[gcc r13-1140] compiler: don't generate stubs for ambiguous direct interface methods

[Ian Lance Taylor <ian@gcc.gnu.org>]

https://gcc.gnu.org/g:b2aaa44d2c9c0e5a31688a6e40a7b132dd03338a

commit r13-1140-gb2aaa44d2c9c0e5a31688a6e40a7b132dd03338a
Author: Mikhail Ablakatov <ablakatov.m@gmail.com>
Date:   Thu May 12 21:45:35 2022 +0300

    compiler: don't generate stubs for ambiguous direct interface methods
    
    Current implementation checks whether it has to generate a stub method for a
    promoted method of an embedded struct field in Type::build_stub_methods(). If
    the promoted method is ambiguous it's simply skipped. But struct types that
    can fit in an interface value (e.g. structs that consist of a single pointer
    field) get a second chance in Type::build_direct_iface_stub_methods().
    
    This patch adds the same check used by Type::build_stub_methods() to
    Type::build_direct_iface_stub_methods().
    
    Fixes golang/go#52870
    
    Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/405974

Diff:
---
 gcc/go/gofrontend/MERGE    | 2 +-
 gcc/go/gofrontend/types.cc | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/gcc/go/gofrontend/MERGE b/gcc/go/gofrontend/MERGE
index aeada9f8d0c..0cda305c648 100644
--- a/gcc/go/gofrontend/MERGE
+++ b/gcc/go/gofrontend/MERGE
@@ -1,4 +1,4 @@
-bbb3a4347714faee620dc205674510a0f20b81ae
+8db6b78110f84e22c409f334aeaefb80a8b39917
 
 The first line of this file holds the git revision number of the last
 merge done from the gofrontend repository.
diff --git a/gcc/go/gofrontend/types.cc b/gcc/go/gofrontend/types.cc
index a8e309041e7..eb3afd94682 100644
--- a/gcc/go/gofrontend/types.cc
+++ b/gcc/go/gofrontend/types.cc
@@ -11891,7 +11891,7 @@ Type::build_direct_iface_stub_methods(Gogo* gogo, const Type* type,
         need_stub = true;
       if (!in_heap && !m->is_value_method())
         need_stub = true;
-      if (!need_stub)
+      if (!need_stub || m->is_ambiguous())
         continue;
 
       Type* receiver_type = const_cast<Type*>(type);