c++: more dummy non_constant_p arg avoidance

As a follow-up to Marek's r14-3088-ga263152643bbec, this patch makes
us avoid passing an effectively dummy non_constant_p argument in two
more spots in the parser so that we further avoid unnecessary
constantness checks from cp_parser_constant_expression.

gcc/cp/ChangeLog:

	* parser.cc (cp_parser_parenthesized_expression_list_elt): Pass
	nullptr as non_constant_p to cp_parser_braced_list if our
	non_constant_p is null.
	(cp_parser_initializer_list): Likewise to
	cp_parser_initializer_clause.  Avoid inspecting
	clause_non_constant_p if it's uninitialized.

diff --git a/gcc/cp/parser.cc b/gcc/cp/parser.cc
index 7811d582b072a66e683dcf547e4437a20b5503fa..ed0675c95992b0e8290b392b79003f001120ab56 100644 (file)
--- a/gcc/cp/parser.cc
+++ b/gcc/cp/parser.cc
@@ -8160,7 +8160,10 @@ cp_parser_parenthesized_expression_list_elt (cp_parser *parser, bool cast_p,
       /* A braced-init-list.  */
       cp_lexer_set_source_position (parser->lexer);
       maybe_warn_cpp0x (CPP0X_INITIALIZER_LISTS);
-      expr = cp_parser_braced_list (parser, &expr_non_constant_p);
+      expr = cp_parser_braced_list (parser,
+                                   (non_constant_p != nullptr
+                                   ? &expr_non_constant_p
+                                   : nullptr));
       if (non_constant_p && expr_non_constant_p)
        *non_constant_p = true;
     }
@@ -25986,9 +25989,11 @@ cp_parser_initializer_list (cp_parser* parser, bool* non_constant_p,
 
       /* Parse the initializer.  */
       initializer = cp_parser_initializer_clause (parser,
-                                                 &clause_non_constant_p);
+                                                 (non_constant_p != nullptr
+                                                  ? &clause_non_constant_p
+                                                  : nullptr));
       /* If any clause is non-constant, so is the entire initializer.  */
-      if (clause_non_constant_p && non_constant_p)
+      if (non_constant_p && clause_non_constant_p)
        *non_constant_p = true;
 
       if (TREE_CODE (initializer) == CONSTRUCTOR)