dist-auxdir-many-subdirs.sh

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Hash : 34001a98
Author :
Date : 2013-01-09T23:16:53

compile: use 'compile' script when "-c -o" is used with losing compilers

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>

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t/dist-auxdir-many-subdirs.sh

#! /bin/sh
# Copyright (C) 2011-2013 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/>.

# It should be legitimate for many subdir Makefiles to require the
# same config-aux files.

am_create_testdir=empty
required=cc
. test-init.sh

count=0
ocwd=$(pwd) || fatal_ "cannot get current working directory"

# Usage: do_check [--add-missing] [CONFIG-AUXDIR-PATH=.]
do_check ()
{
  case $1 in
    -a|--add-missing) add_missing=yes; shift;;
    *) add_missing=no;;
  esac
  auxdir=${1-.}

  count=$(($count + 1))
  mkdir T$count.d
  cd T$count.d

  distdir=$me-$count
  unindent > configure.ac << END
    AC_INIT([$me], [$count])
    AC_CONFIG_AUX_DIR([$auxdir])
    AM_INIT_AUTOMAKE
    AC_PROG_CC
    # We don't want to require python or emcas in this test, so
    # the tricks below.
    AM_PATH_PYTHON([2.2], [], [:])
    EMACS=no; AM_PATH_LISPDIR
    AC_CONFIG_FILES([Makefile])
END

  unindent > Makefile.stub <<'END'
    ## For depcomp.
    bin_PROGRAMS = foo
    foo_SOURCES = foo.c
    ## For py-compile.
    python_PYTHON = bar.py
    ## For test-driver.
    TESTS =
END

  required_files='
    install-sh
    missing
    compile
    depcomp
    py-compile
    test-driver
  '

  echo "SUBDIRS =" > Makefile.am

  suffixes='0 1 2 3 4 5 6 7 8 9'

  for x in $suffixes; do
    mkdir sub$x
    echo "SUBDIRS += sub$x" >> Makefile.am
    echo "AC_CONFIG_FILES([sub$x/Makefile])" >> configure.ac
    cp Makefile.stub sub$x/Makefile.am
    echo 'int main (void) { return 0; }' > sub$x/foo.c
    touch sub$x/bar.py sub$x/baz.el
  done
  echo AC_OUTPUT >> configure.ac

  $ACLOCAL
  $AUTOCONF

  "$am_scriptdir"/install-sh -d $auxdir \
    || fatal_ "creating directory '$auxdir' with install-sh"
  if test $add_missing = yes; then
    $AUTOMAKE -a --copy
    for f in $required_files; do
      test -f $auxdir/$f
      # To ensure that if a auxiliary file is required and distributed
      # by many Makefiles, the "dist" rule won't try to copy it multiple
      # times in $(distdir).
      chmod a-w $auxdir/$f
    done
  else
    for f in $required_files; do
      cp "$am_scriptdir"/$f $auxdir/$f \
        || fatal_ "faild to fetch auxiliary script '$f'"
      # See comments above.
      chmod a-w $auxdir/$f
    done
    $AUTOMAKE
  fi

  for vpath in : false; do
    if $vpath; then
      mkdir build
      cd build
      srcdir=..
    else
      srcdir=.
    fi
    $srcdir/configure
    $MAKE distdir
    find $distdir # For debugging.
    for f in $required_files; do
      test -f $distdir/$auxdir/$f
    done
    cd $srcdir
  done

  cd "$ocwd" || fatal_ "cannot chdir back to '$ocwd'"
}

do_check .
do_check --add-missing .
do_check build-aux
do_check --add-missing build-aux
do_check a/b/c
do_check --add-missing a/b/c

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