c/10719: invalid code generated (x86, "int $5") with __builtin_va_arg(va, char);

[Joseph S. Myers]

On Mon, 12 May 2003 sbiallas@online-club.de wrote:

> I can't agree with this: gcc shouldn't generate
> invalid code on purpose. It knows there is an
> error and should generate an error and not a
> warning. The warning is misleading (it sounds like
> gcc found a problem and corrected it) and will
> probably not recognized.

Please read the response to Defect Report #109.  This code only yields 
undefined behavior if it is ever executed, and it might not be, so GCC 
must not yield an error.  To quote the response:

   A conforming implementation must not fail to translate a strictly
   conforming program simply because _some_ possible execution of that
   program would result in undefined behavior.

http://std.dkuug.dk/JTC1/SC22/WG14/www/docs/dr_109.html

-- 
Joseph S. Myers
jsm28@cam.ac.uk