diff --git a/compiler/ccgexprs.nim b/compiler/ccgexprs.nim
index 171d656230..df50d93954 100644
--- a/compiler/ccgexprs.nim
+++ b/compiler/ccgexprs.nim
@@ -2940,6 +2940,13 @@ proc genEnumToStr(p: BProc, e: PNode, d: var TLoc) =
 
 proc genMagicExpr(p: BProc, e: PNode, d: var TLoc, op: TMagic) =
   case op
+  of mAsgn:
+    let kind = if e[0].sym.name.s == "=sink": nkSinkAsgn else: nkAsgn
+    let lhs = e[1].skipHiddenAddr
+    let n = newTreeI(kind, e.info, lhs, e[2])
+    n.typ = e.typ
+    cow(p, e[2])
+    genAsgn(p, n, fastAsgn = kind != nkAsgn)
   of mOr, mAnd: genAndOr(p, e, d, op)
   of mNot..mUnaryMinusF64: unaryArith(p, e, d, op)
   of mUnaryMinusI..mAbsI: unaryArithOverflow(p, e, d, op)
diff --git a/compiler/ccgtypes.nim b/compiler/ccgtypes.nim
index 58343f2c44..98a85b38ae 100644
--- a/compiler/ccgtypes.nim
+++ b/compiler/ccgtypes.nim
@@ -2279,3 +2279,21 @@ proc genTypeSection(m: BModule, n: PNode) =
       discard getTypeDescAux(m, s.typ, intSet, descKindFromSymKind(s.kind))
       if m.g.generatedHeader != nil:
         discard getTypeDescAux(m.g.generatedHeader, s.typ, intSet, descKindFromSymKind(s.kind))
+
+# Unlike genCppInitializer which returns just the braced value list (e.g. "{a, b}"),
+# genCppConstructorExpr returns a full type-prefixed expression (e.g. "Foo(a, b)").
+# This is used when a standalone construction expression is needed — e.g. on the
+# right-hand side of an assignment — whereas genCppInitializer is used in variable
+# declarations where the type is already written separately before the initializer.
+proc genCppConstructorExpr(m: BModule, prc: BProc; typ: PType; didGenTemp: var bool): Snippet =
+  var params = ""
+  if typ.itemId in m.g.graph.initializersPerType:
+    let call = m.g.graph.initializersPerType[typ.itemId]
+    if call != nil:
+      var p = prc
+      if p == nil:
+        p = BProc(module: m)
+      params = genCppParamsForCtor(p, call, didGenTemp)
+      if prc == nil:
+        assert p.blocks.len == 0, "BProc belongs to a struct doesnt have blocks"
+  result = getTypeDesc(m, typ, dkVar) & "(" & params & ")"
diff --git a/compiler/cgen.nim b/compiler/cgen.nim
index b54160edf8..b1f6f862c7 100644
--- a/compiler/cgen.nim
+++ b/compiler/cgen.nim
@@ -613,7 +613,7 @@ proc resetLoc(p: BProc, loc: var TLoc) =
   if isImportedCppType(typ):
     var didGenTemp = false
     let rl = rdLoc(loc)
-    let init = genCppInitializer(p.module, p, typ, didGenTemp)
+    let init = genCppConstructorExpr(p.module, p, typ, didGenTemp)
     p.s(cpsStmts).addAssignment(rl, init)
     return
   if optSeqDestructors in p.config.globalOptions and typ.kind in {tyString, tySequence}:
diff --git a/compiler/jsgen.nim b/compiler/jsgen.nim
index fd82a127f7..a04c8e8f95 100644
--- a/compiler/jsgen.nim
+++ b/compiler/jsgen.nim
@@ -34,7 +34,7 @@ import
   ropes, wordrecg, renderer,
   cgmeth, lowerings, sighashes, modulegraphs, lineinfos,
   transf, injectdestructors, sourcemap, astmsgs, pushpoppragmas,
-  mangleutils
+  mangleutils, varpartitions
 
