test #25848

Co-authored-by: Gerke Max Preussner <gmpreussner@headcrash.industries>

compiler/ccgexprs.nim

@@ -1904,7 +1904,9 @@ proc genObjConstr(p: BProc, e: PNode, d: var TLoc) =
 
   var tmp: TLoc = default(TLoc)
   var r: Rope
-  let needsZeroMem = p.config.selectedGC notin {gcArc, gcAtomicArc, gcOrc, gcYrc} or nfAllFieldsSet notin e.flags
+  let needsZeroMem =
+    nfAllFieldsSet notin e.flags or
+    (optSeqDestructors notin p.config.globalOptions and containsGarbageCollectedRef(t))
   if useTemp:
     tmp = getTemp(p, t)
     r = rdLoc(tmp)

compiler/injectdestructors.nim

@@ -803,6 +803,23 @@ proc hasCustomDestructor(c: Con, t: PType): bool =
     obj = skipTypes(obj.baseClass, abstractPtrs)
     result = result or isCustomDestructor(c, obj)
 
+const
+  exprBranchKinds = {nkStmtListExpr, nkBlockExpr, nkIfExpr, nkCaseStmt,
+                     nkTryStmt, nkPragmaBlock}
+
+proc distributeAsgn(asgnKind: TNodeKind; dest, ri: PNode; c: var Con; s: var Scope): PNode =
+  ## Distributes an assignment ``dest = ri`` into the leaf expressions of
+  ## ``ri`` when ``ri`` is an expression-based control flow construct. This
+  ## avoids creating pointless intermediate temporaries (bug #25850). The
+  ## descent is recursive so that nestings like ``block: ...; if c: a else: b``
+  ## assign directly to ``dest`` instead of going through a temp per branch.
+  if ri.kind in exprBranchKinds:
+    template process(child, s): untyped =
+      distributeAsgn(asgnKind, dest, child, c, s)
+    handleNestedTempl(ri, process, willProduceStmt = true)
+  else:
+    result = newTree(asgnKind, dest, p(ri, c, s, consumed))
+
 proc p(n: PNode; c: var Con; s: var Scope; mode: ProcessMode; tmpFlags = {sfSingleUsedTemp}; inReturn = false): PNode =
   if n.kind in {nkStmtList, nkStmtListExpr, nkBlockStmt, nkBlockExpr, nkIfStmt,
                 nkIfExpr, nkCaseStmt, nkWhen, nkWhileStmt, nkParForStmt, nkTryStmt, nkPragmaBlock}:
@@ -1004,13 +1021,11 @@ proc p(n: PNode; c: var Con; s: var Scope; mode: ProcessMode; tmpFlags = {sfSing
         result = moveOrCopy(p(n[0], c, s, mode), n[1], c, s, flags)
       elif isDiscriminantField(n[0]):
         result = c.genDiscriminantAsgn(s, n)
-      elif n[1].kind in {nkStmtListExpr, nkBlockExpr, nkIfExpr, nkCaseStmt, nkTryStmt, nkPragmaBlock}:
+      elif n[1].kind in exprBranchKinds:
         # Distribute the assignment into each branch to avoid
         # creating pointless temporaries for expression-based control flow.
         let dest = p(n[0], c, s, mode)
-        template process(child, s): untyped =
-          newTree(n.kind, dest, p(child, c, s, consumed))
-        handleNestedTempl(n[1], process, willProduceStmt = true)
+        result = distributeAsgn(n.kind, dest, n[1], c, s)
       else:
         result = copyNode(n)
         result.add p(n[0], c, s, mode)

compiler/lineinfos.nim

@@ -100,6 +100,7 @@ type
     warnGlobalVarConstructorTemporary = "GlobalVarConstructorTemporary",
     warnImplicitRangeConversion = "ImplicitRangeConversion",
     warnSystemRangeConversion = "SystemRangeConversion",
+    warnInvalidCmpOp = "InvalidCmpOp",
     # hints
     hintSuccess = "Success", hintSuccessX = "SuccessX",
     hintCC = "CC",
@@ -210,6 +211,7 @@ const
     warnGlobalVarConstructorTemporary: "global variable '$1' initialization requires a temporary variable",
     warnImplicitRangeConversion: "implicit range conversion $1",
     warnSystemRangeConversion: "implicit range conversion $1",
+    warnInvalidCmpOp: "$1",
     hintSuccess: "operation successful: $#",
     # keep in sync with `testament.isSuccess`
     hintSuccessX: "$build\n$loc lines; ${sec}s; $mem; proj: $project; out: $output",

