[gcc r12-3537] c++: correct object scope handling

[Jason Merrill]

https://gcc.gnu.org/g:ba9b07d0259b38a9eccd4eb0df327d3aaabad3c6

commit r12-3537-gba9b07d0259b38a9eccd4eb0df327d3aaabad3c6
Author: Jason Merrill <jason@redhat.com>
Date:   Mon Sep 13 16:10:09 2021 -0400

    c++: correct object scope handling
    
    The way cp_parser_lookup_name handles object scope (i.e. the scope on the
    RHS of a . or -> expression) is a bit subtle: before the lookup it's in
    parser->context->object type, and after the lookup it's in
    parser->object_scope.  But a couple of places that elide lookups were
    failing to do the same transform.
    
    I'm not aware of this breaking anything currently.
    
    gcc/cp/ChangeLog:
    
            * parser.c (cp_parser_template_name): Move object type.
            (cp_parser_pre_parsed_nested_name_specifier): Likewise.

Diff:
---
 gcc/cp/parser.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index ab1dc81b997..7a0b6234350 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -18405,6 +18405,7 @@ cp_parser_template_name (cp_parser* parser,
 	    {
 	      /* We're optimizing away the call to cp_parser_lookup_name, but
 		 we still need to do this.  */
+	      parser->object_scope = parser->context->object_type;
 	      parser->context->object_type = NULL_TREE;
 	      return identifier;
 	    }
@@ -33575,7 +33576,8 @@ cp_parser_pre_parsed_nested_name_specifier (cp_parser *parser)
   /* Set the scope from the stored value.  */
   parser->scope = saved_checks_value (check_value);
   parser->qualifying_scope = check_value->qualifying_scope;
-  parser->object_scope = NULL_TREE;
+  parser->object_scope = parser->context->object_type;
+  parser->context->object_type = NULL_TREE;
 }
 
 /* Consume tokens up through a non-nested END token.  Returns TRUE if we