 import pipelineutils
 
@@ -1298,14 +1298,16 @@ proc genAsgnAux(p: PProc, x, y: PNode, noCopyNeeded: bool) =
     xtyp = etySeq
   case xtyp
   of etySeq:
-    if x.typ.kind in {tyVar, tyLent} or (needsNoCopy(p, y) and needsNoCopy(p, x)) or noCopyNeeded:
+    if x.typ.kind in {tyVar, tyLent} or (needsNoCopy(p, y) and needsNoCopy(p, x)) or noCopyNeeded or
+        (x.kind == nkSym and sfCursor in x.sym.flags):
       lineF(p, "$1 = $2;$n", [a.rdLoc, b.rdLoc])
     else:
       useMagic(p, "nimCopy")
       lineF(p, "$1 = nimCopy(null, $2, $3);$n",
                [a.rdLoc, b.res, genTypeInfo(p, y.typ)])
   of etyObject:
-    if x.typ.kind in {tyVar, tyLent, tyOpenArray, tyVarargs} or (needsNoCopy(p, y) and needsNoCopy(p, x)) or noCopyNeeded:
+    if x.typ.kind in {tyVar, tyLent, tyOpenArray, tyVarargs} or (needsNoCopy(p, y) and needsNoCopy(p, x)) or noCopyNeeded or
+        (x.kind == nkSym and sfCursor in x.sym.flags):
       lineF(p, "$1 = $2;$n", [a.rdLoc, b.rdLoc])
     else:
       useMagic(p, "nimCopy")
@@ -2092,7 +2094,8 @@ proc genVarInit(p: PProc, v: PSym, n: PNode) =
     gen(p, n, a)
     case mapType(p, v.typ)
     of etyObject, etySeq:
-      if v.typ.kind in {tyOpenArray, tyVarargs} or needsNoCopy(p, n):
+      if v.typ.kind in {tyOpenArray, tyVarargs} or needsNoCopy(p, n) or
+          sfCursor in v.flags:
         s = a.res
       else:
         useMagic(p, "nimCopy")
@@ -2798,6 +2801,11 @@ proc genProc(oldProc: PProc, prc: PSym): Rope =
   var transformedBody = transformBody(p.module.graph, p.module.idgen, prc, {})
   if sfInjectDestructors in prc.flags:
     transformedBody = injectDestructorCalls(p.module.graph, p.module.idgen, prc, transformedBody)
+  else:
+    # JS has a GC, so the destructor pass is off; but the cursor (alias) analysis
+    # is independent of ownership and always memory-safe on a traced target.
+    # Running it lets last-use `var b = a` aliases skip the deep `nimCopy`.
+    computeCursors(prc, transformedBody, p.module.graph)
 
   p.nested: genStmt(p, transformedBody)
 
diff --git a/compiler/sem.nim b/compiler/sem.nim
index a9f87cd006..7f777a7add 100644
--- a/compiler/sem.nim
+++ b/compiler/sem.nim
@@ -89,6 +89,18 @@ proc fitNodePostMatch(c: PContext, formal: PType, arg: PNode): PNode =
     changeType(c, x, formal, check=true)
   result = arg
   result = skipHiddenSubConv(result, c.graph, c.idgen)
+  # Walk through nested statement-list/block expressions to find the innermost
+  # value node. Empty containers (e.g. `@[]`) inside `nkStmtListExpr` wrappers
+  # need their type resolved to match the formal type, otherwise the C codegen
+  # cannot map `tyEmpty` to a concrete type (fixes #25945).
+  var tail = result
+  while tail.kind in {nkStmtList, nkStmtListExpr, nkBlockStmt, nkBlockExpr, nkPragmaBlock} and tail.len > 0:
+    tail = tail.lastSon
+
+  if tail.typ != nil and tail.typ.isEmptyContainer and
+        formal.kind notin {tyUntyped, tyBuiltInTypeClass, tyAnything}:
+    changeType(c, tail, formal, check=true)
+
   # mark inserted converter as used:
   var a = result
   if a.kind == nkHiddenDeref: a = a[0]
diff --git a/compiler/sempass2.nim b/compiler/sempass2.nim
index 008f2317ba..73e3b4072a 100644
--- a/compiler/sempass2.nim
+++ b/compiler/sempass2.nim
@@ -93,6 +93,7 @@ type
     graph: ModuleGraph
     c: PContext
     escapingParams: IntSet
+    inNimvmBranch: int
   PEffects = var TEffects
 
