diff --git a/.github/workflows/clang-tidy.yml b/.github/workflows/clang-tidy.yml
index 1536e16ac..484eed2e4 100644
--- a/.github/workflows/clang-tidy.yml
+++ b/.github/workflows/clang-tidy.yml
@@ -21,7 +21,7 @@ jobs:
       - name: Install missing software
         run: |
           apt-get update
-          apt-get install -y cmake g++ make
+          apt-get install -y cmake clang-13 make
           apt-get install -y libpcre3-dev
           apt-get install -y libffi7 # work around missing dependency for Qt install step
           apt-get install -y clang-tidy-13
@@ -47,12 +47,15 @@ jobs:
           cd cmake.output
           cmake -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DWITH_QCHART=On -DCMAKE_GLOBAL_AUTOGEN_TARGET=On -DCPPCHK_GLIBCXX_DEBUG=Off ..
           cd ..
+        env:
+          CC: clang-13
+          CXX: clang++-13
 
       - name: Prepare CMake dependencies
         run: |
           # make sure the precompiled headers exist
-          make -C cmake.output lib/CMakeFiles/lib_objs.dir/cmake_pch.hxx.cxx
-          make -C cmake.output test/CMakeFiles/testrunner.dir/cmake_pch.hxx.cxx
+          make -C cmake.output/lib cmake_pch.hxx.pch
+          make -C cmake.output/test cmake_pch.hxx.pch
           # make sure the auto-generated GUI sources exist
           make -C cmake.output autogen
 
diff --git a/cmake/clang_tidy.cmake b/cmake/clang_tidy.cmake
index ecedff056..d2c16170e 100644
--- a/cmake/clang_tidy.cmake
+++ b/cmake/clang_tidy.cmake
@@ -11,7 +11,7 @@ find_program(RUN_CLANG_TIDY NAMES run-clang-tidy run-clang-tidy-13 run-clang-tid
 message(STATUS "RUN_CLANG_TIDY=${RUN_CLANG_TIDY}")
 if (RUN_CLANG_TIDY)
     # disable all compiler warnings since we are just interested in the tidy ones
-    add_custom_target(run-clang-tidy ${RUN_CLANG_TIDY} -checks=-performance-unnecessary-copy-initialization -p=${CMAKE_BINARY_DIR} -j ${NPROC} -extra-arg=-w -quiet)
+    add_custom_target(run-clang-tidy ${RUN_CLANG_TIDY} -p=${CMAKE_BINARY_DIR} -j ${NPROC} -quiet)
     if (BUILD_GUI)
         add_dependencies(run-clang-tidy gui-build-deps)
         if (BUILD_TESTS)
diff --git a/gui/resultstree.cpp b/gui/resultstree.cpp
index 1f54a795e..caa80bb7d 100644
--- a/gui/resultstree.cpp
+++ b/gui/resultstree.cpp
@@ -74,11 +74,6 @@ static const char TAGS[] = "tags";
 static const int COLUMN_SINCE_DATE = 6;
 static const int COLUMN_TAGS       = 7;
 
-static QString getFunction(QStandardItem *item)
-{
-    return item->data().toMap().value("function").toString();
-}
-
 ResultsTree::ResultsTree(QWidget * parent) :
     QTreeView(parent),
     mSettings(nullptr),
@@ -817,7 +812,8 @@ void ResultsTree::startApplication(QStandardItem *target, int application)
 
         const QString cmdLine = QString("%1 %2").arg(program).arg(params);
 
-        bool success = QProcess::startDetached(cmdLine);
+        // this is reported as deprecated in Qt 5.15.2 but no longer in Qt 6
+        bool success = SUPPRESS_DEPRECATED_WARNING(QProcess::startDetached(cmdLine));
         if (!success) {
             QString text = tr("Could not start %1\n\nPlease check the application path and parameters are correct.").arg(program);
 
diff --git a/gui/test/cppchecklibrarydata/testcppchecklibrarydata.cpp b/gui/test/cppchecklibrarydata/testcppchecklibrarydata.cpp
index 3088b007b..973260870 100644
--- a/gui/test/cppchecklibrarydata/testcppchecklibrarydata.cpp
+++ b/gui/test/cppchecklibrarydata/testcppchecklibrarydata.cpp
@@ -543,11 +543,11 @@ void TestCppcheckLibraryData::markupValid()
     }
 }
 
