diff --git a/.github/workflows/iwyu.yml b/.github/workflows/iwyu.yml
index 1daa54ce2..abba6f32b 100644
--- a/.github/workflows/iwyu.yml
+++ b/.github/workflows/iwyu.yml
@@ -82,7 +82,7 @@ jobs:
       - name: iwyu_tool
         run: |
           PWD=$(pwd)
-          iwyu_tool -p cmake.output -j $(nproc) -- -w -Xiwyu --mapping_file=$PWD/qt5.imp > iwyu.log
+          iwyu_tool -p cmake.output -j $(nproc) -- -w -Xiwyu --max_line_length=1024 -Xiwyu --comment_style=long -Xiwyu --quoted_includes_first -Xiwyu --update_comments -Xiwyu --mapping_file=$PWD/qt5.imp > iwyu.log
 
       - uses: actions/upload-artifact@v3
         if: success() || failure()
diff --git a/Makefile b/Makefile
index f5844225c..dfe5082d2 100644
--- a/Makefile
+++ b/Makefile
@@ -833,7 +833,7 @@ test/testsizeof.o: test/testsizeof.cpp lib/addoninfo.h lib/check.h lib/checksize
 test/teststl.o: test/teststl.cpp lib/addoninfo.h lib/check.h lib/checkstl.h lib/color.h lib/config.h lib/errorlogger.h lib/errortypes.h lib/importproject.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/standards.h lib/suppressions.h lib/templatesimplifier.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/vfvalue.h test/fixture.h
 	$(CXX) ${INCLUDE_FOR_TEST} $(CPPFLAGS) $(CXXFLAGS) -c -o $@ test/teststl.cpp
 
-test/teststring.o: test/teststring.cpp externals/simplecpp/simplecpp.h lib/addoninfo.h lib/check.h lib/checkstring.h lib/color.h lib/config.h lib/errorlogger.h lib/errortypes.h lib/importproject.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/standards.h lib/suppressions.h lib/templatesimplifier.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/vfvalue.h test/fixture.h test/helpers.h
+test/teststring.o: test/teststring.cpp lib/addoninfo.h lib/check.h lib/checkstring.h lib/color.h lib/config.h lib/errorlogger.h lib/errortypes.h lib/importproject.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/standards.h lib/suppressions.h lib/templatesimplifier.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/vfvalue.h test/fixture.h test/helpers.h
 	$(CXX) ${INCLUDE_FOR_TEST} $(CPPFLAGS) $(CXXFLAGS) -c -o $@ test/teststring.cpp
 
 test/testsummaries.o: test/testsummaries.cpp lib/addoninfo.h lib/check.h lib/color.h lib/config.h lib/errorlogger.h lib/errortypes.h lib/importproject.h lib/library.h lib/mathlib.h lib/platform.h lib/settings.h lib/standards.h lib/summaries.h lib/suppressions.h lib/templatesimplifier.h lib/token.h lib/tokenize.h lib/tokenlist.h lib/utils.h lib/vfvalue.h test/fixture.h
diff --git a/cli/cppcheckexecutorsig.cpp b/cli/cppcheckexecutorsig.cpp
index c5347d8e5..567b6c79c 100644
--- a/cli/cppcheckexecutorsig.cpp
+++ b/cli/cppcheckexecutorsig.cpp
@@ -30,6 +30,7 @@
 #include <cstdio>
 #include <cstdlib>
 #include <cstring>
+//#include <features.h> // __USE_DYNAMIC_STACK_SIZE
 #include <map>
 #include <string>
 #include <unistd.h>
@@ -48,7 +49,7 @@
 #   include <ucontext.h>
 #endif
 
-
+// TODO: __USE_DYNAMIC_STACK_SIZE is depedent on the features.h include and not a built-in compiler define, so it might be problematic to depedent on it
 #ifdef __USE_DYNAMIC_STACK_SIZE
 static const size_t MYSTACKSIZE = 16*1024+32768; // wild guess about a reasonable buffer
 #else
diff --git a/gui/resultstree.cpp b/gui/resultstree.cpp
index b7ac15602..8d54380db 100644
--- a/gui/resultstree.cpp
+++ b/gui/resultstree.cpp
@@ -23,6 +23,7 @@
 #include "common.h"
 #include "config.h"
 #include "erroritem.h"
+#include "errortypes.h"
 #include "path.h"
 #include "projectfile.h"
 #include "report.h"
diff --git a/gui/resultstree.h b/gui/resultstree.h
index 53ba09067..8d8557660 100644
--- a/gui/resultstree.h
+++ b/gui/resultstree.h
@@ -20,7 +20,6 @@
 #ifndef RESULTSTREE_H
 #define RESULTSTREE_H
 