compiler/nilcheck.nim

@@ -183,12 +183,6 @@ func `<`*(a: ExprIndex, b: ExprIndex): bool =
 func `<=`*(a: ExprIndex, b: ExprIndex): bool =
   a.int16 <= b.int16
 
-func `>`*(a: ExprIndex, b: ExprIndex): bool =
-  a.int16 > b.int16
-
-func `>=`*(a: ExprIndex, b: ExprIndex): bool =
-  a.int16 >= b.int16
-
 func `==`*(a: ExprIndex, b: ExprIndex): bool =
   a.int16 == b.int16
 

compiler/parser.nim

@@ -2241,14 +2241,17 @@ proc parseTypeClassParam(p: var Parser): PNode =
 
 proc parseTypeClass(p: var Parser): PNode =
   #| conceptParam = ('var' | 'out' | 'ptr' | 'ref' | 'static' | 'type')? symbol
-  #| conceptDecl = 'concept' conceptParam ^* ',' (pragma)? ('of' typeDesc ^* ',')?
+  #| conceptDecl = 'concept' (conceptParam ^* ',' (pragma)?)? ('of' typeDesc ^* ',')?
   #|               &IND{>} stmt
   result = newNodeP(nkTypeClassTy, p)
   getTok(p)
   if p.tok.tokType == tkComment:
     skipComment(p, result)
 
-  if p.tok.indent < 0:
+  if p.tok.tokType == tkOf and p.tok.indent < 0:
+    # new-styled `concept of A, B` on the same line as `concept`
+    result.add(p.emptyNode)
+  elif p.tok.indent < 0:
     var args = newNodeP(nkArgList, p)
     result.add(args)
     args.add(p.parseTypeClassParam)
@@ -2274,9 +2277,10 @@ proc parseTypeClass(p: var Parser): PNode =
     result.add(p.emptyNode)
   if p.tok.tokType == tkComment:
     skipComment(p, result)
-  # an initial IND{>} HAS to follow:
+  # an initial IND{>} HAS to follow, unless this concept inherits requirements:
   if not realInd(p):
-    if result.isNewStyleConcept:
+    let hasParents = result[2].kind != nkEmpty
+    if result.isNewStyleConcept and not hasParents:
       parMessage(p, "routine expected, but found '$1' (empty new-styled concepts are not allowed)", p.tok)
     result.add(p.emptyNode)
   else:

compiler/semgnrc.nim

@@ -129,7 +129,14 @@ proc semGenericStmtSymbol(c: PContext, n: PNode, s: PSym,
           result.typ = nil
     onUse(n.info, s)
   of skParam:
-    result = n
+    if s.owner == c.p.owner:
+      # Parameters of the routine currently being semchecked stay as local
+      # identifiers
+      result = n
+    else:
+      # Preserve captured outer parameters so nested generic procs can still
+      # see them after the generic pre-pass.
+      result = newSymNode(s, n.info)
     onUse(n.info, s)
   of skType:
     if (s.typ != nil) and

compiler/sempass2.nim

@@ -1559,10 +1559,9 @@ proc track(tracked: PEffects, n: PNode) =
       message(tracked.config, n.info, warnPtrToCstringConv,
           $n[1].typ)
 
