): PNode =
 proc semStaticStmt(c: PContext, n: PNode): PNode =
  #echo "semStaticStmt"
  #writeStackTrace()
-  let oldErrorCount = c.config.errorCounter
  inc c.inStaticContext
  openScope(c)
  let a = semStmt(c, n[0], {})
  closeScope(c)
  dec c.inStaticContext
  n[0] = a
-  if c.config.errorCounter == oldErrorCount:
-    evalStaticStmt(c.module, c.idgen, c.graph, a, c.p.owner)
+  evalStaticStmt(c.module, c.idgen, c.graph, a, c.p.owner)
  when false:
    # for incremental replays, keep the AST as required for replays:
    result = n
--- a/compiler/semtypes.nim
+++ b/compiler/semtypes.nim
@@ -223,7 +223,7 @@ proc semSet(c: PContext, n: PNode, prev: PType): PType =
    if base.kind in {tyGenericInst, tyAlias, tySink}: base = skipModifier(base)
    if base.kind notin {tyGenericParam, tyGenericInvocation}:
      if base.kind == tyForward:
-        c.forwardTypeUpdates.add (getCurrOwner(c), result, n)
+        c.forwardTypeUpdates.add (base, n[1])
      elif not isOrdinalType(base, allowEnumWithHoles = true):
        localError(c.config, n.info, errOrdinalTypeExpected % typeToString(base, preferDesc))
      elif lengthOrd(c.config, base) > MaxSetElements:
@@ -318,62 +318,6 @@ proc fitDefaultNode(c: PContext, n: var PNode, expectedType: PType) =
    typeAllowedCheck(c, n.info, n.typ, skConst, {taProcContextIsNotMacro, taIsDefaultField})
  dec c.inStaticContext

-proc containsForwardTypeAux(t: PType; seen: var IntSet): bool
-
-proc containsForwardTypeAux(n: PNode; seen: var IntSet): bool =
-  result = false
-  if n.isNil or n.kind in nkLiterals + {nkNilLit, nkEmpty, nkType}:
-    return
-  if containsForwardTypeAux(n.typ, seen) or
-     (n.kind == nkSym and n.sym.typ != n.typ and containsForwardTypeAux(n.sym.typ, seen)):
-    return true
-
-  for i in 0 ..< n.safeLen:
-    if containsForwardTypeAux(n[i], seen):
-      return true
-
-proc containsForwardTypeAux(t: PType; seen: var IntSet): bool =
-  result = false
-  if t.isNil:
-    return
-  if t.kind == tyForward:
-    return true
-
-  if not containsOrIncl(seen, t.id):
-    if containsForwardTypeAux(t.n, seen):
-      return true
-
-    for i in 0 ..< t.len:
-      if containsForwardTypeAux(t[i], seen):
-        return true
-
-proc containsForwardType(arg: PNode): bool =
-  var seen = initIntSet()
-  containsForwardTypeAux(arg, seen)
-
-proc containsForwardType(t: PType): bool =
-  var seen = initIntSet()
-  containsForwardTypeAux(t, seen)
-
-proc semFieldDefault(c: PContext; owner, expectedType: PType; field: PNode): PType =
-  result = expectedType
-  field[^1] = semExprWithType(c, field[^1], {efDetermineType, efAllowSymChoice}, result)
-  if result == nil:
-    result = field[^1].typ
-
-  if c.inGenericContext == 0:
-    if containsForwardType(field[^1]):
-      c.forwardFieldUpdates.add (owner, field, result)
-    else:
-      fitDefaultNode(c, field[^1], result)
-      result = field[^1].typ.skipIntLit(c.idgen)
-      propagateToOwner(owner, result)
-
-proc semDelayedFieldDefault(c: PContext; owner, expectedType: PType; field: PNode) =
-  resetSemFlag(field[^1])
-  fitDefaultNode(c, field[^1], expectedType)
-  propagateToOwner(owner, field[^1].typ.skipIntLit(c.idgen))
-
 proc isRecursiveType*(t: PType): bool =
  # handle simple recusive types before typeFinalPass
  var cycleDetector = initIntSet()
@@ -606,7 +550,13 @@ proc semTuple(c: PContext, n: PNode, prev: PType): PType =
    var hasDefaultField = a[^1].kind != nkEmpty
    if hasDefaultField:
      typ = if a[^2].kind != nkEmpty: semTypeNode(c, a[^2], nil) else: nil
-      typ = semFieldDefault(c, result, typ, a)
+      if c.inGenericContext > 0:
+        a[^1] = semExprWithType(c, a[^1], {efDetermineType, efAllowSymChoice}, typ)
+        if typ == nil:
+          typ = a[^1].typ
+      else:
+        fitDefaultNode(c, a[^1], typ)
+        typ = a[^1].typ.skipIntLit(c.idgen)
    elif a[^2].kind != nkEmpty:
      typ = semTypeNode(c, a[^2], nil)
      if c.graph.config.isDefined("nimPreviewRangeDefault") and typ.skipTypes(abstractInst).kind == tyRange:
@@ -972,7 +922,14 @@ proc semRecordNodeAux(c: PContext, n: PNode, check: var IntSet, pos: var int,
    var hasDefaultField = n[^1].kind != nkEmpty
    if hasDefaultField:
      typ = if n[^2].kind != nkEmpty: semTypeNode(c, n[^2], nil) else: nil
-      typ = semFieldDefault(c, rectype, typ, n)
+      if c.inGenericContext > 0:
+        n[^1] = semExprWithType(c, n[^1], {efDetermineType, efAllowSymChoice}, typ)
+        if typ == nil:
+          typ = n[^1].typ
+      else:
+        fitDefaultNode(c, n[^1], typ)
+        typ = n[^1].typ.skipIntLit(c.idgen)
+        propagateToOwner(rectype, typ)
    elif n[^2].kind == nkEmpty:
      localError(c.config, n.info, errTypeExpected)
      typ = errorType(c)
@@ -1115,7 +1072,7 @@ proc semObjectNode(c: PContext, n: PNode, prev: PType; flags: TTypeFlags): PType
  if needsForwardUpdate:
    # if the inherited object is a forward type,
    # the entire object needs to be checked again
-    c.forwardTypeUpdates.add (getCurrOwner(c), result, n) # we retry in the final pass
+    c.forwardTypeUpdates.add (result, n) # we retry in the final pass
  rawAddSon(result, realBase)
  if realBase == nil and tfInheritable in flags:
    result.incl tfInheritable
@@ -1763,7 +1720,7 @@ proc semGeneric(c: PContext, n: PNode, s: PSym, prev: PType): PType =
    for i in 1..<n.len:
      var elem = semGenericParamInInvocation(c, n[i])
      addToResult(elem, true)
-    c.forwardTypeUpdates.add (getCurrOwner(c), result, n)
+    c.forwardTypeUpdates.add (result, n)
    return
  elif t.kind != tyGenericBody:
    # we likely got code of the form TypeA[TypeB] where TypeA is
@@ -1816,14 +1773,10 @@ proc semGeneric(c: PContext, n: PNode, s: PSym, prev: PType): PType =
        localError(c.config, n.info, errCannotInstantiateX % s.name.s)
        result = newOrPrevType(tyError, prev, c)
      elif containsGenericInvocationWithForward(n[0]) or hasForwardTypeParam:
-        # isConcrete == false means this generic type is not instanciated here because
-        # it invoked with generic parameters.
-        # Even if isConcrete == true, don't instanciate it now if there are
-        # unresolved `tyForward` type params.
-        # Such `tyForward` type params will be semchecked later and we can
-        # instanciate this next time.
-        # Some generic types like std/options.Option[T] need the kind of the
-        # given type argument before their fields can be resolved.
+        # isConcrete == false means this generic type is not instanciated here because it invoked with generic parameters.
+        # Even if isConcrete == true, don't instanciate it now if there are any `tyForward` type params.
+        # Such `tyForward` type params will be semchecked later and we can instanciate this next time.
+        # Some generic types like std/options.Option[T] needs a type kinds of the given type argument.

        # return `tyForward` instead of `tyGenericInvocation` because:
        # ```nim
@@ -1839,7 +1792,7 @@ proc semGeneric(c: PContext, n: PNode, s: PSym, prev: PType): PType =
        else:
          assignType(result, newTypeS(tyForward, c))
          result.sym = s
-        c.forwardTypeUpdates.add (getCurrOwner(c), result, n) #fixes 1500
+        c.forwardTypeUpdates.add (result, n) #fixes 1500
        return
      else:
        result = instGenericContainer(c, n.info, result,
@@ -2381,7 +2334,7 @@ proc semTypeNode(c: PContext, n: PNode, prev: PType): PType =
    else:
      result = typeExpr.typ.base
      if result.isMetaType and
-         result.kind notin tyTypeClasses:
+         result.kind != tyUserTypeClass:
           # the dot expression may refer to a concept type in
           # a different module. allow a normal alias then.
        let preprocessed = semGenericStmt(c, n)
--- a/compiler/sigmatch.nim
+++ b/compiler/sigmatch.nim
@@ -784,17 +784,6 @@ proc procParamTypeRel(c: var TCandidate; f, a: PType): TTypeRelation =
    # if f is metatype.
    result = typeRel(c, f, a)

-  if result == isEqual and
-      procParamTypeBackendAliases notin c.c.config.legacyFeatures:
-    # Ensure types that are semantically equal also match at the backend level.
-    # E.g. reject assigning proc(csize_t) to proc(uint) since these map to
-    # different C types (size_t vs unsigned long long).
-    let fCheck = concreteType(c, f)
-    let aCheck = concreteType(c, a)
-    if fCheck != nil and aCheck != nil and
-        not sameBackendTypePickyAliases(fCheck, aCheck):
-      result = isNone
-
  if result <= isSubrange or inconsistentVarTypes(f, a):
    result = isNone

@@ -2845,11 +2834,9 @@ proc findFirstArgBlock(m: var TCandidate, n: PNode): int =
    else: break

 proc matchesAux(c: PContext, n, nOrig: PNode, m: var TCandidate, marker: var IntSet) =
+
  template noMatch() =
-    if m.calleeSym != nil and m.calleeSym.kind notin {skTemplate, skMacro}:
-      c.mergeShadowScope
-    else:
-      c.closeShadowScope
+    c.mergeShadowScope #merge so that we don't have to resem for later overloads
    m.state = csNoMatch
    m.firstMismatch.arg = a
    m.firstMismatch.formal = formal
--- a/compiler/spawn.nim
+++ b/compiler/spawn.nim
@@ -10,7 +10,7 @@
 ## This module implements threadpool's ``spawn``.

 import ast, types, idents, magicsys, msgs, options, modulegraphs,
-  lowerings, liftdestructors, renderer, trees
+  lowerings, liftdestructors, renderer
 from trees import getMagic, getRoot

 proc callProc(a: PNode): PNode =
@@ -53,24 +53,6 @@ proc typeNeedsNoDeepCopy(t: PType): bool =
  if t.kind in {tyVar, tyLent, tySequence}: t = t.elementType
  result = not containsGarbageCollectedRef(t)

-proc newSpawnMoveStmt(g: ModuleGraph; idgen: IdGenerator; le, ri: PNode): PNode =
-  let op = getAttachedOp(g, ri.typ.skipTypes({tyGenericInst, tyAlias, tyVar, tySink}), attachedWasMoved)
-  if op != nil and sfOverridden in op.flags:
-    result = newNodeI(nkStmtList, le.info)
-    result.add newFastAsgnStmt(le, ri)
-
-    let wasMovedCall = newNodeI(nkCall, ri.info)
-    wasMovedCall.add newSymNode(op)
-    
-    if op.typ != nil and op.typ.signatureLen > 1 and op.typ.firstParamType.kind != tyVar:
-      wasMovedCall.add ri.skipAddr
-    else:
-      wasMovedCall.add makeAddr(ri.skipAddr, idgen)
-    
-    result.add wasMovedCall
-  else:
-    result = newFastMoveStmt(g, le, ri)
-
 proc addLocalVar(g: ModuleGraph; varSection, varInit: PNode; idgen: IdGenerator; owner: PSym; typ: PType;
                 v: PNode; useShallowCopy=false): PSym =
  result = newSym(skTemp, getIdent(g.cache, genPrefix), idgen, owner, varSection.info,
@@ -86,10 +68,10 @@ proc addLocalVar(g: ModuleGraph; varSection, varInit: PNode; idgen: IdGenerator;
  if varInit != nil:
    if g.config.selectedGC in {gcArc, gcOrc, gcAtomicArc, gcYrc}:
      # inject destructors pass will do its own analysis
-      varInit.add newSpawnMoveStmt(g, idgen, newSymNode(result), v)
+      varInit.add newFastMoveStmt(g, newSymNode(result), v)
    else:
      if useShallowCopy and typeNeedsNoDeepCopy(typ) or optTinyRtti in g.config.globalOptions:
-        varInit.add newSpawnMoveStmt(g, idgen, newSymNode(result), v)
+        varInit.add newFastMoveStmt(g, newSymNode(result), v)
      else:
        let deepCopyCall = newNodeI(nkCall, varInit.info, 3)
        deepCopyCall[0] = newSymNode(getSysMagic(g, varSection.info, "deepCopy", mDeepCopy))
--- a/compiler/transf.nim
+++ b/compiler/transf.nim
@@ -120,21 +120,18 @@ proc newAsgnStmt(c: PTransf, kind: TNodeKind, le: PNode, ri: PNode; isFirstWrite

 proc resolveBorrowedRoutineSym(c: PTransf; s: PSym; info: TLineInfo): PSym =
  # Follow borrow aliases to the underlying implementation symbol.
+  result = nil
  var s = s
  while true:
-    # Skips over all borrowed procs getting the last proc symbol without an implementation
+    # Skips over all borrowed procs getting the last proc symbol without an implementation.
    let body = getBody(c.graph, s)
    if body.kind == nkSym and sfBorrow in body.sym.flags and getBody(c.graph, body.sym).kind == nkSym:
      s = body.sym
    else:
-      break
-
-  let body = getBody(c.graph, s)
-  if body.kind == nkSym:
-    result = body.sym
-  else:
-    result = nil
-    internalError(c.graph.config, info, "wrong AST for borrowed symbol")
+      if body.kind != nkSym:
+        internalError(c.graph.config, info, "wrong AST for borrowed symbol")
+      return body.sym
+  internalError(c.graph.config, info, "wrong AST for borrowed symbol")

 proc transformSymAux(c: PTransf, n: PNode): PNode =
  let s = n.sym
@@ -336,7 +333,7 @@ proc introduceNewLocalVars(c: PTransf, n: PNode): PNode =
    if a.kind == nkSym:
      n[1] = transformSymAux(c, a)
    return n
-  of nkLambdaKinds, nkProcDef, nkFuncDef, nkMethodDef, nkConverterDef: # todo optimize nosideeffects?
+  of nkProcDef, nkFuncDef, nkMethodDef, nkConverterDef: # todo optimize nosideeffects?
    result = newTransNode(n)
    let x = newSymNode(copySym(n[namePos].sym, c.idgen))
    c.transCon.mapping[n[namePos].sym.itemId] = x
@@ -702,11 +699,6 @@ proc putArgInto(arg: PNode, formal: PType): TPutArgInto =
  of nkAddr, nkHiddenAddr:
    result = putArgInto(arg[0], formal)
    if result == paViaIndirection: result = paFastAsgn
-  of nkHiddenStdConv, nkHiddenSubConv, nkConv:
-    if compareTypes(arg.typ, arg[1].typ, dcEqIgnoreDistinct, {IgnoreRangeShallow}):
-      result = putArgInto(arg[1], formal)
-    else:
-      result = paFastAsgn
  of nkCurly, nkBracket:
    for i in 0..<arg.len:
      if putArgInto(arg[i], formal) != paDirectMapping:
--- a/compiler/types.nim
+++ b/compiler/types.nim
@@ -897,7 +897,7 @@ proc sameTypeAux(x, y: PType, c: var TSameTypeClosure): bool =
    c.flags = oldFlags

  if x == y: return true
-  let aliasSkipSet = maybeSkipRange({tyAlias, tyInferred})
+  let aliasSkipSet = maybeSkipRange({tyAlias})
  var a = skipTypes(x, aliasSkipSet)
  while a.kind == tyUserTypeClass and tfResolved in a.flags:
    a = skipTypes(a.last, aliasSkipSet)
--- a/doc/ic.md
+++ b/doc/ic.md
@@ -33,7 +33,7 @@ The text representation is particularly valuable for debugging and introspection
 Each ``.nim`` module produces its own ``.nif`` file during compilation.
 The NIF format contains:

- **Header** - Version information (e.g., `(.nif27)`)
+- **Header** - Version information (e.g., `(.nif26)`)
 - **Dependencies** - List of source files and dependencies
 - **Interface** - Exported symbols and their indices
 - **Body** - The intermediate representation of the module's code in Lisp-like syntax
--- a/doc/manual.md
+++ b/doc/manual.md
@@ -34,10 +34,10 @@ To learn how to compile Nim programs and generate documentation see
 the [Compiler User Guide](nimc.html) and the [DocGen Tools Guide](docgen.html).

