Do so seen when only source files in the "current" directory are present.
This commit is part of a series of related changes addressing automake
bug#13378 (see also the plan 'PLANS/subdir-objects.txt').
Before this change, Automake-generated C compilation rules mistakenly
passed the "-c -o" options combination unconditionally (even to losing
compiler) when the 'subdir-objects' was used but sources were only
present in the top-level directory. Issue spotted by Nick Bowler:
<http://debbugs.gnu.org/cgi/bugreport.cgi?bug=13378#35>
<http://debbugs.gnu.org/cgi/bugreport.cgi?bug=13378#44>
We fix this by having Automake redefine AC_PROG_CC to take over the role
of AM_PROG_CC_C_O and to require the 'compile' script unconditionally
(albeit that will continue to be invoked only when inferior compilers
are detected).
Among other things, this means AM_PROG_CC_C_O explicitly is no longer
required; that macro is still supported for backward-compatibility, but
calling it is basically a no-op now.
This change has some pros and some cons (obviously, we believe the former
outweighs the latter). Here are the most relevant ones:
+ Pros 1:
Some logic in the Automake script has been simplified.
+ Pros 2:
That simplification has automatically fixed an actual bug (see
Nick's mails referenced above; admittedly, that was present only in
corner-case situations, but still); the test 't/ccnoco4.sh', which
demonstrated the bug and has been failing so far, now passes.
+ Pros 3:
Things works more "automagically" now (no need to manually add the
AM_PROG_CC_C_O macro to configure.ac anymore).
* Cons 1:
The 'compile' script will be required in all projects using C
compilation; this will only be a problem for packages not using
'--add-missing'. However, such packages are definitely more rare
than the ones using '--add-missing', and adjusting them will be
trivial -- just copy the compile script over from the new Automake
installation.
* Cons 2:
The copy & paste of autoconf internals hack this change has introduced
in our "rewrite" of AC_PROG_CC is really an egregious abomination. It
can only be justified with the fact that we expect future versions of
autoconf to implement the semantics we need directly in AC_PROG_CC, so
that we'll be able to leverage that (since Automake 1.14 will require
the latest Autoconf version released).
Now, the detailed list of file-by-file changes ...
* automake.in ($seen_cc_c_o): Remove this global variable.
(scan_autoconf_traces): Don't set it, and do not trace the
'AM_PROG_CC_C_O' m4 macro.
(lang_c_rewrite): Remove, no longer needed.
* doc/automake.texi: Adjust expected "autoreconf --install" output
in the amhello example. Remove statements about the need for the
AM_PROG_CC_C_O macro. Report it is obsolete now.
* m4/init.m4: Re-write AC_PROG_CC to append checks about whether the
C compiler supports "-c -o" together. These checks have basically
been ripped out (with adaptations) from the 'AC_PROG_CC_C_O' macro
of Autoconf and ...
* m4/minuso.m4 (AM_PROG_CC_C_O): ... this macro of ours, which has
thus basically become a no-op.
* t/ax/am-test-lib.sh (am_setup_testdir): Also copy the 'compile'
script in the test directory; if we don't do so, every test using
AC_PROG_CC should call automake with the "--add-missing" option, or
copy the 'compile' script itself.
* t/cond11.sh: No need to create a dummy 'compile' script: that is
already brought in by 'am_setup_testdir()', that is automatically
invoked when 'test-lib.sh' is sourced.
* t/add-missing.tap: Adjust: we expect the 'compile' script to be
required by a mere AC_PROG_CC call now.
* t/dist-auxdir-many-subdirs.sh: Likewise.
* t/specflg6.sh: Likewise.
* t/subobj4.sh: Likewise.
* t/cxx-lt-demo.sh: Likewise, and update comments to match.
* t/distcom2.sh: Enhance a little.
* t/dollarvar2.sh: Adjust.
* t/extra-portability.sh: Likewise.
* t/libobj19.sh: Likewise.
* t/per-target-flags.sh: Likewise.
* t/repeated-options.sh: Likewise.