-#include "errortypes.h"
 #include "showtypes.h"
 
 #include <QObject>
@@ -40,6 +39,7 @@ class ThreadHandler;
 class QContextMenuEvent;
 class QKeyEvent;
 class QSettings;
+enum class Severity;
 
 /// @addtogroup GUI
 /// @{
diff --git a/gui/showtypes.cpp b/gui/showtypes.cpp
index d59b70843..4ece3ae6a 100644
--- a/gui/showtypes.cpp
+++ b/gui/showtypes.cpp
@@ -19,6 +19,7 @@
 #include "showtypes.h"
 
 #include "common.h"
+#include "errortypes.h"
 
 #include <QSettings>
 
diff --git a/gui/showtypes.h b/gui/showtypes.h
index 3cff501cf..96dc45aec 100644
--- a/gui/showtypes.h
+++ b/gui/showtypes.h
@@ -19,10 +19,10 @@
 #ifndef SHOWTYPES_H
 #define SHOWTYPES_H
 
-#include "errortypes.h"
-
 #include <QVariant>
 
+enum class Severity;
+
 /// @addtogroup GUI
 /// @{
 
diff --git a/lib/astutils.h b/lib/astutils.h
index 111c2a61d..3677a4ddb 100644
--- a/lib/astutils.h
+++ b/lib/astutils.h
@@ -23,6 +23,7 @@
 //---------------------------------------------------------------------------
 
 #include <functional>
+#include <list>
 #include <stack>
 #include <string>
 #include <type_traits>
diff --git a/lib/checkio.cpp b/lib/checkio.cpp
index 583bbc23e..55a6c414a 100644
--- a/lib/checkio.cpp
+++ b/lib/checkio.cpp
@@ -19,6 +19,7 @@
 //---------------------------------------------------------------------------
 #include "checkio.h"
 
+#include "errortypes.h"
 #include "library.h"
 #include "mathlib.h"
 #include "platform.h"
diff --git a/lib/checkio.h b/lib/checkio.h
index 3e9d15bb9..1293bc0de 100644
--- a/lib/checkio.h
+++ b/lib/checkio.h
@@ -23,7 +23,6 @@
 
 #include "check.h"
 #include "config.h"
-#include "errortypes.h"
 #include "tokenize.h"
 
 #include <ostream>
@@ -34,6 +33,7 @@ class Settings;
 class Token;
 class Variable;
 class ErrorLogger;
+enum class Severity;
 
 /// @addtogroup Checks
 /// @{
diff --git a/lib/checkmemoryleak.cpp b/lib/checkmemoryleak.cpp
index 57aacdd2f..2459adb0b 100644
--- a/lib/checkmemoryleak.cpp
+++ b/lib/checkmemoryleak.cpp
@@ -21,6 +21,7 @@
 
 #include "astutils.h"
 #include "errorlogger.h"
+#include "errortypes.h"
 #include "library.h"
 #include "mathlib.h"
 #include "platform.h"
diff --git a/lib/checkmemoryleak.h b/lib/checkmemoryleak.h
index ef8e0564c..20309873c 100644
--- a/lib/checkmemoryleak.h
+++ b/lib/checkmemoryleak.h
@@ -34,7 +34,6 @@
 
 #include "check.h"
 #include "config.h"
-#include "errortypes.h"
 #include "tokenize.h"
 
 #include <list>
@@ -46,6 +45,8 @@ class Settings;
 class Token;
 class Variable;
 class ErrorLogger;
+struct CWE;
+enum class Severity;
 
