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>

22 files changed, 122 insertions, 166 deletions

diff --git a/.gitignore b/.gitignore
index dd55add5f..4b509d70e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -33,6 +33,7 @@
 /doc/amhello/config.h.in~
 /doc/amhello/configure
 /doc/amhello/depcomp
+/doc/amhello/compile
 /doc/amhello/install-sh
 /doc/amhello/missing
 /doc/web-manual
diff --git a/NEWS b/NEWS
index 02a34df75..09bfc1ed6 100644
--- a/NEWS
+++ b/NEWS
@@ -49,6 +49,32 @@ New in 1.13.2:
     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
diff --git a/automake.in b/automake.in
index e8ba73f94..990b60d60 100644
--- a/automake.in
+++ b/automake.in
@@ -387,9 +387,6 @@ my $package_version_location;
 # 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 = ();
 
@@ -5179,7 +5176,6 @@ sub scan_autoconf_traces ($)
 		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,
@@ -5383,10 +5379,6 @@ EOF
 	{
 	  $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);
@@ -5607,45 +5599,6 @@ sub lang_sub_obj
     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
 {
diff --git a/doc/automake.texi b/doc/automake.texi
index 8ace5e5e0..a333a1c33 100644
--- a/doc/automake.texi
+++ b/doc/automake.texi
@@ -1496,6 +1496,7 @@ command as follows:
 ~/amhello % @kbd{autoreconf --install}
 configure.ac: installing './install-sh'
 configure.ac: installing './missing'
+configure.ac: installing './compile'
 src/Makefile.am: installing './depcomp'
 @end example
 
@@ -3994,10 +3995,9 @@ choose the assembler for you (by default the C compiler) and set
 @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
@@ -4068,6 +4068,13 @@ Invocation, , Using @command{autoupdate} to Modernize
 
 @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
@@ -5810,9 +5817,7 @@ different name for the intermediate object files.  Ordinarily a file
 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
@@ -10245,9 +10250,6 @@ the source file.  For instance, if the source file is
 @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}
diff --git a/m4/init.m4 b/m4/init.m4
index 44b24819a..c5af65cce 100644
--- a/m4/init.m4
+++ b/m4/init.m4
@@ -125,6 +125,51 @@ dnl mangled by Autoconf and run in a shell conditional statement.
 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
diff --git a/m4/minuso.m4 b/m4/minuso.m4
index 984427cfc..17fa8c92a 100644
--- a/m4/minuso.m4
+++ b/m4/minuso.m4
@@ -7,26 +7,19 @@
 
 # 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
 ])
diff --git a/t/add-missing.tap b/t/add-missing.tap
index f74c2fd93..9c4b774b3 100755
--- a/t/add-missing.tap
+++ b/t/add-missing.tap
@@ -247,6 +247,7 @@ check_ <<'END'
 depcomp/C
 == Files ==
 depcomp
+compile
 == configure.ac ==
 AC_PROG_CC
 == Makefile.am ==
@@ -271,9 +272,9 @@ compile
 == 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.
@@ -294,6 +295,7 @@ check_ <<'END'
 == Name ==
 ylwrap/Lex
 == Files ==
+compile
 ylwrap
 == configure.ac ==
 AC_PROG_CC
@@ -308,6 +310,7 @@ check_ <<'END'
 == Name ==
 ylwrap/Yacc
 == Files ==
+compile
 ylwrap
 == configure.ac ==
 AC_PROG_CC
diff --git a/t/ax/am-test-lib.sh b/t/ax/am-test-lib.sh
index f3fcacca5..0ceb4d09c 100644
--- a/t/ax/am-test-lib.sh
+++ b/t/ax/am-test-lib.sh
@@ -820,7 +820,7 @@ am_setup_testdir ()
     || 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 $am_scriptdir"
     # Build appropriate environment in test directory.  E.g., create
     # configure.ac, touch all necessary files, etc.  Don't use AC_OUTPUT,
diff --git a/t/ccnoco2.sh b/t/ccnoco2.sh
deleted file mode 100755
index a835fa668..000000000
--- a/t/ccnoco2.sh
+++ /dev/null
@@ -1,55 +0,0 @@
-#! /bin/sh
-# Copyright (C) 2006-2013 Free Software Foundation, Inc.
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2, or (at your option)
-# any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program.  If not, see <http://www.gnu.org/licenses/>.
-
-# Make sure Automake requires AM_PROG_CC_C_O when either per-targets
-# flags or subdir-objects are used.
-
-. test-init.sh
-
-cat >>configure.ac <<EOF
-AC_PROG_CC
-AC_OUTPUT
-EOF
-
-cat >Makefile.am <<EOF
-bin_PROGRAMS = wish
-wish_SOURCES = a.c
-wish_CPPFLAGS = -DWHATEVER
-EOF
-
-touch a.c
-
-$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
-
-:
diff --git a/t/cond11.sh b/t/cond11.sh
index 03c4077ad..7d729d8f1 100755
--- a/t/cond11.sh
+++ b/t/cond11.sh
@@ -47,7 +47,6 @@ END
 
