Re: inconsistent seach orders in AC_PATH_PROGS vs AC_PATH_PROGS_FEATURE_CHECK

[Zack Weinberg]

On Thu, Sep 10, 2020 at 7:23 AM <dmitrii.pasechnik@cs.ox.ac.uk> wrote:
>
> One expects that the macro AC_PATH_PROGS_FEATURE_CHECK
> traverses the list of programs in its 2nd argument
> in the same way as  AC_PATH_PROGS,
> i.e. the outermost loop is over the list of programs.
>
> But in  AC_PATH_PROGS_FEATURE_CHECK the outer loop is
> over the PATH entries, making it in general impossible to
> select programs in the list in order specified (without modifying the
> path), while this is often very desirable.

Thanks for the suggestion.

We are in a feature freeze right now, leading up to the release of
Autoconf 2.70; we're not going to make this change until after the
release.  (It is currently scheduled for mid-to-late October.)  We
would also need to have some confidence that the change won't break
existing configure scripts and third-party macros.  Might you have
time in the next couple months to find existing uses of
AC_PATH_PROG_FEATURE_CHECK and determine how your proposed change
would affect them?  (Start here:
https://codesearch.debian.net/search?q=-pkg%3Aautoconf+%5CbAC_PATH_PROGS_FEATURE_CHECK%5Cb&literal=0
)

It would also be helpful if you could describe a situation where
selecting from the programs in the list in the order specified is
"very desirable".  I've never needed to use
AC_PATH_PROGS_FEATURE_CHECK myself so I don't already know why this
matters.

zw