 const
@@ -1127,7 +1128,7 @@ proc trackCall(tracked: PEffects; n: PNode) =
   # sfCompileTime` path in `semProcAux`.
   if a.kind == nkSym and a.sym.magic in {mNLen..mNError, mSlurp..mQuoteAst} and
       tracked.owner != nil and tracked.owner.kind in routineKinds and
-      tracked.config.cmd != cmdNimscript:
+      tracked.config.cmd != cmdNimscript and tracked.inNimvmBranch == 0:
     # ...but NOT under `nim e`: nimscript has no codegen backend to protect, and
     # marking a routine `sfCompileTime` makes `semExpr` eagerly fold calls to it
     # at sem time (emConst), where module-level globals it reads have no VM slot
@@ -1483,7 +1484,9 @@ proc track(tracked: PEffects, n: PNode) =
   of nkCaseStmt: trackCase(tracked, n)
   of nkWhen: # This should be a "when nimvm" node.
     let oldState = tracked.init.len
+    inc tracked.inNimvmBranch
     track(tracked, n[0][1])
+    dec tracked.inNimvmBranch
     tracked.init.setLen(oldState)
     track(tracked, n[1][0])
   of nkIfStmt, nkIfExpr: trackIf(tracked, n)
diff --git a/compiler/varpartitions.nim b/compiler/varpartitions.nim
index fea6cc540b..3a01eb0bbd 100644
--- a/compiler/varpartitions.nim
+++ b/compiler/varpartitions.nim
@@ -677,9 +677,13 @@ proc deps(c: var Partitions; dest, src: PNode) =
           else:
             let srcid = variableId(c, s)
             if srcid >= 0:
-              if s.kind notin {skResult, skParam} and (
-                  c.s[srcid].aliveEnd < c.s[vid].aliveEnd):
-                # you cannot borrow from a local that lives shorter than 'vid':
+              if s.kind notin {skResult, skParam} and
+                  c.s[srcid].aliveEnd < c.s[vid].aliveEnd and
+                  c.g.config.backend != backendJs:
+                # you cannot borrow from a local that lives shorter than 'vid'.
+                # On a traced (JS/GC) target the source object stays alive as long
+                # as the alias references it, so this lifetime rule does not apply;
+                # value-semantics safety is enforced by `dangerousMutation` instead.
                 when explainCursors: echo "B not a cursor ", d.sym, " ", c.s[srcid].aliveEnd, " ", c.s[vid].aliveEnd
                 c.s[vid].flags.incl preventCursor
               elif {isReassigned, preventCursor} * c.s[srcid].flags != {}:
@@ -1003,13 +1007,22 @@ proc checkBorrowedLocations*(par: var Partitions; body: PNode; config: ConfigRef
       #if par.s[rid].con.kind == isRootOf and dangerousMutation(par.graphs[par.s[rid].con.graphIndex], par.s[i]):
       #  cannotBorrow(config, s, par.graphs[par.s[rid].con.graphIndex])
 
