[Bug c/69507] bogus warning: ISO C does not allow ‘__alignof__ (expression)’

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69507

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |ASSIGNED
   Last reconfirmed|                            |2016-01-27
           Assignee|unassigned at gcc dot gnu.org      |msebor at gcc dot 
gnu.org
     Ever confirmed|0                           |1
      Known to fail|                            |4.9.3, 5.1.0, 6.0

--- Comment #3 from Martin Sebor <msebor at gcc dot gnu.org> ---
This seems like a simple matter of a missed conditional in the parser.  The
following change suppresses the warning.  Let me add a test and post it for
review.

Index: gcc/c/c-parser.c
===================================================================
--- gcc/c/c-parser.c    (revision 232841)
+++ gcc/c/c-parser.c    (working copy)
@@ -7019,9 +7019,10 @@ c_parser_alignof_expression (c_parser *p
       mark_exp_read (expr.value);
       c_inhibit_evaluation_warnings--;
       in_alignof--;
-      pedwarn (start_loc,
-              OPT_Wpedantic, "ISO C does not allow %<%E (expression)%>",
-              alignof_spelling);
+      if (is_c11_alignof)
+       pedwarn (start_loc,
+                OPT_Wpedantic, "ISO C does not allow %<%E (expression)%>",
+                alignof_spelling);
       ret.value = c_alignof_expr (start_loc, expr.value);
       ret.original_code = ERROR_MARK;
       ret.original_type = NULL;