Hi Jim, * Jim Meyering wrote on Thu, Aug 13, 2009 at 08:29:21AM CEST: [...] > systems with automake older than 1.11. > On those systems, it's fine to ignore or disable these > two unsupported options.
Yes. Often, automake's rejection of unsupported options is stricter than it would need to be. Unfortunately, I don't know of a general way to solve that, as just ignoring (and warning about) them is definitely not strict enough: some options cause incompatible behavior that may be desired. > I proposed a configure.ac-modifying "solution", > > https://www.redhat.com/archives/libguestfs/2009-August/msg00160.html > > but it's too ugly. > > Can you think of another way? I think Automake should provide an API to allow users to say "if the Automake version is >= X, then expand this configure.ac code". I think that would be general enough (it could use Automake conditionals to adjust Makefile.am files, it could check for >= X and not >= X+1 to enforce exact versions (or we could just provide a general version compare function) and it could then call AM_INIT_AUTOMAKE with the appropriate options). Also, it would be explicit enough for the developer to be conscious about not using this by accident. However, it would likely allow fool any tools that directly grepped the configure.ac files for AM_INIT_AUTOMAKE invocations, instead of using autom4te --language=Autoconf-without-aclocal-m4 --trace=AM_INIT_AUTOMAKE and even that would probably not give the right answer then (as aclocal.m4 contents will be needed in order to provide it). The initial patch below ought to improve the situation for future Automake versions (but unfortunately not for past ones). With it, you will be able to write code like AM_VERSION_PREREQ([1.12], [# this code assumes Automake 1.12 AM_INIT_AUTOMAKE([foreign fancy-new-option])], [# this code does not assume 1.12 AM_INIT_AUTOMAKE([foreign])]) Does that look like a viable approach to people? Of course, just like m4_version_prereq, it violates the Autoconf principle that you should test the actual feature you would like to use, rather than some version number. I don't know how to solve that without another layer of indirection, which would amount to something you outline in the URL above. (The other rationale why it may not be so bad here is that luckily, distros seem to provide pretty much plain upstream Automake these days, without many patches tacked on and features added, so that a version number actually retains some meaning.) What you can do in the meantime to have things work well for you with git Automake (once that provides AM_VERSION_PREREQ) is something like m4_ifdef([AM_VERSION_PREREQ], [ use AM_VERSION_PREREQ like above ... ], [ backward compat code ... ]) and you could even extend the idea to work back to 1.11 by testing for some macro that was new in 1.11, such as AM_SILENT_RULES or AM_COND_IF. However, there is a glitch: in case these macros are defined, i.e., the version is >= 1.11, you have to also actually use them in your configure.ac, so that not only aclocal (who searches in the .../share/aclocal-X.Y directory by default) finds them as defined, but also actually includes their definition into the aclocal.m4 file, so that a subsequent autoconf (who doesn't search .../share/aclocal-X.Y) finds them defined, too. Clear? As an unrelated side note, we don't use @defmac to define our macros, which can cause bugs when used with @dvar on a @-continued definition line, in the manual. This should be fixed. Cheers, Ralf New macro AM_VERSION_PREREQ. * m4/amversion.in (_AM_AUTOMAKE_VERSION): New define. * m4/prereq.m4 (AM_VERSION_PREREQ): New file, new macro, with code taken from Autoconf's m4_version_prereq. * tests/prereq.test: New test. * tests/Makefile.am: Adjust. * doc/automake.texi (@dvar): New texinfo macro, taken from Autoconf. (Public Macros): Document AM_VERSION_PREREQ. * NEWS: Update. Based on suggestion from Jim Meyering. diff --git a/NEWS b/NEWS index 7e14ed8..fe11327 100644 --- a/NEWS +++ b/NEWS @@ -1,5 +1,10 @@ New in 1.11a: +* Miscellaneous changes: + + - New macro AM_VERSION_PREREQ to allow expanding different code at M4 run + time based upon the Automake version used. + Bugs fixed in 1.11a: * Bugs introduced by 1.11: diff --git a/doc/automake.texi b/doc/automake.texi index b3f4a76..9a489ef 100644 --- a/doc/automake.texi +++ b/doc/automake.texi @@ -15,6 +15,14 @@ @r...@var{\varname\}@r{]} @end macro +...@c @dvar(ARG, DEFAULT) +...@c ------------------- +...@c The ARG is an optional argument, defaulting to DEFAULT. To be used +...@c for macro arguments in their documentation (@defmac). +...@macro dvar{varname, default} +...@r{[}@var{\varname\} = @samp{\defaul...@r{]}@c +...