[PATCH] compat: reinstate AM_CONFIG_HEADER and AM_PROG_CC_STDC

[Stefano Lattarini]

Make them give runtime warnings in the obsolete category, but apart
from that, make them behave as they did in Automake 1.12.x and earlier.

While removing those macros seemed quite harmless, because it didn't
put a real burden on the developers (requiring them just to do a quick
edit to configure.ac), it turned out to place an unsustainable burden
on distro packagers who use the latest Automake to bootstrap existing
packages.  Many of them still used AM_CONFIG_HEADER, and the removal
of this macro would have forced the packages to patch all those.

References:
<http://www.mail-archive.com/address@hidden/msg52840.html>
<http://www.spinics.net/lists/fedora-devel/msg175922.html>
<http://blog.flameeyes.eu/2013/01/autotools-mythbuster-automake-pains>

* t/backcompat6.sh: Use AM_CONFIG_HEADER once again.
* t/am-config-header-no-more.sh: Rename ...
* t/am-config-header.sh: ... like this, and adjust.
* t/am-prog-cc-stdc-no-more.sh: Rename ...
* t/am-prog-cc-stdc.sh: ... like this, and adjust.
* t/list-of-tests.mk: Adjust.
* NEWS: Update.

Signed-off-by: Stefano Lattarini <address@hidden>
---

 After this, I think we should cut a 1.13.2 release.  Since there are
 "incomplete" changes cooking in the 'maint' branch, this new release
 is best cut from an earlier point IMHO, that is, some commits after
 the 1.13.1 release.  Here are the commits I plan to include in the
 release:

    [v1.13.1 here]
    854be48 post-release: minor version bump (1.13.1a)
    2af1069 NEWS: fixlets and updates
    0a52679 build: respect silent rules in generation of "amhello" example 
tarball
    2af418d texi: warn against suffix-less info files
    8563941 cleanup: remove two lines of dead code in automake
    e1ed314 texi: warn against '.txi' and '.texinfo' input suffixes
    1c48cbe docs: re-introduce mention of two-args AM_INIT_AUTOMAKE invocation
    10ead72 cosmetics: remove few occurrences of trailing whitespace
    5fbe39b tests: more significant names for some tests
    17fb9bd tests: tweak tests on obsolete EXTRA_DATA variable
    20b7e1b style: add trailing ':' to some test cases
    fe05207 tests: reorganize tests on backslash issues
    ae4d4fc NEWS: we are not going to remove AM_PROG_MKDIR_P in Automake 1.14
    a7b2069 docs: serial-tests are not deprecated, just discouraged
    81527ed docs: parallel-tests is no longer experimental
    7621f14 compat: reinstate AM_CONFIG_HEADER and AM_PROG_CC_STDC
    [v1.13.2 here]

 In any case, I will do a proper beta release this time; so there will
 be time to smooth out mistakes I hope.

 NEWS                                               | 10 ++++++
 m4/obsolete-err.m4                                 | 20 ++++++-----
 ...onfig-header-no-more.sh => am-config-header.sh} | 41 +++++++++++++---------
 ...-prog-cc-stdc-no-more.sh => am-prog-cc-stdc.sh} | 35 +++++++++---------
 t/backcompat6.sh                                   |  2 +-
 t/list-of-tests.mk                                 |  4 +--
 6 files changed, 66 insertions(+), 46 deletions(-)
 rename t/{am-config-header-no-more.sh => am-config-header.sh} (55%)
 rename t/{am-prog-cc-stdc-no-more.sh => am-prog-cc-stdc.sh} (58%)

diff --git a/NEWS b/NEWS
index 88e5371..d49ed7b 100644
--- a/NEWS
+++ b/NEWS
@@ -64,6 +64,16 @@ New in 1.13.2:
     configure runtime (unfortunately, Autoconf does not yet support this
     scenario, so we cannot delegate the work to it).
 
