ClangCodeModel: Make "live update" of dependent sources opt-in

Not everyone wants to invest the extra computing resources needed for
this feature.
Amends b33b99e2d9.
See 6d805195f6 for the original
motivation.

Task-number: QTCREATORBUG-29943
Change-Id: I4c8cce5bb58b34d930a409ea3e0995377c90d4ab
Reviewed-by: David Schulz <david.schulz@qt.io>
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>

src/plugins/clangcodemodel/clangeditordocumentprocessor.cpp

@@ -18,6 +18,8 @@
 
 #include <languageclient/languageclientmanager.h>
 
+#include <projectexplorer/projectmanager.h>
+
 #include <texteditor/fontsettings.h>
 #include <texteditor/texteditor.h>
 #include <texteditor/texteditorconstants.h>
@@ -84,7 +86,12 @@ void ClangEditorDocumentProcessor::forceUpdate(TextEditor::TextDocument *doc)
 {
     if (const auto client = qobject_cast<ClangdClient *>(
             LanguageClient::LanguageClientManager::clientForDocument(doc))) {
-        client->documentContentsChanged(doc, 0, 0, 0);
+        const CppEditor::ClangdSettings settings(
+            CppEditor::ClangdProjectSettings(
+                ProjectExplorer::ProjectManager::projectForFile(doc->filePath()))
+                .settings());
+        if (settings.updateDependentSources())
+            client->documentContentsChanged(doc, 0, 0, 0);
     }
 }
 

src/plugins/clangcodemodel/test/clangdtests.cpp

@@ -2240,6 +2240,8 @@ public:
     ClangdTestIndirectChanges();
 
 private slots:
+    void initTestCase() override;
+    void cleanupTestCase();
     void test();
 };
 
@@ -2249,6 +2251,20 @@ ClangdTestIndirectChanges::ClangdTestIndirectChanges()
     setSourceFileNames({"main.cpp", "directheader.h", "indirectheader.h", "unrelatedheader.h"});
 }
 
+void ClangdTestIndirectChanges::initTestCase()
+{
+    CppEditor::ClangdSettings &settings = CppEditor::ClangdSettings::instance();
+    CppEditor::ClangdSettings::Data settingsData = settings.data();
+    settingsData.updateDependentSources = true;
+    settings.setData(settingsData, false);
+    ClangdTest::initTestCase();
+}
+
+void ClangdTestIndirectChanges::cleanupTestCase()
+{
+    CppEditor::ClangdSettings::instance().setData({}, false);
+}
+
 void ClangdTestIndirectChanges::test()
 {
     // Initially, everything is fine.