fixes #22058; invalid free with {.noSideEffect.} in template (#22088)

compiler/injectdestructors.nim

@@ -703,6 +703,24 @@ template handleNestedTempl(n, processCall: untyped, willProduceStmt = false,
   of nkWhen: # This should be a "when nimvm" node.
     result = copyTree(n)
     result[1][0] = processCall(n[1][0], s)
+
+  of nkPragmaBlock:
+    var inUncheckedAssignSection = 0
+    let pragmaList = n[0]
+    for pi in pragmaList:
+      if whichPragma(pi) == wCast:
+        case whichPragma(pi[1])
+        of wUncheckedAssign:
+          inUncheckedAssignSection = 1
+        else:
+          discard
+    result = shallowCopy(n)
+    inc c.inUncheckedAssignSection, inUncheckedAssignSection
+    for i in 0 ..< n.len-1:
+      result[i] = p(n[i], c, s, normal)
+    result[^1] = maybeVoid(n[^1], s)
+    dec c.inUncheckedAssignSection, inUncheckedAssignSection
+
   else: assert(false)
 
 proc pRaiseStmt(n: PNode, c: var Con; s: var Scope): PNode =
@@ -732,7 +750,7 @@ proc pRaiseStmt(n: PNode, c: var Con; s: var Scope): PNode =
 
 proc p(n: PNode; c: var Con; s: var Scope; mode: ProcessMode; tmpFlags = {sfSingleUsedTemp}): PNode =
   if n.kind in {nkStmtList, nkStmtListExpr, nkBlockStmt, nkBlockExpr, nkIfStmt,
-                nkIfExpr, nkCaseStmt, nkWhen, nkWhileStmt, nkParForStmt, nkTryStmt}:
+                nkIfExpr, nkCaseStmt, nkWhen, nkWhileStmt, nkParForStmt, nkTryStmt, nkPragmaBlock}:
     template process(child, s): untyped = p(child, c, s, mode)
     handleNestedTempl(n, process, tmpFlags = tmpFlags)
   elif mode == sinkArg:
@@ -928,25 +946,6 @@ proc p(n: PNode; c: var Con; s: var Scope; mode: ProcessMode; tmpFlags = {sfSing
         if mode == normal:
           result = ensureDestruction(result, n, c, s)
 
-    of nkPragmaBlock:
-      var inUncheckedAssignSection = 0
-      let pragmaList = n[0]
-      for pi in pragmaList:
-        if whichPragma(pi) == wCast:
-          case whichPragma(pi[1])
-          of wUncheckedAssign:
-            inUncheckedAssignSection = 1
-          else:
-            discard
-      result = shallowCopy(n)
-      inc c.inUncheckedAssignSection, inUncheckedAssignSection
-      for i in 0 ..< n.len:
-        result[i] = p(n[i], c, s, normal)
-      dec c.inUncheckedAssignSection, inUncheckedAssignSection
-      if n.typ != nil and hasDestructor(c, n.typ):
-        if mode == normal:
-          result = ensureDestruction(result, n, c, s)
-
     of nkHiddenSubConv, nkHiddenStdConv, nkConv:
       # we have an "ownership invariance" for all constructors C(x).
       # See the comment for nkBracket construction. If the caller wants

tests/arc/tmalloc.nim

@@ -0,0 +1,16 @@
+discard """
+  matrix: "--mm:arc -d:useMalloc; --mm:arc"
+"""
+
+block: # bug #22058
+  template foo(): auto =
+    {.noSideEffect.}:
+      newSeq[byte](1)
+
+  type V = object
+    v: seq[byte]
+
+  proc bar(): V =
+    V(v: foo())
+
+  doAssert bar().v == @[byte(0)]