Merge branch 'matthiasc/for-main' into 'main'

gdk: Improve logging for backends

Closes #5704

See merge request GNOME/gtk!5737

gdk/gdkdebugprivate.h

@@ -60,7 +60,11 @@ GdkDebugFlags    gdk_display_get_debug_flags    (GdkDisplay       *display);
 void             gdk_display_set_debug_flags    (GdkDisplay       *display,
                                                  GdkDebugFlags     flags);
 
+#ifdef GLIB_USING_SYSTEM_PRINTF
+#define gdk_debug_message(format, ...) fprintf (stderr, format "\n", ##__VA_ARGS__)
+#else
 #define gdk_debug_message(format, ...) g_fprintf (stderr, format "\n", ##__VA_ARGS__)
+#endif
 
 #ifdef G_ENABLE_DEBUG
 

gdk/gdkdisplaymanager.c

@@ -410,12 +410,19 @@ gdk_display_manager_open_display (GdkDisplayManager *manager,
     {
       const char *backend = backends[i];
       gboolean any = g_str_equal (backend, "*");
+      gboolean found = FALSE;
 
       if (!allow_any && !any && !strstr (allowed_backends, backend))
-        continue;
+        {
+          GDK_DEBUG (MISC, "Skipping %s backend", backend);
+          continue;
+        }
 
       for (j = 0; gdk_backends[j].name != NULL; j++)
         {
+          if (g_str_equal (backend, gdk_backends[j].name))
+            found = TRUE;
+
           if ((any && allow_any) ||
               (any && strstr (allowed_backends, gdk_backends[j].name)) ||
               g_str_equal (backend, gdk_backends[j].name))
@@ -423,9 +430,15 @@ gdk_display_manager_open_display (GdkDisplayManager *manager,
               GDK_DEBUG (MISC, "Trying %s backend", gdk_backends[j].name);
               display = gdk_backends[j].open_display (name);
               if (display)
-                break;
+                {
+                  GDK_DEBUG (MISC, "Using %s display %s", gdk_backends[j].name, gdk_display_get_name (display));
+                  break;
+                }
             }
         }
+
+      if (!found && !display)
+        g_warning ("No such backend: %s", backend);
     }
 
   g_strfreev (backends);

gtk/gtkmain.c

@@ -634,34 +634,29 @@ gtk_init_check (void)
  * gtk_init:
  *
  * Call this function before using any other GTK functions in your GUI
- * applications.  It will initialize everything needed to operate the
+ * applications. It will initialize everything needed to operate the
  * toolkit.
  *
- * If you are using `GtkApplication`, you don't have to call gtk_init()
+ * If you are using `GtkApplication`, you don't have to call this
- * or gtk_init_check(); the `GApplication::startup` handler
+ * function; the `GApplication::startup` handler does it for you.
- * does it for you.
  *
  * This function will terminate your program if it was unable to
  * initialize the windowing system for some reason. If you want
- * your program to fall back to a textual interface you want to
+ * your program to fall back to a textual interface, call
- * call gtk_init_check() instead.
+ * [func@Gtk.init_check] instead.
  *
- * GTK calls `signal (SIGPIPE, SIG_IGN)`
+ * GTK calls `signal (SIGPIPE, SIG_IGN)` during initialization, to ignore
- * during initialization, to ignore SIGPIPE signals, since these are
+ * SIGPIPE signals, since these are almost never wanted in graphical
- * almost never wanted in graphical applications. If you do need to
+ * applications. If you do need to handle SIGPIPE for some reason, reset
- * handle SIGPIPE for some reason, reset the handler after gtk_init(),
+ * the handler after gtk_init(), but notice that other libraries (e.g.
- * but notice that other libraries (e.g. libdbus or gvfs) might do
+ * libdbus or gvfs) might do similar things.
- * similar things.
  */
 void
 gtk_init (void)
 {
   if (!gtk_init_check ())
     {
-      const char *display_name_arg;
+      g_warning ("Failed to open display");
-
-      display_name_arg = getenv ("DISPLAY");
-      g_warning ("cannot open display: %s", display_name_arg ? display_name_arg : "");
       exit (1);
     }
 }
@@ -731,8 +726,9 @@ gtk_init_check_abi_check (int num_checks, size_t sizeof_GtkWindow, size_t sizeof
 /**
  * gtk_is_initialized:
  *
- * Use this function to check if GTK has been initialized with gtk_init()
+ * Use this function to check if GTK has been initialized.
- * or gtk_init_check().
+ *
+ * See [func@Gtk.init].
  *
  * Returns: the initialization status
  */
@@ -769,12 +765,11 @@ gtk_is_initialized (void)
  * update_locale (const char *new_locale)
  * {
  *   setlocale (LC_ALL, new_locale);
- *   GtkTextDirection direction = gtk_get_locale_direction ();
+ *   gtk_widget_set_default_direction (gtk_get_locale_direction ());
- *   gtk_widget_set_default_direction (direction);
  * }
  * ]|
  *
- * Returns: the `GtkTextDirection` of the current locale
+ * Returns: the direction of the current locale
  */
 GtkTextDirection
 gtk_get_locale_direction (void)
@@ -825,12 +820,10 @@ gtk_get_locale_direction (void)
  * locale. It determines, for example, whether GTK uses
  * the right-to-left or left-to-right text direction.
  *
- * This function is equivalent to
+ * This function is equivalent to [func@Pango.Language.get_default].
- * [func@Pango.Language.get_default].
  * See that function for details.
  *
- * Returns: (transfer none): the default language as a
+ * Returns: (transfer none): the default language
- *   `PangoLanguage`
  */
 PangoLanguage *
 gtk_get_default_language (void)