 The language constructs are explained using an extended BNF, in which `(a)*`
-means 0 or more *a*'s, `a+` means 1 or more *a*'s, and `(a)?` means an
+means 0 or more `a`'s, `a+` means 1 or more `a`'s, and `(a)?` means an
 optional *a*. Parentheses may be used to group elements.

-`&` is the lookahead operator; `&a` means that an *a* is expected but
+`&` is the lookahead operator; `&a` means that an `a` is expected but
 not consumed. It will be consumed in the following rule.

 The `|`, `/` symbols are used to mark alternatives and have the lowest
@@ -1024,9 +1024,6 @@ These are the major type classes:
 * procedural type
 * generic type

-The compiler's internal type zoo is richer than this summary suggests:
-some types that are structurally equal still differ in backend representation.
-

 Ordinal types
 -------------
@@ -2177,10 +2174,6 @@ Procedural type
 A procedural type is internally a pointer to a procedure. `nil` is
 an allowed value for a variable of a procedural type.

-Procedure compatibility also checks the backend representation of the
-parameter and result types, not just their source-level shape. Use
-`--legacy:procParamTypeBackendAliases` to restore the older behavior.
-
 Examples:

  ```nim
@@ -8874,7 +8867,7 @@ Byref pragma
 The `byref` pragma can be applied to an object or tuple type or a proc param.
 When applied to a type it instructs the compiler to pass the type by reference
 (hidden pointer) to procs. When applied to a param it will take precedence, even
-if the type was marked as `bycopy`. When an `importc` type has a `byref` pragma or
+if the the type was marked as `bycopy`. When an `importc` type has a `byref` pragma or
 parameters are marked as `byref` in an `importc` proc, these params translate to pointers.
 When an `importcpp` type has a `byref` pragma, these params translate to
 C++ references `&`.
--- a/doc/tut1.md
+++ b/doc/tut1.md
@@ -1144,7 +1144,7 @@ there is a difference between the `$` and `repr` outputs:
  echo myCharacter, ":", repr(myCharacter)
  # --> n:'n'
  echo myString, ":", repr(myString)
-  # --> nim:"nim"
+  # --> nim:0x10fa8c050"nim"
  echo myInteger, ":", repr(myInteger)
  # --> 42:42
  echo myFloat, ":", repr(myFloat)
--- a/koch.nim
+++ b/koch.nim
@@ -16,11 +16,10 @@ const
  ChecksumsStableCommit = "0b8e46379c5bc1bf73d8b3011908389c60fb9b98" # 2.0.1
  SatStableCommit = "e63eaea8baf00bed8bcd5a29ffd8823abb265b39"

-  NimonyStableCommit = "750aa47f2139fe5ad69f04b44428b752011fe873" # unversioned \
+  NimonyStableCommit = "bbfb21529845567c55b67d176354daef0e7d6c29" # unversioned \
    # Note that Nimony uses Nim as a git submodule but we don't want to install
    # Nimony's dependency to Nim as we are Nim. So a `git clone` without --recursive
    # is **required** here.
-    # Commit from 2026-05-05

  # examples of possible values for fusion: #head, #ea82b54, 1.2.3
  FusionStableHash = "#562467452b32cb7a97410ea177f083e6d8405734"
--- a/lib/core/macros.nim
+++ b/lib/core/macros.nim
@@ -1559,8 +1559,6 @@ macro expandMacros*(body: typed): untyped =
  echo body.toStrLit
  result = body

-proc getTypeInstSkipAlias(n: NimNode): NimNode {.magic: "NGetType", noSideEffect.}
-
 proc extractTypeImpl(n: NimNode): NimNode =
  ## attempts to extract the type definition of the given symbol
  case n.kind
@@ -1575,17 +1573,11 @@ proc extractTypeImpl(n: NimNode): NimNode =
      result = n[0].getImpl()
  of nnkTypeDef:
    result = n[2]
-    if result.kind notin {nnkSym, nnkObjectTy, nnkRefTy, nnkPtrTy, nnkBracketExpr}:
-      # Handle typeof() and similar unresolvable type expressions
-      let typSym = if n[0].kind == nnkPragmaExpr: n[0][0] else: n[0]
-      if typSym.kind == nnkSym:
-        let resolved = typSym.getTypeInstSkipAlias()
-        if resolved.kind == nnkSym:
-          return resolved.getImpl.extractTypeImpl()
-      error("Invalid node to retrieve type implementation of: " & $result.kind)
  else: error("Invalid node to retrieve type implementation of: " & $n.kind)


+proc getTypeInstSkipAlias(n: NimNode): NimNode {.magic: "NGetType", noSideEffect.}
+
 proc customPragmaNode(n: NimNode): NimNode =
  result = nil
  expectKind(n, {nnkSym, nnkDotExpr, nnkBracketExpr, nnkTypeOfExpr, nnkType, nnkCheckedFieldExpr})
@@ -1626,15 +1618,6 @@ proc customPragmaNode(n: NimNode): NimNode =
    var typDef = getImpl(typInst)
    while typDef != nil:
      typDef.expectKind(nnkTypeDef)
-      # Resolve typeof() and similar unresolvable type expressions
-      if typDef[2].kind notin {nnkSym, nnkObjectTy, nnkRefTy, nnkPtrTy, nnkBracketExpr}:
-        let typSym = if typDef[0].kind == nnkPragmaExpr: typDef[0][0] else: typDef[0]
-        if typSym.kind == nnkSym:
-          let resolved = typSym.getTypeInstSkipAlias()
-          if resolved.kind == nnkSym:
-            typDef = getImpl(resolved)
-            continue
-        break
      let typ = typDef[2].extractTypeImpl()
      if typ.kind notin {nnkRefTy, nnkPtrTy, nnkObjectTy}: break
      let isRef = typ.kind in {nnkRefTy, nnkPtrTy}
--- a/lib/impure/nre.nim
+++ b/lib/impure/nre.nim
@@ -9,11 +9,6 @@
 when defined(js):
  {.error: "This library needs to be compiled with a c-like backend, and depends on PCRE; See jsre for JS backend.".}

-## .. warning:: NRE is deprecated.
-##   Use [Regex](https://github.com/nitely/nim-regex) or
-##   `NRE2 <nre2.html>`_ that wraps Regex so that you can easily replace NRE.
-##   PCRE library is now at end of life.
-##
 ## What is NRE?
 ## ============
 ##
@@ -89,7 +84,7 @@ type
  Regex* = ref RegexDesc
    ## Represents the pattern that things are matched against, constructed with
    ## `re(string)`. Examples: `re"foo"`, `re(r"(*ANYCRLF)(?x)foo #
-    ## comment")`
+    ## comment".`
    ##
    ## `pattern: string`
    ## :   the string that was used to create the pattern. For details on how
@@ -159,7 +154,7 @@ type
    ## will need to pass these as separate flags to PCRE.

  RegexMatch* = object
-    ## Usually seen as `Option[RegexMatch]`, it represents the result of an
+    ## Usually seen as Option[RegexMatch], it represents the result of an
    ## execution. On failure, it is none, on success, it is some.
    ##
    ## `pattern: Regex`
--- a/lib/impure/re.nim
+++ b/lib/impure/re.nim
@@ -10,10 +10,6 @@
 when defined(js):
  {.error: "This library needs to be compiled with a c-like backend, and depends on PCRE; See jsre for JS backend.".}

-## .. warning:: This module is deprecated.
-##   Use [Regex](https://github.com/nitely/nim-regex).
-##   PCRE library is now at end of life.
-##
 ## Regular expression support for Nim.
 ##
 ## This module is implemented by providing a wrapper around the
--- a/lib/pure/asynchttpserver.nim
+++ b/lib/pure/asynchttpserver.nim
@@ -153,7 +153,7 @@ proc parseProtocol(protocol: string): tuple[orig: string, major, minor: int] =
        protocol)
  result.orig = protocol
  i.inc protocol.parseSaturatedNatural(result.major, i)
-  if i < protocol.len: inc i # Skip .
+  i.inc # Skip .
  i.inc protocol.parseSaturatedNatural(result.minor, i)

 proc sendStatus(client: AsyncSocket, status: string): Future[void] =
--- a/lib/pure/cgi.nim
+++ b/lib/pure/cgi.nim
@@ -128,7 +128,7 @@ proc getContentLength*(): string =

 proc getContentType*(): string =
  ## Returns contents of the `CONTENT_TYPE` environment variable.
-  return getEnv("CONTENT_TYPE")
+  return getEnv("CONTENT_Type")

 proc getDocumentRoot*(): string =
  ## Returns contents of the `DOCUMENT_ROOT` environment variable.
--- a/lib/pure/collections/critbits.nim
+++ b/lib/pure/collections/critbits.nim
@@ -495,16 +495,13 @@ func `$`*[T](c: CritBitTree[T]): string =
      const avgItemLen = 16
    result = newStringOfCap(c.count * avgItemLen)
    result.add("{")
-    var first = true
    when T is void:
      for key in keys(c):
-        if first: first = false
-        else: result.add(", ")
+        if result.len > 1: result.add(", ")
        result.addQuoted(key)
    else:
      for key, val in pairs(c):
-        if first: first = false
-        else: result.add(", ")
+        if result.len > 1: result.add(", ")
        result.addQuoted(key)
        result.add(": ")
        result.addQuoted(val)
--- a/lib/pure/collections/deques.nim
+++ b/lib/pure/collections/deques.nim
@@ -454,10 +454,8 @@ proc `$`*[T](deq: Deque[T]): string =
    assert $a == "[10, 20, 30]"

  result = "["
-  var first = true
  for x in deq:
-    if first: first = false
-    else: result.add(", ")
+    if result.len > 1: result.add(", ")
    result.addQuoted(x)
  result.add("]")

--- a/lib/pure/collections/heapqueue.nim
+++ b/lib/pure/collections/heapqueue.nim
@@ -260,9 +260,7 @@ proc `$`*[T](heap: HeapQueue[T]): string =
    assert $heap == "[1, 2]"

  result = "["
-  var first = true
  for x in heap.data:
-    if first: first = false
-    else: result.add(", ")
+    if result.len > 1: result.add(", ")
    result.addQuoted(x)
  result.add("]")
--- a/lib/pure/collections/lists.nim
+++ b/lib/pure/collections/lists.nim
@@ -304,10 +304,8 @@ proc `$`*[T](L: SomeLinkedCollection[T]): string =
    assert $a == "[1, 2, 3, 4]"

  result = "["
-  var first = true
  for x in nodes(L):
-    if first: first = false
-    else: result.add(", ")
+    if result.len > 1: result.add(", ")
    result.addQuoted(x.value)
  result.add("]")

--- a/lib/pure/parseopt.nim
+++ b/lib/pure/parseopt.nim
@@ -588,9 +588,7 @@ proc handleShortOption(p: var OptParser; cmd: string) =
    
  template next(): untyped = p.cmds[p.idx + 1]

-  let canTakeVal = card(p.shortNoVal) > 0 and
-    p.key.len > 0 and p.key[0] notin p.shortNoVal
-
+  let canTakeVal = card(p.shortNoVal) > 0 and p.key[0] notin p.shortNoVal 
  if i < cmd.len and cmd[i] in p.separators:
    # separator case
    if prShortAllowSep in p.rules:
--- a/lib/pure/pegs.nim
+++ b/lib/pure/pegs.nim
@@ -1668,10 +1668,7 @@ func getSymbol(c: var PegLexer, tok: var Token) =
  while pos < c.buf.len:
    add(tok.literal, c.buf[pos])
    inc(pos)
-    if pos < c.buf.len:
-      let ch = c.buf[pos]
-      # Keep non-ASCII bytes so UTF-8 terminals reach the rune-aware matchers.
-      if ch notin strutils.IdentChars and ord(ch) < 0x80: break
+    if pos < c.buf.len and c.buf[pos] notin strutils.IdentChars: break
  c.bufpos = pos
  tok.kind = tkIdentifier

--- a/lib/pure/ssl_certs.nim
+++ b/lib/pure/ssl_certs.nim
@@ -36,8 +36,6 @@ elif defined(linux):
    # Android
    "/data/data/com.termux/files/usr/etc/tls/cert.pem",
    "/system/etc/security/cacerts",
-    # Nix
-    "/etc/ssl/certs/ca-bundle.crt"
  ]
 elif defined(bsd):
  const certificatePaths = [
--- a/lib/pure/streams.nim
+++ b/lib/pure/streams.nim
@@ -259,7 +259,7 @@ proc readDataStr*(s: Stream, buffer: var string, slice: Slice[int]): int =
    result = s.readDataStrImpl(s, buffer, slice)
  else:
    # fallback
-    result = s.readData(beginStore(buffer, buffer.len, slice.a), slice.b + 1 - slice.a)
+    result = s.readData(beginStore(buffer, slice.b + 1 - slice.a, slice.a), slice.b + 1 - slice.a)
    endStore(buffer)

 template jsOrVmBlock(caseJsOrVm, caseElse: untyped): untyped =
@@ -1226,7 +1226,7 @@ else: # after 1.3 or JS not defined
      jsOrVmBlock:
        buffer[slice.a..<slice.a+result] = s.data[s.pos..<s.pos+result]
      do:
-        copyMem(beginStore(buffer, buffer.len, slice.a), readRawData(s.data, s.pos), result)
+        copyMem(beginStore(buffer, result, slice.a), readRawData(s.data, s.pos), result)
        endStore(buffer)
      inc(s.pos, result)
    else:
@@ -1267,16 +1267,16 @@ else: # after 1.3 or JS not defined
    var s = StringStream(s)
    if bufLen <= 0:
      return
+    if s.pos + bufLen > s.data.len:
+      setLen(s.data, s.pos + bufLen)
    when defined(js):
-      if s.pos + bufLen > s.data.len:
-        setLen(s.data, s.pos + bufLen)
      try:
        s.data[s.pos..<s.pos+bufLen] = cast[ptr string](buffer)[][0..<bufLen]
      except:
        raise newException(Defect, "could not write to string stream, " &
          "did you use a non-string buffer pointer?", getCurrentException())
    elif not defined(nimscript):
-      copyMem(beginStore(s.data, s.pos + bufLen, s.pos), buffer, bufLen)
+      copyMem(beginStore(s.data, bufLen, s.pos), buffer, bufLen)
      endStore(s.data)
    inc(s.pos, bufLen)

@@ -1346,7 +1346,7 @@ proc fsReadData(s: Stream, buffer: pointer, bufLen: int): int =

 proc fsReadDataStr(s: Stream, buffer: var string, slice: Slice[int]): int =
  let len = slice.b + 1 - slice.a
-  result = readBuffer(FileStream(s).f, beginStore(buffer, buffer.len, slice.a), len)
+  result = readBuffer(FileStream(s).f, beginStore(buffer, len, slice.a), len)
  endStore(buffer)

 proc fsPeekData(s: Stream, buffer: pointer, bufLen: int): int =
--- a/lib/pure/strtabs.nim
+++ b/lib/pure/strtabs.nim
@@ -380,10 +380,8 @@ proc `$`*(t: StringTableRef): string {.rtlFunc, extern: "nstDollar".} =
    result = "{:}"
  else:
    result = "{"
-    var first = true
    for key, val in pairs(t):
-      if first: first = false
-      else: result.add(", ")
+      if result.len > 1: result.add(", ")
      result.add(key)
      result.add(": ")
      result.add(val)
--- a/lib/std/formatfloat.nim
+++ b/lib/std/formatfloat.nim
@@ -18,12 +18,12 @@ proc addCstringN(result: var string, buf: cstring; buflen: int) =
  # no nimvm support needed, so it doesn't need to be fast here either
  let oldLen = result.len
  let newLen = oldLen + buflen
+  result.setLen newLen
  {.cast(noSideEffect).}:
-    when declared(beginStore):
-      c_memcpy(beginStore(result, newLen, oldLen), buf, buflen.csize_t)
+    when declared(completeStore):
+      c_memcpy(beginStore(result, buflen, oldLen), buf, buflen.csize_t)
      endStore(result)
    else:
-      result.setLen newLen
      discard c_memcpy(result[oldLen].addr, buf, buflen.csize_t)

