Re: play nice with AC_CACHE_CHECK

[Jim Meyering]

Ralf Wildenhues <address@hidden> wrote:

> 1) readline.m4 gives different results with cached reruns: for example,
> on x86_64-unknown-linux-gnu:
>
> ./configure -C
>         -> LIBREADLINE="-lreadline -lncurses"
> ./config.status --recheck
>         -> LIBREADLINE="-lreadline"
>
> This is because the commands to set the cache variable
> `gl_cv_lib_readline' also adjust LIBREADLINE and LTLIBREADLINE.
>
> The patch below fixes that by (ab)using the cache variable to hold the
> test result contents, making the COMMANDS-TO-SET-IT argument of the
> AC_CACHE_CHECK macro side-effect free.  Do you think the cache variable
> should be renamed (for users keeping the cache over the update; not that
> it was working well before anyway)?

Good catch.  I'm glad you didn't rename the cache variable.  Having a
conforming, well-known name is worth more than avoiding the possibility
of a few ephemeral user problems.  Besides, there may well be packages
that test $gl_cv_lib_readline, and changing the name would make them fail.