+proc jsDeepCopied(t: PType): bool =
+  ## On the JS backend `nimCopy` deep-copies these type classes on every
+  ## assignment, so eliding the copy for a safe alias is worthwhile even when
+  ## the type has no C-style destructor.
+  t.skipTypes({tyGenericInst, tyAlias, tyDistinct, tyVar, tyLent}).kind in
+    {tyObject, tyTuple, tyArray, tySequence, tyString}
+
 proc computeCursors*(s: PSym; n: PNode; g: ModuleGraph) =
+  let jsCursors = g.config.backend == backendJs
   var par = computeGraphPartitions(s, n, g, {cursorInference})
   for i in 0 ..< par.s.len:
     let v = addr(par.s[i])
     if v.flags * {ownsData, preventCursor, isConditionallyReassigned} == {} and
         v.sym.kind notin {skParam, skResult} and
-        v.sym.flags * {sfThread, sfGlobal} == {} and hasDestructor(v.sym.typ) and
+        v.sym.flags * {sfThread, sfGlobal} == {} and
+        (hasDestructor(v.sym.typ) or (jsCursors and jsDeepCopied(v.sym.typ))) and
         v.sym.typ.skipTypes({tyGenericInst, tyAlias}).kind != tyOwned and
         (getAttachedOp(g, v.sym.typ, attachedAsgn) == nil or
         sfError notin getAttachedOp(g, v.sym.typ, attachedAsgn).flags):
diff --git a/config/nim.cfg b/config/nim.cfg
index 6a259321fb..26948ba928 100644
--- a/config/nim.cfg
+++ b/config/nim.cfg
@@ -134,11 +134,11 @@ nimblepath="$home/.nimble/pkgs/"
     # BSD got posix_spawn only recently, so we deactivate it for osproc:
     define:useFork
   @elif haiku:
-    gcc.options.linker = "-Wl,--as-needed -lnetwork"
-    gcc.cpp.options.linker = "-Wl,--as-needed -lnetwork"
-    clang.options.linker = "-Wl,--as-needed -lnetwork"
-    clang.cpp.options.linker = "-Wl,--as-needed -lnetwork"
-    tcc.options.linker = "-Wl,--as-needed -lnetwork"
+    gcc.options.linker = "-Wl,--as-needed -lnetwork -lbsd"
+    gcc.cpp.options.linker = "-Wl,--as-needed -lnetwork -lbsd"
+    clang.options.linker = "-Wl,--as-needed -lnetwork -lbsd"
+    clang.cpp.options.linker = "-Wl,--as-needed -lnetwork -lbsd"
+    tcc.options.linker = "-Wl,--as-needed -lnetwork -lbsd"
   @elif not genode:
     # -fopenmp
     gcc.options.linker = "-ldl"
diff --git a/lib/posix/kqueue.nim b/lib/posix/kqueue.nim
index 2450cdb424..f5edcaf2e0 100644
--- a/lib/posix/kqueue.nim
+++ b/lib/posix/kqueue.nim
@@ -28,6 +28,15 @@ elif defined(netbsd):
     EVFILT_PROC*     = 4 ## attached to struct proc
     EVFILT_SIGNAL*   = 5 ## attached to struct proc
     EVFILT_TIMER*    = 6 ## timers (in ms)
+elif defined(haiku):
+  const
+    EVFILT_READ*     = -1
+    EVFILT_WRITE*    = -2
+    EVFILT_AIO*      = -3 ## attached to aio requests
+    EVFILT_VNODE*    = -4 ## attached to vnodes
+    EVFILT_PROC*     = -5 ## attached to struct proc
+    EVFILT_SIGNAL*   = -6 ## attached to struct proc
+    EVFILT_TIMER*    = -7 ## timers
 when defined(macosx):
   const
     EVFILT_MACHPORT* = -8  ## Mach portsets
diff --git a/lib/system/osalloc.nim b/lib/system/osalloc.nim
index 4177b47b1f..db7f4c1482 100644
--- a/lib/system/osalloc.nim
+++ b/lib/system/osalloc.nim
@@ -89,7 +89,7 @@ elif defined(emscripten) and not defined(StandaloneHeapSize):
 
     var mmapDescrPos = cast[int](result) -% sizeof(EmscriptenMMapBlock)
 
-    var mmapDescr = cast[EmscriptenMMapBlock](mmapDescrPos)
+    var mmapDescr = cast[PEmscriptenMMapBlock](mmapDescrPos)
     mmapDescr.realSize = realSize
     mmapDescr.realPointer = realPointer
 
@@ -99,7 +99,7 @@ elif defined(emscripten) and not defined(StandaloneHeapSize):
 
   proc osDeallocPages(p: pointer, size: int) {.inline.} =
     var mmapDescrPos = cast[int](p) -% sizeof(EmscriptenMMapBlock)
-    var mmapDescr = cast[EmscriptenMMapBlock](mmapDescrPos)
+    var mmapDescr = cast[PEmscriptenMMapBlock](mmapDescrPos)
     munmap(mmapDescr.realPointer, mmapDescr.realSize)
 
 elif defined(genode) and not defined(StandaloneHeapSize):
diff --git a/tests/arc/tisolated_primitive.nim b/tests/arc/tisolated_primitive.nim
new file mode 100644
index 0000000000..05e760b155
--- /dev/null
+++ b/tests/arc/tisolated_primitive.nim
@@ -0,0 +1,12 @@
+# Issue: genMagicExpr: mAsgn internal error when using Isolated[T] with primitive types
+# in tuple assignment to pointer dereference
+
+import std/isolation
+
+proc main() =
+  var x: ptr Isolated[float]
+  x = cast[ptr Isolated[float]](alloc0(sizeof(Isolated[float])))
+  x[] = isolate(42.0)
+  dealloc(x)
+
+main()
diff --git a/tests/ccgbugs2/tcodegen.nim b/tests/ccgbugs2/tcodegen.nim
index bca361e813..da5ab045cc 100644
--- a/tests/ccgbugs2/tcodegen.nim
+++ b/tests/ccgbugs2/tcodegen.nim
@@ -75,3 +75,15 @@ block: # importc type inheritance
   doAssert(cast[cint](b) == 123)
   var c = foo(b)
   doAssert(cast[cint](c) == 123)
+
+block: # bug #25945
+  var stateRefund = 0
+  let authCode =
+    if true:
+      if false:
+        stateRefund += 0
+      @[]
+    else:
+      @([1.byte])
+
+discard (if true: (discard; @[]) else: @[0])
diff --git a/tests/cpp/tcpp_default_ctor_assignment.h b/tests/cpp/tcpp_default_ctor_assignment.h
new file mode 100644
index 0000000000..356cbb9381
--- /dev/null
+++ b/tests/cpp/tcpp_default_ctor_assignment.h
@@ -0,0 +1,30 @@
+#ifndef TCPP_DEFAULT_CTOR_ASSIGNMENT_H
+#define TCPP_DEFAULT_CTOR_ASSIGNMENT_H
+
+struct AmbiguousAssign {
+  int x;
+  const char* y;
+
+  AmbiguousAssign(): x(0), y(nullptr) {}
+  AmbiguousAssign(int x, const char* y): x(x), y(y) {}
+
+  AmbiguousAssign& operator=(int v) {
+    x = v;
+    y = nullptr;
+    return *this;
+  }
+
+  AmbiguousAssign& operator=(const char* s) {
+    x = 0;
+    y = s;
+    return *this;
+  }
+
+  AmbiguousAssign& operator=(const AmbiguousAssign& other) {
+    x = other.x;
+    y = other.y;
+    return *this;
+  }
+};
+
+#endif
\ No newline at end of file
diff --git a/tests/cpp/tcpp_default_ctor_assignment.nim b/tests/cpp/tcpp_default_ctor_assignment.nim
new file mode 100644
index 0000000000..88d9671ae6
--- /dev/null
+++ b/tests/cpp/tcpp_default_ctor_assignment.nim
@@ -0,0 +1,14 @@
+discard """
+  cmd: "nim cpp $file"
+"""
+
+type
+  AmbiguousAssign {.importcpp, header: "tcpp_default_ctor_assignment.h".} = object
+    x: cint
+    y: cstring
+
+proc main =
+  var xs = newSeq[AmbiguousAssign](3)
+  doAssert xs.len == 3
+
+main()
\ No newline at end of file
diff --git a/tests/vm/tvmmisc.nim b/tests/vm/tvmmisc.nim
index 906ced7b83..c8ed29f7ce 100644
--- a/tests/vm/tvmmisc.nim
+++ b/tests/vm/tvmmisc.nim
@@ -855,3 +855,17 @@ block:
     var r = Obj(x: 10)
     r.value = 42
     doAssert r.x == 42
+
+block: # bug #25949
+  template loadFile(filename: string): auto =
+    when nimvm:    
+      staticRead(filename)
+    else:
+      "something"
+    
+  proc roundTrip(): bool =
+    let content = loadFile("tests/tomls/case.toml")
+    content == "something"
+
+  doAssert roundTrip()
+