Add makefile for extended tests to be run before release.

more_tests/Makefile

@@ -0,0 +1,41 @@
+# Additional tests to run before releasing a package.
+#
+# Run like:
+#   make PACKAGE=/path/to/protobuf-VERSION.tar.gz
+#
+# Some of these tests require tools or make assumptions that may not be
+# available on end-user machines, so these cannot be part of "make check".  For
+# example, we test that the headers compile with strict warning settings, but
+# since different compilers produce wildly different warnings we cannot assume
+# that this test will pass everywhere.  If we ran it as part of "make check",
+# it could unnecessarily block users from running the real tests just because
+# their compiler produces some extra warnings that probably aren't a big deal.
+# So we run it separately. 
+
+all: header_warning_test
+
+clean:
+	rm -rf src target header_warning_test.cc header_warning_test.o header_warning_test
+
+# Unpack the package into src, then install it into target.
+PACKAGE=protobuf.tar.gz
+
+src: $(PACKAGE)
+	tar zxvf $(PACKAGE)
+	mv `basename $(PACKAGE) .tar.gz` src
+
+target: src
+	(cd src && ./configure --prefix=$$PWD/../target --disable-shared)
+	(cd src && make -j4 check)
+	(cd src && make install)
+
+# Verify that headers produce no warnings even under strict settings.
+header_warning_test.cc: target
+	( (cd target/include && find google/protobuf -name '*.h') | \
+	  awk '{print "#include \""$$1"\""} ' > header_warning_test.cc )
+
+header_warning_test: header_warning_test.cc
+	# TODO(kenton):  Consider adding -pedantic and -Weffc++.  Currently these
+	#   produce tons of extra warnings so we'll need to do some work first.
+	g++ -Itarget/include -Wall -Werror -Wsign-compare -O2 -c header_warning_test.cc
+	touch header_warning_test