disallow static in return type (#9686) [nobackport]

compiler/semtypes.nim

@@ -1230,6 +1230,9 @@ proc semProcTypeNode(c: PContext, n, genericParams: PNode,
         # 'p(): auto' and 'p(): expr' are equivalent, but the rest of the
         # compiler is hardly aware of 'auto':
         r = newTypeS(tyUntyped, c)
+      elif r.kind == tyStatic:
+        # type allowed should forbid this type
+        discard
       else:
         if r.sym == nil or sfAnon notin r.sym.flags:
           let lifted = liftParamType(c, kind, genericParams, r, "result",

compiler/types.nim

@@ -1238,7 +1238,9 @@ proc typeAllowedAux(marker: var IntSet, typ: PType, kind: TSymKind,
   of tyTypeDesc:
     # XXX: This is still a horrible idea...
     result = nil
-  of tyUntyped, tyTyped, tyStatic:
+  of tyStatic:
+    if kind notin {skParam}: result = t
+  of tyUntyped, tyTyped:
     if kind notin {skParam, skResult}: result = t
   of tyVoid:
     if taField notin flags: result = t

tests/errmsgs/tstaticresult.nim

@@ -0,0 +1,10 @@
+discard """
+errormsg: '''
+invalid type: 'static[int]' in this context: 'proc (x: int): static[int]' for proc
+'''
+"""
+
+proc foo(x: int): static int =
+  x + 123
+
+echo foo(123)