Hide symbols with gcc.

With gcc >= 4 and ELF, set default visibility to hidden and make visible
only the symbols with FLAC_API or FLACPP_API.

A convenience libFLAC-static.la is created for test_libFLAC as it
depends on the hidden symbols.

configure.ac

@@ -361,6 +361,12 @@ if test x$ac_cv_c_compiler_gnu = xyes ; then
 		CFLAGS="-Wall -Wextra -Werror $CFLAGS"
 		CXXFLAGS="-Wall -Wextra -Werror $CXXFLAGS"
 	fi
+
+	if test "$GCC_MAJOR_VERSION" -ge 4 && test "$OBJ_FORMAT" = elf; then
+		CPPFLAGS="$CPPFLAGS -DFLAC__USE_VISIBILITY_ATTR"
+		CFLAGS="$CFLAGS -fvisibility=hidden"
+		CXXFLAGS="$CXXFLAGS -fvisibility=hidden"
+	fi
 fi
 
 

include/FLAC++/export.h

@@ -55,17 +55,22 @@
  * \{
  */
 
-#if defined(FLAC__NO_DLL) || !defined(_MSC_VER)
+#if defined(FLAC__NO_DLL)
 #define FLACPP_API
 
-#else
-
+#elif defined(_MSC_VER)
 #ifdef FLACPP_API_EXPORTS
 #define	FLACPP_API	_declspec(dllexport)
 #else
 #define FLACPP_API	_declspec(dllimport)
-
 #endif
+
+#elif defined(FLAC__USE_VISIBILITY_ATTR)
+#define FLACPP_API __attribute__ ((visibility ("default")))
+
+#else
+#define FLACPP_API
+
 #endif
 
 /* These #defines will mirror the libtool-based library version number, see

include/FLAC/export.h

@@ -55,17 +55,22 @@
  * \{
  */
 
-#if defined(FLAC__NO_DLL) || !defined(_MSC_VER)
+#if defined(FLAC__NO_DLL)
 #define FLAC_API
 
-#else
-
+#elif defined(_MSC_VER)
 #ifdef FLAC_API_EXPORTS
 #define	FLAC_API	_declspec(dllexport)
 #else
 #define FLAC_API	_declspec(dllimport)
-
 #endif
+
+#elif defined(FLAC__USE_VISIBILITY_ATTR)
+#define FLAC_API __attribute__ ((visibility ("default")))
+
+#else
+#define FLAC_API
+
 #endif
 
 /** These #defines will mirror the libtool-based library version number, see

src/libFLAC/Makefile.am

@@ -30,6 +30,7 @@
 
 AM_CPPFLAGS = -I$(top_builddir) -I$(srcdir)/include -I$(top_srcdir)/include
 lib_LTLIBRARIES = libFLAC.la
+noinst_LTLIBRARIES = libFLAC-static.la
 if DEBUG
 DEBUGCFLAGS = -DFLAC__OVERFLOW_DETECT
 endif
@@ -106,7 +107,8 @@ extra_ogg_sources = \
 endif
 # see 'http://www.gnu.org/software/libtool/manual/libtool.html#Libtool-versioning' for numbering convention
 libFLAC_la_LDFLAGS = -version-info 10:0:2 $(LOCAL_EXTRA_LDFLAGS) @LT_NO_UNDEFINED@
-libFLAC_la_SOURCES = \
+
+libFLAC_sources = \
 	bitmath.c \
 	bitreader.c \
 	bitwriter.c \
@@ -125,3 +127,9 @@ libFLAC_la_SOURCES = \
 	stream_encoder_framing.c \
 	window.c \
 	$(extra_ogg_sources)
+
+libFLAC_la_SOURCES = $(libFLAC_sources)
+
+# needed for test_libFLAC
+libFLAC_static_la_LIBADD = $(LOCAL_EXTRA_LIBADD)
+libFLAC_static_la_SOURCES = $(libFLAC_sources)

src/test_libFLAC/Makefile.am

@@ -27,7 +27,7 @@ test_libFLAC_LDADD = \
 	$(top_builddir)/src/share/grabbag/libgrabbag.la \
 	$(top_builddir)/src/share/replaygain_analysis/libreplaygain_analysis.la \
 	$(top_builddir)/src/test_libs_common/libtest_libs_common.la \
-	$(top_builddir)/src/libFLAC/libFLAC.la \
+	$(top_builddir)/src/libFLAC/libFLAC-static.la \
 	@OGG_LIBS@ \
 	-lm