ClangCodeModel: Fix clangd highlighting of string literals

... passed to macros defined in a different file.
This amends e77e57420a. Contrary to our expectation, it is possible that
AST nodes that are marked as belonging (only) to a header file can
contain child nodes that belong to the main file.

Fixes: QTCREATORBUG-26553
Change-Id: I4d1d877d8e1e2dcf7d81b63aa98e1149b5514e3f
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdclient.cpp

@@ -3640,12 +3640,11 @@ void ExtraHighlightingResultsCollector::visitNode(const AstNode &node)
     if (m_future.isCanceled())
         return;
     switch (node.fileStatus(m_filePath)) {
-    case AstNode::FileStatus::Foreign:
-        return;
     case AstNode::FileStatus::Ours:
     case AstNode::FileStatus::Unknown:
         collectFromNode(node);
         [[fallthrough]];
+    case AstNode::FileStatus::Foreign:
     case ClangCodeModel::Internal::AstNode::FileStatus::Mixed: {
         const auto children = node.children();
         if (!children)

src/plugins/clangcodemodel/test/clangdtests.cpp

@@ -1252,6 +1252,10 @@ void ClangdTestHighlighting::test_data()
     QTest::newRow("simple return") << 841 << 12 << 841 << 15 << QList<int>{C_LOCAL} << 0;
     QTest::newRow("lambda parameter") << 847 << 49 << 847 << 52
                                       << QList<int>{C_PARAMETER, C_DECLARATION} << 0;
+    QTest::newRow("string literal passed to macro from same file") << 853 << 32 << 853 << 38
+                                      << QList<int>{C_STRING} << 0;
+    QTest::newRow("string literal passed to macro from header file") << 854 << 32 << 854 << 38
+                                      << QList<int>{C_STRING} << 0;
 }
 
 void ClangdTestHighlighting::test()

src/plugins/clangcodemodel/test/data/highlighting/highlighting.cpp

@@ -846,3 +846,10 @@ void testConstRefAutoLambdaArgs()
 {
     useContainer(FooPtrVector(), [](const auto &arg) {});
 }
+
+#define USE_STRING(s) (s)
+void useString()
+{
+    const char *s = USE_STRING("TEXT");
+    s = USE_STRING_FROM_HEADER("TEXT");
+}

src/plugins/clangcodemodel/test/data/highlighting/highlightingmarks.h

@@ -0,0 +1 @@
+#define USE_STRING_FROM_HEADER(s) (s)