-    # Check for implicit range conversions. Compile-time constants are already
-    # fully known here, so only non-constant values need the downsizing warning.
+    # Check for implicit range conversions
     if n.kind == nkHiddenStdConv and (not tracked.isArrayIndexing) and
-          getConstExpr(tracked.ownerModule, n[1], tracked.c.idgen, tracked.graph) == nil and
+          n[1].kind notin {nkCharLit..nkUInt64Lit, nkFloatLit..nkFloat128Lit} and
           shouldWarnRangeConversion(tracked.config, n.info, n.typ, n[1].typ):
       message(tracked.config, n.info, warnImplicitRangeConversion,
               typeToString(n[1].typ) & " -> " & typeToString(n.typ))

compiler/semstmts.nim

@@ -2642,6 +2642,11 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
       elif s.name.s == "()" and callOperator notin c.features:
         localError(c.config, n.info, "the overloaded " & s.name.s &
           " operator has to be enabled with {.experimental: \"callOperator\".}")
+    elif sfImportc notin s.flags and (s.name.s == ">" or s.name.s == ">=" or s.name.s == "!="):
+      # ignore imported procs as these operators in backend language might have different semantics
+      let op1 = if s.name.s == "!=": "==" elif s.name.s == ">": "<" else: "<="
+      message(c.config, n.info, warnInvalidCmpOp, "define `" & op1 & "` instead of `" & s.name.s & "` to implement user defined comparison operator. " &
+              "it allows you to use `" & s.name.s & "` automatically.")
 
   if sfBorrow in s.flags and c.config.cmd notin cmdDocLike:
     result[bodyPos] = c.graph.emptyNode

compiler/sigmatch.nim

@@ -1759,6 +1759,21 @@ proc typeRel(c: var TCandidate, f, aOrig: PType,
       let ff = last(f)
       if ff != nil:
         result = typeRel(c, ff, a, flags)
+      if result == isNone and a.kind == tyGenericInst and trBindGenericParam in flags:
+        var depth = -1
+        # Generic-parameter constraints like `F: Future` can miss in `last(f)`
+        # when the actual type inherits from a concrete generic instantiation.
+        # Keep this fallback scoped to generic-parameter matching so typedesc
+        # overloads such as `type Future[T]` still prefer more specific
+        # descendants like `InternalRaisesFuture[T, E]`.
+        if isGenericSubtype(c, a, f, depth, f) and depth > 0:
+          var askip = skippedNone
+          let aobj = a.skipToObject(askip)
+          if aobj != nil and tfFinal notin aobj.flags:
+            # Keep overload ranking consistent with other inheritance-based
+            # matches: deeper descendants are slightly worse candidates.
+            inc c.inheritancePenalty, depth + int(c.inheritancePenalty < 0)
+          result = isGeneric
   of tyGenericInvocation:
     var x = a.skipGenericAlias
     if x.kind == tyGenericParam and x.len > 0:

compiler/transf.nim

@@ -22,7 +22,7 @@ import std / tables
 
 import
   options, ast, astalgo, trees, msgs,
-  idents, renderer, types, semfold, magicsys, cgmeth,
+  idents, renderer, types, semfold, magicsys, cgmeth, parampatterns,
   lowerings, liftlocals,
   modulegraphs, lineinfos
 
@@ -90,11 +90,21 @@ proc getCurrOwner(c: PTransf): PSym =
   if c.transCon != nil: result = c.transCon.owner
   else: result = c.module
 
+proc freshOwnedSym(c: PTransf; s, owner: PSym): PNode =
+  # We need to copy the symbol here because we might need to change its owner and
+  # we don't want to mess with the original symbol which might be used in other places.
+  # This can happen for example for iterators which are transformed multiple times when
+  # they are used in different contexts.
+  var fresh = copySym(s, c.idgen)
+  if fresh.kind notin routineKinds:
+    incl(fresh.flagsImpl, sfFromGeneric)
+  setOwner(fresh, owner)
+  result = newSymNode(fresh)
+
 proc newTemp(c: PTransf, typ: PType, info: TLineInfo): PNode =
   let r = newSym(skTemp, getIdent(c.graph.cache, genPrefix), c.idgen, getCurrOwner(c), info)
   r.typ = typ #skipTypes(typ, {tyGenericInst, tyAlias, tySink})
   incl(r.flagsImpl, sfFromGeneric)
-  let owner = getCurrOwner(c)
   result = newSymNode(r)
 
