compile: remove .Tpo file upon failure

When generating a .deps/base.Po file, our emitted rule first writes
to a temporary .Tpo file, so the final creation can be atomic, via
mv's rename.  However, when generation of the .Tpo fails, it stop the
process and does not remove that temporary file.  And nothing else
ever deletes it, either.  Hence, in the unusual case in which one
expects a compilation to fail during a successful build (gnulib's
test-verify.sh does precisely this), a .deps/test-verify.Tpo file
would be left behind, and that would in turn cause a "make distcheck"
failure because that file would exist in one build+distclean hierarchy
but not in the distribution tarball.
* lib/am/depend2.am: Ensure that the temporary file is removed
upon failure.
* t/distcheck-Tpo.sh: New file.
* t/list-of-tests.mk (handwritten_TESTS): Add it.
This addresses bug#23661.

3 files changed, 65 insertions, 4 deletions

diff --git a/lib/am/depend2.am b/lib/am/depend2.am
index 87f62a80d..d1478b916 100644
--- a/lib/am/depend2.am
+++ b/lib/am/depend2.am
@@ -42,8 +42,9 @@ if %?NONLIBTOOL%
 ?!GENERIC?%OBJ%: %SOURCE%
 if %FASTDEP%
 	%VERBOSE%$(am__set_depbase) && \
-	%COMPILE% -MT $@ -MD -MP -MF $$depbase.Tpo -c -o $@ %SOURCEFLAG% %XSOURCE% && \
-	$(am__mv) $$depbase.Tpo $$depbase.Po
+	%COMPILE% -MT $@ -MD -MP -MF $$depbase.Tpo -c -o $@ %SOURCEFLAG% %XSOURCE%; \
+	if test $$? = 0; then $(am__mv) $$depbase.Tpo $$depbase.Po; \
+	  else rm -f $$depbase.Tpo; false; fi
 else !%FASTDEP%
 if %AMDEP%
 	%VERBOSE%source='%SOURCE%' object='$@' libtool=no @AMDEPBACKSLASH@
@@ -56,8 +57,9 @@ endif !%FASTDEP%
 ?!GENERIC?%OBJOBJ%: %SOURCE%
 if %FASTDEP%
 	%VERBOSE%$(am__set_depbase) && \
-	%COMPILE% -MT $@ -MD -MP -MF $$depbase.Tpo -c -o $@ %SOURCEFLAG% $$($(CYGPATH_W) %XSOURCE%) && \
-	$(am__mv) $$depbase.Tpo $$depbase.Po
+	%COMPILE% -MT $@ -MD -MP -MF $$depbase.Tpo -c -o $@ %SOURCEFLAG% $$($(CYGPATH_W) %XSOURCE%); \
+	if test $$? = 0; then $(am__mv) $$depbase.Tpo $$depbase.Po; \
+	  else rm -f $$depbase.Tpo; false; fi
 else !%FASTDEP%
 if %AMDEP%
 	%VERBOSE%source='%SOURCE%' object='$@' libtool=no @AMDEPBACKSLASH@
diff --git a/t/distcheck-Tpo.sh b/t/distcheck-Tpo.sh
new file mode 100644
index 000000000..9d7900cb4
--- /dev/null
+++ b/t/distcheck-Tpo.sh
@@ -0,0 +1,58 @@
+#! /bin/sh
+# Copyright (C) 2016 Free Software Foundation, Inc.
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2, or (at your option)
+# any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+# Ensure that the 'make distcheck'-run distcleancheck does not fail
+# due to a leftover .deps/base.Tpo file when part of a successful build
+# involves a failed attempt to create a .deps/base.Po file.
+
+. test-init.sh
+
+cat >> configure.ac <<END
+AC_PROG_CC
+AC_OUTPUT
+END
+
+cat > foo.c <<\END
+#ifndef FAIL
+int main() { return 0; }
+#else
+int x[no_such];
+#endif
+END
+
+cat > Makefile.am <<\END
+TESTS = foo bar.test
+check_PROGRAMS = foo
+EXTRA_DIST= bar.test foo.c
+END
+
+cat > bar.test <<END
+#!/bin/sh
+rm -f foo.o
+$MAKE AM_CFLAGS=-DFAIL foo.o && exit 1
+exit 0
+END
+chmod a+x bar.test
+
+$ACLOCAL
+$AUTOCONF
+$AUTOMAKE -a
+./configure
+
+# We can build the distribution.
+run_make -M distcheck
+
+:
diff --git a/t/list-of-tests.mk b/t/list-of-tests.mk
index f1c47bb53..060b3ed1c 100644
--- a/t/list-of-tests.mk
+++ b/t/list-of-tests.mk
@@ -433,6 +433,7 @@ t/distcheck-override-infodir.sh \
 t/distcheck-pr9579.sh \
 t/distcheck-pr10470.sh \
 t/distcheck-pr18286.sh \
+t/distcheck-Tpo.sh \
 t/dmalloc.sh \
 t/doc-parsing-buglets-colneq-subst.sh \
 t/doc-parsing-buglets-tabs.sh \