 /// @addtogroup Core
 /// @{
diff --git a/lib/checkstl.cpp b/lib/checkstl.cpp
index e07ffbe86..093cf69d5 100644
--- a/lib/checkstl.cpp
+++ b/lib/checkstl.cpp
@@ -41,7 +41,6 @@
 #include <set>
 #include <sstream>
 #include <tuple>
-#include <type_traits>
 #include <unordered_map>
 #include <utility>
 #include <vector>
diff --git a/lib/config.h b/lib/config.h
index d6ef3c37d..3f98796be 100644
--- a/lib/config.h
+++ b/lib/config.h
@@ -159,6 +159,7 @@ static const std::string emptyString;
 #define USE_WINDOWS_SEH
 #endif
 
+// TODO: __GLIBC__ is depedent on the features.h include and not a built-in compiler define, so it might be problematic to depedent on it
 #if !defined(NO_UNIX_BACKTRACE_SUPPORT) && defined(__GNUC__) && defined(__GLIBC__) && !defined(__CYGWIN__) && !defined(__MINGW32__) && !defined(__NetBSD__) && !defined(__SVR4) && !defined(__QNX__)
 #define USE_UNIX_BACKTRACE_SUPPORT
 #endif
diff --git a/lib/keywords.cpp b/lib/keywords.cpp
index 192b5faac..ab4ab9230 100644
--- a/lib/keywords.cpp
+++ b/lib/keywords.cpp
@@ -20,8 +20,6 @@
 
 #include "utils.h"
 
-#include <cassert>
-
 // see https://en.cppreference.com/w/c/keyword
 
 #define C90_KEYWORDS \
diff --git a/lib/library.cpp b/lib/library.cpp
index 1bd06904d..bcf7dab7d 100644
--- a/lib/library.cpp
+++ b/lib/library.cpp
@@ -19,6 +19,7 @@
 #include "library.h"
 
 #include "astutils.h"
+#include "errortypes.h"
 #include "mathlib.h"
 #include "path.h"
 #include "symboldatabase.h"
@@ -31,7 +32,6 @@
 #include <algorithm>
 #include <cctype>
 #include <climits>
-#include <cstddef>
 #include <cstring>
 #include <list>
 #include <memory>
diff --git a/lib/library.h b/lib/library.h
index e45683a56..e27ca3842 100644
--- a/lib/library.h
+++ b/lib/library.h
@@ -23,7 +23,6 @@
 
 #include "config.h"
 #include "mathlib.h"
-#include "errortypes.h"
 #include "standards.h"
 
 #include <map>
@@ -37,6 +36,7 @@
 
 class Token;
 class Settings;
+enum class Severity;
 
 namespace tinyxml2 {
     class XMLDocument;
diff --git a/lib/pathanalysis.cpp b/lib/pathanalysis.cpp
index 0404dba58..b15bffb95 100644
--- a/lib/pathanalysis.cpp
+++ b/lib/pathanalysis.cpp
@@ -26,7 +26,6 @@
 #include <algorithm>
 #include <string>
 #include <tuple>
-#include <type_traits>
 
 const Scope* PathAnalysis::findOuterScope(const Scope * scope)
 {
diff --git a/lib/symboldatabase.cpp b/lib/symboldatabase.cpp
index 6dbedeafc..665baf4ca 100644
--- a/lib/symboldatabase.cpp
+++ b/lib/symboldatabase.cpp
@@ -48,7 +48,6 @@
 #include <stack>
 #include <string>
 #include <tuple>
-#include <type_traits>
 #include <unordered_map>
 #include <unordered_set>
 //---------------------------------------------------------------------------
diff --git a/lib/symboldatabase.h b/lib/symboldatabase.h
index 8afe804e8..a235527df 100644
--- a/lib/symboldatabase.h
+++ b/lib/symboldatabase.h
@@ -36,7 +36,6 @@
 #include <map>
 #include <set>
 #include <string>
-#include <type_traits>
 #include <utility>
 #include <vector>
 
diff --git a/lib/tokenize.cpp b/lib/tokenize.cpp
index 329bdd3bf..1aac2d76b 100644
--- a/lib/tokenize.cpp
+++ b/lib/tokenize.cpp
@@ -21,6 +21,7 @@
 
