Add check for internal symbols

src/Makefile.am

@@ -99,7 +99,8 @@ main_SOURCES = main.cc
 main_CPPFLAGS = $(HBCFLAGS)
 main_LDADD = libharfbuzz.la $(HBLIBS)
 
-TESTS =
+TESTS = \
+	check-internal-symbols.sh
 
 if HAVE_ICU
 else

src/check-internal-symbols.sh

@@ -0,0 +1,28 @@
+#!/bin/sh
+
+LC_ALL=C
+export LC_ALL
+
+if which nm 2>/dev/null >/dev/null; then
+	:
+else
+	echo "check-internal-symbols.sh: 'nm' not found; skipping test"
+	exit 0
+fi
+
+test -z "$srcdir" && srcdir=.
+test -z "$MAKE" && MAKE=make
+stat=0
+
+so=.libs/libharfbuzz.so
+if test -f "$so"; then
+	echo "Checking that we are exposing internal symbols"
+	if nm $so | grep ' T _hb'; then
+		echo "Ouch, internal symbols exposed"
+		stat=1
+	fi
+else
+	echo "check-internal-symbols.sh: libharfbuzz.so not found; skipping test"
+fi
+
+exit $stat