fix #21727 (#21729)

compiler/semstmts.nim

@@ -2019,6 +2019,9 @@ proc semProcAux(c: PContext, n: PNode, kind: TSymKind,
   s.ast = n
   s.options = c.config.options
   #s.scope = c.currentScope
+  if s.kind in {skMacro, skTemplate}:
+    # push noalias flag at first to prevent unwanted recursive calls:
+    incl(s.flags, sfNoalias)
 
   # before compiling the proc params & body, set as current the scope
   # where the proc was declared
@@ -2335,16 +2338,16 @@ proc semMacroDef(c: PContext, n: PNode): PNode =
   var s = result[namePos].sym
   var t = s.typ
   var allUntyped = true
-  var requiresParams = false
+  var nullary = true
   for i in 1..<t.n.len:
     let param = t.n[i].sym
     if param.typ.kind != tyUntyped: allUntyped = false
     # no default value, parameters required in call
-    if param.ast == nil: requiresParams = true
+    if param.ast == nil: nullary = false
   if allUntyped: incl(s.flags, sfAllUntyped)
-  if requiresParams or n[genericParamsPos].kind != nkEmpty:
-    # macro cannot be called with alias syntax
-    incl(s.flags, sfNoalias)
+  if nullary and n[genericParamsPos].kind == nkEmpty:
+    # macro can be called with alias syntax, remove pushed noalias flag
+    excl(s.flags, sfNoalias)
   if n[bodyPos].kind == nkEmpty:
     localError(c.config, n.info, errImplOfXexpected % s.name.s)
 

compiler/semtempl.nim

@@ -626,6 +626,8 @@ proc semTemplateDef(c: PContext, n: PNode): PNode =
   onDef(n[namePos].info, s)
   # check parameter list:
   #s.scope = c.currentScope
+  # push noalias flag at first to prevent unwanted recursive calls:
+  incl(s.flags, sfNoalias)
   pushOwner(c, s)
   openScope(c)
   n[namePos] = newSymNode(s)
@@ -635,7 +637,7 @@ proc semTemplateDef(c: PContext, n: PNode): PNode =
   setGenericParamsMisc(c, n)
   # process parameters:
   var allUntyped = true
-  var requiresParams = false
+  var nullary = true
   if n[paramsPos].kind != nkEmpty:
     semParamList(c, n[paramsPos], n[genericParamsPos], s)
     # a template's parameters are not gensym'ed even if that was originally the
@@ -648,7 +650,7 @@ proc semTemplateDef(c: PContext, n: PNode): PNode =
         param.flags.excl sfGenSym
       if param.typ.kind != tyUntyped: allUntyped = false
       # no default value, parameters required in call
-      if param.ast == nil: requiresParams = true
+      if param.ast == nil: nullary = false
   else:
     s.typ = newTypeS(tyProc, c)
     # XXX why do we need tyTyped as a return type again?
@@ -660,11 +662,11 @@ proc semTemplateDef(c: PContext, n: PNode): PNode =
     n[genericParamsPos] = n[miscPos][1]
     n[miscPos] = c.graph.emptyNode
   if allUntyped: incl(s.flags, sfAllUntyped)
-  if requiresParams or
-      n[bodyPos].kind == nkEmpty or
-      n[genericParamsPos].kind != nkEmpty:
-    # template cannot be called with alias syntax
-    incl(s.flags, sfNoalias)
+  if nullary and
+      n[genericParamsPos].kind == nkEmpty and
+      n[bodyPos].kind != nkEmpty:
+    # template can be called with alias syntax, remove pushed noalias flag
+    excl(s.flags, sfNoalias)
 
   if n[patternPos].kind != nkEmpty:
     n[patternPos] = semPattern(c, n[patternPos], s)

tests/template/taliassyntax.nim

@@ -61,3 +61,14 @@ block: # issue #13515
     if not test:
       doAssert false
   x
+
+import macros
+
+block: # issue #21727
+  template debugAnnotation(s: typed): string =
+    astToStr s
+
+  macro cpsJump(x: int): untyped =
+    result = newLit(debugAnnotation(cpsJump))
+  
+  doAssert cpsJump(13) == "cpsJump"