[PATCHv2 6/8] aclocal: avoid spurious warnings from autom4te with AC_CONFIG_MACRO_DIRS

[Stefano Lattarini]

When some macro expanded in configure.ac calls AC_REQUIRE on another
macro that is defined in one of the local m4 macro dirs specified
with AC_CONFIG_MACRO_DIRS, aclocal prints spurious warnings like:

    configure.ac:4: warning: MY_BAR is m4_require'd but not m4_defun'd
    configure.ac:3: MY_FOO is expanded from...

Such warnings come from autom4te, and are due to the fact that the
*first* autom4te invocation issued by aclocal is not yet able to
"see" the m4 macro definitions in the local m4 dirs (because they
can be looked for only after the AC_CONFIG_MACRO_DIRS call has been
traced, and tracing it requires running autom4te).

To allow us to work around this issue, autom4te has introduced a new
"witness" macro 'm4_require_silent_probe', that, when defined, allows
us to silence that particular kind of warnings (and only it).

Reported by Nick Bowler; see point (4) of:
<http://lists.gnu.org/archive/html/autoconf-patches/2012-11/msg00000.html>

* aclocal.in (trace_used_macros): Pre-define the special macro
'm4_require_silent_probe' when invoking autom4te.
* t/aclocal-macrodirs.tap ("AC_CONFIG_MACRO_DIR interaction with
AC_REQUIRE"): This test passes now: remove the "TODO" directive.
* t/aclocal-macrodir.tap ("AC_CONFIG_MACRO_DIRS interaction with
AC_REQUIRE"): Likewise.
* t/acloca17.sh: Remove.
* t/list-of-tests.mk: Adjust.

Signed-off-by: Stefano Lattarini <address@hidden>
---
 aclocal.in              |  8 ++++++++
 t/acloca17.sh           | 41 -----------------------------------------
 t/aclocal-macrodir.tap  |  2 +-
 t/aclocal-macrodirs.tap |  2 +-
 t/list-of-tests.mk      |  1 -
 5 files changed, 10 insertions(+), 44 deletions(-)
 delete mode 100755 t/acloca17.sh

diff --git a/aclocal.in b/aclocal.in
index 0220a7d..264ad75 100644
--- a/aclocal.in
+++ b/aclocal.in
@@ -718,6 +718,14 @@ sub trace_used_macros ()
 
   my $traces = ($ENV{AUTOM4TE} || '@am_AUTOM4TE@');
   $traces .= " --language Autoconf-without-aclocal-m4 ";
+  # When AC_CONFIG_MACRO_DIRS is used, avoid possible spurious warnings
+  # from autom4te about macros being "m4_require'd but not m4_defun'd";
+  # for more background, see:
+  # http://lists.gnu.org/archive/html/autoconf-patches/2012-11/msg00004.html
+  # as well as autoconf commit 'v2.69-44-g1ed0548', "warn: allow aclocal
+  # to silence m4_require warnings".
+  $traces = "echo 'm4_define([m4_require_silent_probe], [-])' | " .
+            "$traces - ";
   # All candidate files.
   $traces .= join (' ',
                   (map { "'$_'" }
diff --git a/t/acloca17.sh b/t/acloca17.sh
deleted file mode 100755
index ed8fc32..0000000
--- a/t/acloca17.sh
+++ /dev/null
@@ -1,41 +0,0 @@
-#! /bin/sh
-# Copyright (C) 2004-2012 Free Software Foundation, Inc.
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2, or (at your option)
-# any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-# Make sure aclocal report unused required macros.
-
-am_create_testdir=empty
-. test-init.sh
-
-cat > configure.ac << 'END'
-AC_INIT
-SOME_DEFS
-END
-
-mkdir m4
-cat >m4/somedefs.m4 <<EOF
-AC_DEFUN([SOME_DEFS], [
-  AC_REQUIRE([UNDEFINED_MACRO])
-])
-EOF
-
-# FIXME: We want autom4te's 'undefined required macro' warning to be fatal,
-# but have no means to say so to aclocal.  We use WARNINGS=error instead.
-
-WARNINGS=error $ACLOCAL -I m4 2>stderr && { cat stderr >&2; exit 1; }
-cat stderr >&2
-grep '^configure\.ac:2:.*UNDEFINED_MACRO' stderr
-
-:
diff --git a/t/aclocal-macrodir.tap b/t/aclocal-macrodir.tap
index c48b31f..63ede71 100755
--- a/t/aclocal-macrodir.tap
+++ b/t/aclocal-macrodir.tap
@@ -173,7 +173,7 @@ test_end
 
 #---------------------------------------------------------------------------
 
-test_begin "AC_CONFIG_MACRO_DIR interaction with AC_REQUIRE" TODO
+test_begin "AC_CONFIG_MACRO_DIR interaction with AC_REQUIRE"
 
 cat > configure.ac <<'END'
 AC_INIT([req], [1.0])
diff --git a/t/aclocal-macrodirs.tap b/t/aclocal-macrodirs.tap
index 3007ed4..a443e50 100755
--- a/t/aclocal-macrodirs.tap
+++ b/t/aclocal-macrodirs.tap
@@ -341,7 +341,7 @@ test_end
 
 #---------------------------------------------------------------------------
 
-test_begin "AC_CONFIG_MACRO_DIRS interaction with AC_REQUIRE" TODO
+test_begin "AC_CONFIG_MACRO_DIRS interaction with AC_REQUIRE"
 
 cat > configure.ac <<'END'
 AC_INIT([req], [1.0])
diff --git a/t/list-of-tests.mk b/t/list-of-tests.mk
index 9651dc7..2b19150 100644
--- a/t/list-of-tests.mk
+++ b/t/list-of-tests.mk
@@ -87,7 +87,6 @@ t/acloca14.sh \
 t/acloca14b.sh \
 t/acloca15.sh \
 t/acloca16.sh \
-t/acloca17.sh \
 t/acloca18.sh \
 t/acloca19.sh \
 t/acloca20.sh \
-- 
1.8.0