Clangd: Allow to switch off background indexing

It is conceivable that users don't want to spend the extra CPU time on
this.

Change-Id: Ic3611c8d17d201ae986fad08b344369a8728ce1b
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdclient.cpp

@@ -382,8 +382,11 @@ public:
 
 static BaseClientInterface *clientInterface(const Utils::FilePath &jsonDbDir)
 {
+    QString indexingOption = "--background-index";
+    if (!CppTools::ClangdSettings::indexingEnabled())
+        indexingOption += "=0";
     Utils::CommandLine cmd{CppTools::ClangdSettings::clangdFilePath(),
-                           {"--background-index", "--limit-results=0"}};
+                           {indexingOption, "--limit-results=0"}};
     if (!jsonDbDir.isEmpty())
         cmd.addArg("--compile-commands-dir=" + jsonDbDir.toString());
     if (clangdLog().isDebugEnabled())

src/plugins/cpptools/cppcodemodelsettings.cpp

@@ -65,6 +65,7 @@ static QString indexerFileSizeLimitKey()
 
 static QString useClangdKey() { return QLatin1String("UseClangd"); }
 static QString clangdPathKey() { return QLatin1String("ClangdPath"); }
+static QString clangdIndexingKey() { return QLatin1String("ClangdIndexing"); }
 
 static FilePath g_defaultClangdFilePath;
 static FilePath fallbackClangdFilePath()
@@ -300,7 +301,9 @@ void CppCodeModelSettings::setEnableLowerClazyLevels(bool yesno)
 
 static bool operator==(const ClangdSettings::Data &s1, const ClangdSettings::Data &s2)
 {
-    return s1.useClangd == s2.useClangd && s1.executableFilePath == s2.executableFilePath;
+    return s1.useClangd == s2.useClangd
+            && s1.executableFilePath == s2.executableFilePath
+            && s1.enableIndexing == s2.enableIndexing;
 }
 static bool operator!=(const ClangdSettings::Data &s1, const ClangdSettings::Data &s2)
 {
@@ -338,6 +341,7 @@ void ClangdSettings::loadSettings()
     QSettings * const s = Core::ICore::settings();
     m_data.useClangd = s->value(useClangdKey(), false).toBool();
     m_data.executableFilePath = FilePath::fromString(s->value(clangdPathKey()).toString());
+    m_data.enableIndexing = s->value(clangdIndexingKey(), true).toBool();
 }
 
 void ClangdSettings::saveSettings()
@@ -345,6 +349,7 @@ void ClangdSettings::saveSettings()
     QSettings * const s = Core::ICore::settings();
     s->setValue(useClangdKey(), useClangd());
     s->setValue(clangdPathKey(), m_data.executableFilePath.toString());
+    s->setValue(clangdIndexingKey(), m_data.enableIndexing);
 }
 
 #ifdef WITH_TESTS

src/plugins/cpptools/cppcodemodelsettings.h

@@ -103,6 +103,7 @@ public:
     {
     public:
         bool useClangd = false;
+        bool enableIndexing = true;
         Utils::FilePath executableFilePath;
     };
 
@@ -110,6 +111,7 @@ public:
 
     static void setDefaultClangdPath(const Utils::FilePath &filePath);
     static Utils::FilePath clangdFilePath();
+    static bool indexingEnabled() { return instance().m_data.enableIndexing; }
 
     static void setData(const Data &data);
     static Data data() { return instance().m_data; }

src/plugins/cpptools/cppcodemodelsettingspage.cpp

@@ -205,18 +205,27 @@ public:
         m_clangdChooser.setExpectedKind(Utils::PathChooser::ExistingCommand);
         m_clangdChooser.setFilePath(ClangdSettings::clangdFilePath());
         m_clangdChooser.setEnabled(m_useClangdCheckBox.isChecked());
+        m_indexingCheckBox.setChecked(ClangdSettings::indexingEnabled());
+        m_indexingCheckBox.setToolTip(tr(
+                "If background indexing is enabled, global symbol searches will yield\n"
+                "more accurate results, at the cost of additional CPU load when\n"
+                "the project is first opened."));
 
         const auto layout = new QVBoxLayout(this);
         layout->addWidget(&m_useClangdCheckBox);
         const auto formLayout = new QFormLayout;
         const auto chooserLabel = new QLabel(tr("Path to executable:"));
         formLayout->addRow(chooserLabel, &m_clangdChooser);
+        const auto indexingLabel = new QLabel(tr("Enable background indexing:"));
+        formLayout->addRow(indexingLabel, &m_indexingCheckBox);
         layout->addLayout(formLayout);
         layout->addStretch(1);
 
         const auto toggleEnabled = [=](const bool checked) {
             chooserLabel->setEnabled(checked);
             m_clangdChooser.setEnabled(checked);
+            indexingLabel->setEnabled(checked);
+            m_indexingCheckBox.setEnabled(checked);
         };
         connect(&m_useClangdCheckBox, &QCheckBox::toggled, toggleEnabled);
         toggleEnabled(m_useClangdCheckBox.isChecked());
@@ -228,10 +237,12 @@ private:
         ClangdSettings::Data data;
         data.useClangd = m_useClangdCheckBox.isChecked();
         data.executableFilePath = m_clangdChooser.filePath();
+        data.enableIndexing = m_indexingCheckBox.isChecked();
         ClangdSettings::setData(data);
     }
 
     QCheckBox m_useClangdCheckBox;
+    QCheckBox m_indexingCheckBox;
     Utils::PathChooser m_clangdChooser;
 };