@end macro + @copying This manual is for @acronym{GNU} Automake (version @value{VERSION}, @@ -3896,6 +3904,15 @@ compiler is found. @acindex AM_SILENT_RULES Enable the machinery for less verbose build output (@pxref{Options}). +...@item AM_VERSION_PREREQ(@var{version}, @ovar{if-new-enough}, @dvar{if-old, m4_fatal}) +...@acindex AM_VERSION_PREREQ +If the Automake version used is at least @var{version}, then expand +...@var{if-new-enough}, otherwise expand @var{if-old}, which defaults to +printing an error message and exiting m4sugar with status 63. + +For example, this macro may be used to invoke @code{AM_INIT_AUTOMAKE} +differently based upon the Automake version used. + @item AM_WITH_DMALLOC @acindex AM_WITH_DMALLOC @cindex @command{dmalloc}, support for diff --git a/m4/amversion.in b/m4/amversion.in index 0ca73cf..30f96ef 100644 --- a/m4/amversion.in +++ b/m4/amversion.in @@ -1,11 +1,16 @@ ## -*- Autoconf -*- ## @configure_input@ -# Copyright (C) 2002, 2003, 2005, 2006, 2007, 2008 Free Software Foundation, Inc. +# Copyright (C) 2002, 2003, 2005, 2006, 2007, 2008, 2009 Free Software +# Foundation, Inc. # # This file is free software; the Free Software Foundation # gives unlimited permission to copy and/or distribute it, # with or without modifications, as long as this notice is preserved. +# _AM_AUTOMAKE_VERSION +# -------------------- +m4_define([_AM_AUTOMAKE_VERSION], [...@version@])dnl + # AM_AUTOMAKE_VERSION(VERSION) # ---------------------------- # Automake X.Y traces this macro to ensure aclocal.m4 has been diff --git a/m4/prereq.m4 b/m4/prereq.m4 new file mode 100644 index 0000000..c0b497d --- /dev/null +++ b/m4/prereq.m4 @@ -0,0 +1,25 @@ +# Expand code based on Automake version used. -*- Autoconf -*- + +# Copyright (C) 2009 Free Software Foundation, Inc. +# +# This file is free software; the Free Software Foundation +# gives unlimited permission to copy and/or distribute it, +# with or without modifications, as long as this notice is preserved. + +# serial 1 + +# AM_VERSION_PREREQ(VERSION, [IF-OK], [IF-NOT = FAIL]) +# ---------------------------------------------------- +# If the Automake version used is at least VERSION, expand +# IF-OK, otherwise expand IF-NOT, defaulting to failure. +# This macro may be used before AM_INIT_AUTOMAKE, and AM_INIT_AUTOMAKE +# may be called in the second or third arguments. +AC_DEFUN([AM_VERSION_PREREQ], +m4_ifdef([_AM_AUTOMAKE_VERSION], +[[m4_if(m4_version_compare(]m4_dquote(m4_defn([_AM_AUTOMAKE_VERSION]))[, [$1]), + [-1], + [m4_default([$3], + [m4_fatal([Automake version $1 or higher is required], + [63])])], + [$2])]], +[[m4_fatal([amversion.m4 not found])]])) diff --git a/tests/Makefile.am b/tests/Makefile.am index ae250b6..917ad48 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -544,6 +544,7 @@ pr401.test \ pr401b.test \ pr401c.test \ prefix.test \ +prereq.test \ primary.test \ primary2.test \ primary3.test \ diff --git a/tests/prereq.test b/tests/prereq.test new file mode 100755 index 0000000..50d71ec --- /dev/null +++ b/tests/prereq.test @@ -0,0 +1,83 @@ +#! /bin/sh +# Copyright (C) 2009 Free Software Foundation, Inc. +# +# This program is free software; you can redistribute it and/or modify +# it under the terms of the GNU General Public License as published by +# the Free Software Foundation; either version 2, or (at your option) +# any later version. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. + +# Test AM_VERSION_PREREQ. + +. ./defs || Exit 1 + +set -e + +cat > Makefile.am << 'END' +TESTS = +END + +cat > configure.in << END +AC_INIT([$me], [1.0]) +AM_VERSION_PREREQ([9999.9]) +AM_INIT_AUTOMAKE([foreign]) +AC_CONFIG_FILES(Makefile) +AC_OUTPUT +END + +$ACLOCAL && Exit 1 + +cat > configure.in << END +AC_INIT([$me], [1.0]) +AM_VERSION_PREREQ([9999.9], [], [ ]) +AM_INIT_AUTOMAKE([foreign]) +AC_CONFIG_FILES(Makefile) +AC_OUTPUT +END + +$ACLOCAL --force +$AUTOCONF +$AUTOMAKE --add-missing + +cat > configure.in << END +AC_INIT([$me], [1.0]) +AM_VERSION_PREREQ([9999.9], + [echo version is new + AM_INIT_AUTOMAKE([foreign parallel-tests])], + [echo version is old + AM_INIT_AUTOMAKE([foreign])]) +AM_INIT_AUTOMAKE([foreign]) +AC_CONFIG_FILES(Makefile) +AC_OUTPUT +END + +$ACLOCAL --force +$AUTOMAKE +grep TEST_SUITE_LOG Makefile.in && Exit 1 +$AUTOCONF --force +./configure | grep 'version is old' + +cat > configure.in << END +AC_INIT([$me], [1.0]) +AM_VERSION_PREREQ([1.11], + [echo version is new + AM_INIT_AUTOMAKE([foreign parallel-tests])], + [echo version is old + AM_INIT_AUTOMAKE([foreign])]) +AM_INIT_AUTOMAKE([foreign]) +AC_CONFIG_FILES(Makefile) +AC_OUTPUT +END + +$ACLOCAL --force +$AUTOMAKE +grep TEST_SUITE_LOG Makefile.in +$AUTOCONF --force +./configure | grep 'version is new'