 proc transform(c: PTransf, n: PNode, noConstFold = false): PNode
@@ -185,11 +195,39 @@ proc transformSym(c: PTransf, n: PNode): PNode =
   result = transformSymAux(c, n)
 
 proc freshVar(c: PTransf; v: PSym): PNode =
-  let owner = getCurrOwner(c)
-  var newVar = copySym(v, c.idgen)
-  incl(newVar.flagsImpl, sfFromGeneric)
-  setOwner(newVar, owner)
-  result = newSymNode(newVar)
+  result = freshOwnedSym(c, v, getCurrOwner(c))
+
+proc introduceNewRoutineHeaderSyms(c: PTransf; n: PNode; oldOwner, newOwner: PSym) =
+  # We need to introduce new symbols for the parameters and result of a routine when
+  # we copy it for inlining or closure generation.
+  # Otherwise, we would have multiple nodes referring to the same parameter symbols which
+  # can lead to problems when we need to change the owner of these symbols.
+  case n.kind
+  of nkSym:
+    if n.sym.owner == oldOwner:
+      c.transCon.mapping[n.sym.itemId] = freshOwnedSym(c, n.sym, newOwner)
+  of nkEmpty..pred(nkSym), succ(nkSym)..nkNilLit:
+    discard
+  else:
+    for i in 0..<n.len:
+      introduceNewRoutineHeaderSyms(c, n[i], oldOwner, newOwner)
+
+proc copyRoutineTypeHeader(c: PTransf; oldProc, newProc: PSym) =
+  # We need to copy the routine type header to ensure that
+  # modifications to the newProc do not affect the oldProc.
+  if oldProc.typ != nil and oldProc.typ.kind == tyProc and oldProc.typ.n != nil:
+    newProc.typ = copyType(oldProc.typ, c.idgen, newProc)
+    newProc.typ.n = newNodeI(oldProc.typ.n.kind, oldProc.typ.n.info)
+    if oldProc.typ.n.len > 0:
+      newProc.typ.n.add copyTree(oldProc.typ.n[0])
+      for i in 1..<oldProc.typ.n.len:
+        let oldParam = oldProc.typ.n[i].sym
+        var newParam = getOrDefault(c.transCon.mapping, oldParam.itemId)
+        if newParam == nil:
+          newParam = freshOwnedSym(c, oldParam, newProc)
+          c.transCon.mapping[oldParam.itemId] = newParam
+        doAssert newParam.kind == nkSym
+        newProc.typ.addParam newParam.sym
 
 proc transformVarSection(c: PTransf, v: PNode): PNode =
   result = newTransNode(v)
@@ -338,11 +376,18 @@ proc introduceNewLocalVars(c: PTransf, n: PNode): PNode =
     return n
   of nkLambdaKinds, 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
+    let oldProc = n[namePos].sym
+    let x = freshOwnedSym(c, oldProc, oldProc.owner)
+    c.transCon.mapping[oldProc.itemId] = x
+    introduceNewRoutineHeaderSyms(c, n[paramsPos], oldProc, x.sym)
+    if resultPos < n.len and n[resultPos] != nil:
+      introduceNewRoutineHeaderSyms(c, n[resultPos], oldProc, x.sym)
+    copyRoutineTypeHeader(c, oldProc, x.sym)
     result[namePos] = x # we have to copy proc definitions for iters
     for i in 1..<n.len:
       result[i] = introduceNewLocalVars(c, n[i])
+    if x.sym.typ != nil and x.sym.typ.kind == tyProc:
+      result[paramsPos] = x.sym.typ.n
     result[namePos].sym.ast = result
   else:
     result = newTransNode(n)
@@ -675,7 +720,7 @@ type
     paDirectMapping, paFastAsgn, paFastAsgnTakeTypeFromArg
     paVarAsgn, paComplexOpenarray, paViaIndirection
 