+* Bugs fixed:
+
+  - The obsolete macros AM_CONFIG_HEADER or AM_PROG_CC_STDC work once
+    again, as they did in Automake 1.12.x (albeit printing runtime
+    warnings in the 'obsolete' category).  Removing them has turned
+    out to be a very bad idea, because it complicated distro packing
+    enormously.  Making them issue fatal warnings, as we did in
+    Automake 1.13, has turned out to be a similarly very bad idea,
+    for exactly the same reason.
+
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
 New in 1.13.1:
diff --git a/m4/obsolete-err.m4 b/m4/obsolete-err.m4
index d8119a4..f7ec1db 100644
--- a/m4/obsolete-err.m4
+++ b/m4/obsolete-err.m4
@@ -8,19 +8,21 @@
 # gives unlimited permission to copy and/or distribute it,
 # with or without modifications, as long as this notice is preserved.
 
-dnl TODO: Remove in Automake 1.15.
 AC_DEFUN([AM_CONFIG_HEADER],
-[AC_FATAL(['$0': this macro is obsolete.
-    You should use the 'AC][_CONFIG_HEADERS' macro instead.])])
+[AC_DIAGNOSE([obsolete],
+['$0': this macro is obsolete.
+You should use the 'AC][_CONFIG_HEADERS' macro instead.])dnl
+AC_CONFIG_HEADERS($@)])
 
-dnl TODO: Remove in Automake 1.15.
 AC_DEFUN([AM_PROG_CC_STDC],
-[AC_FATAL(['$0': this macro is obsolete.
-    You should simply use the 'AC][_PROG_CC' macro instead.
-    Also, your code should no longer depend upon 'am_cv_prog_cc_stdc',
-    but upon 'ac_cv_prog_cc_stdc'.])])
+[AC_PROG_CC
+am_cv_prog_cc_stdc=$ac_cv_prog_cc_stdc
+AC_DIAGNOSE([obsolete],
+['$0': this macro is obsolete.
+You should simply use the 'AC][_PROG_CC' macro instead.
+Also, your code should no longer depend upon 'am_cv_prog_cc_stdc',
+but upon 'ac_cv_prog_cc_stdc'.])])
 
-dnl TODO: Remove in Automake 1.14.
 AC_DEFUN([AM_C_PROTOTYPES],
          [AC_FATAL([automatic de-ANSI-fication support has been removed])])
 AU_DEFUN([fp_C_PROTOTYPES], [AM_C_PROTOTYPES])
diff --git a/t/am-config-header-no-more.sh b/t/am-config-header.sh
similarity index 55%
rename from t/am-config-header-no-more.sh
rename to t/am-config-header.sh
index 577ce05..49410e8 100755
--- a/t/am-config-header-no-more.sh
+++ b/t/am-config-header.sh
@@ -14,30 +14,37 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-# Check that any attempt to use the obsolete macro AM_CONFIG_HEADER
-# elicits clear and explicit fatal errors.
+# Check that the obsolete macro AM_CONFIG_HEADER still works.
 
 . test-init.sh
 
-geterr ()
-{
-    "$@" -Wnone 2>stderr && { cat stderr >&2; exit 1; }
-    cat stderr >&2
-    grep "^configure\.ac:4:.*'AM_CONFIG_HEADER'.*obsolete" stderr
-    grep "'AC_CONFIG_HEADERS'.* instead" stderr
-}
+cat > Makefile.am <<'END'
+check-local:
+       test -f oldconf.h
+       test -f $(srcdir)/oldconf.in
+END
 
-$ACLOCAL
-mv aclocal.m4 aclocal.sav
+cat >> configure.ac <<'END'
+AM_CONFIG_HEADER([oldconf.h:oldconf.in])
+AC_OUTPUT
+END
 
-echo AM_CONFIG_HEADER >> configure.ac
+$ACLOCAL -Wno-obsolete
 
-geterr $ACLOCAL
-test ! -f aclocal.m4
+$AUTOCONF -Werror -Wall 2>stderr && { cat stderr >&2; exit 1; }
+cat stderr >&2
+grep "^configure\.ac:4:.*'AM_CONFIG_HEADER'.*obsolete" stderr
+grep "'AC_CONFIG_HEADERS'.* instead" stderr
 
