cmd/compile: fix parsing of inlined interface types with unexported methods

Fixes #14164.

Change-Id: Ib1d1d29674c99cf88e0ae12724823a31f5dbb95c
Reviewed-on: https://go-review.googlesource.com/19087
Run-TryBot: Robert Griesemer <gri@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

test/fixedbugs/issue14164.dir/a.go

@@ -0,0 +1,47 @@
+// Copyright 2016 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 a
+
+// F is an exported function, small enough to be inlined.
+// It defines a local interface with an unexported method
+// f, which will appear with a package-qualified method
+// name in the export data.
+func F(x interface{}) bool {
+	_, ok := x.(interface {
+		f()
+	})
+	return ok
+}
+
+// Like F but with the unexported interface method f
+// defined via an embedded interface t. The compiler
+// always flattens embedded interfaces so there should
+// be no difference between F and G. Alas, currently
+// G is not inlineable (at least via export data), so
+// the issue is moot, here.
+func G(x interface{}) bool {
+	type t0 interface {
+		f()
+	}
+	_, ok := x.(interface {
+		t0
+	})
+	return ok
+}
+
+// Like G but now the embedded interface is declared
+// at package level. This function is inlineable via
+// export data. The export data representation is like
+// for F.
+func H(x interface{}) bool {
+	_, ok := x.(interface {
+		t1
+	})
+	return ok
+}
+
+type t1 interface {
+	f()
+}

test/fixedbugs/issue14164.dir/main.go

@@ -0,0 +1,12 @@
+// Copyright 2016 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
+
+// Verify that we can import package "a" containing an inlineable
+// function F that declares a local interface with a non-exported
+// method f.
+import _ "./a"
+
+func main() {}