 import std/private/[dragonbox, schubfach]
--- a/lib/std/nre2.nim
+++ b/lib/std/nre2.nim
@@ -1,344 +0,0 @@
-#
-#            Nim's Runtime Library
-#        (c) Copyright 2026 Nim Contributors
-#
-#    See the file "copying.txt", included in this
-#    distribution, for details about the copyright.
-#
-
-## What is NRE2?
-## =============
-##
-## A regular expression library for Nim to replace deprecated NRE.
-## It is implemented with `Regex<https://github.com/nitely/nim-regex>`_ ,
-## that is pure Nim regex engine and guarantees linear time matching.
-## It supports compiling regex and matching at compile-time and
-## works with JS backend.
-##
-## NRE2 is mostly compatible with NRE and the syntax of regular expression is similar to PCRE.
-## But it lacks a few features and how to set options in a pattern is different.
-##
-## The syntax of regular expression is explained in https://nitely.github.io/nim-regex/regex.html
-runnableExamples:
-  import std/sugar
-  let vowels = re"[aeoui]"
-  let bounds = collect:
-    for match in "moiga".findIter(vowels): match.matchBounds
-  assert bounds == @[1 .. 1, 2 .. 2, 4 .. 4]
-  from std/sequtils import toSeq
-  let s = sequtils.toSeq("moiga".findIter(vowels))
-    # fully qualified to avoid confusion with nre.toSeq
-  assert s.len == 3
-
-  let firstVowel = "foo".find(vowels)
-  let hasVowel = firstVowel.isSome()
-  assert hasVowel
-  let matchBounds = firstVowel.get().captureBounds[-1]
-  assert matchBounds.a == 1
-
-  # as with module `re`, unless specified otherwise, `start` parameter in each
-  # proc indicates where the scan starts, but outputs are relative to the start
-  # of the input string, not to `start`:
-  assert find("uxabc", re"(?<=x|y)ab", start = 1).get.captures[-1] == "ab"
-  assert find("uxabc", re"ab", start = 3).isNone
-
-import std/[options, tables]
-import regex, regex/nfatype
-
-export options
-export regex.RegexFlags, regex.RegexError
-
-type
-  Regex* = regex.Regex2
-    ## Represents the pattern that things are matched against, constructed with
-    ## `re(string)`. Examples: `re"foo"`, `re(r"(?x)foo #comment")`
-    ##
-    ## `captureCount: int`
-    ## :   the number of captures that the pattern has.
-    ##
-    ## `captureNameId: Table[string, int]`
-    ## :   a table from the capture names to their numeric id.
-    ##
-    ## The syntax of regular expression of Regex is explained in https://nitely.github.io/nim-regex/regex.html
-
-  RegexMatch* = object
-    ## Usually seen as `Option[RegexMatch]`, it represents the result of an
-    ## execution. On failure, it is none, on success, it is some.
-    ##
-    ## `str: string`
-    ## :   the string that was matched against
-    ##
-    ## `captures[]: string`
-    ## :   the string value of whatever was captured at that id. If the value
-    ##     is invalid, then behavior is undefined. If the id is `-1`, then
-    ##     the whole match is returned. If the given capture was not matched,
-    ##     `nil` is returned. See examples for `match`.
-    ##
-    ## `captureBounds[]: HSlice[int, int]`
-    ## :   gets the bounds of the given capture according to the same rules as
-    ##     the above. If the capture is not filled, then `None` is returned.
-    ##     The bounds are both inclusive.  See examples for `match`.
-    ##
-    ## `match: string`
-    ## :   the full text of the match.
-    ##
-    ## `matchBounds: HSlice[int, int]`
-    ## :   the bounds of the match, as in `captureBounds[]`
-    ##
-    ## `(captureBounds|captures).toTable`
-    ## :   returns a table with each named capture as a key.
-    ##
-    ## `(captureBounds|captures).toSeq`
-    ## :   returns all the captures by their number.
-    ##
-    ## `$: string`
-    ## :   same as `match`
-    str*: string  ## The string that was matched against.
-    matchImpl: regex.RegexMatch2
-
-  Captures* {.borrow: `.`.} = distinct RegexMatch
-  CaptureBounds* {.borrow: `.`.} = distinct RegexMatch
-
-func captureCount*(pattern: Regex): int {.inline.} =
-  pattern.toRegex().groupsCount
-
-func captureNameId*(pattern: Regex): Table[string, int] =
-  result = initTable[string, int](pattern.toRegex().namedGroups.len)
-  for k, v in pattern.toRegex().namedGroups:
-    result[k] = v
-
-func captureBounds*(match: RegexMatch): CaptureBounds {.inline.} =
-  CaptureBounds(match)
-
-func captures*(match: RegexMatch): Captures {.inline.} =
-  Captures(match)
-
-func contains*(match: Captures or CaptureBounds, i: int): bool {.inline.} =
-  i >= -1 and i < match.matchImpl.groupsCount and match.matchImpl.group(i) != reNonCapture
-
-func len*(match: Captures or CaptureBounds): int {.inline.} =
-  ## Return the number of capturing groups
-  match.matchImpl.groupsCount
-
-func `[]`*(match: CaptureBounds; i: int): HSlice[int, int] {.inline.} =
-  if i == -1: match.matchImpl.boundaries else: match.matchImpl.group(i)
-
-func `[]`*(match: CaptureBounds; name: string): HSlice[int, int] {.inline.} =
-  result = match.matchImpl.group(name)
-  if result == reNonCapture:
-    raise newException(KeyError, "Group '" & name & "' was not captured")
-
-func `[]`*(match: Captures; i: int): string {.inline.} =
-  match.str[CaptureBounds(match)[i]]
-
-func `[]`*(match: Captures, name: string): string {.inline.} =
-  match.str[CaptureBounds(match)[name]]
-
-func match*(match: RegexMatch): string {.inline.} =
-  match.str[match.matchImpl.boundaries]
-
-func matchBounds*(match: RegexMatch): HSlice[int, int] {.inline.} =
-  match.matchImpl.boundaries
-
-func contains*(match: CaptureBounds or Captures, name: string): bool {.inline.} =
-  name in match.matchImpl.namedGroups and
-  match.matchImpl.group(name) != reNonCapture
-
-func toTable*(match: Captures): Table[string, string] =
-  result = initTable[string, string]()
-  for k, i in match.matchImpl.namedGroups:
-    let r = match.matchImpl.group(i)
-    if r != reNonCapture:
-      result[k] = match.str[r]
-
-func toTable*(match: CaptureBounds): Table[string, HSlice[int, int]] =
-  result = initTable[string, HSlice[int, int]]()
-  for k, i in match.matchImpl.namedGroups:
-    let r = match.matchImpl.group(i)
-    if r != reNonCapture:
-      result[k] = match.matchImpl.group(i)
-
-iterator items*(match: CaptureBounds; default = none(HSlice[int, int])): Option[HSlice[int, int]] =
-  for i in 0 ..< match.len:
-    yield if i in match: some(match[i]) else: default
-
-iterator items*(match: Captures; default = none(string)): Option[string] =
-  for i in 0 ..< match.len:
-    yield if i in match: some(match[i]) else: default
-
-func toSeq*(match: CaptureBounds;
-            default = none(HSlice[int, int])): seq[Option[HSlice[int, int]]] =
-  result = @[]
-  for it in match.items(default): result.add it
-
-func toSeq*(match: Captures;
-            default: Option[string] = none(string)): seq[Option[string]] =
-  result = @[]
-  for it in match.items(default): result.add it
-
-func `$`*(match: RegexMatch): string =
-  match.match
-
-func re*(pattern: static string; flags: static RegexFlags = {}): static[Regex2] =
-  ## Parse and compile a regular expression at compile-time
-  result = regex.re2(pattern, flags)
-
-func re*(pattern: string; flags: RegexFlags = {}): Regex =
-  ## Parse and compile a regular expression at run-time
-  result = regex.re2(pattern, flags)
-
-func match*(str: string, pattern: Regex, start = 0, endpos = int.high): Option[RegexMatch] =
-  ## Like `find(...)<#find,string,Regex,int>`_, but anchored to the start of the
-  ## string.
-  runnableExamples:
-    assert "foo".match(re"f").isSome
-    assert "foo".match(re"o").isNone
-
-    assert "abc".match(re"(\w)").get.captures[0] == "a"
-    assert "abc".match(re"(?P<letter>\w)").get.captures["letter"] == "a"
-    assert "abc".match(re"(\w)\w").get.captures[-1] == "ab"
-
-    assert "abc".match(re"(\w)").get.captureBounds[0] == 0 .. 0
-    assert 0 in "abc".match(re"(\w)").get.captureBounds
-    assert "abc".match(re"").get.captureBounds[-1] == 0 .. -1
-    assert "abc".match(re"abc").get.captureBounds[-1] == 0 .. 2
-  var mat = default(RegexMatch)
-  let r = regex.startsWith(str.toOpenArray(0, min(str.high, endpos)), pattern, mat.matchImpl, start)
-  if r:
-    mat.str = str
-    some(mat)
-  else:
-    none(RegexMatch)
-
-iterator findIter*(str: string; pattern: Regex; start = 0, endpos = int.high): RegexMatch =
-  ## Works the same as `find(...)<#find,string,Regex,int>`_, but finds every
-  ## non-overlapping match:
-  runnableExamples:
-    import std/sugar
-    assert collect(for a in "2222".findIter(re"22"): a.match) == @["22", "22"]
-     # not @["22", "22", "22"]
-  ## Arguments are the same as `find(...)<#find,string,Regex,int>`_
-  ##
-  ## Variants:
-  ##
-  ## -  `proc findAll(...)` returns a `seq[string]`
-  var mat = RegexMatch(str: str)
-  # TODO:
-  # needs following PR to remove `substr` call.
-  # https://github.com/nitely/nim-regex/pull/162
-  for m in regex.findAll(str.substr(start, endpos), pattern):
-    mat.matchImpl = m
-    yield mat
-
-proc find*(str: string; pattern: Regex; start = 0; endpos = int.high): Option[RegexMatch] =
-  ## Finds the given pattern in the string between the end and start
-  ## positions.
-  ##
-  ## `start`
-  ## :   The start point at which to start matching. `|abc` is `0`;
-  ##     `a|bc` is `1`
-  ##
-  ## `endpos`
-  ## :   The maximum index for a match; `int.high` means the end of the
-  ##     string, otherwise it’s an inclusive upper bound.
-  var mat = default(RegexMatch)
-  let r = regex.find(str.substr(start, endpos), pattern, mat.matchImpl)
-
-  # remove following code after regex.find get `start`/`last` parameter
-  for v in mat.matchImpl.captures.mitems:
-    v.a += start
-    v.b += start
-  mat.matchImpl.boundaries.a += start
-  mat.matchImpl.boundaries.b += start
-
-  if r:
-    mat.str = str
-    some(mat)
-  else:
-    none(RegexMatch)
-
-proc findAll*(str: string; pattern: Regex; start = 0; endpos = int.high): seq[string] =
-  result = @[]
-  for match in str.findIter(pattern, start, endpos):
-    result.add(match.match)
-
-proc contains*(str: string; pattern: Regex; start = 0; endpos = int.high): bool =
-  ## Determine if the string contains the given pattern between the end and
-  ## start positions:
-  ## This function is equivalent to `isSome(str.find(pattern, start, endpos))`.
-  runnableExamples:
-    assert "abc".contains(re"bc")
-    assert not "abc".contains(re"cd")
-    assert not "abc".contains(re"a", start = 1)
-
-  isSome(str.find(pattern, start, endpos))
-
-proc split*(str: string; pattern: Regex; maxSplit = -1; start = 0): seq[string] =
-  ## Splits the string with the given regex. This works according to the
-  ## rules that Perl and Javascript use.
-  ##
-  ## `start` behaves the same as in `find(...)<#find,string,Regex,int>`_.
-  ##
-  runnableExamples:
-    # -  If the match is zero-width, then the string is still split:
-    assert "123".split(re"") == @["1", "2", "3"]
-
-    # -  If the pattern has a capture in it, it is added after the string
-    #    split:
-    assert "12".split(re"(\d)") == @["", "1", "", "2", ""]
-
-    # -  If `maxsplit != -1`, then the string will only be split
-    #    `maxsplit - 1` times. This means that there will be `maxsplit`
-    #    strings in the output seq.
-    assert "1.2.3".split(re"\.", maxsplit = 2) == @["1", "2.3"]
-
-  result = splitIncl(str, pattern, maxSplit, start)
-
-proc replace*(str: string; pattern: Regex;
-              subproc: proc (match: RegexMatch): string): string =
-  ## Replaces each match of Regex in the string with `subproc`, which should
-  ## never be or return `nil`.
-  ##
-  ## If `subproc` is a `proc (RegexMatch): string`, then it is executed with
-  ## each match and the return value is the replacement value.
-  ##
-  ## If `subproc` is a `proc (string): string`, then it is executed with the
-  ## full text of the match and the return value is the replacement value.
-  ##
-  ## If `subproc` is a string, the syntax is as follows:
-  ##
-  ## -  `$$` - literal `$`
-  ## -  `$123` - capture number `123`
-  ## -  `$1$#` - first and second captures
-  ## -  `$#` - first capture
-  ##
-  ## Following syntax is not supported in NRE2
-  ##
-  ## -  `$foo` - named capture `foo`
-  ## -  `${foo}` - same as above
-  ## -  `$0` - full match
-  ##
-  ## If a given capture is missing, `ValueError` is thrown.
-  proc by(m: RegexMatch2, s: string): string =
-    let mat = RegexMatch(str: s, matchImpl: m)
-    result = subproc(mat)
-
-  result = regex.replace(str, pattern, by)
-
-proc replace*(str: string; pattern: Regex;
-              subproc: proc (match: string): string): string =
-  proc by(m: RegexMatch2; s: string): string =
-    result = subproc(s)
-
-  result = regex.replace(str, pattern, by)
-
-proc replace*(str: string; pattern: Regex; sub: string): string =
-  result = regex.replace(str, pattern, sub)
-
-func escapeRe*(str: string): string =
-  ## Escapes the string so it doesn't match any special characters.
-  runnableExamples:
-    assert escapeRe("fly+wind") == "fly\\+wind"
-    assert escapeRe("nim*") == "nim\\*"
-
-  result = regex.escapeRe(str)
--- a/lib/std/nre2.nims
+++ b/lib/std/nre2.nims
@@ -1,14 +0,0 @@
-import std/os
-
-if getCommand() == "doc":
-  # std/nre2 requires nim-regex and it requires nim-unicodedb.
-  # when build documentation on CI, git clone them as nimble is not available
-
-  const PkgDir = "build/deps"
-  const Pkgs = ["nim-regex", "nim-unicodedb"]
-
-  for n in Pkgs:
-    if not dirExists(PkgDir / n):
-      exec("git clone -q https://github.com/nitely/" & n & " " & (PkgDir / n))
-
-    switch("path", "$nim" / PkgDir / n / "src")
--- a/lib/std/packedsets.nim
+++ b/lib/std/packedsets.nim
@@ -294,11 +294,7 @@ proc containsOrIncl*[A](s: var PackedSet[A], key: A): bool =
