ClangCodeModel: Try harder to catch bogus AST ranges

String literals that are adjacent after preprocessing are reported as a
single AST node, leading to potentially wrong highlighting.
We can catch this condition at least for the case where there are
semantic tokens in between the string components.

Fixes: QTCREATORBUG-27601
Change-Id: If023d06db74bd6cfefa670649f0e733ceaaede2d
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdsemantichighlighting.cpp

@@ -482,6 +482,15 @@ void ExtraHighlightingResultsCollector::insertResult(const HighlightingResult &r
             return;
         }
 
+        // Bogus ranges; e.g. QTCREATORBUG-27601
+        if (it != m_results.end()) {
+            const int nextStartPos = Utils::Text::positionInText(m_doc, it->line, it->column);
+            const int resultEndPos = Utils::Text::positionInText(m_doc, result.line, result.column)
+                    + result.length;
+            if (resultEndPos > nextStartPos)
+                return;
+        }
+
         qCDebug(clangdLogHighlight) << "adding additional highlighting result"
                                     << result.line << result.column << result.length;
         m_results.insert(it, result);