LanguageClient: Support limit parameter for completion request

... and make use of it in the ClangCodeModel tests.

Change-Id: Ib2186273aec1db9b354892c2e1c4ebd82e3c1c96
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/libs/languageserverprotocol/completion.h

@@ -83,6 +83,9 @@ public:
     void setContext(const CompletionContext &context)
     { insert(contextKey, context); }
     void clearContext() { remove(contextKey); }
+
+    // clangd extension
+    void setLimit(int limit) { insert(limitKey, limit); }
 };
 
 class LANGUAGESERVERPROTOCOL_EXPORT CompletionItem : public JsonObject

src/libs/languageserverprotocol/jsonkeys.h

@@ -139,6 +139,7 @@ constexpr char labelKey[] = "label";
 constexpr char languageIdKey[] = "languageId";
 constexpr char languageKey[] = "language";
 constexpr char legendKey[] = "legend";
+constexpr char limitKey[] = "limit";
 constexpr char lineKey[] = "line";
 constexpr char linesKey[] = "lines";
 constexpr char locationKey[] = "location";

src/plugins/clangcodemodel/clangdclient.cpp

@@ -167,13 +167,7 @@ static BaseClientInterface *clientInterface(Project *project, const Utils::FileP
         indexingOption += "=0";
     const QString headerInsertionOption = QString("--header-insertion=")
             + (settings.autoIncludeHeaders() ? "iwyu" : "never");
-#ifdef WITH_TESTS
-    // For the #include < test, which needs to get a local header file, but the list
-    // is being flooded with system include headers. 4280 on Windows!
-    const QString limitResults = QString("--limit-results=0");
-#else
     const QString limitResults = QString("--limit-results=%1").arg(settings.completionResults());
-#endif
     Utils::CommandLine cmd{settings.clangdFilePath(),
                            {indexingOption,
                             headerInsertionOption,

src/plugins/clangcodemodel/test/clangdtests.cpp

@@ -1550,6 +1550,9 @@ void ClangdTestCompletion::testCompletePreprocessorKeywords()
 
 void ClangdTestCompletion::testCompleteIncludeDirective()
 {
+    // Our local include is way down in the result list.
+    client()->setCompletionResultsLimit(0);
+
     ProposalModelPtr proposal;
     getProposal("includeDirectiveCompletion.cpp", proposal);
 
@@ -1558,6 +1561,7 @@ void ClangdTestCompletion::testCompleteIncludeDirective()
     QVERIFY(hasItem(proposal, " otherFile.h>"));
     QVERIFY(hasItem(proposal, " mylib/"));
     QVERIFY(!hasSnippet(proposal, "class "));
+    client()->setCompletionResultsLimit(-1);
 }
 
 void ClangdTestCompletion::testCompleteGlobals()

src/plugins/languageclient/client.cpp

@@ -328,6 +328,7 @@ public:
     QTimer m_shutdownTimer;
     LanguageServerProtocol::ClientInfo m_clientInfo;
     QJsonValue m_configuration;
+    int m_completionResultsLimit = -1;
 };
 
 Client::Client(BaseClientInterface *clientInterface)
@@ -1578,6 +1579,16 @@ TextEditor::RefactoringChangesData *Client::createRefactoringChangesBackend() co
     return new TextEditor::RefactoringChangesData;
 }
 
+void Client::setCompletionResultsLimit(int limit)
+{
+    d->m_completionResultsLimit = limit;
+}
+
+int Client::completionResultsLimit() const
+{
+    return d->m_completionResultsLimit;
+}
+
 const ServerCapabilities &Client::capabilities() const
 {
     return d->m_serverCapabilities;

src/plugins/languageclient/client.h

@@ -202,6 +202,9 @@ public:
     // Caller takes ownership
     virtual TextEditor::RefactoringChangesData *createRefactoringChangesBackend() const;
 
+    void setCompletionResultsLimit(int limit);
+    int completionResultsLimit() const;
+
 signals:
     void initialized(const LanguageServerProtocol::ServerCapabilities &capabilities);
     void capabilitiesChanged(const DynamicCapabilities &capabilities);

src/plugins/languageclient/languageclientcompletionassist.cpp

@@ -379,6 +379,8 @@ IAssistProposal *LanguageClientCompletionAssistProcessor::perform(const AssistIn
     params.setPosition({line, column});
     params.setContext(context);
     params.setTextDocument(TextDocumentIdentifier(DocumentUri::fromFilePath(interface->filePath())));
+    if (const int limit = m_client->completionResultsLimit(); limit >= 0)
+        params.setLimit(limit);
     CompletionRequest completionRequest(params);
     completionRequest.setResponseCallback([this](auto response) {
         this->handleCompletionResponse(response);