    for i in 0..<s.elems:
      if s.a[i] == ord(key):
        return true
-    if s.elems < s.a.len:
-      s.a[s.elems] = ord(key)
-      inc(s.elems)
-    else:
-      incl(s, key)
+    incl(s, key)
    result = false
  else:
    var t = packedSetGet(s, ord(key) shr TrunkShift)
--- a/lib/std/strbasics.nim
+++ b/lib/std/strbasics.nim
@@ -84,7 +84,7 @@ func setSlice*(s: var string, slice: Slice[int]) =
      when not declared(moveMem):
        impl()
      else:
-        let p = beginStore(s, s.len)
+        let p = beginStore(s, last - first + 1)
        moveMem(p, addr p[first], last - first + 1)
        endStore(s)
  s.setLen(last - first + 1)
--- a/lib/std/syncio.nim
+++ b/lib/std/syncio.nim
@@ -485,7 +485,7 @@ proc readLine*(f: File, line: var string): bool {.tags: [ReadIOEffect],
    while true:
      # fixes #9634; this pattern may need to be abstracted as a template if reused;
      # likely other io procs need this for correctness.
-      fgetsSuccess = c_fgets(cast[cstring](beginStore(line, pos + sp, pos)), sp.cint, f) != nil
+      fgetsSuccess = c_fgets(cast[cstring](beginStore(line, sp, pos)), sp.cint, f) != nil
      endStore(line)
      if fgetsSuccess: break
      when not defined(nimscript):
--- a/lib/system.nim
+++ b/lib/system.nim
@@ -166,7 +166,7 @@ proc wasMoved*[T](obj: var T) {.magic: "WasMoved", noSideEffect.}
  ## it was "moved" and to signify its destructor should do nothing and
  ## ideally be optimized away.

-proc move*[T](x: var T): T {.magic: "Move", noSideEffect, nodestroy.} =
+proc move*[T](x: var T): T {.magic: "Move", noSideEffect.} =
  result = x
  {.cast(raises: []), cast(tags: []).}:
    `=wasMoved`(x)
@@ -1703,8 +1703,7 @@ when not (notJSnotNims and defined(nimSeqsV2)):
  # Needed so modules imported by system (e.g. syncio) can reference these without guards.
  when notJSnotNims:
    # mm:refc: string = ptr NimStringDesc with data: UncheckedArray[char]
-    proc beginStore*(s: var string; newLen: int; start = 0): ptr UncheckedArray[char] {.inline, noSideEffect, raises: [], tags: [].} =
-      {.cast(noSideEffect).}: s.setLen(newLen)
+    proc beginStore*(s: var string; ensuredLen: int; start = 0): ptr UncheckedArray[char] {.inline, noSideEffect, raises: [], tags: [].} =
      let ns = cast[NimString](s)
      if ns == nil: nil
      else: cast[ptr UncheckedArray[char]](addr ns.data[start])
@@ -1715,7 +1714,7 @@ when not (notJSnotNims and defined(nimSeqsV2)):
      else: cast[ptr UncheckedArray[char]](addr ns.data[start])
  else:
    # JS/nimscript: callers are guarded by whenNotVmJsNims/when not defined(js)
-    proc beginStore*(s: var string; newLen: int; start = 0): ptr UncheckedArray[char] {.inline, noSideEffect, raises: [], tags: [].} = nil
+    proc beginStore*(s: var string; ensuredLen: int; start = 0): ptr UncheckedArray[char] {.inline, noSideEffect, raises: [], tags: [].} = nil
    proc endStore*(s: var string) {.inline, noSideEffect, raises: [], tags: [].} = discard
    template readRawData*(s: string; start = 0): ptr UncheckedArray[char] = nil

@@ -2419,33 +2418,6 @@ when notJSnotNims and hasAlloc:
  when not defined(nimV2):
    include "system/repr"

-func setLenUninit*(s: var string, newlen: Natural) {.nodestroy.} =
-  ## Sets the length of string `s` to `newlen`.
-  ## New slots will not be initialized.
-  ##
-  ## If the new length is smaller than the new length,
-  ## `s` will be truncated.
-  let n = max(newLen, 0)
-  when nimvm:
-    s.setLen(n)
-  else:
-    when notJSnotNims:
-      when defined(nimSeqsV2):
-        {.noSideEffect.}:
-          let str = unsafeAddr s
-          when defined(nimsso):
-            setLengthStrV3Uninit(cast[ptr SmallString](str)[], newlen)
-          else:
-            setLengthStrV2Uninit(cast[ptr NimStringV2](str)[], newlen)
-      else:
-        {.noSideEffect.}:
-          when hasAlloc:
-            setLengthStrUninit(s, newlen)
-          else:
-            s.setLen(n)
-    else: s.setLen(n)
-
-
 when notJSnotNims and hasThreadSupport and hostOS != "standalone":
  when not defined(nimPreviewSlimSystem):
    include "system/channels_builtin"
@@ -2694,9 +2666,7 @@ when hasAlloc or defined(nimscript):
    setLen(x, xl+item.len)
    var j = xl-1
    while j >= i:
-      when defined(nimsso):
-        x[j+item.len] = x[j]
-      elif defined(gcArc) or defined(gcOrc) or defined(gcYrc) or defined(gcAtomicArc):
+      when defined(gcArc) or defined(gcOrc) or defined(gcYrc) or defined(gcAtomicArc):
        x[j+item.len] = move x[j]
      else:
        shallowCopy(x[j+item.len], x[j])
--- a/lib/system/alloc.nim
+++ b/lib/system/alloc.nim
@@ -127,12 +127,11 @@ type
                             #  reaches dealloc while the source chunk is active.
                             # Instead, the receiving chunk gains the capacity and thus reserves space in the foreign chunk.
    acc: uint32              # Offset from data, used when there are no free cells available but the chunk is considered free.
-    foreignCells: int32      # When a free cell is given to a chunk that is not its origin,
+    foreignCells: int        # When a free cell is given to a chunk that is not its origin,
                             #  both the cell and the source chunk are considered foreign.
                             # Receiving a foreign cell can happen both when deallocating from another thread or when
                             #  the active chunk in `a.freeSmallChunks` is not the current chunk.
                             # Freeing a chunk while `foreignCells > 0` leaks memory as all references to it become lost.
-    chunkAlignOff: int32     # Byte offset from `data` where cells begin. Non-zero for alignment > MemAlign.
    data {.align: MemAlign.}: UncheckedArray[byte]      # start of usable memory

  BigChunk = object of BaseChunk # not necessarily > PageSize!
@@ -473,8 +472,8 @@ iterator allObjects(m: var MemRegion): pointer {.inline.} =
          var c = cast[PSmallChunk](c)

          let size = c.size
-          var a = cast[int](addr(c.data)) + c.chunkAlignOff.int
-          let limit = cast[int](addr(c.data)) + c.acc.int
+          var a = cast[int](addr(c.data))
+          let limit = a + c.acc.int
          while a <% limit:
            yield cast[pointer](a)
            a = a +% size
@@ -691,7 +690,7 @@ proc getBigChunk(a: var MemRegion, size: int): PBigChunk =
    removeChunkFromMatrix2(a, result, fl, sl)
    if result.size >= size + PageSize:
      splitChunk(a, result, size)
-  # set 'used' to true:
+  # set 'used' to to true:
  result.prevSize = 1
  track("setUsedToFalse", addr result.size, sizeof(int))
  sysAssert result.owner == addr a, "getBigChunk: No owner set!"
@@ -708,7 +707,7 @@ proc getHugeChunk(a: var MemRegion; size: int): PBigChunk =
  result.next = nil
  result.prev = nil
  result.size = size
-  # set 'used' to true:
+  # set 'used' to to true:
  result.prevSize = 1
  result.owner = addr a
  incl(a, a.chunkStarts, pageIndex(result))
@@ -852,15 +851,6 @@ when defined(heaptrack):
  proc heaptrack_malloc(a: pointer, size: int) {.cdecl, importc, dynlib: heaptrackLib.}
  proc heaptrack_free(a: pointer) {.cdecl, importc, dynlib: heaptrackLib.}

-proc smallChunkAlignOffset(alignment: int): int {.inline.} =
-  ## Compute the initial data offset so that data + result + sizeof(FreeCell)
-  ## is alignment-aligned within a page-aligned small chunk.
-  if alignment <= MemAlign:
-    result = 0
-  else:
-    result = align(smallChunkOverhead() + sizeof(FreeCell), alignment) -
-             smallChunkOverhead() - sizeof(FreeCell)
-
 proc bigChunkAlignOffset(alignment: int): int {.inline.} =
  ## Compute the alignment offset for big chunk data.
  if alignment == 0:
@@ -873,13 +863,14 @@ proc rawAlloc(a: var MemRegion, requestedSize: int, alignment: int = 0): pointer
    inc(a.allocCounter)
  sysAssert(allocInv(a), "rawAlloc: begin")
  sysAssert(roundup(65, 8) == 72, "rawAlloc: roundup broken")
-  var size = roundup(requestedSize, max(MemAlign, alignment))
-  let alignOff = smallChunkAlignOffset(alignment)
+  var size = roundup(requestedSize, MemAlign)
  sysAssert(size >= sizeof(FreeCell), "rawAlloc: requested size too small")
  sysAssert(size >= requestedSize, "insufficient allocated size!")
  #c_fprintf(stdout, "alloc; size: %ld; %ld\n", requestedSize, size)

-  if size + alignOff <= SmallChunkSize-smallChunkOverhead():
+  # For custom alignments > MemAlign, force big chunk allocation
+  # Small chunks cannot handle arbitrary alignments due to fixed cell boundaries
+  if size <= SmallChunkSize-smallChunkOverhead() and alignment == 0:
    template fetchSharedCells(tc: PSmallChunk) =
      # Consumes cells from (potentially) foreign threads from `a.sharedFreeLists[s]`
      when defined(gcDestructors):
@@ -897,19 +888,16 @@ proc rawAlloc(a: var MemRegion, requestedSize: int, alignment: int = 0): pointer
    # allocate a small block: for small chunks, we use only its next pointer
    let s = size div MemAlign
    var c = a.freeSmallChunks[s]
-    if c != nil and c.chunkAlignOff != alignOff.int32:
-      c = nil
    if c == nil:
      # There is no free chunk of the requested size available, we need a new one.
      c = getSmallChunk(a)
      # init all fields in case memory didn't get zeroed
      c.freeList = nil
      c.foreignCells = 0
-      c.chunkAlignOff = alignOff.int32
      sysAssert c.size == PageSize, "rawAlloc 3"
      c.size = size
-      c.acc = (alignOff + size).uint32
-      c.free = SmallChunkSize - smallChunkOverhead() - alignOff.int32 - size.int32
+      c.acc = size.uint32
+      c.free = SmallChunkSize - smallChunkOverhead() - size.int32
      sysAssert c.owner == addr(a), "rawAlloc: No owner set!"
      c.next = nil
      c.prev = nil
@@ -920,7 +908,7 @@ proc rawAlloc(a: var MemRegion, requestedSize: int, alignment: int = 0): pointer
        # Because removals from `a.freeSmallChunks[s]` only happen in the other alloc branch and during dealloc,
        #  we must not add it to the list if it cannot be used the next time a pointer of `size` bytes is needed.
        listAdd(a.freeSmallChunks[s], c)
-      result = addr(c.data) +! alignOff
+      result = addr(c.data)
      sysAssert((cast[int](result) and (MemAlign-1)) == 0, "rawAlloc 4")
    else:
      # There is a free chunk of the requested size available, use it.
@@ -962,7 +950,7 @@ proc rawAlloc(a: var MemRegion, requestedSize: int, alignment: int = 0): pointer
        sysAssert(allocInv(a), "rawAlloc: before listRemove test")
        listRemove(a.freeSmallChunks[s], c)
        sysAssert(allocInv(a), "rawAlloc: end listRemove test")
-    sysAssert(((cast[int](result) and PageMask) - smallChunkOverhead() - c.chunkAlignOff) %%
+    sysAssert(((cast[int](result) and PageMask) - smallChunkOverhead()) %%
               size == 0, "rawAlloc 21")
    sysAssert(allocInv(a), "rawAlloc: end small size")
    inc a.occ, size
@@ -1030,7 +1018,7 @@ proc rawDealloc(a: var MemRegion, p: pointer) =
      dec a.occ, s
      untrackSize(s)
      sysAssert a.occ >= 0, "rawDealloc: negative occupied memory (case A)"
-      sysAssert(((cast[int](p) and PageMask) - smallChunkOverhead() - c.chunkAlignOff) %%
+      sysAssert(((cast[int](p) and PageMask) - smallChunkOverhead()) %%
                s == 0, "rawDealloc 3")
      when not defined(gcDestructors):
        #echo("setting to nil: ", $cast[int](addr(f.zeroField)))
@@ -1041,8 +1029,7 @@ proc rawDealloc(a: var MemRegion, p: pointer) =
        nimSetMem(cast[pointer](cast[int](p) +% sizeof(FreeCell)), -1'i32,
                s -% sizeof(FreeCell))
      let activeChunk = a.freeSmallChunks[s div MemAlign]
-      if activeChunk != nil and c != activeChunk and
-          activeChunk.chunkAlignOff == c.chunkAlignOff:
+      if activeChunk != nil and c != activeChunk:
        # This pointer is not part of the active chunk, lend it out
        #  and do not adjust the current chunk (same logic as compensateCounters.)
        # Put the cell into the active chunk,
@@ -1089,7 +1076,7 @@ proc rawDealloc(a: var MemRegion, p: pointer) =

      when defined(gcDestructors):
        addToSharedFreeList(c, f, s div MemAlign)
-    sysAssert(((cast[int](p) and PageMask) - smallChunkOverhead() - c.chunkAlignOff) %%
+    sysAssert(((cast[int](p) and PageMask) - smallChunkOverhead()) %%
               s == 0, "rawDealloc 2")
  else:
    # set to 0xff to check for usage after free bugs:
@@ -1115,11 +1102,8 @@ when not defined(gcDestructors):
          var c = cast[PSmallChunk](c)
          var offset = (cast[int](p) and (PageSize-1)) -%
                      smallChunkOverhead()
-          if c.acc.int >% offset:
-            let ao = c.chunkAlignOff.int
-            result = (offset >= ao) and
-              ((offset -% ao) %% c.size == 0) and
-              (cast[ptr FreeCell](p).zeroField >% 1)
+          result = (c.acc.int >% offset) and (offset %% c.size == 0) and
+            (cast[ptr FreeCell](p).zeroField >% 1)
        else:
          var c = cast[PBigChunk](c)
          # prev stores the aligned data pointer set during rawAlloc
@@ -1138,12 +1122,11 @@ when not defined(gcDestructors):
          var c = cast[PSmallChunk](c)
          var offset = (cast[int](p) and (PageSize-1)) -%
                      smallChunkOverhead()
-          let ao = c.chunkAlignOff.int
-          if c.acc.int >% offset and offset >= ao:
+          if c.acc.int >% offset:
            sysAssert(cast[int](addr(c.data)) +% offset ==
                      cast[int](p), "offset is not what you think it is")
            var d = cast[ptr FreeCell](cast[int](addr(c.data)) +%
-                      ao +% ((offset -% ao) -% ((offset -% ao) %% c.size)))
+                      offset -% (offset %% c.size))
