Re: PKG_LIB_DIR/PKGMODULEDIR expansion issues

On 7/1/22 23:30, Matsumura, George wrote:
> Greetings,
> 
> My build of Gutenprint, built through Void Linux's standardized build
> process, was unable to find the module directories due to PKGMODULEDIR
> being defined in config.h as:
> #define PKGMODULEDIR "${exec_prefix}/lib64/gutenprint/5.3/modules"
> 
> Since the C processor cannot expand exec_prefix, it remains in the path
> at runtime and cannot be resolved.
> 
> Attached is the config.summary from the build. In particular, the
> following flag passed to configure seemed to be responsible:
> --libdir=\${exec_prefix}/lib64

That definitely isn't valid; configure doesn't perform any expansion of its own, but rather takes
what was provided on its command line.

Why is it using

--libdir=\${exec_prefix}/lib64

rather than expanding it out?

> There seems to be a specific case in configure.ac for when libdir is
> defined as \${exec_prefix}/lib, but this would not cover my case.
> 
> This seems to be similar to the problem described here:
> https://www.gnu.org/savannah-checkouts/gnu/autoconf/manual/autoconf-2.71/html_node/Defining-Directories.html
> 
> Is there a recommended way to patch configure.ac so that such an option
> works correctly? The above reference suggests either moving definitions
> to compile-time options in Makefile.am, which, looking at the repository
> history, seems to have been done in gutenprint in the past, or using an
> additional macro to resolve the pathname.
> 
> Thank you for reading this and in advance for any reply.
> 
> Regards,
>     George