* t/subobj.sh: Likewise, and enhance a little.
* t/ccnoco2.sh: Remove as obsolete.
* t/list-of-tests.mk (handwritten_TESTS): Adjust.
(XFAIL_TESTS): Remove 't/ccnoco4.sh'.
* NEWS: Update.
Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>
/doc/amhello/config.h.in~
/doc/amhello/configure
/doc/amhello/depcomp
+/doc/amhello/compile
/doc/amhello/install-sh
/doc/amhello/missing
/doc/web-manual
should take precedence over the same-named automake-provided macro
(defined in '/usr/local/share/aclocal-1.14/vala.m4').
+* C compilation, and the AC_PROG_CC and AM_PROG_CC_C_O macros:
+
+ - The 'compile' script is now unconditionally required for all
+ packages that perform C compilation (note that if you are using
+ the '--add-missing' option, automake will fetch that script for
+ you, so you shouldn't need any explicit adjustment).
+ This new behaviour is needed to avoid obscure errors when the
+ 'subdir-objects' option is used, and the compiler is an inferior
+ one that doesn't grasp the combined use of both the "-c -o"
+ options; see discussion about automake bug#13378 for more details:
+ <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=13378#35>
+ <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=13378#44>
+
+ - Automake will automatically enhance the AC_PROG_CC autoconf macro
+ to make it check, at configure time, that the C compiler supports
+ the combined use of both the "-c -o" options. This "rewrite" of
+ AC_PROG_CC is only meant to be temporary, since future Autoconf
+ versions should provide all the features Automake needs.
+
+ - The AM_PROG_CC_C_O is no longer useful, and its use is a no-op
+ now. Future Automake versions might start warning that this
+ macro is obsolete. For better backward-compatibility, this macro
+ still sets a proper 'ac_cv_prog_cc_*_c_o' cache variable, and
+ define the 'NO_MINUS_C_MINUS_O' C preprocessor symbol, but you
+ should really stop relying on that.
+
* Obsolescent features:
- Use of suffix-less info files (that can be specified through the
# TRUE if we've seen AM_PROG_AR
my $seen_ar = 0;
-# TRUE if we've seen AM_PROG_CC_C_O
-my $seen_cc_c_o = 0;
-
# Location of AC_REQUIRE_AUX_FILE calls, indexed by their argument.
my %required_aux_file = ();
AM_INIT_AUTOMAKE => 0,
AM_MAINTAINER_MODE => 0,
AM_PROG_AR => 0,
- AM_PROG_CC_C_O => 0,
_AM_SUBST_NOTMAKE => 1,
_AM_COND_IF => 1,
_AM_COND_ELSE => 1,
{
$seen_ar = $where;
}
- elsif ($macro eq 'AM_PROG_CC_C_O')
- {
- $seen_cc_c_o = $where;
- }
elsif ($macro eq '_AM_COND_IF')
{
cond_stack_if ('', $args[1], $where);
return option 'subdir-objects' ? LANG_SUBDIR : LANG_PROCESS;
}
-# Rewrite a single C source file.
-sub lang_c_rewrite
-{
- my ($directory, $base, $ext, $obj, $have_per_exec_flags, $var) = @_;
-
- my $r = LANG_PROCESS;
- if (option 'subdir-objects')
- {
- $r = LANG_SUBDIR;
- if ($directory && $directory ne '.')
- {
- $base = $directory . '/' . $base;
-
- # libtool is always able to put the object at the proper place,
- # so we do not have to require AM_PROG_CC_C_O when building .lo files.
