qmlcompiler: Suggest fix for multiline strings

We can now suggest a template string to use instead that is properly
escaped. Once auto-fixing becomes available we can automatically replace
deprecated multiline strings with the new suggestion.

Task-number: QTBUG-92448
Change-Id: I4e77820b66ae960cde558a62689c5da328b8df5b
Reviewed-by: Fabian Kosmale <fabian.kosmale@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>

src/qmlcompiler/qqmljsimportvisitor.cpp

@@ -1112,10 +1112,36 @@ bool QQmlJSImportVisitor::visit(QQmlJS::AST::StringLiteral *sl)
 
     if (s.contains(QLatin1Char('\r')) || s.contains(QLatin1Char('\n')) || s.contains(QChar(0x2028u))
         || s.contains(QChar(0x2029u))) {
+        QString templateString;
+
+        bool escaped = false;
+        const QChar stringQuote = s[0];
+        for (qsizetype i = 1; i < s.length() - 1; i++) {
+            const QChar c = s[i];
+
+            if (c == u'\\') {
+                escaped = !escaped;
+            } else if (escaped) {
+                // If we encounter an escaped quote, unescape it since we use backticks here
+                if (c == stringQuote)
+                    templateString.chop(1);
+
+                escaped = false;
+            } else {
+                if (c == u'`')
+                    templateString += u'\\';
+                if (c == u'$' && i + 1 < s.length() - 1 && s[i + 1] == u'{')
+                    templateString += u'\\';
+            }
+
+            templateString += c;
+        }
+
+        const FixSuggestion suggestion = { { { u"Use a template literal instead"_qs,
+                                               sl->literalToken, u"`" + templateString + u"`" } } };
         m_logger->log(QStringLiteral("String contains unescaped line terminator which is "
-                                     "deprecated. Use a template "
-                                     "literal instead."),
-                      Log_MultilineString, sl->literalToken);
+                                     "deprecated."),
+                      Log_MultilineString, sl->literalToken, true, true, suggestion);
     }
 
     return true;

src/qmlcompiler/qqmljslogger.cpp

@@ -241,6 +241,11 @@ void QQmlJSLogger::printFix(const FixSuggestion &fix)
         m_output.write(issueLocationWithContext.afterText().toString() + u'\n');
 
         int tabCount = issueLocationWithContext.beforeText().count(u'\t');
+
+        // Do not draw location indicator for multiline replacement strings
+        if (fixItem.replacementString.contains(u'\n'))
+            continue;
+
         m_output.write(u" "_qs.repeated(
                                issueLocationWithContext.beforeText().length() - tabCount)
                        + u"\t"_qs.repeated(tabCount)

tests/auto/qml/qmllint/data/multilineStringTortureQuote.qml

@@ -0,0 +1,10 @@
+import QtQml
+
+QtObject {
+    property string quote: "
+    quote: \" \\\" \\\\\"
+    ticks: ` \` \\\` \\\`
+    singleTicks: ' \' \\' \\\'
+    expression: \${expr} \${expr} \\\${expr} \\\${expr}
+    "
+}

tests/auto/qml/qmllint/data/multilineStringTortureTick.qml

@@ -0,0 +1,10 @@
+import QtQml
+
+QtObject {
+    property string quote: '
+    quote: " \" \\" \\\"
+    ticks: \` \` \\\` \\\`
+    singleTicks: \' \\\' \\\\\'
+    expression: \${expr} \${expr} \\\${expr} \\\${expr}
+    '
+}

tests/auto/qml/qmllint/tst_qmllint.cpp

@@ -659,9 +659,26 @@ void TestQmllint::dirtyQmlCode_data()
             << QString() << false;
     QTest::newRow("multilineString")
             << QStringLiteral("multilineString.qml")
-            << QStringLiteral("String contains unescaped line terminator which is deprecated. Use "
-                              "a template literal instead.")
+            << QStringLiteral("String contains unescaped line terminator which is deprecated.")
             << QString() << QString() << true;
+    QTest::newRow("multilineStringTortureQuote")
+            << QStringLiteral("multilineStringTortureQuote.qml")
+            << QStringLiteral("String contains unescaped line terminator which is deprecated.")
+            << QString() << QStringLiteral(R"(`
+    quote: " \\" \\\\"
+    ticks: \` \` \\\` \\\`
+    singleTicks: ' \' \\' \\\'
+    expression: \${expr} \${expr} \\\${expr} \\\${expr}
+    `)") << true;
+    QTest::newRow("multilineStringTortureTick")
+            << QStringLiteral("multilineStringTortureTick.qml")
+            << QStringLiteral("String contains unescaped line terminator which is deprecated.")
+            << QString() << QStringLiteral(R"(`
+    quote: " \" \\" \\\"
+    ticks: \` \` \\\` \\\`
+    singleTicks: ' \\' \\\\'
+    expression: \${expr} \${expr} \\\${expr} \\\${expr}
+    `)") << true;
     QTest::newRow("unresolvedType")
             << QStringLiteral("unresolvedType.qml")
             << QStringLiteral("UnresolvedType was not found. Did you add all import paths?")
@@ -1278,10 +1295,17 @@ void TestQmllint::searchWarnings(const QJsonArray &warnings, const QString &subs
                 contains = true;
                 break;
             }
-            if (searchReplacements == DoReplacementSearch
-                && fix[u"replacement"].toString().contains(substring)) {
-                contains = true;
-                break;
+            if (searchReplacements == DoReplacementSearch) {
+                QString replacement = fix[u"replacement"].toString();
+#ifdef Q_OS_WIN
+                // Replacements can contain native line endings
+                // but we need them to be uniform in order for them to conform to our test data
+                replacement = replacement.replace(u"\r\n"_qs, u"\n"_qs);
+#endif
+                if (replacement.contains(substring)) {
+                    contains = true;
+                    break;
+                }
             }
         }
     }