Re: vsnprintf unnecessarily configures and builds vasnprintf.o etc.

[Bruno Haible]

Hi Paul,

> the gnulib code added quite a bit of of unnecessary work
> to configure and build vasnprintf.o, printf-parse.o, printf-args.o,
> and asnprintf.o. None of these object files were needed: they were put
> into libgnu.a but were not used by anybody.

Additionally, when a shared library is built from libgnu.a, vasnprintf.o
gets included and installed in public locations although it's not needed.

> If an application uses vsnprintf, but does not use vasnprintf
> directly, then there's no need to configure and build those .o files
> on hosts that have a working vsnprintf. I'd like to fix gnulib to
> avoid this work.

Yes, this is a long-standing deficiency of gnulib.

> One way that comes to mind is to modify modules/vsnprintf so that it
> depends on a new module (modules/vasnprintf-if, say), which acts like
> modules/vasnprintf but does not put gl_FUNC_VASNPRINTF into
> configure.ac. Most of the contents of modules/vasnprintf would be
> moved into modules/vasnprintf-if. Then, gl_REPLACE_VSNPRINTF could
> invoke gl_FUNC_VASNPRINTF.

I believe the solution should be in gnulib-tool proper, and would involve
extending the syntax of the 'Dependencies' section in the module description.

But I have never been able to work out the details. Maybe if you present
a complete patch for the vasnprintf case, it will show in the daylight how
gnulib-tool should perform this extended dependency tracking?

Bruno
-- 
In memoriam Siegfried Buback <http://en.wikipedia.org/wiki/Siegfried_Buback>