- msg_var ('portability', $var,
- "compiling '$base.c' in subdir requires "
- . "'AM_PROG_CC_C_O' in '$configure_ac'",
- uniq_scope => US_GLOBAL,
- uniq_part => 'AM_PROG_CC_C_O subdir')
- unless $seen_cc_c_o || $obj eq '.lo';
- }
- }
-
- if (! $seen_cc_c_o
- && $have_per_exec_flags
- && ! option 'subdir-objects'
- && $obj ne '.lo')
- {
- msg_var ('portability',
- $var, "compiling '$base.c' with per-target flags requires "
- . "'AM_PROG_CC_C_O' in '$configure_ac'",
- uniq_scope => US_GLOBAL,
- uniq_part => 'AM_PROG_CC_C_O per-target')
- }
-
- return $r;
-}
-
# Rewrite a single header file.
sub lang_header_rewrite
{
~/amhello % @kbd{autoreconf --install}
configure.ac: installing './install-sh'
configure.ac: installing './missing'
+configure.ac: installing './compile'
src/Makefile.am: installing './depcomp'
@end example
@item AM_PROG_CC_C_O
@acindex AM_PROG_CC_C_O
@acindex AC_PROG_CC_C_O
-This is like @code{AC_PROG_CC_C_O}, but it generates its results in
-the manner required by Automake. You must use this instead of
-@code{AC_PROG_CC_C_O} when you need this functionality, that is, when
-using per-target flags or subdir-objects with C sources.
+This is an @emph{obsolete wrapper} around @code{AC_PROG_CC_C_O}.
+New code needs not use this macro. It might be deprecated and
+@emph{retired in future Automake versions}.
@item AM_PROG_LEX
@acindex AM_PROG_LEX
@table @code
+@item AM_PROG_CC_C_O
+@acindex AM_PROG_CC_C_O
+@acindex AC_PROG_CC_C_O
+This is an @emph{obsolete wrapper} around @code{AC_PROG_CC_C_O}. New
+code needs not to use this macro. It will be deprecated, and then
+removed, in future Automake versions.
+
@item AM_PROG_MKDIR_P
@acindex AM_PROG_MKDIR_P
@cindex @code{mkdir -p}, macro check
like @file{sample.c} will be compiled to produce @file{sample.o}.
However, if the program's @code{_CFLAGS} variable is set, then the
object file will be named, for instance, @file{maude-sample.o}. (See
-also @ref{Renamed Objects}.) The use of per-target compilation flags
-with C sources requires that the macro @code{AM_PROG_CC_C_O} be called
-from @file{configure.ac}.
+also @ref{Renamed Objects}).
In compilations with per-target flags, the ordinary @samp{AM_} form of
the flags variable is @emph{not} automatically included in the
@file{subdir/file.cxx}, then the output file would be
@file{subdir/file.o}.
-In order to use this option with C sources, you should add
-@code{AM_PROG_CC_C_O} to @file{configure.ac}.
-
@anchor{tar-formats}
@item @option{tar-v7}
@itemx @option{tar-ustar}
m4_define([_AC_COMPILER_EXEEXT],
m4_defn([_AC_COMPILER_EXEEXT])[m4_provide([_AM_COMPILER_EXEEXT])])
+dnl We have to redefine AC_PROG_CC to allow our compile rules to use
+dnl "-c -o" together also with losing compilers.
+dnl FIXME: Add references to the original discussion and bug report.
+dnl FIXME: Shameless copy & paste from Autoconf internals, since trying to
+dnl play smart among tangles of AC_REQUIRE, m4_defn, m4_provide and
+dnl other tricks was proving too difficult, and in the end, likely
+dnl more brittle too. And this should anyway be just a temporary
+dnl band-aid, until Autoconf provides the semantics and/or hooks we
+dnl need (hint hint, nudge nudge) ...
+AC_DEFUN([AC_PROG_CC],
+m4_defn([AC_PROG_CC])
+[AC_REQUIRE([AM_AUX_DIR_EXPAND])dnl
+AC_REQUIRE_AUX_FILE([compile])dnl
+dnl FIXME The following abomination is expected to disappear in
+dnl Automake 1.14.
+AC_MSG_CHECKING([whether $CC understands -c and -o together])
+set dummy $CC; am__cc=`AS_ECHO(["$[2]"]) | \
+ sed 's/[[^a-zA-Z0-9_]]/_/g;s/^[[0-9]]/_/'`
+AC_CACHE_VAL([am_cv_prog_cc_${am__cc}_c_o],
+[AC_LANG_CONFTEST([AC_LANG_PROGRAM([])])
+# Make sure it works both with $CC and with simple cc.