 #include "check.h"
 #include "errorlogger.h"
+#include "errortypes.h"
 #include "library.h"
 #include "mathlib.h"
 #include "platform.h"
@@ -50,7 +51,6 @@
 #include <sstream> // IWYU pragma: keep
 #include <stack>
 #include <stdexcept>
-#include <type_traits>
 #include <unordered_map>
 #include <unordered_set>
 #include <utility>
diff --git a/lib/tokenize.h b/lib/tokenize.h
index 07b526ca0..17ae2f5d3 100644
--- a/lib/tokenize.h
+++ b/lib/tokenize.h
@@ -22,7 +22,6 @@
 //---------------------------------------------------------------------------
 
 #include "config.h"
-#include "errortypes.h"
 #include "tokenlist.h"
 
 #include <cassert>
@@ -40,6 +39,7 @@ class TemplateSimplifier;
 class ErrorLogger;
 class Preprocessor;
 class VariableMap;
+enum class Severity;
 
 namespace simplecpp {
     class TokenList;
diff --git a/lib/utils.h b/lib/utils.h
index 73aec4aa1..d5721574a 100644
--- a/lib/utils.h
+++ b/lib/utils.h
@@ -31,6 +31,7 @@
 #include <limits>
 #include <stdexcept>
 #include <string>
+#include <type_traits>
 #include <vector>
 
 struct SelectMapKeys {
diff --git a/test/fixture.h b/test/fixture.h
index 07710b49a..49e765513 100644
--- a/test/fixture.h
+++ b/test/fixture.h
@@ -24,7 +24,6 @@
 #include "color.h"
 #include "config.h"
 #include "errorlogger.h"
-#include "errortypes.h"
 #include "library.h"
 #include "platform.h"
 #include "settings.h"
@@ -39,6 +38,8 @@
 
 class options;
 class Tokenizer;
+enum class Certainty;
+enum class Severity;
 
 class TestFixture : public ErrorLogger {
 private:
diff --git a/test/testcmdlineparser.cpp b/test/testcmdlineparser.cpp
index 3bc957d7c..ed7ef85d0 100644
--- a/test/testcmdlineparser.cpp
+++ b/test/testcmdlineparser.cpp
@@ -16,11 +16,13 @@
  * along with this program.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+#include "cmdlinelogger.h"
 #include "cmdlineparser.h"
 #include "config.h"
 #include "cppcheckexecutor.h"
 #include "errortypes.h"
 #include "helpers.h"
+#include "importproject.h"
 #include "platform.h"
 #include "redirect.h"
 #include "settings.h"
@@ -33,8 +35,11 @@
 #include <cstdint>
 #include <cstdio>
 #include <list>
+#include <memory>
 #include <set>
+#include <stdexcept>
 #include <string>
+#include <unordered_set>
 #include <vector>
 
 class TestCmdlineParser : public TestFixture {
diff --git a/test/testprocessexecutor.cpp b/test/testprocessexecutor.cpp
index 94fe7ee8d..0bcfb447e 100644
--- a/test/testprocessexecutor.cpp
+++ b/test/testprocessexecutor.cpp
@@ -26,7 +26,6 @@
 #include "library.h"
 
 #include <algorithm>
-#include <cstddef>
 #include <cstdlib>
 #include <list>
 #include <map>
diff --git a/test/testsingleexecutor.cpp b/test/testsingleexecutor.cpp
index a5f6a519e..054e8a547 100644
--- a/test/testsingleexecutor.cpp
+++ b/test/testsingleexecutor.cpp
@@ -27,7 +27,6 @@
 #include "timer.h"
 
 #include <algorithm>
-#include <cstddef>
 #include <cstdlib>
 #include <list>
 #include <map>
diff --git a/test/teststring.cpp b/test/teststring.cpp
index 57cea1b97..8d443e215 100644
--- a/test/teststring.cpp
+++ b/test/teststring.cpp
@@ -28,8 +28,6 @@
 #include <string>
 #include <vector>
 
-#include <simplecpp.h>
-
 class TestString : public TestFixture {
 public:
     TestString() : TestFixture("TestString") {}
diff --git a/test/testthreadexecutor.cpp b/test/testthreadexecutor.cpp
index 49d2160b3..c37223b26 100644
--- a/test/testthreadexecutor.cpp
+++ b/test/testthreadexecutor.cpp
@@ -26,7 +26,6 @@
 #include "timer.h"
 
 #include <algorithm>
-#include <cstddef>
 #include <cstdlib>
 #include <list>
 #include <map>