-proc putArgInto(arg: PNode, formal: PType): TPutArgInto =
+proc putArgInto(arg: PNode, formal: PType; borrowedFirstArg = false): TPutArgInto =
   # This analyses how to treat the mapping "formal <-> arg" in an
   # inline context.
   if formal.kind == tyTypeDesc: return paDirectMapping
@@ -726,6 +771,13 @@ proc putArgInto(arg: PNode, formal: PType): TPutArgInto =
     if skipTypes(formal, abstractInst).kind in {tyVar, tyLent}: result = paVarAsgn
     else: result = paFastAsgn
 
+  if borrowedFirstArg and result == paDirectMapping and parampatterns.exprRoot(arg) == nil and
+           parampatterns.isAssignable(nil, arg) == arNone:
+    # Inline iterators like `items(array)` borrow from the first argument.
+    # If that argument is just a transient expression, materialize it so the
+    # lifted closure keeps the backing storage alive across yields.
+    result = paFastAsgnTakeTypeFromArg
+
 proc findWrongOwners(c: PTransf, n: PNode) =
   if n.kind == nkVarSection:
     let x = n[0][0]
@@ -824,13 +876,16 @@ proc transformFor(c: PTransf, n: PNode): PNode =
   if iter.kind != skIterator: return result
   # generate access statements for the parameters (unless they are constant)
   pushTransCon(c, newC)
+  let borrowedIterResult =
+    iter.typ != nil and iter.typ.returnType != nil and
+    skipTypes(iter.typ.returnType, abstractInst).kind in {tyLent, tyVar}
   for i in 1..<call.len:
     var arg = transform(c, call[i])
     let ff = skipTypes(iter.typ, abstractInst)
     # can happen for 'nim check':
     if i >= ff.n.len: return result
     var formal = ff.n[i].sym
-    let pa = putArgInto(arg, formal.typ)
+    let pa = putArgInto(arg, formal.typ, borrowedIterResult and i == 1)
     case pa
     of paDirectMapping:
       newC.mapping[formal.itemId] = arg

compiler/varpartitions.nim

@@ -185,6 +185,9 @@ proc root(v: var Partitions; start: int): int =
 proc potentialMutation(v: var Partitions; s: PSym; level: int; info: TLineInfo) =
   let id = variableId(v, s)
   if id >= 0:
+    # mutated here => alive here: keep aliveEnd in sync so dangerousMutation catches
+    # mutations recorded after the var's last use (e.g. via a call arg). See #25595.
+    v.s[id].aliveEnd = max(v.s[id].aliveEnd, v.abstractTime)
     let r = root(v, id)
     let flags = if s.kind == skParam:
                   if isConstParam(s):

compiler/vtables.nim

@@ -152,6 +152,8 @@ proc sortVTableDispatchers*(g: ModuleGraph) =
         rootItemIdCount.inc(baseType.itemId)
       for idx in 0..<g.methods[bucket].methods.len:
         let obj = g.methods[bucket].methods[idx].typ.firstParamType.skipTypes(skipPtrs)
+        if obj.itemId notin itemTable:
+          itemTable[obj.itemId] = newSeq[PSym](methodIndexLen)
         itemTable[obj.itemId][mIndex] = g.methods[bucket].methods[idx]
 
   for baseType in rootTypeSeq:

doc/grammar.txt

@@ -188,7 +188,7 @@ objectPart = IND{>} objectPart^+IND{=} DED
            / objectWhen / objectCase / 'nil' / 'discard' / declColonEquals
 objectDecl = 'object' ('of' typeDesc)? COMMENT? objectPart
 conceptParam = ('var' | 'out' | 'ptr' | 'ref' | 'static' | 'type')? symbol
-conceptDecl = 'concept' conceptParam ^* ',' (pragma)? ('of' typeDesc ^* ',')?
+conceptDecl = 'concept' (conceptParam ^* ',' (pragma)?)? ('of' typeDesc ^* ',')?
               &IND{>} stmt
 typeDef = identVisDot genericParamList? pragma '=' optInd typeDefValue
             indAndComment?

koch.nim

@@ -16,11 +16,11 @@ const
   ChecksumsStableCommit = "0b8e46379c5bc1bf73d8b3011908389c60fb9b98" # 2.0.1
   SatStableCommit = "e63eaea8baf00bed8bcd5a29ffd8823abb265b39"
 
