This patch makes GTK+ look for additional modules in a list of directories
specified by the environment variable "GUIX_GTK2_PATH".  This can be used
instead of "GTK_PATH" to make GTK+ find modules that are incompatible with
other major versions of GTK+.

--- a/gtk/gtkmodules.c	2014-09-29 22:02:17.000000000 +0200
+++ b/gtk/gtkmodules.c	2015-12-02 18:41:53.306396938 +0100
@@ -55,6 +55,7 @@
 get_module_path (void)
 {
   const gchar *module_path_env;
+  const gchar *module_guix_gtk2_path_env;
   const gchar *exe_prefix;
   const gchar *home_dir;
   gchar *home_gtk_dir = NULL;
@@ -70,6 +71,7 @@
     home_gtk_dir = g_build_filename (home_dir, ".gtk-2.0", NULL);
 
   module_path_env = g_getenv ("GTK_PATH");
+  module_guix_gtk2_path_env = g_getenv ("GUIX_GTK2_PATH");
   exe_prefix = g_getenv ("GTK_EXE_PREFIX");
 
   if (exe_prefix)
@@ -77,9 +79,21 @@
   else
     default_dir = g_build_filename (GTK_LIBDIR, "gtk-2.0", NULL);
 
-  if (module_path_env && home_gtk_dir)
+  if (module_guix_gtk2_path_env && module_path_env && home_gtk_dir)
+    module_path = g_build_path (G_SEARCHPATH_SEPARATOR_S,
+				module_guix_gtk2_path_env, module_path_env, home_gtk_dir, default_dir, NULL);
+  else if (module_guix_gtk2_path_env && home_gtk_dir)
+    module_path = g_build_path (G_SEARCHPATH_SEPARATOR_S,
+				module_guix_gtk2_path_env, home_gtk_dir, default_dir, NULL);
+  else if (module_guix_gtk2_path_env && module_path_env)
+    module_path = g_build_path (G_SEARCHPATH_SEPARATOR_S,
+				module_guix_gtk2_path_env, module_path_env, default_dir, NULL);
+  else if (module_path_env && home_gtk_dir)
     module_path = g_build_path (G_SEARCHPATH_SEPARATOR_S,
 				module_path_env, home_gtk_dir, default_dir, NULL);
+  else if (module_guix_gtk2_path_env)
+    module_path = g_build_path (G_SEARCHPATH_SEPARATOR_S,
+				module_guix_gtk2_path_env, default_dir, NULL);
   else if (module_path_env)
     module_path = g_build_path (G_SEARCHPATH_SEPARATOR_S,
 				module_path_env, default_dir, NULL);
436e76dbac312aa0cf1f45f48398c956d34b'>root</a>/<a href='/guix/log/gnu?id=0e45436e76dbac312aa0cf1f45f48398c956d34b'>gnu</a>/<a href='/guix/log/gnu/tests.scm?id=0e45436e76dbac312aa0cf1f45f48398c956d34b'>tests.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/tests.scm?id=0e45436e76dbac312aa0cf1f45f48398c956d34b&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-11-05 23:23:23 +0100'>2023-11-05</span></td><td><a href='/guix/commit/gnu/tests.scm?id=0c695bbf8dbd5a5c1224f331a78b6316bc16e4d1'>tests: Honor system and target when lowering &lt;system-test&gt;.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/tests.scm (compile-system-test): Wrap ‘system-test-value’ call in
‘mparameterize’.

Change-Id: I4be28913a86f43059b0886ad2fcf81a9c699b730
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-04-21 16:16:38 +0200'>2023-04-21</span></td><td><a href='/guix/commit/gnu/tests.scm?id=a09c7da8f8d8e732f969cf0a09aaa78f87032ab1'>tests: Fork and exec a new Guile for the marionette REPL.</a><span class='msg-avail'>...<span class='msg-tooltip'>By merely forking PID 1, details from PID 1 (shepherd) would leak into
the marionette process, such as the set of modules in scope and state
inherited from the shepherd process (&lt;service&gt; instances, fibers,
etc.).  Running a fresh Guile instance avoids that.

* gnu/tests.scm (marionette-program): New procedure.
(marionette-shepherd-service): Change 'start' to use
'make-forkexec-constructor', and run the result of 'marionette-program'.
</span></span></td><td>Ludovic Courtès</td></tr>