Make `PREVENT_STUCK_MODIFIERS` the default (#3107)

* Remove chording as it is not documented, not used, and needs work.

* Make Leader Key an optional feature.

* Switch from `PREVENT_STUCK_MODIFIERS` to `STRICT_LAYER_RELEASE`

* Remove `#define PREVENT_STUCK_MODIFIERS` from keymaps.

6 files changed, 5 insertions, 125 deletions

diff --git a/quantum/process_keycode/process_chording.c b/quantum/process_keycode/process_chording.c
deleted file mode 100644
index 6c6ebe300a..0000000000
--- a/quantum/process_keycode/process_chording.c
+++ /dev/null
@@ -1,76 +0,0 @@
-/* Copyright 2016 Jack Humbert
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#include "process_chording.h"
-
-bool keys_chord(uint8_t keys[]) {
-  uint8_t keys_size = sizeof(keys)/sizeof(keys[0]);
-  bool pass = true;
-  uint8_t in = 0;
-  for (uint8_t i = 0; i < chord_key_count; i++) {
-    bool found = false;
-    for (uint8_t j = 0; j < keys_size; j++) {
-      if (chord_keys[i] == (keys[j] & 0xFF)) {
-        in++; // detects key in chord
-        found = true;
-        break;
-      }
-    }
-    if (found)
-      continue;
-    if (chord_keys[i] != 0)  {
-      pass = false; // makes sure rest are blank
-    }
-  }
-  return (pass && (in == keys_size));
-}
-
-bool process_chording(uint16_t keycode, keyrecord_t *record) {
-  if (keycode >= QK_CHORDING && keycode <= QK_CHORDING_MAX) {
-    if (record->event.pressed) {
-      if (!chording) {
-        chording = true;
-        for (uint8_t i = 0; i < CHORDING_MAX; i++)
-          chord_keys[i] = 0;
-        chord_key_count = 0;
-        chord_key_down = 0;
-      }
-      chord_keys[chord_key_count] = (keycode & 0xFF);
-      chord_key_count++;
-      chord_key_down++;
-      return false;
-    } else {
-      if (chording) {
-        chord_key_down--;
-        if (chord_key_down == 0) {
-          chording = false;
-          // Chord Dictionary
-          if (keys_chord((uint8_t[]){KC_ENTER, KC_SPACE})) {
-            register_code(KC_A);
-            unregister_code(KC_A);
-            return false;
-          }
-          for (uint8_t i = 0; i < chord_key_count; i++) {
-            register_code(chord_keys[i]);
-            unregister_code(chord_keys[i]);
-            return false;
-          }
-        }
-      }
-    }
-  }
-  return true;
-}
diff --git a/quantum/process_keycode/process_chording.h b/quantum/process_keycode/process_chording.h
deleted file mode 100644
index 8c0f4862a8..0000000000
--- a/quantum/process_keycode/process_chording.h
+++ /dev/null
@@ -1,32 +0,0 @@
-/* Copyright 2016 Jack Humbert
- *
- * This program is free software: you can redistribute it and/or modify
- * it under the terms of the GNU General Public License as published by
- * the Free Software Foundation, either version 2 of the License, or
- * (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program.  If not, see <http://www.gnu.org/licenses/>.
- */
-
-#ifndef PROCESS_CHORDING_H
-#define PROCESS_CHORDING_H
-
-#include "quantum.h"
-
-// Chording stuff
-#define CHORDING_MAX 4
-bool chording = false;
-
-uint8_t chord_keys[CHORDING_MAX] = {0};
-uint8_t chord_key_count = 0;
-uint8_t chord_key_down = 0;
-
-bool process_chording(uint16_t keycode, keyrecord_t *record);
-
-#endif
diff --git a/quantum/process_keycode/process_leader.c b/quantum/process_keycode/process_leader.c
index c87ef115af..eddbf71f70 100644
--- a/quantum/process_keycode/process_leader.c
+++ b/quantum/process_keycode/process_leader.c
@@ -14,7 +14,7 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
-#ifndef DISABLE_LEADER
+#ifdef LEADER_ENABLE
 
 #include "process_leader.h"
 
diff --git a/quantum/quantum.c b/quantum/quantum.c
index 9d352a94cf..9bf91eb865 100644
--- a/quantum/quantum.c
+++ b/quantum/quantum.c
@@ -196,7 +196,7 @@ bool process_record_quantum(keyrecord_t *record) {
   keypos_t key = record->event.key;
   uint16_t keycode;
 
-  #if !defined(NO_ACTION_LAYER) && defined(PREVENT_STUCK_MODIFIERS)
+  #if !defined(NO_ACTION_LAYER) && !defined(STRICT_LAYER_RELEASE)
     /* TODO: Use store_or_get_action() or a similar function. */
     if (!disable_action_cache) {
       uint8_t layer;
@@ -251,12 +251,9 @@ bool process_record_quantum(keyrecord_t *record) {
   #ifdef TAP_DANCE_ENABLE
     process_tap_dance(keycode, record) &&
   #endif
-  #ifndef DISABLE_LEADER
+  #ifdef LEADER_ENABLE
     process_leader(keycode, record) &&
   #endif
-  #ifndef DISABLE_CHORDING
-    process_chording(keycode, record) &&
-  #endif
   #ifdef COMBO_ENABLE
     process_combo(keycode, record) &&
   #endif
diff --git a/quantum/quantum.h b/quantum/quantum.h
index d1f761f17a..7cf16d81e6 100644
--- a/quantum/quantum.h
+++ b/quantum/quantum.h
@@ -89,15 +89,10 @@ extern uint32_t default_layer_state;
     #include "process_music.h"
 #endif
 
-#ifndef DISABLE_LEADER
+#ifdef LEADER_ENABLE
     #include "process_leader.h"
 #endif
 
-#define DISABLE_CHORDING
-#ifndef DISABLE_CHORDING
-    #include "process_chording.h"
-#endif
-
 #ifdef UNICODE_ENABLE
     #include "process_unicode.h"
 #endif
diff --git a/quantum/quantum_keycodes.h b/quantum/quantum_keycodes.h
index 0ecc293a82..3b87954960 100644
--- a/quantum/quantum_keycodes.h
+++ b/quantum/quantum_keycodes.h
@@ -63,10 +63,6 @@ enum quantum_keycodes {
     QK_ONE_SHOT_LAYER_MAX = 0x54FF,
     QK_ONE_SHOT_MOD       = 0x5500,
     QK_ONE_SHOT_MOD_MAX   = 0x55FF,
-#ifndef DISABLE_CHORDING
-    QK_CHORDING           = 0x5600,
-    QK_CHORDING_MAX       = 0x56FF,
-#endif
     QK_TAP_DANCE          = 0x5700,
     QK_TAP_DANCE_MAX      = 0x57FF,
     QK_LAYER_TAP_TOGGLE   = 0x5800,
@@ -123,7 +119,7 @@ enum quantum_keycodes {
     GRAVE_ESC,
 
     // Leader key
-#ifndef DISABLE_LEADER
+#ifdef LEADER_ENABLE
     KC_LEAD,
 #endif