 : > config.guess
 : > config.sub
-: > compile
 
 $ACLOCAL
 $AUTOCONF
diff --git a/t/cxx-lt-demo.sh b/t/cxx-lt-demo.sh
index 8afc974aa..3a87cfdfc 100755
--- a/t/cxx-lt-demo.sh
+++ b/t/cxx-lt-demo.sh
@@ -94,10 +94,12 @@ $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++"
diff --git a/t/dist-auxdir-many-subdirs.sh b/t/dist-auxdir-many-subdirs.sh
index d49372a1f..ec1a9641f 100755
--- a/t/dist-auxdir-many-subdirs.sh
+++ b/t/dist-auxdir-many-subdirs.sh
@@ -63,6 +63,7 @@ END
   required_files='
     install-sh
     missing
+    compile
     depcomp
     py-compile
     test-driver
diff --git a/t/distcom2.sh b/t/distcom2.sh
index 57154d97c..dc0cb4d29 100755
--- a/t/distcom2.sh
+++ b/t/distcom2.sh
@@ -44,6 +44,8 @@ $ACLOCAL
 
 for opt in '' --no-force; do
 
+  rm -f compile depcomp
+
   $AUTOMAKE $opt --add-missing
 
   test -f compile
diff --git a/t/dollarvar2.sh b/t/dollarvar2.sh
index 718374370..ef2dd06af 100755
--- a/t/dollarvar2.sh
+++ b/t/dollarvar2.sh
@@ -65,27 +65,22 @@ grep 'recursive variable expansion' stderr
 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
 
 :
diff --git a/t/extra-portability.sh b/t/extra-portability.sh
index 94dd799e2..1ea23ad75 100755
--- a/t/extra-portability.sh
+++ b/t/extra-portability.sh
@@ -62,30 +62,29 @@ $AUTOMAKE -Wall -Wno-portability
 # 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.
diff --git a/t/libobj19.sh b/t/libobj19.sh
index fdca575b5..65172fb21 100755
--- a/t/libobj19.sh
+++ b/t/libobj19.sh
@@ -55,7 +55,6 @@ extern int dummy;
 END
 
 cp "$am_scriptdir/ar-lib" . || fatal_ "fetching auxiliary script 'ar-lib'"
-cp "$am_scriptdir/compile" . || fatal_ "fetching auxiliary script 'compile'"
 
 $ACLOCAL
 $AUTOCONF
diff --git a/t/list-of-tests.mk b/t/list-of-tests.mk
index 2052bd8ee..baccdca6d 100644
--- a/t/list-of-tests.mk
+++ b/t/list-of-tests.mk
@@ -30,7 +30,6 @@ t/pm/Version3.pl
 
 XFAIL_TESTS = \
 t/all.sh \
-t/ccnoco4.sh \
 t/cond17.sh \
 t/gcj6.sh \
 t/override-conditional-2.sh \
@@ -208,7 +207,6 @@ t/canon7.sh \
 t/canon8.sh \
 t/canon-name.sh \
 t/ccnoco.sh \
-t/ccnoco2.sh \
 t/ccnoco3.sh \
 t/ccnoco4.sh \
 t/check.sh \
diff --git a/t/per-target-flags.sh b/t/per-target-flags.sh
index ef19e6925..333242f9d 100755
--- a/t/per-target-flags.sh
+++ b/t/per-target-flags.sh
@@ -55,15 +55,8 @@ cat - libMakefile.am > libMakefile2.am << 'END'
 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.
diff --git a/t/repeated-options.sh b/t/repeated-options.sh
index af1897bcb..d3fe96207 100755
--- a/t/repeated-options.sh
+++ b/t/repeated-options.sh
@@ -58,7 +58,7 @@ int main (void)
 }
 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; }
diff --git a/t/specflg6.sh b/t/specflg6.sh
index 77d837a53..bbc83343f 100755
--- a/t/specflg6.sh
+++ b/t/specflg6.sh
@@ -36,8 +36,6 @@ foo_CFLAGS = -DFOO
 foo_SOURCES = foo.c
 END
 
-: > compile
-
 $ACLOCAL
 $AUTOMAKE
 
diff --git a/t/subobj.sh b/t/subobj.sh
index 2431184b6..6e5fd9800 100755
--- a/t/subobj.sh
+++ b/t/subobj.sh
@@ -20,6 +20,8 @@
 
 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
 
@@ -30,10 +32,11 @@ wish_SOURCES = generic/a.c generic/b.c
 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
diff --git a/t/subobj4.sh b/t/subobj4.sh
index b1b577d6a..45d9666ab 100755
--- a/t/subobj4.sh
+++ b/t/subobj4.sh
@@ -41,7 +41,6 @@ END
 cat > d2/Makefile.am << 'END'
 END
 
-: > compile
 : > d2/z.c
 
 $ACLOCAL