+# We do the test twice because some compilers refuse to overwrite an
+# existing .o file with -o, though they will create one.
+ac_try='$CC -c conftest.$ac_ext -o conftest2.$ac_objext >&AS_MESSAGE_LOG_FD'
+rm -f conftest2.*
+if _AC_DO_VAR(ac_try) && test -f conftest2.$ac_objext
+then
+ eval am_cv_prog_cc_${am__cc}_c_o=yes
+else
+ eval am_cv_prog_cc_${am__cc}_c_o=no
+fi
+rm -f core conftest*
+])dnl
+if eval test \"\$am_cv_prog_cc_${am__cc}_c_o\" = yes; then
+ AC_MSG_RESULT([yes])
+else
+ AC_MSG_RESULT([no])
+ # Losing compiler, so wrap it with the 'compile' script.
+ # FIXME: It is wrong to rewrite CC.
+ # But if we don't then we get into trouble of one sort or another.
+ # A longer-term fix would be to have automake use am__CC in this case,
+ # and then we could set am__CC="\$(top_srcdir)/compile \$(CC)"
+ CC="$am_aux_dir/compile $CC"
+fi
+])
# When config.status generates a header, we must update the stamp-h file.
# This file resides in the same directory as the config header
# AM_PROG_CC_C_O
# --------------
-# Like AC_PROG_CC_C_O, but changed for automake.
+# Basically a no-op now, completely superseded by the AC_PROG_CC
+# adjusted by Automake. Kept for backward-compatibility.
AC_DEFUN([AM_PROG_CC_C_O],
-[AC_REQUIRE([AC_PROG_CC_C_O])dnl
-AC_REQUIRE([AM_AUX_DIR_EXPAND])dnl
-AC_REQUIRE_AUX_FILE([compile])dnl
-# FIXME: we rely on the cache variable name because
-# there is no other way.
-set dummy $CC
-am_cc=`echo $[2] | sed ['s/[^a-zA-Z0-9_]/_/g;s/^[0-9]/_/']`
-eval am_t=\$ac_cv_prog_cc_${am_cc}_c_o
-if test "$am_t" != yes; then
- # Losing compiler, so override with the script.
- # FIXME: It is wrong to rewrite CC.
- # But if we don't then we get into trouble of one sort or another.
- # A longer-term fix would be to have automake use am__CC in this case,
- # and then we could set am__CC="\$(top_srcdir)/compile \$(CC)"
- CC="$am_aux_dir/compile $CC"
-fi
+[AC_REQUIRE([AC_PROG_CC])dnl
dnl Make sure AC_PROG_CC is never called again, or it will override our
dnl setting of CC.
m4_define([AC_PROG_CC],
[m4_fatal([AC_PROG_CC cannot be called after AM_PROG_CC_C_O])])
+# For better backward-compatibility. Users are advised to stop
+# relying on this cache variable and C preprocessor symbol ASAP.
+eval ac_cv_prog_cc_${am__cc}_c_o=\$am_cv_prog_cc_${am__cc}_c_o
+if eval test \"\$ac_cv_prog_cc_${am__cc}_c_o\" != yes; then
+ AC_DEFINE([NO_MINUS_C_MINUS_O], [1],
+ [Define to 1 if your C compiler doesn't accept -c and -o together.])
+fi
])
depcomp/C
== Files ==
depcomp
+compile
== configure.ac ==
AC_PROG_CC
== Makefile.am ==
== Files ==
compile
== configure.ac ==
-# Using AM_PROG_CC_C_O in configure.ac should be enough. No need to
-# use AC_PROG_CC too, nor to define xxx_PROGRAMS in Makefile.am.
-AM_PROG_CC_C_O
+# Using AC_PROG_CC in configure.ac should be enough. No
+# need to also define, say, xxx_PROGRAMS in Makefile.am.
