fixes #13622 (#13679)

compiler/injectdestructors.nim

@@ -31,6 +31,7 @@ type
     emptyNode: PNode
     otherRead: PNode
     inLoop: int
+    declaredVars: IntSet # variables we already moved to the top level
     uninit: IntSet # set of uninit'ed vars
     uninitComputed: bool
 
@@ -345,7 +346,7 @@ proc passCopyToSink(n: PNode; c: var Con): PNode =
     var m = genCopy(c, tmp, n)
     m.add p(n, c, normal)
     result.add m
-    if isLValue(n) and not isClosureEnv(n):
+    if isLValue(n) and not isClosureEnv(n) and n.typ.skipTypes(abstractInst).kind != tyRef:
       message(c.graph.config, n.info, hintPerformance,
         ("passing '$1' to a sink parameter introduces an implicit copy; " &
         "use 'move($1)' to prevent it") % $n)
@@ -589,6 +590,7 @@ proc p(n: PNode; c: var Con; mode: ProcessMode): PNode =
             if v.kind == nkSym:
               if sfCompileTime in v.sym.flags: continue
               # move the variable declaration to the top of the frame:
+              if not containsOrIncl(c.declaredVars, v.sym.id):
                 c.addTopVar v
               # make sure it's destroyed at the end of the proc:
               if not isUnpackedTuple(v) and sfThread notin v.sym.flags:

tests/arc/tstrformat.nim

@@ -0,0 +1,20 @@
+discard """
+  output: '''verstuff'''
+  cmd: "nim c --gc:arc $file"
+"""
+
+# bug #13622
+
+import strformat
+
+template necho*(args: string) {.dirty.} =
+  if getCurrentException() != nil:
+    echo args
+  else:
+    stdout.writeLine(args)
+
+proc main(cond: bool; arg: string) =
+  if cond:
+    necho &"ver{arg}\n"
+
+main(true, "stuff")