Re: [Vincent Lefevre] Bug#325866: autoconf: AC_COMPILE_IFELSE generates a test that doesn't work on IRIX64

[Noah Misch]

On Fri, Sep 02, 2005 at 08:17:51AM +0200, Vincent Lefevre wrote:
> On 2005-09-01 12:58:40 -0700, Noah Misch wrote:
> > It would be nice to handle this automatically, but I doubt we could
> > do so without breaking something elsewhere. Ralf has more experience
> > with matters like this one, and he mentioned some of the major
> > obstacles to a reliable implementation.
> 
> Would grepping "^  #error directive:" break anything elsewhere?

That is probably safe, but it adds a fork to every AC_COMPILE_IFELSE.  Cygwin
would suffer especially.

If we did use that approach, it would remain unwise to use #error in tests,
because you would introduce a silent dependency on the next release of Autoconf.
Older versions would produce a `configure' that works almost everywhere, but not
with this compiler on IRIX.

I recommend removing usage of #error from tests if portability to compilers with
this flaw is important.