cmd/compile: allow exporting .rcvr ident

Noder pass will build a closure to implement generic function
instantiation which may produce `.dict` and `.rcvr` ident.
Since we allow `.dict` during exporting, we should allow `.rcvr` too.

Fixes #52241.

Change-Id: Ifc3912ba5155b5ac1887f20830da64f4fb3fceb6
Reviewed-on: https://go-review.googlesource.com/c/go/+/404314
Run-TryBot: Wayne Zuo <wdvxdr@golangcn.org>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>

src/cmd/compile/internal/typecheck/iexport.go

@@ -2188,7 +2188,7 @@ func (w *exportWriter) localIdent(s *types.Sym) {
 		return
 	}
 
-	if i := strings.LastIndex(name, "."); i >= 0 && !strings.HasPrefix(name, LocalDictName) {
+	if i := strings.LastIndex(name, "."); i >= 0 && !strings.HasPrefix(name, LocalDictName) && !strings.HasPrefix(name, ".rcvr") {
 		base.Fatalf("unexpected dot in identifier: %v", name)
 	}
 

test/typeparam/issue52241.go

@@ -0,0 +1,22 @@
+// compile
+
+// Copyright 2022 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+type Collector[T any] struct {
+}
+
+func (c *Collector[T]) Collect() {
+}
+
+func TestInOrderIntTree() {
+	collector := Collector[int]{}
+	_ = collector.Collect
+}
+
+func main() {
+	TestInOrderIntTree()
+}