-void TestCppcheckLibraryData::loadCfgFile(QString filename, CppcheckLibraryData &data, QString &result, bool removeFile)
+void TestCppcheckLibraryData::loadCfgFile(QString filename, CppcheckLibraryData &data, QString &res, bool removeFile)
 {
     QFile file(filename);
     QVERIFY(file.open(QIODevice::ReadOnly | QIODevice::Text));
-    result = data.open(file);
+    res = data.open(file);
     file.close();
     if (removeFile) {
         file.remove();
diff --git a/gui/test/cppchecklibrarydata/testcppchecklibrarydata.h b/gui/test/cppchecklibrarydata/testcppchecklibrarydata.h
index dfaa0c674..64cd1d28c 100644
--- a/gui/test/cppchecklibrarydata/testcppchecklibrarydata.h
+++ b/gui/test/cppchecklibrarydata/testcppchecklibrarydata.h
@@ -41,7 +41,7 @@ private slots:
     void markupValid();
 
 private:
-    void loadCfgFile(QString filename, CppcheckLibraryData &data, QString &result, bool removeFile = false);
+    void loadCfgFile(QString filename, CppcheckLibraryData &data, QString &res, bool removeFile = false);
     void saveCfgFile(QString filename, CppcheckLibraryData &data);
 
     CppcheckLibraryData libraryData;
diff --git a/gui/test/translationhandler/CMakeLists.txt b/gui/test/translationhandler/CMakeLists.txt
index 77b1e4168..7fb6aeefc 100644
--- a/gui/test/translationhandler/CMakeLists.txt
+++ b/gui/test/translationhandler/CMakeLists.txt
@@ -7,7 +7,7 @@ add_executable(test-translationhandler
         ${CMAKE_SOURCE_DIR}/gui/common.cpp
         ${CMAKE_SOURCE_DIR}/gui/translationhandler.cpp
         )
-target_include_directories(test-translationhandler PRIVATE ${CMAKE_SOURCE_DIR}/gui)
+target_include_directories(test-translationhandler PRIVATE ${CMAKE_SOURCE_DIR}/gui ${CMAKE_SOURCE_DIR}/lib)
 target_link_libraries(test-translationhandler ${QT_CORE_LIB} ${QT_WIDGETS_LIB} ${QT_TEST_LIB})
 
 if (CMAKE_CXX_COMPILER_ID MATCHES "Clang")
diff --git a/gui/translationhandler.cpp b/gui/translationhandler.cpp
index 64d6567c4..1da57c28b 100644
--- a/gui/translationhandler.cpp
+++ b/gui/translationhandler.cpp
@@ -18,6 +18,7 @@
 
 #include "translationhandler.h"
 
+#include "config.h"
 #include "common.h"
 
 #include <QApplication>
@@ -29,7 +30,7 @@
 
 
 // Provide own translations for standard buttons. This (garbage) code is needed to enforce them to appear in .ts files even after "lupdate gui.pro"
-static void unused()
+static UNUSED void unused()
 {
     Q_UNUSED(QT_TRANSLATE_NOOP("QPlatformTheme", "OK"))
     Q_UNUSED(QT_TRANSLATE_NOOP("QPlatformTheme", "Cancel"))
diff --git a/lib/astutils.h b/lib/astutils.h
index 184bad415..12ff07190 100644
--- a/lib/astutils.h
+++ b/lib/astutils.h
@@ -315,8 +315,8 @@ bool isAliased(const Variable *var);
 const Token* getArgumentStart(const Token* ftok);
 
 /** Determines the number of arguments - if token is a function call or macro
- * @param start token which is supposed to be the function/macro name.
- * \return Number of arguments
+ * @param ftok start token which is supposed to be the function/macro name.
+ * @return Number of arguments
  */
 int numberOfArguments(const Token* ftok);
 
diff --git a/lib/config.h b/lib/config.h
index 2f3d247cb..dbe3aa908 100644
--- a/lib/config.h
+++ b/lib/config.h
@@ -39,7 +39,7 @@
 
 // C++11 noexcept
 #if (defined(__GNUC__) && (__GNUC__ >= 5)) \
-    || (defined(__clang__) && (defined (__cplusplus)) && (__cplusplus >= 201103L)) \
+    || defined(__clang__) \
     || defined(__CPPCHECK__)
 #  define NOEXCEPT noexcept
 #else
@@ -48,7 +48,7 @@
 