-  NimonyStableCommit = "750aa47f2139fe5ad69f04b44428b752011fe873" # unversioned \
+  NimonyStableCommit = "fca0e938b04695a3aa4e85abcc976571189f2bd2" # 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
+    # Commit from 2026-06-08
 
   # examples of possible values for fusion: #head, #ea82b54, 1.2.3
   FusionStableHash = "#562467452b32cb7a97410ea177f083e6d8405734"

lib/system/iterators.nim

@@ -3,7 +3,7 @@
 when defined(nimPreviewSlimSystem):
   import std/assertions
 
-when not defined(nimNoLentIterators):
+when (not defined(nimNoLentIterators)) and not defined(js) and not defined(nimscript):
   template lent2(T): untyped = lent T
 else:
   template lent2(T): untyped = T
@@ -37,7 +37,7 @@ iterator mitems*[T](a: var openArray[T]): var T {.inline.} =
     yield a[i]
     unCheckedInc(i)
 
-iterator items*[IX, T](a: array[IX, T]): T {.inline.} =
+iterator items*[IX, T](a: array[IX, T]): lent2 T {.inline.} =
   ## Iterates over each item of `a`.
   when a.len > 0:
     var i = low(IX)
@@ -143,7 +143,7 @@ iterator items*[T: Ordinal](s: Slice[T]): T =
   for x in s.a .. s.b:
     yield x
 
-iterator pairs*[T](a: openArray[T]): tuple[key: int, val: T] {.inline.} =
+iterator pairs*[T](a: openArray[T]): tuple[key: int, val: lent T] {.inline.} =
   ## Iterates over each item of `a`. Yields `(index, a[index])` pairs.
   var i = 0
   while i < len(a):
@@ -158,7 +158,7 @@ iterator mpairs*[T](a: var openArray[T]): tuple[key: int, val: var T]{.inline.}
     yield (i, a[i])
     unCheckedInc(i)
 
-iterator pairs*[IX, T](a: array[IX, T]): tuple[key: IX, val: T] {.inline.} =
+iterator pairs*[IX, T](a: array[IX, T]): tuple[key: IX, val: lent T] {.inline.} =
   ## Iterates over each item of `a`. Yields `(index, a[index])` pairs.
   when a.len > 0:
     var i = low(IX)
@@ -177,7 +177,7 @@ iterator mpairs*[IX, T](a: var array[IX, T]): tuple[key: IX, val: var T] {.inlin
       if i >= high(IX): break
       unCheckedInc(i)
 
-iterator pairs*[T](a: seq[T]): tuple[key: int, val: T] {.inline.} =
+iterator pairs*[T](a: seq[T]): tuple[key: int, val: lent T] {.inline.} =
   ## Iterates over each item of `a`. Yields `(index, a[index])` pairs.
   var i = 0
   let L = len(a)

tests/arc/t25595.nim

@@ -0,0 +1,43 @@
+discard """
+  matrix: "--mm:orc; --mm:arc; --mm:refc"
+"""
+
+# bug #25595: cursor inference must not borrow a case object whose source can be
+# mutated through the cursor's own ref across a call. `let c = h.w` was inferred as a
+# non-owning cursor; `clear(c.r)` overwrites `h.w` via the cursor's back-reference,
+# freeing the ref while the borrow still uses it -> use-after-free. Detected here
+# deterministically: the element's destructor must not run during the call.
+
+var destroyed = false
+
+type
+  O = ref object
+    value: int
+    home: H
+  W = object
+    case k: bool
+    of true: r: O
+    of false: discard
+  H = ref object
+    w: W
+
+proc `=destroy`(o: var typeof(O()[])) =
+  destroyed = true
+
+proc clear(o: O): int =
+  o.home.w = W()
+  doAssert not destroyed, "use-after-free: element destroyed during the call"
+  result = o.value
+
+proc go(h: H): int =
+  let c = h.w
+  result = clear(c.r)
+
+proc main =
+  let h = H()
+  let o = O(value: 42)
+  o.home = h
+  h.w = W(k: true, r: o)
+  doAssert go(h) == 42
+
+main()