+AC_PROG_CC
END
# For config.guess and config.sub.
== Name ==
ylwrap/Lex
== Files ==
+compile
ylwrap
== configure.ac ==
AC_PROG_CC
== Name ==
ylwrap/Yacc
== Files ==
+compile
ylwrap
== configure.ac ==
AC_PROG_CC
|| framework_failure_ "cannot chdir into test subdirectory"
if test x"$am_create_testdir" != x"empty"; then
cp "$am_scriptdir"/install-sh "$am_scriptdir"/missing \
- "$am_scriptdir"/depcomp . \
+ "$am_scriptdir"/compile "$am_scriptdir"/depcomp . \
|| framework_failure_ "fetching common files from $am_scriptdir"
# Build appropriate environment in test directory. E.g., create
# configure.ac, touch all necessary files, etc. Don't use AC_OUTPUT,
+++ /dev/null
-#! /bin/sh
-# Copyright (C) 2006-2013 Free Software Foundation, Inc.
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2, or (at your option)
-# any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program. If not, see <http://www.gnu.org/licenses/>.
-
-# Make sure Automake requires AM_PROG_CC_C_O when either per-targets
-# flags or subdir-objects are used.
-
-. test-init.sh
-
-cat >>configure.ac <<EOF
-AC_PROG_CC
-AC_OUTPUT
-EOF
-
-cat >Makefile.am <<EOF
-bin_PROGRAMS = wish
-wish_SOURCES = a.c
-wish_CPPFLAGS = -DWHATEVER
-EOF
-
-touch a.c
-
-$ACLOCAL
-$AUTOCONF
-AUTOMAKE_fails --copy --add-missing
-grep '^Makefile\.am:2:.*per-target.*AM_PROG_CC_C_O' stderr
-
-
-cat >Makefile.am <<EOF
-bin_PROGRAMS = wish
-wish_SOURCES = sub/a.c
-EOF
-
-mkdir sub
-mv a.c sub
-
-$AUTOMAKE --copy --add-missing
-
-echo 'AUTOMAKE_OPTIONS = subdir-objects' >> Makefile.am
-AUTOMAKE_fails --copy --add-missing
-grep '^Makefile\.am:2:.*subdir.*AM_PROG_CC_C_O' stderr
-
-:
: > config.guess
: > config.sub
-: > compile
$ACLOCAL
$AUTOCONF
$AUTOMAKE --add-missing --copy
ls -l . ax # For debugging.
-for f in ltmain.sh depcomp config.guess config.sub; do
+# Ideally, the 'compile' script should not be required by C++ compilers.
+# But alas, LT_INIT seems to invoke AC_PROG_CC anyway, and that brings in
+# that script.
+for f in ltmain.sh depcomp compile config.guess config.sub; do
test -f ax/$f && test ! -h ax/$f || exit 1
done
-test ! -e ax/compile # Not required by C++ compilers.
cat > src/main.cc << 'END'
#include "libfoo.h++"
required_files='
install-sh
missing
+ compile
depcomp
py-compile
test-driver
for opt in '' --no-force; do
+ rm -f compile depcomp
+
$AUTOMAKE $opt --add-missing
test -f compile
cat >Makefile.am <<'EOF'
x = 1
bla = $(foo$(x))
-noinst_PROGRAMS = foo
-foo_CPPFLAGS = -Dwhatever
+oops = $(var-with-dash)
EOF
-echo AC_PROG_CC >> configure.ac
-
-$ACLOCAL --force
-
# Can disable both 'portability' and 'portability-recursive' warnings.
$AUTOMAKE -Wno-portability
# Disabling 'portability-recursive' warnings should not disable
# 'portability' warnings.
AUTOMAKE_fails -Wportability -Wno-portability-recursive
-grep AM_PROG_CC_C_O stderr
+grep 'var-with-dash' stderr
grep 'recursive variable expansion' stderr && exit 1
# Enabling 'portability-recursive' warnings should not enable
# all the 'portability' warning.
AUTOMAKE_fails -Wno-portability -Wportability-recursive
-grep AM_PROG_CC_C_O stderr && exit 1
+grep 'var-with-dash' stderr && exit 1
grep 'recursive variable expansion' stderr
:
# Now, a setup where also a "simple" portability warning is present.
#
-# Per-target flags require the use of AM_PROG_CC_C_O in configure.ac.