            if d.zeroField >% 1:
              result = d
              sysAssert isAllocatedPtr(a, result), " result wrong pointer!"
@@ -1274,20 +1257,6 @@ template instantiateForRegion(allocator: untyped) {.dirty.} =
  proc alloc0Impl(size: Natural): pointer =
    result = alloc0(allocator, size)

-  when defined(gcOrc) or defined(gcYrc):
-    proc nimAlignedAlloc0(size: Natural, alignment: int): pointer =
-      incStat(allocCount)
-      result = rawAlloc(allocator, size, alignment)
-      zeroMem(result, size)
-
-    proc nimAlignedAlloc(size: Natural, alignment: int): pointer =
-      incStat(allocCount)
-      result = rawAlloc(allocator, size, alignment)
-
-    proc nimAlignedDealloc(p: pointer) =
-      incStat(deallocCount)
-      rawDealloc(allocator, p)
-
  proc deallocImpl(p: pointer) =
    dealloc(allocator, p)

--- a/lib/system/arc.nim
+++ b/lib/system/arc.nim
@@ -92,27 +92,12 @@ else:
 when not defined(nimHasQuirky):
  {.pragma: quirky.}

-# Forward declarations for native allocator alignment (implemented in alloc.nim).
-# rawAlloc's contract: result + sizeof(FreeCell) is alignment-aligned.
-# For ORC/YRC, sizeof(FreeCell) == sizeof(RefHeader).
-const useNativeAlignedAlloc = (defined(gcOrc) or defined(gcYrc)) and
-  not defined(useMalloc) and not defined(nimscript) and
-  not defined(nimdoc) and not defined(useNimRtl)
-
-when useNativeAlignedAlloc:
-  proc nimAlignedAlloc0(size: Natural, alignment: int): pointer {.gcsafe, raises: [].}
-  proc nimAlignedAlloc(size: Natural, alignment: int): pointer {.gcsafe, raises: [].}
-  proc nimAlignedDealloc(p: pointer) {.gcsafe, raises: [].}
-
 proc nimNewObj(size, alignment: int): pointer {.compilerRtl.} =
-  when defined(nimscript) or defined(nimdoc):
+  let hdrSize = align(sizeof(RefHeader), alignment)
+  let s = size +% hdrSize
+  when defined(nimscript):
    discard
-  elif useNativeAlignedAlloc:
-    let s = size +% sizeof(RefHeader)
-    result = nimAlignedAlloc0(s, alignment) +! sizeof(RefHeader)
  else:
-    let hdrSize = align(sizeof(RefHeader), alignment)
-    let s = size +% hdrSize
    result = alignedAlloc0(s, alignment) +! hdrSize
  when defined(nimArcDebug) or defined(nimArcIds):
    head(result).refId = gRefId
@@ -126,14 +111,12 @@ proc nimNewObj(size, alignment: int): pointer {.compilerRtl.} =

 proc nimNewObjUninit(size, alignment: int): pointer {.compilerRtl.} =
  # Same as 'newNewObj' but do not initialize the memory to zero.
-  when defined(nimscript) or defined(nimdoc):
+  # The codegen proved for us that this is not necessary.
+  let hdrSize = align(sizeof(RefHeader), alignment)
+  let s = size + hdrSize
+  when defined(nimscript):
    discard
-  elif useNativeAlignedAlloc:
-    let s = size + sizeof(RefHeader)
-    result = cast[ptr RefHeader](nimAlignedAlloc(s, alignment) +! sizeof(RefHeader))
  else:
-    let hdrSize = align(sizeof(RefHeader), alignment)
-    let s = size + hdrSize
    result = cast[ptr RefHeader](alignedAlloc(s, alignment) +! hdrSize)
  head(result).rc = 0
  when defined(gcOrc) or defined(gcYrc):
@@ -206,11 +189,8 @@ proc nimRawDispose(p: pointer, alignment: int) {.compilerRtl.} =
      if freedCells.data == nil: init(freedCells)
      freedCells.incl head(p)
    else:
-      when useNativeAlignedAlloc:
-        nimAlignedDealloc(p -! sizeof(RefHeader))
-      else:
-        let hdrSize = align(sizeof(RefHeader), alignment)
-        alignedDealloc(p -! hdrSize, alignment)
+      let hdrSize = align(sizeof(RefHeader), alignment)
+      alignedDealloc(p -! hdrSize, alignment)

 template `=dispose`*[T](x: owned(ref T)) = nimRawDispose(cast[pointer](x), T.alignOf)
 #proc dispose*(x: pointer) = nimRawDispose(x)
--- a/lib/system/gc_common.nim
+++ b/lib/system/gc_common.nim
@@ -143,7 +143,7 @@ when nimCoroutines:

  proc find(first: var GcStack, bottom: pointer): ptr GcStack =
    ## Find stack struct based on bottom pointer. If `bottom` is nil then main
-    ## thread stack is returned.
+    ## thread stack is is returned.
    if bottom == nil:
      return addr(gch.stack)

--- a/lib/system/indices.nim
+++ b/lib/system/indices.nim
@@ -59,35 +59,16 @@ template `[]=`*(s: string; i: int; val: char) = arrPut(s, i, val)
 template `^^`(s, i: untyped): untyped =
  (when i is BackwardsIndex: s.len - int(i) else: int(i))

-template spliceStringImpl(s, a, L, b: typed): untyped =
+template spliceImpl(s, a, L, b: typed): untyped =
  # make room for additional elements or cut:
  var shift = b.len - max(0,L)  # ignore negative slice size
  var newLen = s.len + shift
  if shift > 0:
    # enlarge:
    setLen(s, newLen)
-    for i in countdown(newLen-1, a+b.len):
-      s[i] = s[i-shift]
+    for i in countdown(newLen-1, a+b.len): movingCopy(s[i], s[i-shift])
  else:
-    for i in countup(a+b.len, newLen-1):
-      s[i] = s[i-shift]
-    # cut down:
-    setLen(s, newLen)
-  # fill the hole:
-  for i in 0 ..< b.len: s[a+i] = b[i]
-
-template spliceSeqImpl(s, a, L, b: typed): untyped =
-  # make room for additional elements or cut:
-  var shift = b.len - max(0,L)  # ignore negative slice size
-  var newLen = s.len + shift
-  if shift > 0:
-    # enlarge:
-    setLen(s, newLen)
-    for i in countdown(newLen-1, a+b.len):
-      movingCopy(s[i], s[i-shift])
-  else:
-    for i in countup(a+b.len, newLen-1):
-      movingCopy(s[i], s[i-shift])
+    for i in countup(a+b.len, newLen-1): movingCopy(s[i], s[i-shift])
    # cut down:
    setLen(s, newLen)
  # fill the hole:
@@ -121,7 +102,7 @@ proc `[]=`*[T, U: Ordinal](s: var string, x: HSlice[T, U], b: string) {.systemRa
  if L == b.len:
    for i in 0..<L: s[i+a] = b[i]
  else:
-    spliceStringImpl(s, a, L, b)
+    spliceImpl(s, a, L, b)

 proc `[]`*[Idx, T; U, V: Ordinal](a: array[Idx, T], x: HSlice[U, V]): seq[T] {.systemRaisesDefect.} =
  ## Slice operation for arrays.
@@ -181,4 +162,4 @@ proc `[]=`*[T; U, V: Ordinal](s: var seq[T], x: HSlice[U, V], b: openArray[T]) {
  if L == b.len:
    for i in 0 ..< L: s[i+a] = b[i]
  else:
-    spliceSeqImpl(s, a, L, b)
+    spliceImpl(s, a, L, b)
--- a/lib/system/seqs_v2.nim
+++ b/lib/system/seqs_v2.nim
@@ -262,11 +262,8 @@ proc setLen[T](s: var seq[T], newlen: Natural) {.nodestroy.} =
        if xu.p == nil or (xu.p.cap and not strlitFlag) < newlen:
          xu.p = cast[typeof(xu.p)](prepareSeqAddUninit(oldLen, xu.p, newlen - oldLen, sizeof(T), alignof(T)))
        xu.len = newlen
-
-        {.push overflowChecks: off.}
        for i in oldLen..<newlen:
          xu.p.data[i] = default(T)
-        {.pop.}

 proc newSeq[T](s: var seq[T], len: Natural) =
  shrink(s, 0)
--- a/lib/system/strs_v2.nim
+++ b/lib/system/strs_v2.nim
@@ -158,26 +158,6 @@ proc setLengthStrV2(s: var NimStringV2, newLen: int) {.compilerRtl.} =
    s.p.data[newLen] = '\0'
  s.len = newLen

-proc setLengthStrV2Uninit(s: var NimStringV2, newLen: int) =
-  if newLen == 0:
-    discard "do not free the buffer here, pattern 's.setLen 0' is common for avoiding allocations"
-  else:
-    if isLiteral(s):
-      let oldP = s.p
-      s.p = allocPayload(newLen)
-      s.p.cap = newLen
-      if s.len > 0:
-        copyMem(unsafeAddr s.p.data[0], unsafeAddr oldP.data[0], min(s.len, newLen))
-      s.p.data[newLen] = '\0'
-    elif newLen > s.len:
-      let oldCap = s.p.cap and not strlitFlag
-      if newLen > oldCap:
-        let newCap = max(newLen, resize(oldCap))
-        s.p = reallocPayload0(s.p, oldCap, newCap)
-        s.p.cap = newCap
-    s.p.data[newLen] = '\0'
-  s.len = newLen
-
 proc nimAsgnStrV2(a: var NimStringV2, b: NimStringV2) {.compilerRtl.} =
  if a.p == b.p and a.len == b.len: return
  if isLiteral(b):
@@ -236,17 +216,13 @@ func capacity*(self: string): int {.inline.} =
  let str = cast[ptr NimStringV2](unsafeAddr self)
  result = if str.p != nil: str.p.cap and not strlitFlag else: 0

-proc beginStore*(s: var string; newLen: int; start = 0): ptr UncheckedArray[char] {.inline, noSideEffect, raises: [], tags: [].} =
-  ## Sets s.len to `newLen` (new bytes are uninitialized), ensures unique
-  ## ownership, and returns a pointer to s[start] for bulk writing.
+proc beginStore*(s: var string; ensuredLen: int; start = 0): ptr UncheckedArray[char] {.inline, noSideEffect, raises: [], tags: [].} =
+  ## Returns a writable pointer for bulk write of `ensuredLen` bytes starting at `start`.
  ## Call `endStore(s)` afterwards for portability.
-  ## To keep the current length, pass `s.len`.
-  {.cast(noSideEffect).}:
-    let p = cast[ptr NimStringV2](addr s)
-    setLengthStrV2Uninit(p[], newLen)
-    prepareMutation(s)
-    if p.p == nil: nil
-    else: cast[ptr UncheckedArray[char]](addr p.p.data[start])
+  {.cast(noSideEffect).}: prepareMutation(s)
+  let str = cast[ptr NimStringV2](unsafeAddr s)
+  if str.p == nil: nil
+  else: cast[ptr UncheckedArray[char]](addr str.p.data[start])

 proc endStore*(s: var string) {.inline, noSideEffect, raises: [], tags: [].} =
  ## No-op for non-SSO strings; call after bulk writes via `beginStore`.
--- a/lib/system/strs_v3.nim
+++ b/lib/system/strs_v3.nim
@@ -224,14 +224,13 @@ proc cmpStringPtrs(a, b: ptr SmallString): int {.inline.} =
        minLen - AlwaysAvail)
    if result == 0: result = aslen - bslen
    return
-  # At least one is long. Hot prefix mirrors heap data, but only up to fullLen:
-  # shrinking can leave stale bytes in the inline cache past the logical length.
+  # At least one is long. Hot prefix: inlinePtr[0..AlwaysAvail-1] mirrors heap data.
+  let pfxLen = min(min(aslen, bslen), AlwaysAvail)
+  result = cmpInlineBytes(inlinePtrOf(a), inlinePtrOf(b), pfxLen)
+  if result != 0: return
  let la = if aslen > PayloadSize: a.more.fullLen else: aslen
  let lb = if bslen > PayloadSize: b.more.fullLen else: bslen
  let minLen = min(la, lb)
-  let pfxLen = min(minLen, AlwaysAvail)
-  result = cmpInlineBytes(inlinePtrOf(a), inlinePtrOf(b), pfxLen)
-  if result != 0: return
  if minLen <= AlwaysAvail:
    result = la - lb
    return
@@ -497,75 +496,28 @@ proc mnewString(len: int): SmallString {.compilerproc.} =
    result.more = p
    setSSLen(result, HeapSlen)

-proc setLengthStr(s: var SmallString; newLen: int; zeroing: bool) =
-  # Shared implementation for setLengthStrV2 (zeroing) and setLengthStrV3Uninit
-  # Difference between the two modes:
-  #   - inline/medium -> long growth: alloc0 (zeroing) vs alloc (uninit)
-  #   - long -> long growth: zeroMem the new tail (zeroing) or skip it (uninit)
+proc setLengthStrV2(s: var SmallString; newLen: int) {.compilerRtl.} =
+  ## Sets the length of s to newLen, zeroing new bytes on growth.
  let slen = ssLen(s)
  let curLen = if slen > PayloadSize: s.more.fullLen else: slen
  if newLen == curLen: return
-  if newLen < curLen:
-    # Shrinking:
+  if newLen <= 0:
    if slen > PayloadSize:
      if slen == HeapSlen and s.more.rc == 1:
-        # Unique heap block: keep the buffer allocated to avoid alloc/dealloc
-        # ping-pong when callers shrink then grow (e.g. setLen(0) + add loops).
-        s.more.fullLen = newLen
-        s.more.data[newLen] = '\0'
+        s.more.fullLen = 0
+        s.more.data[0] = '\0'
      else:
-        # shared or static block: detach and go back to inline
-        if newLen <= 0:
-          nimDestroyStrV1(s)
-          s.bytes = 0
-        else:
-          let old = s.more
-          let inl = inlinePtr(s)
-          copyMem(inl, addr old.data[0], newLen)
-          inl[newLen] = '\0'
-          if slen == HeapSlen and atomicSubFetch(old.rc, 1) == 0:
-            dealloc(old)
-          if newLen < AlwaysAvail:
-            when system.cpuEndian == littleEndian:
-              let keepBits = (newLen + 1) * 8
-              let charMask = ((uint(1) shl keepBits) - 1'u) and not 0xFF'u
-              s.bytes = (s.bytes and charMask) or uint(newLen)
-            else:
-              let discardBits = (AlwaysAvail - newLen) * 8
-              let slenBit = 8 * (sizeof(uint) - 1)
-              let charMask = not ((uint(1) shl discardBits) - 1'u) and not (0xFF'u shl slenBit)
-              s.bytes = (s.bytes and charMask) or (uint(newLen) shl slenBit)
-          else:
-            setSSLen(s, newLen)
+        # shared or static block: detach and go back to empty inline
+        nimDestroyStrV1(s)
+        s.bytes = 0  # slen=0, all inline chars zeroed
    else:
-      # inline/medium shrink
-      if newLen <= 0:
-        s.bytes = 0
-      else:
-        let inl = inlinePtr(s)
-        inl[newLen] = '\0'
-        if newLen < AlwaysAvail:
-          when system.cpuEndian == littleEndian:
-            let keepBits = (newLen + 1) * 8
-            let charMask = ((uint(1) shl keepBits) - 1'u) and not 0xFF'u
-            s.bytes = (s.bytes and charMask) or uint(newLen)
-          else:
-            let discardBits = (AlwaysAvail - newLen) * 8
-            let slenBit = 8 * (sizeof(uint) - 1)
-            let charMask = not ((uint(1) shl discardBits) - 1'u) and not (0xFF'u shl slenBit)
-            s.bytes = (s.bytes and charMask) or (uint(newLen) shl slenBit)
-        else:
-          setSSLen(s, newLen)
+      s.bytes = 0  # slen=0, all inline chars zeroed (SWAR safe)
    return
  if slen <= PayloadSize:
    if newLen <= PayloadSize:
      let inl = inlinePtr(s)
      if newLen > curLen:
-        # Grow within inline/medium
-        # Bytes above newLen already zero by the SWAR invariant,
-        # so setSSLen is sufficient.
-        if zeroing:
-          zeroMem(addr inl[curLen], newLen - curLen)
+        zeroMem(addr inl[curLen], newLen - curLen)
        inl[newLen] = '\0'
        setSSLen(s, newLen)
      else:
@@ -590,33 +542,43 @@ proc setLengthStr(s: var SmallString; newLen: int; zeroing: bool) =
    else:
      # grow into long
      let newCap = resize(newLen)
-      let p = if zeroing:
-          # bytes [curLen..newLen] and p.data[newLen] zeroed by alloc0
-          cast[ptr LongString](alloc0(LongStringDataOffset + newCap + 1))
-        else:
-          let p = cast[ptr LongString](alloc(LongStringDataOffset + newCap + 1))
-          p.data[newLen] = '\0'
-          p
+      let p = cast[ptr LongString](alloc0(LongStringDataOffset + newCap + 1))
      p.rc = 1
      p.fullLen = newLen
      p.capImpl = newCap
      copyMem(addr p.data[0], inlinePtr(s), curLen)
+      # bytes [curLen..newLen] zeroed by alloc0; p.data[newLen] = '\0' by alloc0
      s.more = p
      setSSLen(s, HeapSlen)
  else:
-    # currently long: grow within the heap buffer (shrinking already returned above)
-    ensureUniqueLong(s, curLen, newLen) # sets fullLen = newLen
-    if zeroing and newLen > curLen:
-      zeroMem(addr s.more.data[curLen], newLen - curLen)
-    s.more.data[newLen] = '\0'
-
-proc setLengthStrV2(s: var SmallString; newLen: int) {.compilerRtl.} =
-  ## Sets the length of `s` to `newLen`, zeroing new bytes on growth.
-  setLengthStr(s, newLen, zeroing = true)
-
-proc setLengthStrV3Uninit(s: var SmallString; newLen: int) {.compilerRtl.} =
-  ## Sets the length of `s` to `newLen`, NOT zeroing new bytes on growth.
-  setLengthStr(s, newLen, zeroing = false)
+    # currently long
+    if newLen <= PayloadSize:
+      # shrink back to inline
+      let old = s.more
+      let inl = inlinePtr(s)
+      copyMem(inl, addr old.data[0], newLen)
+      inl[newLen] = '\0'
+      if slen == HeapSlen and atomicSubFetch(old.rc, 1) == 0:
+        dealloc(old)
+      # Zero padding bytes in `bytes` for SWAR invariant
+      if newLen < AlwaysAvail:
+        when system.cpuEndian == littleEndian:
+          let keepBits = (newLen + 1) * 8
+          let charMask = ((uint(1) shl keepBits) - 1'u) and not 0xFF'u
+          s.bytes = (s.bytes and charMask) or uint(newLen)
+        else:
+          let discardBits = (AlwaysAvail - newLen) * 8
+          let slenBit = 8 * (sizeof(uint) - 1)
+          let charMask = not ((uint(1) shl discardBits) - 1'u) and not (0xFF'u shl slenBit)
+          s.bytes = (s.bytes and charMask) or (uint(newLen) shl slenBit)
+      else:
+        setSSLen(s, newLen)
+    else:
+      ensureUniqueLong(s, curLen, newLen)
+      if newLen > curLen:
+        zeroMem(addr s.more.data[curLen], newLen - curLen)
+      s.more.data[newLen] = '\0'
+      s.more.fullLen = newLen

 proc nimAsgnStrV2(a: var SmallString; b: SmallString) {.compilerRtl, inline.} =
  if ssLen(b) <= PayloadSize:
@@ -722,37 +684,18 @@ proc completeStore(s: var SmallString) {.compilerproc, inline.} =
 proc completeStore*(s: var string) {.inline.} =
  completeStore(cast[ptr SmallString](addr s)[])

-proc beginStore*(s: var string; newLen: int; start = 0): ptr UncheckedArray[char] {.inline, noSideEffect, raises: [], tags: [].} =
-  ## Sets s.len to `newLen` (new bytes are uninitialized), ensures unique
-  ## ownership, and returns a pointer to s[start] for bulk writing.
+proc beginStore*(s: var string; ensuredLen: int; start = 0): ptr UncheckedArray[char] {.inline, noSideEffect, raises: [], tags: [].} =
+  ## Prepares `s` for a bulk write of `ensuredLen` bytes starting at `start`.
+  ## The caller must ensure `s.len >= start + ensuredLen` (e.g. via `newString` or `setLen`).
  ## Call `endStore(s)` afterwards to sync the inline cache.
-  ## To keep the current length, pass `s.len`.
  {.cast(noSideEffect).}:
    let ss = cast[ptr SmallString](addr s)
    let slen = ssLen(ss[])
-    let curLen = if slen > PayloadSize: ss[].more.fullLen else: slen
-    if newLen <= PayloadSize and slen <= PayloadSize:
-      # Stay inline/medium.
-      if newLen != curLen:
-        setSSLen(ss[], newLen)
-      result = cast[ptr UncheckedArray[char]](cast[uint](inlinePtr(ss[])) + uint(start))
-    elif slen <= PayloadSize:
-      # Inline/medium → long.
-      let newCap = resize(newLen)
-      let p = cast[ptr LongString](alloc(LongStringDataOffset + newCap + 1))
-      p.rc = 1
-      p.fullLen = newLen
-      p.capImpl = newCap
-      copyMem(addr p.data[0], inlinePtr(ss[]), curLen)
-      p.data[newLen] = '\0'
-      ss[].more = p
-      setSSLen(ss[], HeapSlen)
+    if slen > PayloadSize:
+      ensureUniqueLong(ss[], ss[].more.fullLen, ss[].more.fullLen)
      result = cast[ptr UncheckedArray[char]](addr ss[].more.data[start])
    else:
-      # Already long: resize within heap (no transition back to inline).
-      ensureUniqueLong(ss[], curLen, newLen)
-      ss[].more.data[newLen] = '\0'
-      result = cast[ptr UncheckedArray[char]](addr ss[].more.data[start])
+      result = cast[ptr UncheckedArray[char]](cast[uint](inlinePtr(ss[])) + uint(start))

 proc endStore*(s: var string) {.inline, noSideEffect, raises: [], tags: [].} =
  ## Syncs the inline cache after bulk writes via `beginStore`. No-op for short/medium strings.
--- a/lib/system/sysstr.nim
+++ b/lib/system/sysstr.nim
@@ -244,31 +244,6 @@ proc setLengthStr(s: NimString, newLen: int): NimString {.compilerRtl.} =
  result.len = n
  result.data[n] = '\0'

-proc setLengthStrUninit(s: var string, newlen: Natural) {.nodestroy.} =
-  ## Sets the `s` length to `newlen` without zeroing memory on growth.
-  ## Terminating zero for cstring compatibility is set.
-  var str = cast[NimString](s)
-  let n = max(newLen, 0)
-  if str == nil:
-    if n == 0: return
-    else:
-      str = rawNewStringNoInit(n)
-      str.data[n] = '\0'
-      str.len = n
-      s = cast[string](str)
-  else:
-    if n > str.space:
-      let sp = max(resize(str.space), n)
-      str = rawNewStringNoInit(sp)
-      copyMem(addr str.data[0], unsafeAddr s[0], s.len)
-      str.data[n] = '\0'
-      str.len = n
-      s = cast[string](str)
-    elif n != s.len:
-      str.data[n] = '\0'
-      str.len = n
-    else: return
-
 # ----------------- sequences ----------------------------------------------

 proc incrSeq(seq: PGenericSeq, elemSize, elemAlign: int): PGenericSeq {.compilerproc.} =
@@ -299,22 +274,12 @@ proc incrSeqV3(s: PGenericSeq, typ: PNimType): PGenericSeq {.compilerproc.} =
      # since we steal the content from 's', it's crucial to set s's len to 0.
      s.len = 0

-proc newSeqUninitRaw(typ: PNimType; len: int): pointer {.inline.} =
-  ## Creates a sequence payload with capacity and length `len` without
-  ## forcing zero-initialization for `ntfNoRefs` element types.
-  result = nimNewSeqOfCap(typ, len)
-  cast[PGenericSeq](result).len = len
-
 proc extendCapacityRaw(src: PGenericSeq; typ: PNimType;
-                      elemSize, elemAlign, newLen: int;
-                      doInit: static bool): PGenericSeq {.inline.} =
+                      elemSize, elemAlign, newLen: int): PGenericSeq {.inline.} =
  ## Reallocs `src` to fit `newLen` elements without any checks.
  ## Capacity always increases to at least next `resize` step.
  let newCap = max(resize(src.space), newLen)
-  when doInit:
-    result = cast[PGenericSeq](newSeq(typ, newCap))
-  else:
-    result = cast[PGenericSeq](newSeqUninitRaw(typ, newCap))
+  result = cast[PGenericSeq](newSeq(typ, newCap))
  copyMem(dataPointer(result, elemAlign), dataPointer(src, elemAlign), src.len * elemSize)
  # since we steal the content from 's', it's crucial to set s's len to 0.
  src.len = 0
@@ -345,19 +310,15 @@ proc truncateRaw(src: PGenericSeq; baseFlags: set[TNimTypeFlag]; isTrivial: bool
            ((result.len-%newLen) *% elemSize))

 template setLengthSeqImpl(s: PGenericSeq, typ: PNimType, newLen: int; isTrivial: bool;
-                          doInit: static bool) =
+                          doInit: static bool) = 
  if s == nil:
    if newLen == 0: return s
-    else:
-      when doInit:
-        return cast[PGenericSeq](newSeq(typ, newLen)) # newSeq zeroes!
-      else:
-        return cast[PGenericSeq](newSeqUninitRaw(typ, newLen))
+    else: return cast[PGenericSeq](newSeq(typ, newLen)) # newSeq zeroes!
  else:
    let elemSize = typ.base.size
    let elemAlign = typ.base.align
    result = if newLen > s.space:
-        s.extendCapacityRaw(typ, elemSize, elemAlign, newLen, doInit)
+        s.extendCapacityRaw(typ, elemSize, elemAlign, newLen)
      elif newLen < s.len:
        s.truncateRaw(typ.base.flags, isTrivial, elemSize, elemAlign, newLen)
      else:
--- a/nimsuggest/nimsuggest.nim
+++ b/nimsuggest/nimsuggest.nim
@@ -1042,7 +1042,7 @@ proc iterateOutlineNodes(graph: ModuleGraph, n: PNode, infoPairs: SuggestFileSym
    if symData != nil and symData.sym.kind == skEnumField and symData.info.exactEquals(symData.sym.info):
       let sym = symData.sym
       graph.suggestResult(sym, sym.info, ideOutline, n.endInfo.line, n.endInfo.col)
-  elif (n.kind in {nkFuncDef, nkProcDef, nkMethodDef, nkIteratorDef, nkTypeDef, nkMacroDef, nkTemplateDef, nkConverterDef, nkEnumFieldDef, nkConstDef}):
+  elif (n.kind in {nkFuncDef, nkProcDef, nkTypeDef, nkMacroDef, nkTemplateDef, nkConverterDef, nkEnumFieldDef, nkConstDef}):
    matched = handleIdentOrSym(graph, n, n.endInfo, infoPairs)
  else:
    matched = false
--- a/nimsuggest/tests/tv3_outline.nim
+++ b/nimsuggest/tests/tv3_outline.nim
@@ -36,9 +36,7 @@ outline	skType	tv3_outline.FooPrivate	FooPrivate	$file	7	2	""	100	8	22
 outline	skMacro	tv3_outline.m	macro (arg: untyped): untyped{.noSideEffect, gcsafe, raises: <inferred> [].}	$file	10	6	""	100	10	40
 outline	skTemplate	tv3_outline.t	template (arg: untyped): untyped	$file	11	9	""	100	11	43
 outline	skProc	tv3_outline.p	proc (){.noSideEffect, gcsafe, raises: <inferred> [].}	$file	12	5	""	100	12	24
-outline	skIterator	tv3_outline.i	iterator (): int{.inline, noSideEffect, gcsafe, raises: <inferred> [].}	$file	13	9	""	100	13	27
 outline	skConverter	tv3_outline.c	converter (s: string): int{.noSideEffect, gcsafe, raises: <inferred> [].}	$file	14	10	""	100	14	37
-outline	skMethod	tv3_outline.m	proc (f: Foo){.noSideEffect, gcsafe, raises: <inferred> [].}	$file	15	7	""	100	15	32
 outline	skFunc	tv3_outline.f	proc (){.noSideEffect, gcsafe, raises: <inferred> [].}	$file	16	5	""	100	16	24
 outline	skConst	tv3_outline.con	int literal(2)	$file	20	6	""	100	20	13
 outline	skProc	tv3_outline.outer	proc (){.noSideEffect, gcsafe, raises: <inferred> [].}	$file	22	5	""	100	23	24
--- a/readme.md
+++ b/readme.md
@@ -39,7 +39,7 @@ architecture combinations:
 |--------------------------------|----------------------------------------|
 | Windows (Windows XP or greater) | x86 and x86_64                             |
 | Linux (most distributions)     | x86, x86_64, ppc64, and armv6l             |
-| Mac OS X (10.4 or greater)     | x86, x86_64, ppc64, and Apple Silicon (ARM64) |
+| Mac OS X (10.04 or greater)    | x86, x86_64, ppc64, and Apple Silicon (ARM64) |

 More platforms are supported, however, they are not tested regularly and they
 may not be as stable as the above-listed platforms.
--- a/tests/align/talign_heap.nim
+++ b/tests/align/talign_heap.nim
@@ -1,23 +0,0 @@
-discard """
-  matrix: "--mm:refc; --mm:orc; --mm:arc"
-  targets: "c cpp"
-  output: "ok"
-"""
-
-# Test that heap-allocated objects with .align use small chunks,
-# not a big chunk per object (regression test for #25577).
-type U = object
-  d {.align: 32.}: int8
-
-var e: seq[ref U]
-for _ in 0 ..< 10000: e.add(new U)
-
-# Without small-chunk alignment, each object gets its own page (~46 MB).
-# With the fix, 10000 objects fit in ~1-3 MB depending on the GC.
-doAssert getTotalMem() < 8 * 1024 * 1024, "align:32 heap objects use too much memory"
-
-# Verify alignment is actually correct
-for i in 0 ..< e.len:
-  doAssert (cast[int](addr e[i].d) and 31) == 0, "field not 32-byte aligned"
-
-echo "ok"
--- a/tests/arc/tdistinct_for_nodup.nim
+++ b/tests/arc/tdistinct_for_nodup.nim
@@ -1,33 +0,0 @@
-discard """
-  cmd: '''nim c --mm:arc --expandArc:foo $file'''
-  nimout: '''
--expandArc: foo
-
-var broken_cursor
-block :tmp:
-  var i
-  var i_1 = 0
-  let L = len(seq[Large](broken_cursor))
-  block :tmp_1:
-    while i_1 < L:
-      i = seq[Large](broken_cursor)[i_1]
-      discard i
-      {.push, overflowChecks: false.}
-      inc(i_1, 1)
-      {.pop.}
-- end of expandArc ------------------------
-'''
-"""
-
-
-type
-  Large = array[1024, byte]
-  List = distinct seq[Large]
-
-proc foo =
-  var
-    broken: List
-  for i in seq[Large](broken):
-    discard i
-
-foo()
--- a/tests/arc/tnodestroyexplicithook2.nim
+++ b/tests/arc/tnodestroyexplicithook2.nim
@@ -1,45 +0,0 @@
-discard """
-  output: '''
-246
-246
-'''
-"""
-
-# issue #25730
-
-type
-  Inner[T] = object
-    x: T
-  Foo[T] = object
-    inner: Inner[T]
-  Bar[T] = object
-    foo: Foo[T]
-
-proc `=sink`[T](a: var Inner[T], b: Inner[T]) {.nodestroy.} =
-  a.x = b.x * 2
-
-proc `=copy`[T](a: var Inner[T], b: Inner[T]) {.nodestroy.} =
-  a.x = b.x * 2
-
-when true:
-  proc `=sink`[T](a: var Bar[T], b: Bar[T]) {.nodestroy.} =
-    `=sink`(a.foo, b.foo)
-
-  proc `=copy`[T](a: var Bar[T], b: Bar[T]) {.nodestroy.} =
-    `=copy`(a.foo, b.foo)
-
-proc useSink() =
-  let a = Bar[int](foo: Foo[int](inner: Inner[int](x: 123)))
-  var b: Bar[int]
-  `=sink`(b, a)
-  echo b.foo.inner.x
-
-useSink()
-
-proc useCopy() =
-  let a = Bar[int](foo: Foo[int](inner: Inner[int](x: 123)))
-  var b: Bar[int]
-  `=copy`(b, a)
-  echo b.foo.inner.x
-
-useCopy()
--- a/tests/ccgbugs2/m25294/c.nim
+++ b/tests/ccgbugs2/m25294/c.nim
@@ -1,13 +0,0 @@
-template a(T: type): int =
-  when T is uint64: 1 else: 2
-
-type
-  M*[T] = object
-    data*: seq[T]
-    b: seq[int]
-    indices*: array[a(T), int64]
-  U = distinct uint64
-  D* = object
-    c: M[U]
-    v: array[180000, int64]
-    g*: M[uint64]
--- a/tests/ccgbugs2/m25294/t.nim
+++ b/tests/ccgbugs2/m25294/t.nim
@@ -1,5 +0,0 @@
-import ./c
-
-proc p*(): D =
