GHOST/Wayland: silence warnings for modifier key handling in GNOME

GNOME (mutter) intentionally doesn't follow the Wayland spec for the
keyboard_enter events (held keys are always an empty array).

This means we can't know which keys are held on window activation,
making the result of getModifierKeys invalid (in that we don't know
which modifiers are held).

Detect this situation and suppress warnings as the issue has been
reported and it doesn't help for users to see noisy warnings for
a known problem.

1 files changed, 53 insertions, 6 deletions

diff --git a/intern/ghost/intern/GHOST_SystemWayland.cpp b/intern/ghost/intern/GHOST_SystemWayland.cpp
index d569d24926d..c54d9769eeb 100644
--- a/intern/ghost/intern/GHOST_SystemWayland.cpp
+++ b/intern/ghost/intern/GHOST_SystemWayland.cpp
@@ -86,6 +86,20 @@ static void output_handle_done(void *data, struct wl_output *wl_output);
 static bool use_gnome_confine_hack = false;
 #endif
 
+/**
+ * GNOME (mutter 42.5) doesn't follow the WAYLAND spec regarding keyboard handling,
+ * unlike (other compositors: KDE-plasma, River & Sway which work without problems).
+ *
+ * This means GNOME can't know which modifiers are held when activating windows,
+ * so we guess the left modifiers are held.
+ *
+ * This define could be removed without changing any functionality,
+ * it just means GNOME users will see verbose warning messages that alert them about
+ * a known problem that needs to be fixed up-stream.
+ * See: https://gitlab.gnome.org/GNOME/mutter/-/issues/2457
+ */
+#define USE_GNOME_KEYBOARD_SUPPRESS_WARNING
+
 /* -------------------------------------------------------------------- */
 /** \name Inline Event Codes
  *
@@ -385,6 +399,13 @@ struct GWL_Seat {
   /** Keys held matching `xkb_state`. */
   struct WGL_KeyboardDepressedState key_depressed;
 
+#ifdef USE_GNOME_KEYBOARD_SUPPRESS_WARNING
+  struct {
+    bool any_mod_held = false;
+    bool any_keys_held_on_enter = false;
+  } key_depressed_suppress_warning;
+#endif
+
   /**
    * Cache result of `xkb_keymap_mod_get_index`
    * so every time a modifier is accessed a string lookup isn't required.
@@ -2312,6 +2333,10 @@ static void keyboard_handle_enter(void *data,
   }
 
   keyboard_depressed_state_push_events_from_change(seat, key_depressed_prev);
+
+#ifdef USE_GNOME_KEYBOARD_SUPPRESS_WARNING
+  seat->key_depressed_suppress_warning.any_keys_held_on_enter = keys->size != 0;
+#endif
 }
 
 /**
@@ -2337,6 +2362,11 @@ static void keyboard_handle_leave(void *data,
   if (seat->key_repeat.timer) {
     keyboard_handle_key_repeat_cancel(seat);
   }
+
+#ifdef USE_GNOME_KEYBOARD_SUPPRESS_WARNING
+  seat->key_depressed_suppress_warning.any_mod_held = false;
+  seat->key_depressed_suppress_warning.any_keys_held_on_enter = false;
+#endif
 }
 
 /**
@@ -2555,6 +2585,10 @@ static void keyboard_handle_modifiers(void *data,
   if (seat->key_repeat.timer) {
     keyboard_handle_key_repeat_reset(seat, true);
   }
+
+#ifdef USE_GNOME_KEYBOARD_SUPPRESS_WARNING
+  seat->key_depressed_suppress_warning.any_mod_held = mods_depressed != 0;
+#endif
 }
 
 static void keyboard_repeat_handle_info(void *data,
@@ -3164,6 +3198,15 @@ GHOST_TSuccess GHOST_SystemWayland::getModifierKeys(GHOST_ModifierKeys &keys) co
 
   const xkb_mod_mask_t state = xkb_state_serialize_mods(seat->xkb_state, XKB_STATE_MODS_DEPRESSED);
 
+  bool show_warning = true;
+#ifdef USE_GNOME_KEYBOARD_SUPPRESS_WARNING
+  if ((seat->key_depressed_suppress_warning.any_mod_held == true) &&
+      (seat->key_depressed_suppress_warning.any_keys_held_on_enter == false)) {
+    /* The compositor gave us invalid information, don't show a warning. */
+    show_warning = false;
+  }
+#endif
+
   /* Use local #WGL_KeyboardDepressedState to check which key is pressed.
    * Use XKB as the source of truth, if there is any discrepancy. */
   for (int i = 0; i < MOD_INDEX_NUM; i++) {
@@ -3179,18 +3222,22 @@ GHOST_TSuccess GHOST_SystemWayland::getModifierKeys(GHOST_ModifierKeys &keys) co
      * Warn so if this happens it can be investigated. */
     if (val) {
       if (UNLIKELY(!(val_l || val_r))) {
-        CLOG_WARN(&LOG_WL_KEYBOARD_DEPRESSED_STATE,
-                  "modifier (%s) state is inconsistent (GHOST held keys do not match XKB)",
-                  mod_info.display_name);
+        if (show_warning) {
+          CLOG_WARN(&LOG_WL_KEYBOARD_DEPRESSED_STATE,
+                    "modifier (%s) state is inconsistent (GHOST held keys do not match XKB)",
+                    mod_info.display_name);
+        }
         /* Picking the left is arbitrary. */
         val_l = true;
       }
     }
     else {
       if (UNLIKELY(val_l || val_r)) {
-        CLOG_WARN(&LOG_WL_KEYBOARD_DEPRESSED_STATE,
-                  "modifier (%s) state is inconsistent (GHOST released keys do not match XKB)",
-                  mod_info.display_name);
+        if (show_warning) {
+          CLOG_WARN(&LOG_WL_KEYBOARD_DEPRESSED_STATE,
+                    "modifier (%s) state is inconsistent (GHOST released keys do not match XKB)",
+                    mod_info.display_name);
+        }
         val_l = false;
         val_r = false;
       }