[libvirt] [PATCH] Improve compiler flag checking

[Daniel P. Berrange]

On Tue, Dec 16, 2008 at 06:48:56PM -0800, john.levon at sun.com wrote:
> # HG changeset patch
> # User john.levon at sun.com
> # Date 1229399267 28800
> # Node ID 1f7707a3d49b20397011897cdc04c347322ad0c5
> # Parent  a6c317b5fe1b4081ccb40ba90af7d31298cf6b44
> Improve compiler flag checking
> 
> Some compilers (including GCC) don't set the return value consistently
> if an erroneous option is passed on the command line. Account for that.

This isn't quite correct. We do explicitly need to do a
AC_TRY_LINK test, because on Debian there are flags which
are accepted by the compiler OK, but will then fail to
link.

So we should keep the AC_TRY_LINK check, and upon success
of that, then also do your additional new check for zero-
length stderr output.

Daniel
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