fix nim-lang#1385 type alias to tyor type in proc mismatch

compiler/semtypes.nim

@@ -1261,6 +1261,14 @@ proc isMagic(sym: PSym): bool =
   let nPragmas = sym.ast[pragmasPos]
   return hasPragma(nPragmas, wMagic)
 
+proc maybeForkType(c: PContext, t: PType): PType =
+  if t.kind in {tyOr} and t.sym != nil:
+    result = newTypeS(t.kind, c)
+    newSons(result, t.len)
+    for i in 0..<t.len: result[i] = t[i]
+  else:
+    return t
+
 proc semProcTypeNode(c: PContext, n, genericParams: PNode,
                      prev: PType, kind: TSymKind; isType=false): PType =
   # for historical reasons (code grows) this is invoked for parameter
@@ -1352,6 +1360,7 @@ proc semProcTypeNode(c: PContext, n, genericParams: PNode,
         else:
           localError(c.config, a.info, "parameter '$1' requires a type" % arg.name.s)
           typ = errorType(c)
+      typ = maybeForkType(c, typ)
       let lifted = liftParamType(c, kind, genericParams, typ,
                                  arg.name.s, arg.info)
       let finalType = if lifted != nil: lifted else: typ.skipIntLit(c.idgen)

tests/typerel/t1385.nim

@@ -0,0 +1,8 @@
+type intorfloat = int or float
+
+proc x(a: intorfloat; b: intorfloat): string =
+  result = $a & " " & $b
+
+var c: float = 2.0
+var d: int = 3
+doAssert x(c, d) == "2.0 3"