[FYI] {maint} coverage: obsolete macro AM_PROG_CC_C_O should cause no warning nor errors

[Stefano Lattarini]

Suggested by Eric Blake.

* t/am-prog-cc-c-o.sh: New test.
* t/list-of-tests.mk: Add it.

Signed-off-by: Stefano Lattarini <address@hidden>
---
 t/am-prog-cc-c-o.sh | 85 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 t/list-of-tests.mk  |  1 +
 2 files changed, 86 insertions(+)
 create mode 100755 t/am-prog-cc-c-o.sh

diff --git a/t/am-prog-cc-c-o.sh b/t/am-prog-cc-c-o.sh
new file mode 100755
index 0000000..f9cc04a
--- /dev/null
+++ b/t/am-prog-cc-c-o.sh
@@ -0,0 +1,85 @@
+#! /bin/sh
+# Copyright (C) 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/>.
+
+# Check that uses of the obsolescent AM_PROG_CC_C_O macro doesn't
+# cause spurious warnings or errors.  Suggested by Eric Blake.
+
+# We need gcc for for two reasons:
+#  1. to ensure our C compiler grasps "-c -o" together.
+#  2. to be able to later fake a dumb compiler not grasping that
+#     (done with 'cc-no-c-o' script below, which required gcc).
+required=gcc
+. test-init.sh
+
+echo bin_PROGRAMS = foo > Makefile.am
+echo 'int main (void) { return 0; }' > foo.c
+
+cp configure.ac configure.bak
+
+cat >> configure.ac << 'END'
+# Since AM_PROG_CC_C_O rewrites $CC, it's an error to call AC_PROG_CC
+# after it.
+AM_PROG_CC_C_O
+AC_PROG_CC
+END
+
+$ACLOCAL -Wnone 2>stderr && { cat stderr >&2; exit 1; }
+cat stderr >&2
+grep '^configure\.ac:7:.* AC_PROG_CC .*called after AM_PROG_CC_C_O' stderr
+
+cat configure.bak - > configure.ac << 'END'
+dnl It's OK to call AM_PROG_CC_C_O after AC_PROG_CC.
+AC_PROG_CC
+AM_PROG_CC_C_O
+AC_OUTPUT
+END
+
+$ACLOCAL
+$AUTOCONF
+$AUTOMAKE --add-missing
+
+./configure >stdout || { cat stdout; exit 1; }
+cat stdout
+grep 'understands -c and -o together.* yes$' stdout
+# No repeated checks please.
+test $(grep -c ".*-c['\" ].*-o['\" ]" stdout) -eq 1
+$MAKE
+
+$MAKE maintainer-clean
+
+rm -rf autom4te*.cache
+
+cat configure.bak - > configure.ac << 'END'
+dnl It's also OK to call AM_PROG_CC_C_O *without* AC_PROG_CC.
+AM_PROG_CC_C_O
+AC_OUTPUT
+END
+
+$ACLOCAL
+$AUTOCONF
+$AUTOMAKE --add-missing
+
+# Make sure the compiler doesn't understand '-c -o'
+CC=$am_testaux_builddir/cc-no-c-o; export CC
+
+./configure >stdout || { cat stdout; exit 1; }
+cat stdout
+grep 'understands -c and -o together.* no$' stdout
+# No repeated checks please.
+test $(grep -c ".*-c['\" ].*-o['\" ]" stdout) -eq 1
+$MAKE
+
+:
diff --git a/t/list-of-tests.mk b/t/list-of-tests.mk
index baccdca..a6e1cee 100644
--- a/t/list-of-tests.mk
+++ b/t/list-of-tests.mk
@@ -132,6 +132,7 @@ t/aminit-moreargs-deprecation.sh \
 t/amassign.sh \
 t/am-config-header-no-more.sh \
 t/am-prog-cc-stdc-no-more.sh \
+t/am-prog-cc-c-o.sh \
 t/am-macro-not-found.sh \
 t/amopt.sh \
 t/amopts-location.sh \
-- 
1.8.1.rc3.192.g2d0029e