-cat aclocal.sav "$am_automake_acdir"/obsolete-err.m4 > aclocal.m4
+$AUTOCONF -Werror -Wall -Wno-obsolete
 
-geterr $AUTOCONF
-geterr $AUTOMAKE
+$AUTOHEADER
+test -f oldconf.in
+
+$AUTOMAKE
+
+./configure
+$MAKE check-local
+$MAKE distcheck
 
 :
diff --git a/t/am-prog-cc-stdc-no-more.sh b/t/am-prog-cc-stdc.sh
similarity index 58%
rename from t/am-prog-cc-stdc-no-more.sh
rename to t/am-prog-cc-stdc.sh
index a43e2d1..e3e469c 100755
--- a/t/am-prog-cc-stdc-no-more.sh
+++ b/t/am-prog-cc-stdc.sh
@@ -14,30 +14,31 @@
 # You should have received a copy of the GNU General Public License
 # along with this program.  If not, see <http://www.gnu.org/licenses/>.
 
-# Check that any attempt to use the obsolete macro AM_CONFIG_HEADER
-# elicits clear and explicit fatal errors.
+# Check that the obsolete macro the obsolete macro AM_PROG_CC_STDC
+# still works.
 
+required=gcc
 . test-init.sh
 
-geterr ()
-{
-    "$@" -Wnone 2>stderr && { cat stderr >&2; exit 1; }
-    cat stderr >&2
-    grep "^configure\.ac:4:.*'AM_PROG_CC_STDC'.*obsolete" stderr
-    grep "'AC_PROG_CC'.* instead" stderr
-}
+cat >> configure.ac <<'END'
+AM_PROG_CC_STDC
+AC_OUTPUT
+END
 
-$ACLOCAL
-mv aclocal.m4 aclocal.sav
+echo bin_PROGRAMS = foo > Makefile.am
 
-echo AM_PROG_CC_STDC >> configure.ac
+$ACLOCAL
+$AUTOMAKE
 
-geterr $ACLOCAL
-test ! -f aclocal.m4
+$AUTOCONF -Wnone -Wobsolete -Werror 2>stderr && { cat stderr >&2; exit 1; }
+cat stderr >&2
+grep "^configure\.ac:4:.*'AM_PROG_CC_STDC'.*obsolete" stderr
+grep "'AC_PROG_CC'.* instead" stderr
 
-cat aclocal.sav "$am_automake_acdir"/obsolete-err.m4 > aclocal.m4
+echo 'int main (void) { return 0; }' > foo.c
 
-geterr $AUTOCONF
-geterr $AUTOMAKE
+./configure
+$MAKE
+$MAKE distcheck
 
 :
diff --git a/t/backcompat6.sh b/t/backcompat6.sh
index 75e5c4f..d84ea97 100755
--- a/t/backcompat6.sh
+++ b/t/backcompat6.sh
@@ -38,7 +38,7 @@ AC_SUBST(two, $two)
 three=3
 AC_SUBST(three)
 AC_PROG_CC
-AC_CONFIG_HEADERS(config.h:config.hin)
+AM_CONFIG_HEADER(config.h:config.hin)
 AM_CONDITIONAL(CROSS_COMPILING, test "$cross_compiling" = yes)
 AC_OUTPUT(Makefile foo.got:foo1.in:foo2.in:foo3.in)
 END
diff --git a/t/list-of-tests.mk b/t/list-of-tests.mk
index 2a042ef..f1e3dca 100644
--- a/t/list-of-tests.mk
+++ b/t/list-of-tests.mk
@@ -130,8 +130,8 @@ t/amhello-cross-compile.sh \
 t/amhello-binpkg.sh \
 t/aminit-moreargs-deprecation.sh \
 t/amassign.sh \
-t/am-config-header-no-more.sh \
-t/am-prog-cc-stdc-no-more.sh \
+t/am-config-header.sh \
+t/am-prog-cc-stdc.sh \
 t/am-macro-not-found.sh \
 t/amopt.sh \
 t/amopts-location.sh \
-- 
1.8.1.rc3.192.g2d0029e