1 files changed, 92 insertions, 0 deletions
diff --git a/t/spy-pattern-rules.sh b/t/spy-pattern-rules.sh
new file mode 100644
index 000000000..7781dd31d
--- /dev/null
+++ b/t/spy-pattern-rules.sh
@@ -0,0 +1,92 @@
+#! /bin/sh
+# Copyright (C) 2012-2014 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/>.
+
+# Two checks are done here:
+# - if there are two pattern rules from which the same file (or set of
+#   files) can be built, and both are applicable, and both results in
+#   the same target stem, then the first one wins.
+# - if there are two pattern rules from which the same file (or set of
+#   files) can be built, and both are applicable, but the resulting
+#   target stems are different, then the "most specific" one (i.e.,
+#   that which result in the *shortest* stem) is used.
+# We take advantage of such features at least in our 'parallel-tests'
+# support.
+
+am_create_testdir=empty
+. test-init.sh
+
+cat > Makefile <<'END'
+default:
+	@echo recipe for $@ should not run >&2; exit 1;
+
+%.foo: %
+	cp $< $@
+%.foo: %.x
+	cp $< $@
+
+%.bar: %.x
+	cp $< $@
+%.bar: %
+	cp $< $@
+
+%.mu %.fu: %.1
+	cp $< $*.mu && cp $< $*.fu
+%.mu %.fu: %.2
+	cp $< $*.mu && cp $< $*.fu
+
+%.o: %.c
+	@cp $< $@ && echo TOP >> $@
+lib/%.o: lib/%.c
+	@cp $< $@ && echo LIB >> $@
+
+bar%: foo%
+	echo .$* >$@
+ba%: foo%
+	@echo '$@: longest stem rule selected!' >&2; exit 1
+END
+
+echo one > all
+echo two > all.x
+$MAKE all.foo all.bar
+diff all all.foo
+diff all.x all.bar
+
+echo one > x.1
+echo two > x.2
+$MAKE x.mu
+diff x.mu x.1
+diff x.fu x.1
+
+mkdir lib
+echo foo > a.c
+echo bar > lib/a.c
+$MAKE a.o lib/a.o
+test "$(cat a.o)" = "foo${nl}TOP"
+test "$(cat lib/a.o)" = "bar${nl}LIB"
+
+: > foozap
+: > foo-mu
+: > foox
+$MAKE barzap bar-mu
+test "$(cat barzap)" = .zap
+test "$(cat bar-mu)" = .-mu
+
+# Sanity check.
+run_make -e FAIL -M bax \
+  && grep '^bax: longest stem rule selected!' output \
+  || fatal_ 'the longest stem rule was not selected'
+
+: