test: Add include from C++ build test

configure.ac

@@ -75,6 +75,9 @@ fi
 if test "x$build_tests" = "xyes" -a "x$HAVE_CHECK" = "xno"; then
        AC_MSG_ERROR([Cannot build tests, check is missing])
 fi
+if test "x$build_tests" = "xyes"; then
+	AC_PROG_CXX
+fi
 
 AM_CONDITIONAL(BUILD_TESTS, [test "x$build_tests" = "xyes"])
 

test/Makefile.am

@@ -20,7 +20,11 @@ liblitest_la_SOURCES = \
 	litest.c
 
 run_tests = test-udev test-path test-pointer test-touch test-log test-touchpad
-build_tests = test-build-linker test-build-pedantic-c99 test-build-std-gnuc90
+build_tests = \
+	test-build-cxx \
+	test-build-linker \
+	test-build-pedantic-c99 \
+	test-build-std-gnuc90
 
 noinst_PROGRAMS = $(build_tests) $(run_tests)
 TESTS = $(run_tests)
@@ -67,4 +71,8 @@ test_build_linker_SOURCES = build-pedantic.c
 test_build_linker_CFLAGS = -I$(top_srcdir)/src
 test_build_linker_LDADD = $(top_builddir)/src/libinput.la
 
+# test including from C++
+test_build_cxx_SOURCES = build-cxx.cc
+test_build_cxx_CXXFLAGS = -Wall -Wextra -Wno-unused-parameter $(AM_CXXFLAGS)
+
 endif

test/build-cxx.cc

@@ -0,0 +1,11 @@
+#include <libinput.h>
+
+/* This is a build-test only */
+
+using namespace std;
+
+int
+main(int argc, char **argv)
+{
+	return 0;
+}