Re: [PATCH] m4: Update invocation of AC_PROG_LEX

[Zack Weinberg]

On Wed, Aug 16, 2023, at 2:38 AM, Łukasz Stelmach wrote:
> Commit 73f1be5e42e3 to autoconf has introduced an argument to
> AC_PROG_LEX. Invocation without the argument has been treated as
> obsolete since then.

This should go to automake-patches, not autoconf-patches.  Also, you
should update the manual (automake.texi) to document that AM_PROG_LEX
now takes an argument and what that argument is.  Finally, I'd like to
suggest a small improvement to the code: instead of

> -AC_REQUIRE([AC_PROG_LEX])dnl
> +AC_PROG_LEX([$1])dnl

you should have

-AC_REQUIRE([AC_PROG_LEX])dnl
+AC_PROVIDE_IFELSE([AC_PROG_LEX], [], [AC_PROG_LEX([$@])])dnl

This change ensures that AC_PROG_LEX will not be invoked a second time
if it has already been used directly, which is important both because
that's the way it has always worked, and because we (autoconf maintainers)
have been telling people to work around the problem you're fixing by using
AC_PROG_LEX _as well as_ AM_PROG_LEX.  It also makes AM_PROG_LEX oblivious
to how many arguments AC_PROG_LEX actually takes, which could be important
future-proofing.

zw