qmlls: check user-supplied names on renaming

Implement the checking of user-supplied names for renaming operations
in QmlLSUtils and qqmlrenamesymbolsupport.cpp

Add a helper method QQmlLSUtils::isValidEcmaScriptIdentifier that runs
the lexer on an identifier. Reject identifiers that do not parse as
T_IDENTIFIER, like keywords and invalid unicode escapes, for example.

Extend QQmlLSUtilsExpressionType to contain the name of the current
object.

Drive-by change: fix a off-by-one bug in the lexer, where files (or
identifiers, in this case) could not be lexed when they were ending with
an unicode-sequence.

Also, do not crash on JSIdentifiers without semantic scope in
resolveIdentifierExpressionType.

Add some tests, and fix a warning about positionAfterOneIndent
not being used in tst_qmlls_modules.cpp.

Add QQmlLSUtils::isChangedSignalName next to
QQmlLSUtils::isChangedHandlerName, and QQmlLSUtils::isHandlerName
and add tests for all three.

Fixes: QTBUG-114951
Task-number: QTBUG-114788
Change-Id: I0f1a544b70dfb69bca4aef355a8a8658f1d23081
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>

3 files changed, 15 insertions, 1 deletions

diff --git a/src/qml/common/qqmlsignalnames.cpp b/src/qml/common/qqmlsignalnames.cpp
index c08277e7f1..5d46531dfb 100644
--- a/src/qml/common/qqmlsignalnames.cpp
+++ b/src/qml/common/qqmlsignalnames.cpp
@@ -174,6 +174,18 @@ std::optional<QString> QQmlSignalNames::handlerNameToSignalName(QStringView hand
     return signalName;
 }
 
+bool QQmlSignalNames::isChangedSignalName(QStringView signalName)
+{
+    const qsizetype smallestAllowedSize = strlen("XChanged");
+    if (signalName.size() < smallestAllowedSize || !signalName.endsWith(u"Changed"_s))
+        return false;
+
+    if (auto letter = firstLetter(signalName, 0, strlen("Changed")))
+        return letter->isLower();
+
+    return true;
+}
+
 bool QQmlSignalNames::isChangedHandlerName(QStringView signalName)
 {
     const qsizetype smallestAllowedSize = strlen("onXChanged");
diff --git a/src/qml/common/qqmlsignalnames_p.h b/src/qml/common/qqmlsignalnames_p.h
index 7c46a71b3a..f777e89812 100644
--- a/src/qml/common/qqmlsignalnames_p.h
+++ b/src/qml/common/qqmlsignalnames_p.h
@@ -44,6 +44,7 @@ public:
     static std::optional<QString> handlerNameToSignalName(QStringView handler);
 
     static bool isChangedHandlerName(QStringView signalName);
+    static bool isChangedSignalName(QStringView signalName);
     static bool isHandlerName(QStringView signalName);
 
     static QString addPrefixToPropertyName(QStringView prefix, QStringView propertyName);
diff --git a/src/qml/parser/qqmljslexer.cpp b/src/qml/parser/qqmljslexer.cpp
index 28f4684649..704c7eb00d 100644
--- a/src/qml/parser/qqmljslexer.cpp
+++ b/src/qml/parser/qqmljslexer.cpp
@@ -368,7 +368,8 @@ uint Lexer::decodeUnicodeEscapeCharacter(bool *ok)
 {
     Q_ASSERT(_state.currentChar == u'u');
     scanChar(); // skip u
-    if (_codePtr + 4 <= _endPtr && isHexDigit(_state.currentChar)) {
+    constexpr int distanceFromFirstHexToLastHex = 3;
+    if (_codePtr + distanceFromFirstHexToLastHex <= _endPtr && isHexDigit(_state.currentChar)) {
         uint codePoint = 0;
         for (int i = 0; i < 4; ++i) {
             int digit = hexDigit(_state.currentChar);