typed/untyped return type is invalid for everything except templates and macros (#10275)

compiler/semstmts.nim

@@ -1253,9 +1253,6 @@ proc semTypeSection(c: PContext, n: PNode): PNode =
 
 proc semParamList(c: PContext, n, genericParams: PNode, s: PSym) =
   s.typ = semProcTypeNode(c, n, genericParams, nil, s.kind)
-  if s.kind notin {skMacro, skTemplate}:
-    if s.typ.sons[0] != nil and s.typ.sons[0].kind == tyStmt:
-      localError(c.config, n.info, "invalid return type: 'stmt'")
 
 proc addParams(c: PContext, n: PNode, kind: TSymKind) =
   for i in countup(1, sonsLen(n)-1):

compiler/semtypes.nim

@@ -1158,12 +1158,15 @@ proc semProcTypeNode(c: PContext, n, genericParams: PNode,
     # turn explicit 'void' return type into 'nil' because the rest of the
     # compiler only checks for 'nil':
     if skipTypes(r, {tyGenericInst, tyAlias, tySink}).kind != tyVoid:
+      if kind notin {skMacro, skTemplate} and r.kind in {tyStmt, tyExpr}:
+        localError(c.config, n.sons[0].info, "return type '" & typeToString(r) & 
+            "' is only valid for macros and templates")
       # 'auto' as a return type does not imply a generic:
-      if r.kind == tyAnything:
+      elif r.kind == tyAnything:
         # 'p(): auto' and 'p(): expr' are equivalent, but the rest of the
         # compiler is hardly aware of 'auto':
         r = newTypeS(tyExpr, c)
-      elif r.kind != tyExpr:
+      else:
         if r.sym == nil or sfAnon notin r.sym.flags:
           let lifted = liftParamType(c, kind, genericParams, r, "result",
                                      n.sons[0].info)

tests/proc/tillegalreturntype.nim

@@ -0,0 +1,12 @@
+discard """
+  cmd: "nim check $file"
+  errmsg: ""
+  nimout: '''tillegalreturntype.nim(8, 11) Error: return type 'typed' is only valid for macros and templates
+tillegalreturntype.nim(11, 11) Error: return type 'untyped' is only valid for macros and templates'''
+"""
+
+proc x(): typed =
+  discard
+
+proc y(): untyped =
+  discard