* lib/am/remake-hdr.am ($(srcdir)/%CONFIG_HIN%): Erase %STAMP%.

* tests/Makefile.am (TESTS): Add autohdr3.test
* tests/autohdr3.test: New file.

5 files changed, 90 insertions, 1 deletions

diff --git a/ChangeLog b/ChangeLog
index e3ce68e00..b7d2dfd42 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,9 @@
 2003-10-27  Alexandre Duret-Lutz  <adl@gnu.org>
 
+	* lib/am/remake-hdr.am ($(srcdir)/%CONFIG_HIN%): Erase %STAMP%.
+	* tests/Makefile.am (TESTS): Add autohdr3.test
+	* tests/autohdr3.test: New file.
+
 	* automake.in (handle_configure): Rename am__configure_deps
 	as am__aclocal_m4_deps and include $(ACLOCAL_M4_SOURCES) and
 	$configure_ac.  Define am__configure_deps as am__aclocal_m4_deps
diff --git a/lib/am/remake-hdr.am b/lib/am/remake-hdr.am
index 1ae7c0f27..067c34844 100644
--- a/lib/am/remake-hdr.am
+++ b/lib/am/remake-hdr.am
@@ -38,7 +38,38 @@
 if %?FIRST_CONFIG_HIN%
 $(srcdir)/%CONFIG_HIN%: %MAINTAINER-MODE% $(am__configure_deps) %FILES%
 	cd $(top_srcdir) && $(AUTOHEADER)
-## Autoheader has the bad habit of not changing the time stamp if
+## Whenever $(AUTOHEADER) has run, we must make sure that
+## ./config.status will rebuild config.h.  The dependency from %STAMP%
+## on %CONFIG_H_DEPS% (which contains config.hin) is not enough to
+## express his.
+##
+## There are some tricky cases where this rule will build a
+## config.hin which has the same timestamp as %STAMP%, in which case
+## ./config.status will not be rerun (meaning that users will use in
+## out-of-date config.h without knowing it).  One situation where this
+## can occurs is the following:
+## 1. the user updates some configure dependency (let's say foo.m4)
+##    and run `make'
+## 2. the rebuild rules detect that a foo.m4 has changed,
+##    run aclocal, autoconf, automake, and then run ./config.status.
+##    (Note that autoheader hasn't been called yet, so ./config.status
+##    outputs a config.h from an obsolete config.hin.)
+## 3. Once Makefile has been regenerated, make continues, and
+##    discover that config.h is a dependency of the `all' rule.
+##    Because config.h depends on stamp-h1, stamp-h1 depends on
+##    config.hin, and config.hin depends on aclocal.m4, make runs
+##    autoheader to rebuild config.hin.
+## Now make ought to call ./config.status once again to rebuild
+## config.h from the new config.hin, but if you have a sufficiently
+## fast box, steps 2 and 3 will occur within the same second: the
+## config.h/stamp-h1 generated from the outdated config.hin will have
+## the same mtime as the new config.hin.  Hence make will think that
+## config.h is up to date.
+##
+## A solution is to erase %STAMP% here so that the %STAMP% rule
+## is always triggered after the this one.
+	rm -f %STAMP%
+## Autoheader has the bad habit of not changing the timestamp if
 ## config.hin is unchanged, which breaks Make targets.  Since what
 ## must not changed gratuitously is config.h, which is already handled
 ## by config.status, there is no reason to make things complex for
diff --git a/tests/Makefile.am b/tests/Makefile.am
index e6063031a..e5646c26e 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -46,6 +46,7 @@ ar.test \
 asm.test \
 autohdr.test \
 autohdr2.test \
+autohdr3.test \
 autohdr4.test \
 auxdir.test \
 auxdir2.test \
diff --git a/tests/Makefile.in b/tests/Makefile.in
index f7e88e2c0..9dcff8f22 100644
--- a/tests/Makefile.in
+++ b/tests/Makefile.in
@@ -158,6 +158,7 @@ ar.test \
 asm.test \
 autohdr.test \
 autohdr2.test \
+autohdr3.test \
 autohdr4.test \
 auxdir.test \
 auxdir2.test \
diff --git a/tests/autohdr3.test b/tests/autohdr3.test
new file mode 100755
index 000000000..fefc95744
--- /dev/null
+++ b/tests/autohdr3.test
@@ -0,0 +1,52 @@
+#!/bin/sh
+# Copyright (C) 2003  Free Software Foundation, Inc.
+#
+# This file is part of GNU Automake.
+#
+# GNU Automake 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.
+#
+# GNU Automake 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 Automake; see the file COPYING.  If not, write to
+# the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+# Boston, MA 02111-1307, USA.
+
+# Check rebuild rules for autoheader.
+
+required=GNUmake
+. ./defs
+
+set -e
+
+cat >>configure.in <<EOF
+m4_include([foo.m4])
+AC_CONFIG_HEADERS([config.h:config.hin])
+AC_OUTPUT
+EOF
+
+: > Makefile.am
+: > foo.m4
+
+$ACLOCAL
+$AUTOCONF
+$AUTOHEADER
+$AUTOMAKE
+
+./configure
+$MAKE
+
+$sleep
+echo 'AC_DEFINE([GREPME], 1, [Doc for GREPME])' > foo.m4
+
+$MAKE
+grep GREPME config.hin
+grep GREPME config.h
+
+$MAKE distcheck