Re: Messed up gl_COMPILER_PREPARE_CHECK_DECL

[Bruno Haible]

Paul Eggert wrote:
> I can reproduce the problem when building GNU Emacs on Fedora 31 
> (Autoconf 2.69, Automake 1.16.1, m4 1.4.18)

Good, that means the problem does not come from an older version of Automake.

> by running the following recipe:
> 
> mkdir d
> cd d
> git clone https://git.savannah.gnu.org/git/emacs.git
> cd emacs
> admin/merge-gnulib
> ./autogen.sh

Thanks for the simple-to-reproduce recipe. I've pushed this fix:


2020-01-10  Bruno Haible  <address@hidden>

        Fix major regression from 2020-01-04.
        Reported by Mats Erik Andersson <address@hidden> in
        <https://lists.gnu.org/archive/html/bug-gnulib/2020-01/msg00072.html>.
        * m4/00gnulib.m4 (gl_COMPILER_PREPARE_CHECK_DECL): Define through
        AC_DEFUN_ONCE.
        (AC_CHECK_DECL): Invoke, not require, it.

diff --git a/m4/00gnulib.m4 b/m4/00gnulib.m4
index 77503ea..58bc4ef 100644
--- a/m4/00gnulib.m4
+++ b/m4/00gnulib.m4
@@ -1,4 +1,4 @@
-# 00gnulib.m4 serial 4
+# 00gnulib.m4 serial 5
 dnl Copyright (C) 2009-2020 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
@@ -62,7 +62,7 @@ barfbarf
        [gl_cv_compiler_clang=no])
     ])
 ])
-AC_DEFUN([gl_COMPILER_PREPARE_CHECK_DECL],
+AC_DEFUN_ONCE([gl_COMPILER_PREPARE_CHECK_DECL],
 [
   AC_REQUIRE([AC_PROG_CC])
   AC_REQUIRE([gl_COMPILER_CLANG])
@@ -95,10 +95,11 @@ m4_define([_AC_CHECK_DECL_BODY],
 m4_defn([_AC_CHECK_DECL_BODY])[  ac_compile="$ac_save_ac_compile"
 ])
   ])
-dnl Redefine AC_CHECK_DECL so that it starts with
-dnl AC_REQUIRE([gl_COMPILER_PREPARE_CHECK_DECL]).
+dnl Redefine AC_CHECK_DECL so that it starts with an invocation of
+dnl gl_COMPILER_PREPARE_CHECK_DECL.
 m4_define([AC_CHECK_DECL],
-  [AC_REQUIRE([gl_COMPILER_PREPARE_CHECK_DECL])]m4_defn([AC_CHECK_DECL]))
+  [gl_COMPILER_PREPARE_CHECK_DECL dnl
+]m4_defn([AC_CHECK_DECL]))
 
 # gl_00GNULIB
 # -----------