tests/arc/t25850.nim

@@ -0,0 +1,47 @@
+discard """
+  cmd: '''nim c --mm:orc --expandArc:uIf --expandArc:uCase $file'''
+  nimout: '''
+--expandArc: uIf
+
+block :tmp:
+  let s = w()
+  if true:
+    r[] = s
+  else:
+    r[] = s
+-- end of expandArc ------------------------
+--expandArc: uCase
+
+block :tmp:
+  let s = w()
+  case n
+  of 0:
+    r[] = s
+  else:
+    r[] = w()
+-- end of expandArc ------------------------
+'''
+"""
+
+# bug #25850
+# Assigning an expression-based control flow construct (an `if`/`case` nested in
+# a `block`) must distribute the assignment directly into the leaf branches
+# instead of creating redundant intermediate temporaries per branch.
+
+proc w(): array[1000, byte] {.noinline.} = discard
+
+proc uIf(r: ptr array[1000, byte]) =
+  r[] = (block:
+    let s = w()
+    if true: s else: s)
+
+proc uCase(r: ptr array[1000, byte], n: int) =
+  r[] = (block:
+    let s = w()
+    case n
+    of 0: s
+    else: w())
+
+var d: array[1000, byte]
+uIf(addr d)
+uCase(addr d, 0)

tests/generics/t20811.nim

@@ -0,0 +1,16 @@
+discard """
+  output: '''42
+42'''
+"""
+
+proc outer(j: int) =
+  proc genericInner[T](): int =
+    j
+
+  proc plainInner(): int =
+    j
+
+  echo genericInner[int]()
+  echo plainInner()
+
+outer(42)

tests/iter/titer_issues.nim

@@ -465,4 +465,24 @@ block: # bug #25724
     else: yield 1
   for w in c():
     let n = w
-    (proc() = discard n)()
+    (proc() = discard n)()
+
+block:
+  iterator c(): int =
+    yield 1
+    yield 1
+
+  for w in c():
+    proc p(s: int) =
+      let sap = s
+    p(0)
+
+block: # bug #25725
+  iterator c(): int =
+    when nimvm: yield 0
+    else: yield 1
+  for w in c():
+    let n = w
+    proc p(s: int) =
+      let s = s; discard n
+    p(0)

tests/lent/titems_array_lent.nim

@@ -0,0 +1,38 @@
+discard """
+  targets: "c cpp js"
+"""
+
+template sameAddress(a, b): bool =
+  when defined(js):
+    a == b
+  else:
+    a.unsafeAddr == b.unsafeAddr
+
+proc main() =
+  block:
+    let a = [10, 11, 12]
+    for ai in items(a):
+      doAssert sameAddress(ai, a[0])
+      break
+
+  block:
+    let a = [[1, 2], [1, 2], [1, 2]]
+    for ai in items(a):
+      doAssert sameAddress(ai[0], a[0][0])
+      break
+
+  block:
+    let s = @[(1, 2), (3, 4), (5, 6)]
+    doAssert (3, 4) in s
+
+main()
+
+static:
+  main()
+
+block: # issue #25849
+  static:
+    const key = "NIM_TESTS_TOSENV_KEY"
+    for val in ["val", "", "\xc3\x86"]:
+      let s = @[(key, "val"), (key, ""), (key, "\xc3\x86")]
+      doAssert (key, val) in s

tests/method/mvtables_reentry_a.nim

@@ -0,0 +1,5 @@
+type
+  VtableBaseA* = ref object of RootObj
+
+method say*(a: VtableBaseA): string {.base.} =
+  "base"

tests/method/mvtables_reentry_b.nim

@@ -0,0 +1,7 @@
+import mvtables_reentry_a
+
+type
+  VtableDerivedB* = ref object of VtableBaseA
+
+method say*(d: VtableDerivedB): string =
+  "derived"