-  let c = M[uint64](data: @[0], indices: [1])
-  result = D(g: c)
--- a/tests/ccgbugs2/m25800.h
+++ b/tests/ccgbugs2/m25800.h
@@ -1,7 +0,0 @@
-/*TYPESECTION*/
-struct CppRef {
-  int* data;
-  CppRef() : data(new int(42)) {}
-  ~CppRef() { delete data; data = nullptr; }
-  void reset() { delete data; data = nullptr; }
-};
--- a/tests/ccgbugs2/t25294.nim
+++ b/tests/ccgbugs2/t25294.nim
@@ -1,18 +0,0 @@
-discard """
-  matrix: "--mm:refc; --mm:orc"
-"""
-
-import ./m25294/[c, t]
-
-block:
-  let a = new D
-  a[] = p()
-  discard a[]
-block:
-  let a = new D
-  a[] = p()
-  discard a[]
-block:
-  let a = new D
-  a[] = p()
-  discard a[]
--- a/tests/ccgbugs2/t25800.nim
+++ b/tests/ccgbugs2/t25800.nim
@@ -1,23 +0,0 @@
-discard """
-  cmd: "nim cpp $file"
-  action: "compile"
-"""
-
-# Bug Report 1: {.importcpp.} on =wasMoved generates invalid preprocessor directive #.
-
-
-type CppRef* {.importcpp, bycopy, noInit, header: "m25800.h".} = object
-
-proc `=destroy`(x: var CppRef) {.importcpp: "#.~CppRef()".}
-proc `=wasMoved`(x: var CppRef) {.importcpp: "#.reset()".}
-proc `=copy`(dest: var CppRef; src: CppRef) {.importcpp: "dest = src".}
-proc `=sink`(dest: var CppRef; src: CppRef) {.importcpp: "dest = std::move(src)".}
-
-# This triggers =wasMoved when passing to sink parameter
-proc consume(x: sink CppRef) = discard
-
-proc test() =
-  var x: CppRef
-  consume(move(x))  # =wasMoved MUST be called here after the move
-
-test()
--- a/tests/compiler/tcmdline_import_std_prefix.nim
+++ b/tests/compiler/tcmdline_import_std_prefix.nim
@@ -1,10 +0,0 @@
-discard """
-  matrix: "-d:nimPreviewSlimSystem --warning:StdPrefix:on --warningAsError:StdPrefix:on --import:std/objectdollar"
-  output: "(a: 23, b: 45)"
-"""
-
-type Foo = object
-  a, b: int
-
-let x = Foo(a: 23, b: 45)
-echo x
--- a/tests/concepts/tconcepts_issues.nim
+++ b/tests/concepts/tconcepts_issues.nim
@@ -176,42 +176,6 @@ block t6462:
  var s = SeqGen[int](fil: FilterMixin[int](test: nil, trans: nil))
  doAssert s.test() == nil

-block concept_with_cint:
-  # Generic proc matching through concepts with cint should still work
-  type
-    FilterMixin[T] = ref object
-      test: (T) -> bool
-      trans: (T) -> T
-
-    SeqGen[T] = ref object
-      fil: FilterMixin[T]
-
-    WithFilter[T] = concept a
-      a.fil is FilterMixin[T]
-
-  proc test[T](a: WithFilter[T]): (T) -> bool =
-    a.fil.test
-
-  var s = SeqGen[cint](fil: FilterMixin[cint](test: nil, trans: nil))
-  doAssert s.test() == nil
-
-block concept_with_int:
-  type
-    FilterMixin[T] = ref object
-      test: (T) -> bool
-      trans: (T) -> T
-
-    SeqGen[T] = ref object
-      fil: FilterMixin[T]
-
-    WithFilter[T] = concept a
-      a.fil is FilterMixin[T]
-
-  proc test[T](a: WithFilter[T]): (T) -> bool =
-    a.fil.test
-
-  var s = SeqGen[int](fil: FilterMixin[int](test: nil, trans: nil))
-  doAssert s.test() == nil


 block t6770:
--- a/tests/destructor/twasmoved.nim
+++ b/tests/destructor/twasmoved.nim
@@ -12,51 +12,3 @@ proc foo =
  doAssert m.id == 999

 foo()
-
-block:
-  type Foo = object
-    a,b,c: int
-
-  var dest: Foo
-
-  # proc `=wasMoved`(x: var Foo) =
-  #   debugEcho "wasMoved called"
-
-  proc main() =
-    var x = Foo(a:11, b:12, c:13)
-    dest = move(x)
-
-  main()
-
-block:
-  type Foo = object
-    a,b,c: int
-
-  var dest: Foo
-
-  proc `=wasMoved`(x: var Foo) =
-    discard "wasMoved called"
-
-  proc main() =
-    var x = Foo(a:11, b:12, c:13)
-    dest = move(x)
-
-  main()
-
-
-import std/threadpool
-
-block:
-  type Foo = object
-    data: string
-
-  proc `=wasMoved`(x: var Foo) =
-    discard
-
-  proc work(x: Foo) =
-    discard
-
-  var x = Foo(data: "hello")
-  spawn work(x)
-  sync()
-
--- a/tests/errmsgs/t25732.nim
+++ b/tests/errmsgs/t25732.nim
@@ -1,15 +0,0 @@
-discard """
-cmd: "nim check --hints:off $file"
-action: "reject"
-nimout: '''
-t25732.nim(15, 32) Error: undeclared identifier: 'a'
-t25732.nim(15, 32) Error: expression 'a' has no type (or is ambiguous)
-t25732.nim(15, 33) Error: undeclared field: 'b'
-t25732.nim(15, 33) Error: undeclared field: '.'
-t25732.nim(15, 33) Error: undeclared field: '.'
-'''
-"""
-
-
-
-static: (for f in [0]: discard a.b == f)
--- a/tests/errmsgs/tsso_string_index_var.nim
+++ b/tests/errmsgs/tsso_string_index_var.nim
@@ -1,13 +0,0 @@
-discard """
-  cmd: "nim check --strings:sso --mm:orc --hints:off $file"
-  action: "reject"
-  nimout: '''
-tsso_string_index_var.nim(13, 12) Error: expression 's[0]' is immutable, not 'var'
-'''
-"""
-
-proc passByVar(c: var char) =
-  c = 'x'
-
-var s = "abc"
-passByVar(s[0])
--- a/tests/exception/tcpp_handler_raise_finally.nim
+++ b/tests/exception/tcpp_handler_raise_finally.nim
@@ -1,61 +0,0 @@
-discard """
-  targets: "cpp"
-  matrix: "--mm:arc; --mm:orc; --mm:refc"
-  output: '''
-inner: orig
-finally
-outer: re:orig
-inner-typeless: orig
-finally-typeless
-outer-typeless: re-tl:orig
-no-catch-finally
-caught-propagated: prop
-'''
-"""
-
-# When an `except` handler raises a new exception, the enclosing `finally`
-# block must still run before the new exception propagates to the outer
-# try.
-#
-# The C++ backend previously emitted the finally's `catch (...)` as a
-# sibling of the user-written catches.  C++ does not allow sibling catches
-# to catch each other's throws, so a handler-raised exception bypassed the
-# finally entirely.  The fix wraps the inner try/catch sequence in an
-# outer try, so any escaping exception (whether from the body or from a
-# handler) is captured before the finally runs.
-
-block typed_except:
-  try:
-    try:
-      raise newException(CatchableError, "orig")
-    except CatchableError as e:
-      echo "inner: ", e.msg
-      raise newException(CatchableError, "re:" & e.msg)
-    finally:
-      echo "finally"
-  except CatchableError as outer:
-    echo "outer: ", outer.msg
-
-block typeless_except:
-  try:
-    try:
-      raise newException(CatchableError, "orig")
-    except:
-      let e = getCurrentException()
-      echo "inner-typeless: ", e.msg
-      raise newException(CatchableError, "re-tl:" & e.msg)
-    finally:
-      echo "finally-typeless"
-  except CatchableError as outer:
-    echo "outer-typeless: ", outer.msg
-
-# try/finally without an except: the body's exception must still propagate
-# after the finally runs.
-block no_catch_finally:
-  try:
-    try:
-      raise newException(CatchableError, "prop")
-    finally:
-      echo "no-catch-finally"
-  except CatchableError as e:
-    echo "caught-propagated: ", e.msg
--- a/tests/exception/tcpp_imported_exc.nim
+++ b/tests/exception/tcpp_imported_exc.nim
@@ -1,5 +1,5 @@
 discard """
-matrix: "--mm:refc; --mm:orc"
+matrix: "--mm:refc"
 targets: "cpp"
 output: '''
 caught as std::exception
--- a/tests/ic/tmiscs.nim
+++ b/tests/ic/tmiscs.nim
@@ -7,10 +7,8 @@ discard """
 1.0
 2.0
 55
-@[1, 2]
 '''
 """
-import std/strbasics

 # Object variant / case object
 type
@@ -81,14 +79,3 @@ let x = compute:

 echo x

-# Crash: bridge.nim(206, 5) `allowEmpty` unexpected nkEmpty [AssertionDefect]
-# Bare closure iterator type alias
-type IntIter = iterator(): int {.closure.}
-proc run(it: IntIter): seq[int] =
-  result = @[]
-  for x in it():
-    result.add(x)
-let gen: IntIter = iterator(): int {.closure.} =
-  yield 1
-  yield 2
-echo run(gen)
--- a/tests/iter/titer_issues.nim
+++ b/tests/iter/titer_issues.nim
@@ -239,17 +239,6 @@ block t2023_objiter:
  var o = init()
  echo(o.iter())

-  block: # bug #25591
-    iterator h(): int =
-      let n = 0
-      (proc() = discard n)()
-      yield 0
-
-    proc a() =
-      iterator m(): int {.closure.} = (for _ in h(): discard)
-      let _ = m
-
-    a()

 block:
  # bug #13739
@@ -468,12 +457,3 @@ let runes1 = buggyVersion("en")  # <-- CRASHES HERE

 doAssert runes1.len == runes2.len
 # echo "Got ", runes1.len, " runes"
-
-
-block: # bug #25724
-  iterator c(): int =
-    when nimvm: yield 0
-    else: yield 1
-  for w in c():
-    let n = w
-    (proc() = discard n)()
--- a/tests/js/test2.nim
+++ b/tests/js/test2.nim
@@ -4,12 +4,7 @@ js 3.14
 7
 1
 -21550
-21550
-none(TT)
-()
-destroyed
-destroyed
-'''
+-21550'''
 """

 # This file tests the JavaScript generator
@@ -61,15 +56,3 @@ proc foo09() =
    const y = 86400
    echo (x - (y - 1)) div y # Still gives `-21551`
 foo09()
-
-import std/options
-
-type TT = object
-
-proc `=destroy`(x: TT) = echo "destroyed"
-
-func test1: Option[TT] = discard
-func test2: TT = discard
-
-echo test1() # Crash in JS backend, not crash in C backend
-echo test2() # Not crash
--- a/tests/lent/tlent_tuple_address.nim
+++ b/tests/lent/tlent_tuple_address.nim
@@ -1,12 +0,0 @@
-discard """
-  errormsg: "expression has no address"
-"""
-
-iterator foo(x: int): (lent int, lent int) =
-  yield (x, x + 1)
-
-
-var x = 12
-for i in foo(x):
-  echo i[0]
-  echo i[1]
--- a/tests/metatype/deps/cisaorb.nim
+++ b/tests/metatype/deps/cisaorb.nim
@@ -1,8 +0,0 @@
-type
-  A* = object
-    discard
-
-  B* = object
-    discard
-
-  C* = A | B
--- a/tests/metatype/tcisaorb.nim
+++ b/tests/metatype/tcisaorb.nim
@@ -1,22 +0,0 @@
-discard """
-  action: "compile"
-"""
-import deps/cisaorb
-
-when true:
-  # These work fine.
-  discard default(cisaorb.A)
-  proc f1(x: cisaorb.A) = discard
-  discard default(cisaorb.B)
-  proc f2(x: cisaorb.B) = discard
-  discard default(A)
-  proc f3(x: A) = discard
-  discard default(B)
-  proc f4(x: B) = discard
-  proc f5(x: C) = discard
-  proc f6(x: cisaorb.C | C) = discard
-
-proc doesWork(x: A | B) = discard
-
-# Doesn't compile.
-proc f(x: cisaorb.C) = discard
--- a/tests/metatype/ttypetraits.nim
+++ b/tests/metatype/ttypetraits.nim
@@ -434,32 +434,3 @@ block: # bug #24378
  type Win222[T] = typeof("foobar")
  doAssert not supportsCopyMem((int, Win222[int]))
  doAssert not supportsCopyMem(tuple[a: int, b: Win222[int]])
-
-block: # bug #25789
-  type
-    L[T; N: static int] = distinct seq[T]
-    EPF = distinct L[int, 100]
-
-  var e: EPF = EPF(L[int, 100](@[1, 2, 3]))
-
-  template classifyGeneric[T](x: T): bool =
-    when typeof(x) is L:
-      true
-    else:
-      false
-
-  template classifyConcrete[T](x: T): bool =
-    when typeof(x) is L[int, 100]:
-      true
-    else:
-      false
-
-  let viaConv = L[int, 100](e)
-  doAssert $type(viaConv) == "L[system.int, 100]"
-  doAssert classifyGeneric(viaConv)
-  doAssert classifyConcrete(viaConv)
-
-  let viaDB = distinctBase(e, recursive = false)
-  doAssert $type(viaDB) == "L[system.int, 100]"
-  doAssert classifyGeneric(viaDB)
-  doAssert classifyConcrete(viaDB)
--- a/tests/misc/tparseopt.nim
+++ b/tests/misc/tparseopt.nim
@@ -31,9 +31,6 @@ cmdShortOption key: v value: ''
 cmdArgument key: ABC value: ''
 cmdShortOption key: j value: '4'
 cmdArgument key: ok value: ''
-parseopt stdin
-cmdShortOption key: j value: '4'
-cmdShortOption key:  value: ''
 '''
 joinable: false
 """
@@ -157,9 +154,3 @@ arg 6 ai.len:4 :{a7'b}"""
    var n = parseopt.initOptParser("-j4 ok", shortnoVal = {'n'}, longnoVal = @["novalue"])
    for kind, key, val in parseopt.getopt(n):
      echo kind," key: ", key, " value: '", val, "'"
-
-  block: # fix #25738
-    echo "parseopt stdin"
-    var p = parseopt.initOptParser("-j4 -", shortNoVal = {'n'})
-    for kind, key, val in parseopt.getopt(p):
-      echo kind," key: ", key, " value: '", val, "'"
--- a/tests/objects/t25627.nim
+++ b/tests/objects/t25627.nim
@@ -1,87 +0,0 @@
-# issue #25627
-
-import std/tables
-
-type
-  FsoKind = enum
-    fsoFile
-    fsoDir
-    fsoLink
-
-  FakeFso = ref object
-    kind: FsoKind
-    dirName: string
-    files: OrderedTable[string, FakeFso]
-
-  DirStruct = object
-    root = FakeFso(kind: fsoDir, dirName: "/")
-
-let dir = DirStruct()
-doAssert dir.root.kind == fsoDir
-doAssert dir.root.dirName == "/"
-doAssert dir.root.files.len == 0
-
-block:
-  type
-    Opt[T] = object
-      when T is ref:
-        val: T
-        x: int
-      else:
-        val: T
-        x: string
-
-    DefaultOpt = ref object
-      files: Opt[DefaultOpt]
-
-    OptDirStruct = object
-      root = DefaultOpt()
-
-  let dir = OptDirStruct()
-  doAssert dir.root.files.x is int
-
-block:
-  type
-    Opt[T] = object
-      when T is ref:
-        x: int
-      else:
-        x: string
-
-    Foo[T] = object
-      x: Opt[T]
-
-    Nested = ref object
-      files: Foo[Nested]
-
-  let nested = Nested()
-  doAssert nested.files.x.x is int
-
-block:
-  type
-    Foo[T] = object
-      x = sizeof(T)
-
-    Sized = ref object
-      files: Foo[Sized]
-
-  let sized = Sized()
-  doAssert sized.files.x == sizeof(Sized)
-
-block:
-  type
-    Generic[T] = object
-      t: T
-
-    WindowObj = object
-      svgCache: Generic[SVGSVGElement]
-
-    SVGSVGElement = Generic[SVGSVGElementObj]
-
-    SVGSVGElementObj = object
-
-  proc foo() =
-    let p: pointer = nil
-    discard cast[ptr WindowObj](p)
-
-  foo()
--- a/tests/objects/tobject_default_value.nim
+++ b/tests/objects/tobject_default_value.nim
@@ -833,37 +833,4 @@ proc overloaded[T: object](x: T) =
    var v: typeof(val)
    overloaded(v)

-overloaded(Thing())
-
-block:
-  type
-    Foo = object
-      x = Bar()
-
-    Bar = object
-      x: int
-
-  var f = Foo()
-  doassert f.x.x == 0
-
-block:
-  type
-    Foo = object
-      x = Bar(x: 55)
-
-    Bar = object
-      x: int
-
-  var f = Foo()
-  doassert f.x.x == 55
-
-block:
-  type
-    Bar = object
-      x: int
-
-    Foo = object
-      x = Bar()
-
-  var f = Foo()
-  doassert f.x.x == 0
+overloaded(Thing())
--- a/tests/objvariant/treassign.nim
+++ b/tests/objvariant/treassign.nim
@@ -27,11 +27,9 @@ t.curr = TokenObject(kind: Token.foo, foo: "foo")
 echo "SUCCESS"

 proc passToVar(x: var Token) = discard
-proc passToPtr(x: ptr Token) = discard

