ClangUtils: Get rid of GenerateCompilationDbResult struct

Replace it with expected_str<FilePath>.
Check periodically for cancel request inside
generateCompilationDB() body.

Cancel the possibly running task on ClangCodeModelPlugin
destruction.

Handle the cancellation.

Change-Id: I8bcb956bc03627b4a17a3510a76810e66c82815d
Reviewed-by: Christian Kandeler <christian.kandeler@qt.io>

src/plugins/clangcodemodel/clangcodemodelplugin.cpp

@@ -68,6 +68,7 @@ private:
 
 ClangCodeModelPlugin::~ClangCodeModelPlugin()
 {
+    m_generatorWatcher.cancel();
     m_generatorWatcher.waitForFinished();
 }
 
@@ -140,13 +141,18 @@ void ClangCodeModelPlugin::createCompilationDBAction()
 
     connect(&m_generatorWatcher, &QFutureWatcher<GenerateCompilationDbResult>::finished,
             this, [this] {
-        const GenerateCompilationDbResult result = m_generatorWatcher.result();
         QString message;
-        if (result.error.isEmpty()) {
+        if (m_generatorWatcher.future().resultCount()) {
+            const GenerateCompilationDbResult result = m_generatorWatcher.result();
+            if (result) {
                 message = Tr::tr("Clang compilation database generated at \"%1\".")
-                    .arg(QDir::toNativeSeparators(result.filePath));
+                              .arg(result->toUserOutput());
             } else {
-            message = Tr::tr("Generating Clang compilation database failed: %1").arg(result.error);
+                message
+                    = Tr::tr("Generating Clang compilation database failed: %1").arg(result.error());
+            }
+        } else {
+            message = Tr::tr("Generating Clang compilation database canceled.");
         }
         MessageManager::writeFlashing(message);
         m_generateCompilationDBAction->setEnabled(true);

src/plugins/clangcodemodel/clangmodelmanagersupport.cpp

@@ -540,11 +540,15 @@ void ClangModelManagerSupport::updateLanguageClient(Project *project)
         generatorWatcher->deleteLater();
         if (!isProjectDataUpToDate(project, projectInfo, jsonDbDir))
             return;
-        const GenerateCompilationDbResult result = generatorWatcher->result();
+        if (generatorWatcher->future().resultCount() == 0) {
-        if (!result.error.isEmpty()) {
             MessageManager::writeDisrupting(
-                        Tr::tr("Cannot use clangd: Failed to generate compilation database:\n%1")
+                Tr::tr("Cannot use clangd: Generating compilation database canceled."));
-                        .arg(result.error));
+            return;
+        }
+        const GenerateCompilationDbResult result = generatorWatcher->result();
+        if (!result) {
+            MessageManager::writeDisrupting(Tr::tr("Cannot use clangd: "
+                "Failed to generate compilation database:\n%1").arg(result.error()));
             return;
         }
         Id previousId;

src/plugins/clangcodemodel/clangutils.cpp

@@ -146,23 +146,26 @@ static QJsonObject createFileObject(const FilePath &buildDir,
     return fileObject;
 }
 