tests/method/tvtable_reentry.nim

@@ -0,0 +1,19 @@
+discard """
+  targets: "c cpp"
+"""
+
+import mvtables_reentry_a
+
+type
+  MainType = ref object of VtableBaseA
+
+method say*(m: MainType): string =
+  "main"
+
+when isMainModule:
+  import mvtables_reentry_b
+
+  let a: VtableBaseA = VtableDerivedB()
+  doAssert a.say() == "derived"
+  let m: VtableBaseA = MainType()
+  doAssert m.say() == "main"

tests/proc/tinvalid_cmp_op1.nim

@@ -0,0 +1,12 @@
+discard """
+  cmd: "nim check $file"
+  action: compile
+  nimout: '''
+tinvalid_cmp_op1.nim(12, 1) Warning: define `<=` instead of `>=` to implement user defined comparison operator. it allows you to use `>=` automatically. [InvalidCmpOp]
+'''
+"""
+
+# issue #25655
+
+type Foo = distinct int
+func `>=`(a, b: Foo): bool = int(a) >= int(b)

tests/proc/tinvalid_cmp_op2.nim

@@ -0,0 +1,12 @@
+discard """
+  cmd: "nim check $file"
+  action: compile
+  nimout: '''
+tinvalid_cmp_op2.nim(12, 1) Warning: define `<` instead of `>` to implement user defined comparison operator. it allows you to use `>` automatically. [InvalidCmpOp]
+'''
+"""
+
+# issue #25655
+
+type Foo = distinct int
+func `>`(a, b: Foo): bool = int(a) > int(b)

tests/proc/tinvalid_cmp_op3.nim

@@ -0,0 +1,12 @@
+discard """
+  cmd: "nim check $file"
+  action: compile
+  nimout: '''
+tinvalid_cmp_op3.nim(12, 1) Warning: define `==` instead of `!=` to implement user defined comparison operator. it allows you to use `!=` automatically. [InvalidCmpOp]
+'''
+"""
+
+# issue #25655
+
+type Foo = distinct int
+func `!=`(a, b: Foo): bool = int(a) != int(b)

tests/range/timplicitrangeconsts.nim

@@ -1,30 +0,0 @@
-discard """
-cmd: "nim check $options --hints:off --warning:ImplicitRangeConversion --warningaserror:ImplicitRangeConversion $file"
-action: "compile"
-"""
-
-type
-  E = enum
-    ea, eb
-
-  R = range[eb..eb]
-  I = range[0..3]
-
-proc accept(r: R) = discard
-proc accept(i: I) = discard
-
-var r: R
-var i: I
-const enumOk = eb
-const enumAlias = enumOk
-const intOk = 1 + 2
-
-r = eb
-r = enumOk
-r = enumAlias
-accept(eb)
-accept(enumOk)
-accept(enumAlias)
-
-i = intOk
-accept(intOk)

tests/template/topensym.nim

@@ -135,6 +135,19 @@ block: # issue #22605 for templates, original complex example
 
   doAssert g2(int) == "error"
 
+block: # issue #20811
+  template injectError(body: untyped): untyped =
+    template error: untyped {.used, inject.} = "injected"
+    body
+
+  proc outerOpen(error: string): string =
+    injectError:
+      proc genericInner[T](): string =
+        error
+      genericInner[int]()
+
+  doAssert outerOpen("captured") == "injected"
+
 block: # issue #23865 for templates
   type Xxx = enum
     error

tests/typerel/t8905.nim

@@ -5,3 +5,31 @@ type
 proc newFoo[T](): Foo[T] = Foo[T](newSeq[T]())
 
 var x = newFoo[Bar[int]]()
+
+# issue #22936
+
+import std/macros
+
+type
+  InternalFutureBase = object of RootObj
+
+  FutureBase = ref object of InternalFutureBase
+
+  Future[T] = ref object of FutureBase
+    internalValue: T
+
+  B[T, E] = ref object of Future[T]
+
+proc take[F: Future](fut: F) = discard
+
+proc takeMany[F: Future](futs: seq[F]) = discard
+
+macro checkFutures[F: Future](futs: seq[F]): untyped =
+  newEmptyNode()
+
+var future: B[void, void]
+var futures: seq[B[void, void]]
+
+take(future)
+takeMany(futures)
+checkFutures(futures)