 {.cast(uncheckedAssign).}:
  passToVar(t.curr.kind)
-  passToPtr(addr t.curr.kind)

  t.curr = TokenObject(kind: t.curr.kind, foo: "abc")

--- a/tests/overload/t25290.nim
+++ b/tests/overload/t25290.nim
@@ -1,34 +0,0 @@
-proc temp(one: int, two: int, three: int)  =
-  discard
-
-template temp(body: untyped): untyped =
-  body
-
-temp:
-  proc a(tp: int) =
-    discard
-
-proc mixedTemp(x: int) =
-  discard
-
-proc mixedTemp(x: bool) =
-  discard
-
-template mixedTemp(body: untyped): untyped =
-  body
-
-# The `bool` proc should win here so `xx` survives
-mixedTemp (let xx = 1; true)
-discard xx
-
-proc sinkTemp(x: int) =
-  discard
-
-template sinkTemp(body: untyped): untyped =
-  discard
-
-# Here the template should win here so `let xy` is sunk into template as AST
-sinkTemp (let xy = "template"; xy)
-
-when declared(xy):
-  {.error: "xy leaked from failed proc candidate".}
--- a/tests/pragmas/tcustom_pragma.nim
+++ b/tests/pragmas/tcustom_pragma.nim
@@ -549,20 +549,3 @@ block:

  type X {.p.} = object
  doAssert foo(X())
-
-block: # typeof() type alias preserves field pragmas
-  template myFieldPragma {.pragma.}
-  type Orig = object
-    x {.myFieldPragma.}: int
-
-  var orig: Orig
-
-  # Direct typeof alias
-  type TAlias = typeof(orig)
-  var a: TAlias
-  doAssert a.x.hasCustomPragma(myFieldPragma)
-
-  # Indirect alias of typeof alias
-  type TAlias2 = TAlias
-  var b: TAlias2
-  doAssert b.x.hasCustomPragma(myFieldPragma)
--- a/tests/proc/tbackendtypealias.nim
+++ b/tests/proc/tbackendtypealias.nim
@@ -1,44 +0,0 @@
-# bug #25617
-# Ensure that proc types with backend type alias mismatches
-# (e.g. uint vs csize_t) are rejected at the Nim level rather
-# than producing invalid C code.
-
-discard """
-  cmd: "nim check --hints:off --warnings:off --errorMax:0 $file"
-  action: "reject"
-  nimout: '''
-tbackendtypealias.nim(21, 7) Error: type mismatch: got <proc (len: csize_t){.closure.}> but expected 'proc (len: uint){.closure.}'
-tbackendtypealias.nim(28, 7) Error: type mismatch: got <proc (len: uint){.closure.}> but expected 'proc (len: csize_t){.closure.}'
-'''
-"""
-
-block direct_assignment:
-  # Direct proc variable assignment with backend type alias mismatch
-  var
-    a: proc (len: uint)
-    b: proc (len: csize_t)
-    c = a
-  c = b
-
-block direct_assignment_reverse:
-  var
-    a: proc (len: csize_t)
-    b: proc (len: uint)
-    c = a
-  c = b
-
-block same_backend_type:
-  # Same backend type should still work
-  var
-    a: proc (len: uint)
-    b: proc (len: uint)
-    c = a
-  c = b
-
-block cint_same_type:
-  # cint to cint should work
-  var
-    a: proc (len: cint)
-    b: proc (len: cint)
-    c = a
-  c = b
--- a/tests/stdlib/tdeques.nim
+++ b/tests/stdlib/tdeques.nim
@@ -241,12 +241,3 @@ proc main() =

 static: main()
 main()
-
-# https://github.com/nim-lang/Nim/issues/18583
-# $ separator must be emitted even when the item's string repr is empty
-type EmptyStr18583 = object
-proc `$`(x: EmptyStr18583): string = ""
-
-block:
-  var d = [EmptyStr18583(), EmptyStr18583()].toDeque
-  doAssert $d == "[, ]", "got: " & $d
--- a/tests/stdlib/theapqueue.nim
+++ b/tests/stdlib/theapqueue.nim
@@ -104,15 +104,3 @@ template main() =

 static: main()
 main()
-
-# https://github.com/nim-lang/Nim/issues/18583
-type EmptyStr18583HeapQ = object
-proc `$`(x: EmptyStr18583HeapQ): string = ""
-proc `<`(a, b: EmptyStr18583HeapQ): bool = false
-
-block:
-  var h = initHeapQueue[EmptyStr18583HeapQ]()
-  push(h, EmptyStr18583HeapQ())
-  push(h, EmptyStr18583HeapQ())
-  let s = $h
-  doAssert s == "[, ]", "got: " & s
--- a/tests/stdlib/tlists.nim
+++ b/tests/stdlib/tlists.nim
@@ -287,14 +287,3 @@ template main =

 static: main()
 main()
-
-# https://github.com/nim-lang/Nim/issues/18583
-type EmptyStr18583List = object
-proc `$`(x: EmptyStr18583List): string = ""
-
-block:
-  var L: SinglyLinkedList[EmptyStr18583List]
-  L.prepend(EmptyStr18583List())
-  L.prepend(EmptyStr18583List())
-  let s = $L
-  doAssert s == "[, ]", "got: " & s
--- a/tests/stdlib/tnre2.nim
+++ b/tests/stdlib/tnre2.nim
@@ -1,196 +0,0 @@
-import std/[assertions, options, sequtils, strutils, tables]
-import std/nre2
-
-block:
-  let pattern = "[0-9"
-  doAssertRaises(RegexError): discard re(pattern)
-
-block: # captures
-  block: # capture bounds are correct
-    let ex1 = re("([0-9])")
-    doAssert "1 23".find(ex1).get.matchBounds == 0 .. 0
-    doAssert "1 23".find(ex1).get.captureBounds[0] == 0 .. 0
-    doAssert "1 23".find(ex1, 1).get.matchBounds == 2 .. 2
-    doAssert "1 23".find(ex1, 3).get.matchBounds == 3 .. 3
-
-    let ex2 = re("()()()()()()()()()()([0-9])")
-    doAssert "824".find(ex2).get.captureBounds[0] == 0 .. -1
-    doAssert "824".find(ex2).get.captureBounds[10] == 0 .. 0
-
-    let ex3 = re("([0-9]+)")
-    doAssert "824".find(ex3).get.captureBounds[0] == 0 .. 2
-
-  block: # named captures
-    let ex1 = "foobar".find(re("(?P<foo>foo)(?P<bar>bar)"))
-    doAssert ex1.get.captures["foo"] == "foo"
-    doAssert ex1.get.captures["bar"] == "bar"
-
-    let ex2 = "foo".find(re("(?P<foo>foo)(?P<bar>bar)?"))
-    doAssert "foo" in ex2.get.captureBounds
-    doAssert ex2.get.captures["foo"] == "foo"
-    doAssert not ("bar" in ex2.get.captures)
-    doAssertRaises(KeyError):
-      discard ex2.get.captures["bar"]
-
-  block: # named capture bounds
-    let ex1 = "foo".find(re("(?P<foo>foo)(?P<bar>bar)?"))
-    doAssert "foo" in ex1.get.captureBounds
-    doAssert ex1.get.captureBounds["foo"] == 0..2
-    doAssert not ("bar" in ex1.get.captures)
-    doAssertRaises(KeyError):
-      discard ex1.get.captureBounds["bar"]
-
-  block: # capture count
-    let ex1 = re("(?P<foo>foo)(?P<bar>bar)?")
-    doAssert ex1.captureCount == 2
-    doAssert ex1.captureNameId == {"foo" : 0, "bar" : 1}.toTable()
-
-  block: # named capture table
-    let ex1 = "foo".find(re("(?P<foo>foo)(?P<bar>bar)?"))
-    doAssert ex1.get.captures.toTable == {"foo" : "foo"}.toTable()
-    doAssert ex1.get.captureBounds.toTable == {"foo" : 0..2}.toTable()
-
-    let ex2 = "foobar".find(re("(?P<foo>foo)(?P<bar>bar)?"))
-    doAssert ex2.get.captures.toTable == {"foo" : "foo", "bar" : "bar"}.toTable()
-
-  block: # capture sequence
-    let ex1 = "foo".find(re("(?P<foo>foo)(?P<bar>bar)?"))
-    doAssert ex1.get.captures.toSeq == @[some("foo"), none(string)]
-    doAssert ex1.get.captureBounds.toSeq == @[some(0..2), none(Slice[int])]
-    doAssert ex1.get.captures.toSeq(some("")) == @[some("foo"), some("")]
-
-    let ex2 = "foobar".find(re("(?P<foo>foo)(?P<bar>bar)?"))
-    doAssert ex2.get.captures.toSeq == @[some("foo"), some("bar")]
-
-block: # match
-  block: # upper bound must be inclusive
-    doAssert "abc".match(re"abc", endpos = -1) == none(RegexMatch)
-    doAssert "abc".match(re"abc", endpos = 1) == none(RegexMatch)
-    doAssert "abc".match(re"abc", endpos = 2) != none(RegexMatch)
-
-  block: # match examples
-    doAssert "abc".match(re"(\w)").get.captures[0] == "a"
-    doAssert "abc".match(re"(?P<letter>\w)").get.captures["letter"] == "a"
-    doAssert "abc".match(re"(\w)\w").get.captures[-1] == "ab"
-    doAssert "abc".match(re"(\w)").get.captureBounds[0] == 0 .. 0
-    doAssert "abc".match(re"").get.captureBounds[-1] == 0 .. -1
-    doAssert "abc".match(re"abc").get.captureBounds[-1] == 0 .. 2
-
-    let cap1 = "abc".match(re"(\w)(\w)+").get.captures
-    doAssert cap1.len == 2
-    doAssert 0 in cap1
-    doAssert 1 in cap1
-    doAssert cap1[0] == "a" and cap1[1] == "c"
-    doAssert 0 in "abc".match(re"(\w)+").get.captureBounds
-
-  block: # match test cases
-    doAssert "123".match(re"").get.matchBounds == 0 .. -1
-    let mat1 = "123".match(re"123").get
-    doAssert mat1.matchBounds == 0 .. 2
-    doAssert mat1.match == "123"
-
-block: # find
-  block: # find text
-    doAssert "3213a".find(re"[a-z]").get.match == "a"
-    doAssert sequtils.toSeq(findIter("1 2 3 4 5 6 7 8 ", re" ")).mapIt(
-      it.match
-    ) == @[" ", " ", " ", " ", " ", " ", " ", " "]
-
-  block: # find bounds
-    doAssert sequtils.toSeq(findIter("1 2 3 4 5 ", re" ")).mapIt(
-      it.matchBounds
-    ) == @[1..1, 3..3, 5..5, 7..7, 9..9]
-
-  block: # overlapping find
-    doAssert "222".findAll(re"22") == @["22"]
-    doAssert "2222".findAll(re"22") == @["22", "22"]
-
-  block: # len 0 find
-    doAssert "".findAll(re"\ ") == newSeq[string]()
-    doAssert "".findAll(re"") == @[""]
-    doAssert "abc".findAll(re"") == @["", "", "", ""]
-    doAssert "word word".findAll(re"\b") == @["", "", "", ""]
-    doAssert "word\r\lword".findAll(re"(?m)$") == @["", ""]
-    doAssert "слово слово".findAll(re"\b") == @["", "", "", ""]
-
-block: # contains
-  doAssert "abc".contains(re"bc")
-  doAssert not "abc".contains(re"cd")
-  doAssert not "abc".contains(re"a", start = 1)
-
-block: # string splitting
-  block: # splitting strings
-    doAssert "1 2 3 4 5 6 ".split(re" ") == @["1", "2", "3", "4", "5", "6", ""]
-    doAssert "1  2  ".split(re(" ")) == @["1", "", "2", "", ""]
-    doAssert "1 2".split(re(" ")) == @["1", "2"]
-    doAssert "foo".split(re("foo")) == @["", ""]
-    doAssert "".split(re"foo") == @[""]
-    doAssert "9".split(re"\son\s") == @["9"]
-
-  block: # captured patterns
-    doAssert "12".split(re"(\d)") == @["", "1", "", "2", ""]
-
-  block: # maxsplit
-    doAssert "123".split(re"", maxsplit = 2) == @["1", "23"]
-    doAssert "123".split(re"", maxsplit = 1) == @["123"]
-    doAssert "123".split(re"", maxsplit = -1) == @["1", "2", "3"]
-    doAssert "1 2 3".split(re" ", maxsplit = 1) == @["1 2 3"]
-    doAssert "1 2 3".split(re" ", maxsplit = 2) == @["1", "2 3"]
-    doAssert "1 2 3".split(re"( )", maxsplit = 2) == @["1", " ", "2 3"]
-
-  block: # split with 0-length match
-    doAssert "12345".split(re("")) == @["1", "2", "3", "4", "5"]
-    doAssert "".split(re"") == newSeq[string]()
-    doAssert "word word".split(re"\b") == @["word", " ", "word"]
-    #doAssert "word\r\lword".split(re"(?m)$") == @["word", "\r\lword"]
-    doAssert "слово слово".split(re"(\b)") == @["слово", "", " ", "", "слово", ""]
-
-  block: # perl split tests
-    doAssert "forty-two"                    .split(re"")      .join(",") == "f,o,r,t,y,-,t,w,o"
-    doAssert "forty-two"                    .split(re"", 3)   .join(",") == "f,o,rty-two"
-    doAssert "split this string"            .split(re" ")     .join(",") == "split,this,string"
-    doAssert "split this string"            .split(re" ", 2)  .join(",") == "split,this string"
-    doAssert "try$this$string"              .split(re"\$")    .join(",") == "try,this,string"
-    doAssert "try$this$string"              .split(re"\$", 2) .join(",") == "try,this$string"
-    doAssert "comma, separated, values"     .split(re", ")    .join("|") == "comma|separated|values"
-    doAssert "comma, separated, values"     .split(re", ", 2) .join("|") == "comma|separated, values"
-    doAssert "Perl6::Camelia::Test"         .split(re"::")    .join(",") == "Perl6,Camelia,Test"
-    doAssert "Perl6::Camelia::Test"         .split(re"::", 2) .join(",") == "Perl6,Camelia::Test"
-    doAssert "split,me,please"              .split(re",")     .join("|") == "split|me|please"
-    doAssert "split,me,please"              .split(re",", 2)  .join("|") == "split|me,please"
-    doAssert "Hello World    Goodbye   Mars".split(re"\s+")   .join(",") == "Hello,World,Goodbye,Mars"
-    doAssert "Hello World    Goodbye   Mars".split(re"\s+", 3).join(",") == "Hello,World,Goodbye   Mars"
-    doAssert "Hello test"                   .split(re"(\s+)") .join(",") == "Hello, ,test"
-    doAssert "this will be split"           .split(re" ")     .join(",") == "this,will,be,split"
-    doAssert "this will be split"           .split(re" ", 3)  .join(",") == "this,will,be split"
-    doAssert "a.b"                          .split(re"\.")    .join(",") == "a,b"
-    doAssert ""                             .split(re"")      .len       == 0
-    doAssert ":"                            .split(re"")      .len       == 1
-
-  block: # start position
-    doAssert "abc".split(re"", start = 1) == @["b", "c"]
-    doAssert "abc".split(re"", start = 2) == @["c"]
-    doAssert "abc".split(re"", start = 3) == newSeq[string]()
-    doAssert "abc".split(re"^b", start = 1) == @["bc"]
-
-block: # replace
-  block: # replace with 0-length strings
-    doAssert "".replace(re"1", proc (v: RegexMatch): string = "1") == ""
-    doAssert " ".replace(re"", proc (v: RegexMatch): string = "1") == "1 1"
-    doAssert "".replace(re"", proc (v: RegexMatch): string = "1") == "1"
-
-  block: # regular replace
-    doAssert "123".replace(re"\d", "foo") == "foofoofoo"
-    doAssert "123".replace(re"(\d)", "$1$1") == "112233"
-    doAssert "123".replace(re"(\d)(\d)", "$1$2") == "123"
-    doAssert "123".replace(re"(\d)(\d)", "$#$#") == "123"
-    doAssert "abcdefghijklm".replace(re"(a)(b)(c)(d)(e)(f)(g)(h)(i)(j)(k)(l)(m)", "$12") == "l"
-
-  block: # replacing missing captures should throw instead of segfaulting
-    doAssertRaises(ValueError): discard "ab".replace(re"(a)", "$1$2")
-
-block: # escape strings
-  block: # escape strings
-    doAssert "123".escapeRe() == "123"
-    doAssert "[]".escapeRe() == r"\[\]"
-    doAssert "()".escapeRe() == r"\(\)"
--- a/Show More
+++ b/Show More
Author	SHA1	Message	Date
ringabout	063b03e0ed	fixes #25697 ; {.borrow.} on iterator for distinct seq triggers internal error	2026-04-06 16:20:22 +08:00
ringabout	a6222bb2a6	Merge remote-tracking branch 'origin/devel' into pr_so_so	2026-04-06 16:17:43 +08:00
ringabout	8785e64efc	tests: move regression t22842 into tests/types (auto-related)	2026-04-04 13:07:55 +08:00
ringabout	63f2cd33f8	tests: add regression test for issue #22842 (auto in proc type)	2026-04-04 12:59:32 +08:00