[glib] gobject: try to link with -Wl,-z,nodelete

[Alexandre Rostovtsev <arostovtsev src gnome org>]

commit 2b178c762fbc0706031e9890ba190233e243a602
Author: Alexandre Rostovtsev <tetromino gentoo org>
Date:   Mon Sep 2 13:59:18 2013 -0400

    gobject: try to link with -Wl,-z,nodelete
    
    Since the type system does not support reloading its data and assumes
    that libgobject remains loaded for the lifetime of the process, we
    should link libgobject with a flag indicating that it can't be unloaded.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=707298

 configure.ac        |   34 ++++++++++++++++++++++++++++++++++
 gobject/Makefile.am |    1 +
 2 files changed, 35 insertions(+), 0 deletions(-)
---
diff --git a/configure.ac b/configure.ac
index b94e6f3..806b6df 100644
--- a/configure.ac
+++ b/configure.ac
@@ -3469,6 +3469,40 @@ fi
 AC_SUBST(GLIB_LINK_FLAGS)
 
 dnl
+dnl Check for -z,nodelete linker flag: the type system assumes that
+dnl libgobject stays loaded for the lifetime of the process.
+dnl Since ld.bfd does not treat wrong -z options as fatal by default,
+dnl we also try to check for the --fatal-warnings linker flag if
+dnl auto-detecting.
+dnl
+
+AC_ARG_ENABLE([znodelete],
+              [AS_HELP_STRING([--disable-znodelete],
+                              [avoid linking with -z,nodelete])],,
+              [SAVED_LDFLAGS="${LDFLAGS}"
+               AC_MSG_CHECKING([for --fatal-warnings linker flag])
+               LDFLAGS=-Wl,--fatal-warnings
+               AC_TRY_LINK([], [int main (void) { return 0; }],
+                           AC_MSG_RESULT(yes)
+                           [ldflags_fatal=-Wl,--fatal-warnings],
+                           AC_MSG_RESULT(no)
+                           ldflags_fatal=)
+               AC_MSG_CHECKING([for -z,nodelete linker flag])
+               LDFLAGS="$ldflags_fatal -Wl,-z,nodelete"
+               AC_TRY_LINK([], [int main (void) { return 0; }],
+                           AC_MSG_RESULT(yes)
+                           enable_znodelete=yes,
+                           AC_MSG_RESULT(no)
+                           enable_znodelete=no)
+               LDFLAGS="${SAVED_LDFLAGS}"])
+
+if test "x${enable_znodelete}" = "xyes"; then
+  GOBJECT_LINK_FLAGS=-Wl,-z,nodelete
+fi
+
+AC_SUBST(GOBJECT_LINK_FLAGS)
+
+dnl
 dnl Check for -fvisibility=hidden to determine if we can do GNU-style
 dnl visibility attributes for symbol export control
 dnl
diff --git a/gobject/Makefile.am b/gobject/Makefile.am
index c683e84..02e9c25 100644
--- a/gobject/Makefile.am
+++ b/gobject/Makefile.am
@@ -45,6 +45,7 @@ endif
 
 libgobjectincludedir = $(includedir)/glib-2.0/gobject
 libgobject_2_0_la_LDFLAGS = $(GLIB_LINK_FLAGS) \
+  $(GOBJECT_LINK_FLAGS) \
   $(gobject_win32_res_ldflag) \
   -version-info $(LT_CURRENT):$(LT_REVISION):$(LT_AGE) \
   -export-dynamic $(no_undefined)