Re: [PATCH] config: Pass the compiler -Werror during warning detection

[Mark Wielaard <mjw at redhat dot com>]

On Mon, May 02, 2016 at 01:26:13PM -0700, Filipe Brandenburger wrote:
> Otherwise the compilation prints a warning but exits with 0 return code.
> However, later during the compilation, when -Werror is enforced to about
> every file, the unsupported options start breaking the builds.

Odd. Normally bad command line options should always cause a non-zero
exit code. Do you know if that was done deliberate or if it was fixed
in a later version of the compiler?

> Tested: Ran configure with clang-3.5 and built libelf/ tree with it.
> 
>   $ autoreconf -i
>   $ ./configure CC=clang-3.5 ...
>   $ make -C libelf

I am not against this patch if it makes our compiler feature detection
better. But clang really isn't supported. There have been many patches
to try to make elfutils build with it. But it seems there are just too
many missing features. In fact configure should check all basic language
constructs we are using ("gcc with GNU99 support"), so people don't
accidentially try building with a broken compiler. Does clang now
implement all gnu99 extensions or is our feature check broken?

Thanks,

Mark