 // C++11 noreturn
 #if (defined(__GNUC__) && (__GNUC__ >= 5)) \
-    || (defined(__clang__) && (defined (__cplusplus)) && (__cplusplus >= 201103L)) \
+    || defined(__clang__) \
     || defined(__CPPCHECK__)
 #  define NORETURN [[noreturn]]
 #else
@@ -64,6 +64,15 @@
 #  define FALLTHROUGH
 #endif
 
+// unused
+#if defined(__GNUC__) \
+    || defined(__clang__) \
+    || defined(__CPPCHECK__)
+#  define UNUSED __attribute__((unused))
+#else
+#  define UNUSED
+#endif
+
 #define REQUIRES(msg, ...) class=typename std::enable_if<__VA_ARGS__::value>::type
 
 #include <string>
@@ -114,6 +123,7 @@ static const std::string emptyString;
 #define SUPPRESS_DEPRECATED_WARNING(...) SUPPRESS_WARNING("-Wdeprecated", __VA_ARGS__)
 #define SUPPRESS_FLOAT_EQUAL_WARNING(...) SUPPRESS_WARNING("-Wfloat-equal", __VA_ARGS__)
 #else
+#define SUPPRESS_WARNING(warning, ...) __VA_ARGS__
 #define SUPPRESS_DEPRECATED_WARNING(...) __VA_ARGS__
 #define SUPPRESS_FLOAT_EQUAL_WARNING(...) __VA_ARGS__
 #endif
diff --git a/lib/importproject.cpp b/lib/importproject.cpp
index 4446f5ebd..179e7e4fc 100644
--- a/lib/importproject.cpp
+++ b/lib/importproject.cpp
@@ -150,6 +150,7 @@ static bool simplifyPathWithVariables(std::string &s, std::map<std::string, std:
 void ImportProject::FileSettings::setIncludePaths(const std::string &basepath, const std::list<std::string> &in, std::map<std::string, std::string, cppcheck::stricmp> &variables)
 {
     std::set<std::string> found;
+    // NOLINTNEXTLINE(performance-unnecessary-copy-initialization)
     const std::list<std::string> copyIn(in);
     includePaths.clear();
     for (const std::string &ipath : copyIn) {
diff --git a/lib/suppressions.h b/lib/suppressions.h
index c381eb75b..360f0f527 100644
--- a/lib/suppressions.h
+++ b/lib/suppressions.h
@@ -210,7 +210,6 @@ public:
 
     /**
      * @brief Marks Inline Suppressions as checked if source line is in the token stream
-     * @return No return.
      */
     void markUnmatchedInlineSuppressionsAsChecked(const Tokenizer &tokenizer);
 
diff --git a/lib/valueflow.cpp b/lib/valueflow.cpp
index 39038e549..1ca38b67d 100644
--- a/lib/valueflow.cpp
+++ b/lib/valueflow.cpp
@@ -131,13 +131,7 @@ static void bailoutInternal(const std::string& type, TokenList *tokenlist, Error
     errorLogger->reportErr(errmsg);
 }
 
-#if (defined __cplusplus) && __cplusplus >= 201103L
 #define bailout2(type, tokenlist, errorLogger, tok, what) bailoutInternal(type, tokenlist, errorLogger, tok, what, __FILE__, __LINE__, __func__)
-#elif (defined __GNUC__) || (defined __clang__) || (defined _MSC_VER)
-#define bailout2(type, tokenlist, errorLogger, tok, what) bailoutInternal(type, tokenlist, errorLogger, tok, what, __FILE__, __LINE__, __FUNCTION__)
-#else
-#define bailout2(type, tokenlist, errorLogger, tok, what) bailoutInternal(type, tokenlist, errorLogger, tok, what, __FILE__, __LINE__, "(valueFlow)")
-#endif
 
 #define bailout(tokenlist, errorLogger, tok, what) bailout2("valueFlowBailout", tokenlist, errorLogger, tok, what)
 
diff --git a/oss-fuzz/main.cpp b/oss-fuzz/main.cpp
index 8567fb5ca..0a07db407 100644
--- a/oss-fuzz/main.cpp
+++ b/oss-fuzz/main.cpp
@@ -30,7 +30,9 @@ public:
                         const std::size_t) override {}
 };
 
-extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t dataSize)
+extern "C" int LLVMFuzzerTestOneInput(const uint8_t *data, size_t dataSize);
+
+int LLVMFuzzerTestOneInput(const uint8_t *data, size_t dataSize)
 {
     if (dataSize < 10000) {
         const std::string code = generateCode2(data, dataSize);