-GenerateCompilationDbResult generateCompilationDB(QList<ProjectInfo::ConstPtr> projectInfoList,
+void generateCompilationDB(
-                                                  FilePath baseDir,
+    QPromise<expected_str<FilePath>> &promise,
+    const QList<ProjectInfo::ConstPtr> &projectInfoList,
+    const FilePath &baseDir,
     CompilationDbPurpose purpose,
-                                                  ClangDiagnosticConfig warningsConfig,
+    const ClangDiagnosticConfig &warningsConfig,
-                                                  QStringList projectOptions,
+    const QStringList &projectOptions,
-                                                  FilePath clangIncludeDir)
+    const FilePath &clangIncludeDir)
 {
-    QTC_ASSERT(!baseDir.isEmpty(), return GenerateCompilationDbResult(QString(),
+    QTC_ASSERT(!baseDir.isEmpty(),
-        Tr::tr("Could not retrieve build directory.")));
+        promise.addResult(make_unexpected(Tr::tr("Could not retrieve build directory."))); return);
     QTC_ASSERT(!projectInfoList.isEmpty(),
-               return GenerateCompilationDbResult(QString(), "Could not retrieve project info."));
+        promise.addResult(make_unexpected(Tr::tr("Could not retrieve project info."))); return);
     QTC_CHECK(baseDir.ensureWritableDir());
     QFile compileCommandsFile(baseDir.pathAppended("compile_commands.json").toFSPathString());
     const bool fileOpened = compileCommandsFile.open(QIODevice::WriteOnly | QIODevice::Truncate);
     if (!fileOpened) {
-        return GenerateCompilationDbResult(QString(), Tr::tr("Could not create \"%1\": %2")
+        promise.addResult(make_unexpected(Tr::tr("Could not create \"%1\": %2")
-                    .arg(compileCommandsFile.fileName(), compileCommandsFile.errorString()));
+            .arg(compileCommandsFile.fileName(), compileCommandsFile.errorString())));
+        return;
     }
     compileCommandsFile.write("[");
 
@@ -182,6 +185,8 @@ GenerateCompilationDbResult generateCompilationDB(QList<ProjectInfo::ConstPtr> p
                                                    jsonProjectOptions);
             }
             for (const ProjectFile &projFile : projectPart->files) {
+                if (promise.isCanceled())
+                    return;
                 const QJsonObject json
                     = createFileObject(baseDir,
                                        args,
@@ -200,7 +205,7 @@ GenerateCompilationDbResult generateCompilationDB(QList<ProjectInfo::ConstPtr> p
 
     compileCommandsFile.write("]");
     compileCommandsFile.close();
-    return GenerateCompilationDbResult(compileCommandsFile.fileName(), QString());
+    promise.addResult(FilePath::fromUserInput(compileCommandsFile.fileName()));
 }
 
 FilePath currentCppEditorDocumentFilePath()
@@ -262,7 +267,6 @@ QString DiagnosticTextInfo::clazyCheckName(const QString &option)
     return option;
 }
 
-
 QJsonArray clangOptionsForFile(const ProjectFile &file, const ProjectPart &projectPart,
                                const QJsonArray &generalOptions, UsePrecompiledHeaders usePch,
                                bool clStyle)

src/plugins/clangcodemodel/clangutils.h

@@ -53,23 +53,16 @@ Utils::FilePath currentCppEditorDocumentFilePath();
 
 QString diagnosticCategoryPrefixRemoved(const QString &text);
 
-class GenerateCompilationDbResult
+using GenerateCompilationDbResult = Utils::expected_str<Utils::FilePath>;
-{
-public:
-    GenerateCompilationDbResult() = default;
-    GenerateCompilationDbResult(const QString &filePath, const QString &error)
-        : filePath(filePath), error(error)
-    {}
-
-    QString filePath;
-    QString error;
-};
-
 enum class CompilationDbPurpose { Project, CodeModel };
-GenerateCompilationDbResult generateCompilationDB(QList<CppEditor::ProjectInfo::ConstPtr> projectInfo,
+void generateCompilationDB(
-        Utils::FilePath baseDir, CompilationDbPurpose purpose,
+    QPromise<GenerateCompilationDbResult> &promise,
-        CppEditor::ClangDiagnosticConfig warningsConfig, QStringList projectOptions,
+    const QList<CppEditor::ProjectInfo::ConstPtr> &projectInfoList,
-        Utils::FilePath clangIncludeDir);
+    const Utils::FilePath &baseDir,
+    CompilationDbPurpose purpose,
+    const CppEditor::ClangDiagnosticConfig &warningsConfig,
+    const QStringList &projectOptions,
+    const Utils::FilePath &clangIncludeDir);
 
 class DiagnosticTextInfo
 {