compile: rewrite AC_PROG_CC with AM_PROG_CC_C_O contents

This is a much simpler rewrite than the one we attempted in the past,
and that was later removed by commit 'v1.13.1d-137-g32eb770' of
2013-05-11 (compile: avoid AC_PROG_CC messy rewrite).

Not only this change simplifies the code a little, but has the welcome
collateral effect of making automatic dependency tracking work better
with compilers that doesn't grasp the '-c' and '-o' options together.
Issues in that setup have been caught by several failures in the target
'check-no-cc-c-o'.

Unfortunately, this change has less welcome collateral effects:

  1. AM_PROG_AR must now be called *after* AC_PROG_CC;

  2. Autoconf emits extra warnings when used with Automake-generated
     aclocal.m4.

These are unacceptable regressions for a release, but since we are
going to fix them soon enough in a follow-up patch (surely to be
applied before Automake 1.14 is released) we don't worry too much.

* m4/init.m4: Redefine AC_PROG_CC early, to automatically invoke
AM_PROG_CC_C_O as well.  Accordingly, drop now-unneeded "automagical"
AM_PROG_CC_C_O expansion at later time (which took place thanks to
a AC_CONFIG_COMMANDS_PRE call).
* m4/minuso.m4 (AM_PROG_CC_C_O): Ensure the expansion of the body
of this macro takes place with C as "current Autoconf language" (use
AC_LANG_PUSH/AC_LANG_POP).
* m4/ar-lib.m4 (AM_PROG_AR): Likewise.  Also, require this macro to
be expanded *after* AC_PROG_CC (so that any rewrite of $CC, if required,
has already taken place).
* t/add-missing.tap: Adjust to avoid spurious failures.
* t/aclocal-deps.sh: Likewise, by having AM_PROG_AR called *after*
AC_PROG_CC.
* t/subobj-clean-lt-pr10697.sh: Likewise.
* t/alloca.sh: Likewise.
* t/condlib.sh: Likewise.
* t/discover.sh: Likewise.
* t/objc-megademo.sh: Likewise.
* t/ccnoco.sh: Extend a little.
* t/ccnoco-deps.sh: New test.
* t/ccnoco-lib.sh: Likewise.
* t/ccnoco-lt.sh: Likewise.
* t/list-of-tests.mk: Add them.

Signed-off-by: Stefano Lattarini <stefano.lattarini@gmail.com>

3 files changed, 11 insertions, 9 deletions

diff --git a/m4/ar-lib.m4 b/m4/ar-lib.m4
index f895f6bd2..53c8c2a7e 100644
--- a/m4/ar-lib.m4
+++ b/m4/ar-lib.m4
@@ -13,13 +13,15 @@
 AC_DEFUN([AM_PROG_AR],
 [AC_BEFORE([$0], [LT_INIT])dnl
 AC_BEFORE([$0], [AC_PROG_LIBTOOL])dnl
+AC_BEFORE([AC_PROG_CC])
 AC_REQUIRE([AM_AUX_DIR_EXPAND])dnl
 AC_REQUIRE_AUX_FILE([ar-lib])dnl
 AC_CHECK_TOOLS([AR], [ar lib "link -lib"], [false])
 : ${AR=ar}
 
 AC_CACHE_CHECK([the archiver ($AR) interface], [am_cv_ar_interface],
-  [am_cv_ar_interface=ar
+  [AC_LANG_PUSH([C])
+   am_cv_ar_interface=ar
    AC_COMPILE_IFELSE([AC_LANG_SOURCE([[int some_variable = 0;]])],
      [am_ar_try='$AR cru libconftest.a conftest.$ac_objext >&AS_MESSAGE_LOG_FD'
       AC_TRY_EVAL([am_ar_try])
@@ -36,7 +38,7 @@ AC_CACHE_CHECK([the archiver ($AR) interface], [am_cv_ar_interface],
       fi
       rm -f conftest.lib libconftest.a
      ])
-   ])
+   AC_LANG_POP([C])])
 
 case $am_cv_ar_interface in
 ar)
diff --git a/m4/init.m4 b/m4/init.m4
index a6f27339d..fb6ed5851 100644
--- a/m4/init.m4
+++ b/m4/init.m4
@@ -9,6 +9,10 @@
 # This macro actually does too much.  Some checks are only needed if
 # your package does certain things.  But this isn't really a big deal.
 
+dnl Redefine AC_PROG_CC to automatically invoke AM_PROG_CC_C_O.
+m4_define([AC_PROG_CC], m4_defn([AC_PROG_CC])[AM_PROG_CC_C_O
+])
+
 # AM_INIT_AUTOMAKE(PACKAGE, VERSION, [NO-DEFINE])
 # AM_INIT_AUTOMAKE([OPTIONS])
 # -----------------------------------------------
@@ -110,12 +114,6 @@ AC_PROVIDE_IFELSE([AC_PROG_OBJCXX],
 		  [m4_define([AC_PROG_OBJCXX],
 			     m4_defn([AC_PROG_OBJCXX])[_AM_DEPENDENCIES([OBJCXX])])])dnl
 ])
-dnl Automatically invoke AM_PROG_CC_C_O as necessary.  Since AC_PROG_CC is
-dnl usually called after AM_INIT_AUTOMAKE, we arrange for the test to be
-dnl done later by AC_CONFIG_COMMANDS_PRE.
-AC_CONFIG_COMMANDS_PRE([AC_PROVIDE_IFELSE(
-    [AC_PROG_CC],
-    [AC_LANG_PUSH([C]) AM_PROG_CC_C_O AC_LANG_POP([C])])])dnl
 AC_REQUIRE([AM_SILENT_RULES])dnl
 dnl The testsuite driver may need to know about EXEEXT, so add the
 dnl 'am__EXEEXT' conditional if _AM_COMPILER_EXEEXT was seen.  This
diff --git a/m4/minuso.m4 b/m4/minuso.m4
index 06f74c906..3e68f2b72 100644
--- a/m4/minuso.m4
+++ b/m4/minuso.m4
@@ -9,7 +9,8 @@
 # --------------
 # Like AC_PROG_CC_C_O, but changed for automake.
 AC_DEFUN_ONCE([AM_PROG_CC_C_O],
-[AC_REQUIRE([AC_PROG_CC_C_O])dnl
+[AC_LANG_PUSH([C])
+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
@@ -25,6 +26,7 @@ if test "$am_t" != yes; then
    # and then we could set am__CC="\$(top_srcdir)/compile \$(CC)"
    CC="$am_aux_dir/compile $CC"
 fi
+AC_LANG_POP([C])
 dnl Make sure AC_PROG_CC is never called again, or it will override our
 dnl setting of CC.
 m4_define([AC_PROG_CC],