[dev.typeparams] cmd/compile/internal/types2: provide valid signature in errors involving method expressions

This is an adjusted port of a similar fix in https://golang.org/cl/324733.

Fixes #46583.

Change-Id: Ica1410e4de561e64e58b753e3da04b32156cbaf6
Reviewed-on: https://go-review.googlesource.com/c/go/+/325369
Trust: Robert Griesemer <gri@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>

1 files changed, 28 insertions, 0 deletions

diff --git a/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46583.src b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46583.src
new file mode 100644
index 0000000000..da1f1ffbba
--- /dev/null
+++ b/src/cmd/compile/internal/types2/testdata/fixedbugs/issue46583.src
@@ -0,0 +1,28 @@
+// Copyright 2021 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 p
+
+type T1 struct{}
+func (t T1) m(int) {}
+var f1 func(T1)
+
+type T2 struct{}
+func (t T2) m(x int) {}
+var f2 func(T2)
+
+type T3 struct{}
+func (T3) m(int) {}
+var f3 func(T3)
+
+type T4 struct{}
+func (T4) m(x int) {}
+var f4 func(T4)
+
+func _() {
+	f1 = T1 /* ERROR func\(T1, int\) */ .m
+	f2 = T2 /* ERROR func\(t T2, x int\) */ .m
+	f3 = T3 /* ERROR func\(T3, int\) */ .m
+	f4 = T4 /* ERROR func\(_ T4, x int\) */ .m
+}