c++: add parsing_function_declarator predicate

While looking at PR96184 I noticed that we were recognizing the situation of
parsing a function declarator based on current_binding_level, and that we
ought to make that a predicate function.  This patch is just refactoring,
but I just suggested using it in a review of another patch.

gcc/cp/ChangeLog:

	* cp-tree.h (parsing_function_declarator): Declare.
	* name-lookup.c (set_decl_context_in_fn): Use it.
	* parser.c (cp_parser_direct_declarator): Use it.
	(parsing_function_declarator): New.

1 files changed, 12 insertions, 1 deletions

diff --git a/gcc/cp/parser.c b/gcc/cp/parser.c
index 7a0b623..8d60f40 100644
--- a/gcc/cp/parser.c
+++ b/gcc/cp/parser.c
@@ -23107,7 +23107,7 @@ cp_parser_direct_declarator (cp_parser* parser,
 	      else if (!cp_parser_uncommitted_to_tentative_parse_p (parser))
 		/* Let compute_array_index_type diagnose this.  */;
 	      else if (!parser->in_function_body
-		       || current_binding_level->kind == sk_function_parms)
+		       || parsing_function_declarator ())
 		{
 		  /* Normally, the array bound must be an integral constant
 		     expression.  However, as an extension, we allow VLAs
@@ -23831,6 +23831,17 @@ parsing_nsdmi (void)
   return false;
 }
 
+/* True if we're parsing a function declarator.  */
+
+bool
+parsing_function_declarator ()
+{
+  /* this_entity is NULL for a function parameter scope while parsing the
+     declarator; it is set when parsing the body of the function.  */
+  return (current_binding_level->kind == sk_function_parms
+	  && !current_binding_level->this_entity);
+}
+
 /* Parse a late-specified return type, if any.  This is not a separate
    non-terminal, but part of a function declarator, which looks like