Re: ./configure find gmp.h but not gmpxx.h

[Stepan Kasal]

Hello Johan,

On Wed, May 28, 2008 at 11:08:22AM +0200, Johan Oudinet wrote:
> checking gmp.h usability... yes
> checking gmp.h presence... yes
> checking for gmp.h... yes
> checking gmpxx.h usability... no
> checking gmpxx.h presence... no
> checking for gmpxx.h... no
...
> $ find /usr/include/ -name 'gmp*.h'
> /usr/include/gmpxx.h
> /usr/include/gmp.h
> 
> How the configure can find one but not the other ?!

this is hard to guess.  configure creates a small file in the current
language (default is C), containing "#include <gmpxx.h>" and tries to
process it.  The "usability" check tries to compile it, which
"presence" means processing by the preprocessor only; but in any
case, it's not a mere check whether the file exists.

These attempts are logged in config.log; visit the log to see the
exact test source file and the error messages from the compiler and
preprocessor.

HTH,
        Stepan