Add tde_setup_gcc_visibility macro.

For the GCC visibility setting, a test is performed
whether the system is UNIX-type and also whether TQt
and tdelibs are built with GCC visibility support.

Signed-off-by: Slávek Banko <slavek.banko@axis.cz>
(cherry picked from commit b034c47597)

modules/TDEMacros.cmake

@@ -1708,6 +1708,55 @@ macro( tde_setup_architecture_flags )
 endmacro( )
 
 
+#################################################
+#####
+##### tde_setup_gcc_visibility
+
+macro( tde_setup_gcc_visibility )
+  if( NOT DEFINED __KDE_HAVE_GCC_VISIBILITY )
+    if( NOT UNIX )
+      tde_message_fatal( "gcc visibility support was requested, but your system is not *NIX" )
+    endif( NOT UNIX )
+
+    find_library( TQT_LIBFILE qt-mt HINTS "${TQT_LIBRARY_DIRS}" )
+    if( NOT "${TQT_LIBFILE}" STREQUAL "TQT_LIBFILE-NOTFOUND" )
+      message( STATUS "Performing Test HAVE_TQT_VISIBILITY" )
+      execute_process(
+        COMMAND readelf --syms "${TQT_LIBFILE}"
+        OUTPUT_VARIABLE HAVE_TQT_VISIBILITY
+      )
+      if( "${HAVE_TQT_VISIBILITY}" STREQUAL "" OR
+          "${HAVE_TQT_VISIBILITY}" MATCHES "DEFAULT[^\n]*QSettingsPrivate" )
+        message( STATUS "Performing Test HAVE_TQT_VISIBILITY - Failed" )
+        tde_message_fatal( "gcc visibility support was requested, but not supported in qt library" )
+      endif( )
+      message( STATUS "Performing Test HAVE_TQT_VISIBILITY - Success" )
+    endif( )
+
+    find_file( TDEMACROS_H kdemacros.h HINTS "${TDE_INCLUDE_DIR}" )
+    if( NOT "${TDEMACROS_H}" STREQUAL "TDEMACROS_H-NOTFOUND" )
+      tde_save_and_set( CMAKE_REQUIRED_INCLUDES "${TDE_INCLUDE_DIR}" )
+      check_cxx_source_compiles( "
+        #include <kdemacros.h>
+          #ifndef __KDE_HAVE_GCC_VISIBILITY
+          #error gcc visibility is not enabled in tdelibs
+          #endif
+          int main() { return 0; } "
+        HAVE_TDE_VISIBILITY
+      )
+      tde_restore( CMAKE_REQUIRED_INCLUDES )
+      if( NOT HAVE_TDE_VISIBILITY )
+        tde_message_fatal( "gcc visibility support was requested, but not supported in tdelibs" )
+      endif( NOT HAVE_TDE_VISIBILITY )
+    endif( )
+
+    set( __KDE_HAVE_GCC_VISIBILITY 1 )
+    set( CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fvisibility=hidden -fvisibility-inlines-hidden")
+    set( CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fvisibility=hidden -fvisibility-inlines-hidden")
+  endif( )
+endmacro( )
+
+
 ################################################
 #####
 ##### Restore CMP0026 policy