-echo libfoo_a_CPPFLAGS = -Dwhatever >> Makefile.am
+echo 'var = $(foo--bar)' >> Makefile.am
# Enabling extra-portability enables portability as well ...
AUTOMAKE_fails -Wextra-portability
-grep 'requires.*AM_PROG_CC_C_O' stderr
+grep 'foo--bar' stderr
grep 'requires.*AM_PROG_AR' stderr
# ... even if it had been previously disabled.
AUTOMAKE_fails -Wno-portability -Wextra-portability
-grep 'requires.*AM_PROG_CC_C_O' stderr
+grep 'foo--bar' stderr
grep 'requires.*AM_PROG_AR' stderr
# Disabling extra-portability leaves portability intact (1).
AUTOMAKE_fails -Wportability -Wno-extra-portability
-grep 'requires.*AM_PROG_CC_C_O' stderr
+grep 'foo--bar' stderr
grep 'requires.*AM_PROG_AR' stderr && exit 1
# Disabling extra-portability leaves portability intact (2).
AUTOMAKE_fails -Wall -Wno-extra-portability
-grep 'requires.*AM_PROG_CC_C_O' stderr
+grep 'foo--bar' stderr
grep 'requires.*AM_PROG_AR' stderr && exit 1
# Enabling portability does not enable extra-portability.
AUTOMAKE_fails -Wportability
-grep 'requires.*AM_PROG_CC_C_O' stderr
+grep 'foo--bar' stderr
grep 'requires.*AM_PROG_AR' stderr && exit 1
# Disabling portability disables extra-portability.
END
cp "$am_scriptdir/ar-lib" . || fatal_ "fetching auxiliary script 'ar-lib'"
-cp "$am_scriptdir/compile" . || fatal_ "fetching auxiliary script 'compile'"
$ACLOCAL
$AUTOCONF
XFAIL_TESTS = \
t/all.sh \
-t/ccnoco4.sh \
t/cond17.sh \
t/gcj6.sh \
t/override-conditional-2.sh \
t/canon8.sh \
t/canon-name.sh \
t/ccnoco.sh \
-t/ccnoco2.sh \
t/ccnoco3.sh \
t/ccnoco4.sh \
t/check.sh \
AUTOMAKE_OPTIONS = no-dependencies
END
-# Make sure 'compile' is required.
-for m in $makefiles; do
- AUTOMAKE_fails $m
- $EGREP " required file.* '(compile|\./compile)'" stderr
-done
-
makefiles=$(for mkf in $makefiles; do echo $mkf.in; done)
-: > compile
$AUTOMAKE
# Sanity check.
}
END
-cp "$am_scriptdir"/compile "$am_scriptdir"/test-driver .
+cp "$am_scriptdir"/test-driver .
$ACLOCAL
$AUTOMAKE --foreign --foreign -Wall 2>stderr || { cat stderr >&2; exit 1; }
foo_SOURCES = foo.c
END
-: > compile
-
$ACLOCAL
$AUTOMAKE
cat >> configure.ac << 'END'
AC_PROG_CC
+dnl This should be a no-op now, but still be supported
+dnl without causing warnings.
AM_PROG_CC_C_O
END
END
$ACLOCAL
+rm -f compile
$AUTOMAKE --add-missing 2>stderr || { cat stderr >&2; exit 1; }
cat stderr >&2
# Make sure compile is installed, and that Automake says so.
-grep 'install.*compile' stderr
+grep '^configure\.ac:4:.*install.*compile' stderr
test -f compile
grep '^generic/a\.\$(OBJEXT):' Makefile.in
cat > d2/Makefile.am << 'END'
END
-: > compile
: > d2/z.c
$ACLOCAL
projects / platform / upstream / automake.git / commitdiff