C++: Fix Macrouse::utf16charsBegin()

This caused displaced highlighting of macro uses after #if constructs.

MacroUse::utf16charBegin() was based on the last "continuation token",
which was wrong.

Change-Id: I89983d82fcf804ba853c04a59a7533c489785d05
Reviewed-by: Erik Verbruggen <erik.verbruggen@digia.com>

src/libs/cplusplus/pp-engine.cpp

@@ -1788,6 +1788,7 @@ QByteArray Preprocessor::expand(PPToken *tk, PPToken *lastConditionToken)
 {
     unsigned line = tk->lineno;
     unsigned bytesBegin = tk->bytesBegin();
+    unsigned utf16charsBegin = tk->utf16charsBegin();
     PPToken lastTk;
     while (isContinuationToken(*tk)) {
         lastTk = *tk;
@@ -1801,7 +1802,7 @@ QByteArray Preprocessor::expand(PPToken *tk, PPToken *lastConditionToken)
     QByteArray result;
     result.reserve(256);
     preprocess(m_state.m_currentFileName, condition, &result, 0, true, false, true,
-               bytesBegin, tk->utf16charsBegin(), line);
+               bytesBegin, utf16charsBegin, line);
     result.squeeze();
 //    qDebug("*** Condition after: [%s]", result.constData());
 

src/plugins/cpptools/cpppreprocessor_test.cpp

@@ -180,3 +180,25 @@ void CppToolsPlugin::test_cpppreprocessor_includes_allDiagnostics()
     QCOMPARE(document->unresolvedIncludes().size(), 3);
     QCOMPARE(document->diagnosticMessages().size(), 3);
 }
+
+void CppToolsPlugin::test_cpppreprocessor_macroUses()
+{
+    QByteArray source =
+        "#define SOMEDEFINE 1\n"
+        "#if SOMEDEFINE == 1\n"
+        "    int someNumber;\n"
+        "#endif\n"
+        ;
+
+    SourcePreprocessor processor;
+    Document::Ptr document = processor.run(source);
+    QVERIFY(document);
+    const QList<Document::MacroUse> macroUses = document->macroUses();
+    QCOMPARE(macroUses.size(), 1);
+    const Document::MacroUse macroUse = macroUses.at(0);
+    QCOMPARE(macroUse.bytesBegin(), 25U);
+    QCOMPARE(macroUse.bytesEnd(), 35U);
+    QCOMPARE(macroUse.utf16charsBegin(), 25U);
+    QCOMPARE(macroUse.utf16charsEnd(), 35U);
+    QCOMPARE(macroUse.beginLine(), 2U);
+}

src/plugins/cpptools/cpptoolsplugin.h

@@ -128,6 +128,7 @@ private slots:
     void test_cpppreprocessor_includes_resolvedUnresolved();
     void test_cpppreprocessor_includes_cyclic();
     void test_cpppreprocessor_includes_allDiagnostics();
+    void test_cpppreprocessor_macroUses();
 
     void test_functionutils_virtualFunctions();
     void test_functionutils_virtualFunctions_data();