Add a check for mixed linkageprevent-mixed-linkage

Having both pango 1.x and pango 2 linked into
the same process will cause trouble, because the
type and function names conflict.

Error out if we detect this situation.

2 files changed, 27 insertions, 1 deletions

diff --git a/meson.build b/meson.build
index d7a1168b..b50e99ca 100644
--- a/meson.build
+++ b/meson.build
@@ -240,11 +240,13 @@ pango_deps += mathlib_dep
 # gobject
 glib_dep = dependency('glib-2.0', version: glib_req_version,
                       fallback: ['glib', 'libglib_dep'])
+gmodule_dep = dependency('gmodule-2.0', version: glib_req_version,
+                         fallback : ['glib', 'libgmodule_dep'])
 gobject_dep = dependency('gobject-2.0', version: glib_req_version,
                          fallback: ['glib', 'libgobject_dep'])
 gio_dep = dependency('gio-2.0', version: glib_req_version,
                          fallback: ['glib', 'libgio_dep'])
-pango_deps += [glib_dep, gobject_dep, gio_dep]
+pango_deps += [glib_dep, gmodule_dep, gobject_dep, gio_dep]
 
 fribidi_dep = dependency('fribidi', version: fribidi_req_version,
                          fallback: ['fribidi', 'libfribidi_dep'],
diff --git a/pango/pango-context.c b/pango/pango-context.c
index d5e73cfe..a7444865 100644
--- a/pango/pango-context.c
+++ b/pango/pango-context.c
@@ -23,6 +23,8 @@
 #include <string.h>
 #include <stdlib.h>
 
+#include <gio/gio.h>
+
 #include "pango-context.h"
 #include "pango-context-private.h"
 #include "pango-impl-utils.h"
@@ -80,11 +82,33 @@ pango_context_init (PangoContext *context)
   pango_font_description_set_size (context->font_desc, 12 * PANGO_SCALE);
 }
 
+static gboolean
+pango_has_mixed_deps (void)
+{
+  GModule *module;
+  gpointer func;
+  gboolean result = FALSE;
+
+  module = g_module_open (NULL, 0);
+
+  if (g_module_symbol (module, "pango_hb_font_new", &func))
+    result = TRUE;
+
+  g_module_close (module);
+
+  return result;
+}
+
 static void
 pango_context_class_init (PangoContextClass *klass)
 {
   GObjectClass *object_class = G_OBJECT_CLASS (klass);
 
+ /* Put the check for mixed linkage here, for lack of a better place */
+  if (pango_has_mixed_deps ())
+    g_error ("Pango 2 symbols detected.\n"
+             "Using Pango 1.x and 2 in the same process is not supported.");
+
   object_class->finalize = pango_context_finalize;
 }