ClangCodeModel: Suppress "Unknown argument" error

Unknown compiler flags are an unsuppressable error in clang.
But we do not want to maintain a blacklist of unsupported GCC and MSVC
options or a whitelist of supported clang options, as both would
constantly go out of date.
As clangd seems to work fine despite the error message, we simply filter
out this type of diagnostic.

Fixes: QTCREATORBUG-27113
Change-Id: Ib32601831eded60daf80eb0ca5cf01bbd71493fa
Reviewed-by: <github-actions-qt-creator@cristianadam.eu>
Reviewed-by: David Schulz <david.schulz@qt.io>

src/plugins/clangcodemodel/clangdclient.cpp

@@ -1321,7 +1321,12 @@ ClangdClient::ClangdClient(Project *project, const Utils::FilePath &jsonDbDir)
         return new ClangdTextMark(filePath, diag, isProjectFile, this);
     };
     const auto hideDiagsHandler = []{ ClangDiagnosticManager::clearTaskHubIssues(); };
-    setDiagnosticsHandlers(textMarkCreator, hideDiagsHandler);
+    static const auto diagsFilter = [](const Diagnostic &diag) {
+        const Diagnostic::Code code = diag.code().value_or(Diagnostic::Code());
+        const QString * const codeString = Utils::get_if<QString>(&code);
+        return !codeString || *codeString != "drv_unknown_argument";
+    };
+    setDiagnosticsHandlers(textMarkCreator, hideDiagsHandler, diagsFilter);
     setSymbolStringifier(displayNameFromDocumentSymbol);
     setSemanticTokensHandler([this](TextDocument *doc, const QList<ExpandedSemanticToken> &tokens,
                                     int version, bool force) {

src/plugins/clangcodemodel/test/data/completion/completion.pro

@@ -27,5 +27,7 @@ SOURCES = \
     privateFuncDefCompletion.cpp \
     signalCompletion.cpp
 
+QMAKE_CXXFLAGS += -ffoo
+
 HEADERS = mainwindow.h
 FORMS = mainwindow.ui

src/plugins/clangcodemodel/test/data/find-usages/find-usages.pro

@@ -2,3 +2,4 @@ TEMPLATE = app
 QT = core
 HEADERS = defs.h
 SOURCES = main.cpp
+QMAKE_CXXFLAGS += -ffoo

src/plugins/clangcodemodel/test/data/follow-symbol/follow-symbol.pro

@@ -2,3 +2,4 @@ TEMPLATE = app
 CONFIG -= qt
 HEADERS = cursor.h header.h
 SOURCES = cursor.cpp main.cpp
+QMAKE_CXXFLAGS += -ffoo

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

@@ -1,3 +1,4 @@
 TEMPLATE = app
 CONFIG -= qt
 SOURCES = highlighting.cpp
+QMAKE_CXXFLAGS += -ffoo

src/plugins/clangcodemodel/test/data/local-references/local-references.pro

@@ -1,5 +1,4 @@
 TEMPLATE = app
-
 CONFIG -= qt
-
 SOURCES = references.cpp
+QMAKE_CXXFLAGS += -ffoo

src/plugins/languageclient/client.cpp

@@ -1054,9 +1054,10 @@ bool Client::hasDiagnostic(const LanguageServerProtocol::DocumentUri &uri,
 }
 
 void Client::setDiagnosticsHandlers(const TextMarkCreator &textMarkCreator,
-                                    const HideDiagnosticsHandler &hideHandler)
+                                    const HideDiagnosticsHandler &hideHandler,
+                                    const DiagnosticsFilter &filter)
 {
-    m_diagnosticManager.setDiagnosticsHandlers(textMarkCreator, hideHandler);
+    m_diagnosticManager.setDiagnosticsHandlers(textMarkCreator, hideHandler, filter);
 }
 
 void Client::setSemanticTokensHandler(const SemanticTokensHandler &handler)

src/plugins/languageclient/client.h

@@ -186,7 +186,7 @@ public:
     bool hasDiagnostic(const LanguageServerProtocol::DocumentUri &uri,
                        const LanguageServerProtocol::Diagnostic &diag) const;
     void setDiagnosticsHandlers(const TextMarkCreator &textMarkCreator,
-                                const HideDiagnosticsHandler &hideHandler);
+                                const HideDiagnosticsHandler &hideHandler, const DiagnosticsFilter &filter);
     void setSemanticTokensHandler(const SemanticTokensHandler &handler);
     void setSymbolStringifier(const LanguageServerProtocol::SymbolStringifier &stringifier);
     LanguageServerProtocol::SymbolStringifier symbolStringifier() const;

src/plugins/languageclient/diagnosticmanager.cpp

@@ -90,7 +90,9 @@ void DiagnosticManager::setDiagnostics(const LanguageServerProtocol::DocumentUri
                                        const Utils::optional<int> &version)
 {
     hideDiagnostics(uri.toFilePath());
-    m_diagnostics[uri] = {version, diagnostics};
+    const QList<Diagnostic> filteredDiags = m_filter
+            ? Utils::filtered(diagnostics, m_filter) : diagnostics;
+    m_diagnostics[uri] = {version, filteredDiags};
 }
 
 void DiagnosticManager::hideDiagnostics(const Utils::FilePath &filePath)
@@ -201,10 +203,12 @@ bool DiagnosticManager::hasDiagnostic(const LanguageServerProtocol::DocumentUri
 }
 
 void DiagnosticManager::setDiagnosticsHandlers(const TextMarkCreator &textMarkCreator,
-                                               const HideDiagnosticsHandler &removalHandler)
+                                               const HideDiagnosticsHandler &removalHandler,
+                                               const DiagnosticsFilter &filter)
 {
     m_textMarkCreator = textMarkCreator;
     m_hideHandler = removalHandler;
+    m_filter = filter;
 }
 
 } // namespace LanguageClient

src/plugins/languageclient/diagnosticmanager.h

@@ -45,6 +45,7 @@ class Client;
 using TextMarkCreator = std::function<TextEditor::TextMark *(const Utils::FilePath &,
         const LanguageServerProtocol::Diagnostic &, bool)>;
 using HideDiagnosticsHandler = std::function<void()>;
+using DiagnosticsFilter = std::function<bool(const LanguageServerProtocol::Diagnostic &)>;
 
 class DiagnosticManager
 {
@@ -70,7 +71,8 @@ public:
                        const LanguageServerProtocol::Diagnostic &diag) const;
 
     void setDiagnosticsHandlers(const TextMarkCreator &shownHandler,
-                                const HideDiagnosticsHandler &removalHandler);
+                                const HideDiagnosticsHandler &removalHandler,
+                                const DiagnosticsFilter &filter);
 
 private:
     TextEditor::TextMark *createTextMark(const Utils::FilePath &filePath,
@@ -83,6 +85,7 @@ private:
     QMap<Utils::FilePath, QList<TextEditor::TextMark *>> m_marks;
     TextMarkCreator m_textMarkCreator;
     HideDiagnosticsHandler m_hideHandler;
+    DiagnosticsFilter m_filter;
     Client *m_client;
 };