Dead keys: act on compose status at press time

- Two dead keys that compose (´´ → ´) type the result right away; a dead
  key that can't continue the sequence types the old accents and starts anew
- With Ctrl/Alt/Super, a dead key sends its dead keysym, as the physical
  key does, not the spacing accent from its label

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/input/DeadKeys.cpp

@@ -37,11 +37,36 @@ DeadKeys::DeadKeys(const QString &locale)
 
 DeadKeys::~DeadKeys() = default;
 
-void DeadKeys::press(quint32 deadKeysym)
+QString DeadKeys::press(quint32 deadKeysym)
 {
+    if (!m_state) {
         m_pending += deadKeyText(deadKeysym);
-    if (m_state)
+        return {};
+    }
     xkb_compose_state_feed(m_state.get(), deadKeysym);
+    switch (xkb_compose_state_get_status(m_state.get())) {
+    case XKB_COMPOSE_COMPOSED: {
+        const QString composed = composedText();
+        cancel();
+        return composed;
+    }
+    case XKB_COMPOSE_CANCELLED: {
+        // No sequence goes on like this: type the old accents, start anew.
+        const QString accents = m_pending;
+        cancel();
+        return accents + press(deadKeysym);
+    }
+    default:
+        m_pending += deadKeyText(deadKeysym);
+        return {};
+    }
+}
+
+QString DeadKeys::composedText() const
+{
+    char utf8[64];
+    xkb_compose_state_get_utf8(m_state.get(), utf8, sizeof utf8);
+    return QString::fromUtf8(utf8);
 }
 
 QString DeadKeys::compose(const QString &text)
@@ -50,11 +75,8 @@ QString DeadKeys::compose(const QString &text)
     if (m_state && !text.isEmpty()) {
         const char32_t ucs = text.toUcs4().first();
         xkb_compose_state_feed(m_state.get(), xkb_utf32_to_keysym(ucs));
-        if (xkb_compose_state_get_status(m_state.get()) == XKB_COMPOSE_COMPOSED) {
-            char utf8[64];
-            xkb_compose_state_get_utf8(m_state.get(), utf8, sizeof utf8);
-            result = QString::fromUtf8(utf8) + text.mid(QString::fromUcs4(&ucs, 1).size());
-        }
+        if (xkb_compose_state_get_status(m_state.get()) == XKB_COMPOSE_COMPOSED)
+            result = composedText() + text.mid(QString::fromUcs4(&ucs, 1).size());
     }
     cancel();
     return result;

src/input/DeadKeys.h

@@ -17,14 +17,18 @@ public:
     ~DeadKeys();
 
     bool isPending() const { return !m_pending.isEmpty(); }
-    // A dead key was typed: starts or extends the sequence.
-    void press(quint32 deadKeysym);
+    // A dead key was typed: starts or extends the sequence. Returns text to
+    // type now: what two dead keys composed (´´ → ´), or the accents of a
+    // sequence the new one can't continue; empty while still pending.
+    QString press(quint32 deadKeysym);
     // `text` typed while pending: the composed character, or the accents
     // followed by `text` when nothing composes. Ends the sequence.
     QString compose(const QString &text);
     void cancel();
 
 private:
+    QString composedText() const;
+
     std::unique_ptr<xkb_context, void (*)(xkb_context *)> m_context;
     std::unique_ptr<xkb_compose_table, void (*)(xkb_compose_table *)> m_table;
     std::unique_ptr<xkb_compose_state, void (*)(xkb_compose_state *)> m_state;

src/input/KeyboardController.cpp

@@ -220,15 +220,18 @@ void KeyboardController::typeCharacter(const KeyDef &key, KeyOutput output, cons
 {
     const QString base = key.type == KeyType::Space ? QStringLiteral(" ") : key.label;
     if (m_modifiers.active()) {
-        // A shortcut such as Ctrl+C: the key's unshifted symbol, with modifiers.
+        // A shortcut such as Ctrl+C: the key's unshifted symbol, with modifiers;
+        // for a dead key its dead keysym, as the physical key sends.
         m_deadKeys.cancel();
-        sendKey(xkb_utf32_to_keysym(base.toLower().toUcs4().value(0)));
+        sendKey(key.dead ? key.dead : xkb_utf32_to_keysym(base.toLower().toUcs4().value(0)));
         return;
     }
 
     const ShiftLevel level = shiftLevel();
     if (const quint32 dead = key.deadAt(level); dead && output == KeyOutput::Primary) {
-        m_deadKeys.press(dead);
+        if (const QString done = m_deadKeys.press(dead); !done.isEmpty())
+            typeText(done);
+        else
             changeShift([&] { m_shift.characterTyped(); });
         return;
     }

tests/tst_controller.cpp

@@ -373,6 +373,16 @@ private Q_SLOTS:
         QCOMPARE(engine.output, u"+Ľ2");
     }
 
+    void ctrlWithDeadKeySendsTheDeadKeysym()
+    {
+        KeyDef acute = makeKey(KeyType::Character, u"´"_s);
+        acute.dead = XKB_KEY_dead_acute;
+        tap(modifierKey(u"ctrl"_s));
+        tap(acute);
+        QCOMPARE(engine.keysyms, QList<quint32>{XKB_KEY_dead_acute});
+        QCOMPARE(engine.lastModifiers, Qt::ControlModifier);
+    }
+
     void deadKeyComposesWithNextCharacter()
     {
         KeyDef acute = makeKey(KeyType::Character, u"´"_s);

tests/tst_deadkeys.cpp

@@ -30,6 +30,16 @@ private Q_SLOTS:
         QCOMPARE(dead.compose(u"q"_s), u"ˇq");
     }
 
+    void twoDeadKeysComposeAtOnce()
+    {
+        DeadKeys dead(u"en_US.UTF-8"_s);
+        QVERIFY(dead.press(XKB_KEY_dead_acute).isEmpty());
+        QCOMPARE(dead.press(XKB_KEY_dead_acute), u"´");
+        QVERIFY(!dead.isPending());
+        dead.press(XKB_KEY_dead_acute); // a fresh sequence
+        QCOMPARE(dead.compose(u"e"_s), u"é");
+    }
+
     void cancelForgetsTheAccent()
     {
         DeadKeys dead(u"en_US.UTF-8"_s);