On Wed, Apr 25, 2012 at 9:04 AM, Dodji Seketeli <do...@redhat.com> wrote:
> In gcc/testsuite/gcc.dg/pr30457.c, the first warning was not being
> emitted because the relevant location was inside the var_start macro
> defined in a system header. It can even point to a token for a
> builtin macro there. This patch unwinds to the first token in real
> source code in that case.
While you are at it, could you also use a non-zero value for the second
argument argument to warning_at?
>
> Tested on x86_64-unknown-linux-gnu against trunk.
>
> * builtins.c (fold_builtin_next_arg): Unwinds to the first
> location in real source code.
> ---
> gcc/builtins.c | 16 ++++++++++++++--
> 1 files changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/gcc/builtins.c b/gcc/builtins.c
> index b47f218..ef90b25 100644
> --- a/gcc/builtins.c
> +++ b/gcc/builtins.c
> @@ -12164,8 +12164,20 @@ fold_builtin_next_arg (tree exp, bool va_start_p)
> the default argument promotions, the behavior is undefined."
> */
> else if (DECL_REGISTER (arg))
> - warning (0, "undefined behaviour when second parameter of "
> - "%<va_start%> is declared with %<register%> storage");
> + {
> + /* There is good chance the current input_location points
> + inside the definition of the va_start macro (perhaps on
> + the token for builtin) in a system header, so the warning
> + will not be emitted. Use the location in real source
> + code. */
> + source_location current_location =
> + linemap_unwind_to_first_non_reserved_loc (line_table,
> input_location,
> + NULL);
> + warning_at (current_location,
> + 0,
> + "undefined behaviour when second parameter of "
> + "%<va_start%> is declared with %<register%> storage");
> + }
>
> /* We want to verify the second parameter just once before the tree
> optimizers are run and then avoid keeping it in the tree,
> --
> Dodji
