Fix #21532: Check if template return is untyped (#22517)

* Don't ignore return in semTemplateDef

* Add test

---------

Co-authored-by: SirOlaf <>

compiler/semtempl.nim

@@ -674,6 +674,9 @@ proc semTemplateDef(c: PContext, n: PNode): PNode =
     # a template's parameters are not gensym'ed even if that was originally the
     # case as we determine whether it's a template parameter in the template
     # body by the absence of the sfGenSym flag:
+    let retType = s.typ[0]
+    if retType != nil and retType.kind != tyUntyped:
+      allUntyped = false
     for i in 1..<s.typ.n.len:
       let param = s.typ.n[i].sym
       if param.name.id != ord(wUnderscore):

tests/template/t21532.nim

@@ -0,0 +1,8 @@
+
+template elementType(a: untyped): typedesc =
+  typeof(block: (for ai in a: ai))
+
+func fn[T](a: T) =
+  doAssert elementType(a) is int
+
+@[1,2,3].fn