diff --git a/.clang-tidy b/.clang-tidy
index 7617f792e..7088c1b7a 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -44,7 +44,9 @@ Checks: >
         -modernize-raw-string-literal,
         -modernize-replace-auto-ptr,
         -modernize-return-braced-init-list,
+        -modernize-type-traits,
         -modernize-use-auto,
+        -modernize-use-nodiscard,
         -modernize-use-trailing-return-type,
         -performance-avoid-endl,
         -performance-inefficient-string-concatenation,
diff --git a/.github/workflows/CI-unixish-docker.yml b/.github/workflows/CI-unixish-docker.yml
index c8095c54a..d6489f191 100644
--- a/.github/workflows/CI-unixish-docker.yml
+++ b/.github/workflows/CI-unixish-docker.yml
@@ -20,6 +20,10 @@ jobs:
     strategy:
       matrix:
         image: ["centos:7", "ubuntu:14.04", "ubuntu:16.04", "ubuntu:18.04", "ubuntu:23.04"]
+        include:
+          - build_gui: false
+          - image: "ubuntu:23.04"
+            build_gui: true
       fail-fast: false # Prefer quick result
 
     runs-on: ubuntu-22.04
@@ -48,11 +52,10 @@ jobs:
           apt-get update
           apt-get install -y cmake g++ make libxml2-utils libpcre3-dev
 
-      # required so a default Qt installation is configured
-      - name: Install missing software on ubuntu 18.04
-        if: false # matrix.os == 'ubuntu-18.04'
+      - name: Install missing software on ubuntu 23.04
+        if: matrix.build_gui
         run: |
-          sudo apt-get install qt5-default
+          apt-get install -y qt6-base-dev qt6-charts-dev qt6-tools-dev
 
       # needs to be called after the package installation since
       # - it doesn't call "apt-get update"
@@ -82,13 +85,19 @@ jobs:
           cmake --build . -- -j$(nproc)
 
       - name: CMake build
-        if: matrix.image != 'centos:7' && matrix.image != 'ubuntu:14.04' && matrix.image != 'ubuntu:16.04'
+        if: ${{ !matrix.build_gui && matrix.image != 'centos:7' && matrix.image != 'ubuntu:14.04' && matrix.image != 'ubuntu:16.04' }}
         run: |
           mkdir cmake.output
           cd cmake.output
           cmake -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DCMAKE_DISABLE_PRECOMPILE_HEADERS=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache ..
           cmake --build . -- -j$(nproc)
 
+      - name: CMake build (with GUI)
+        if: matrix.build_gui
+        run: |
+          cmake -S . -B cmake.output -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DUSE_QT6=On -DWITH_QCHART=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
+          cmake --build cmake.output -- -j$(nproc)
+
       - name: Run CMake test
         if: matrix.image != 'centos:7' && matrix.image != 'ubuntu:14.04' && matrix.image != 'ubuntu:16.04'
         run: |
diff --git a/.github/workflows/CI-unixish.yml b/.github/workflows/CI-unixish.yml
index c5f29ff73..d21e71d23 100644
--- a/.github/workflows/CI-unixish.yml
+++ b/.github/workflows/CI-unixish.yml
@@ -20,6 +20,10 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-20.04, ubuntu-22.04, macos-11, macos-12]
+        include:
+          - use_qt6: On
+          - os: ubuntu-20.04
+            use_qt6: Off
       fail-fast: false # Prefer quick result
 
     runs-on: ${{ matrix.os }}
@@ -37,28 +41,36 @@ jobs:
           key: ${{ github.workflow }}-${{ github.job }}-${{ matrix.os }}
 
       - name: Install missing software on ubuntu
-        if: contains(matrix.os, 'ubuntu')
+        if: contains(matrix.os, 'ubuntu') && matrix.use_qt6 == 'Off'
         run: |
           sudo apt-get update
           sudo apt-get install libxml2-utils libtinyxml2-dev qtbase5-dev qttools5-dev libqt5charts5-dev qtchooser
 
+      - name: Install missing software on ubuntu
+        if: contains(matrix.os, 'ubuntu') && matrix.use_qt6 == 'On'
+        run: |
+          sudo apt-get update
+          # qt6-tools-dev-tools for lprodump
+          # qt6-l10n-tools for lupdate
+          sudo apt-get install libxml2-utils libtinyxml2-dev qt6-base-dev libqt6charts6-dev qt6-tools-dev qt6-tools-dev-tools qt6-l10n-tools libglx-dev libgl1-mesa-dev
+
       # coreutils contains "nproc"
       - name: Install missing software on macos
         if: contains(matrix.os, 'macos')
         run: |
           # pcre was removed from runner images in November 2022
-          brew install coreutils qt@5 tinyxml2 pcre
+          brew install coreutils qt@6 tinyxml2 pcre
 
       - name: CMake build on ubuntu (with GUI / system tinyxml2)
         if: contains(matrix.os, 'ubuntu')
         run: |
-          cmake -S . -B cmake.output.tinyxml2 -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DWITH_QCHART=On -DUSE_BUNDLED_TINYXML2=Off -DCMAKE_DISABLE_PRECOMPILE_HEADERS=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
+          cmake -S . -B cmake.output.tinyxml2 -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DUSE_QT6=${{ matrix.use_qt6 }} -DWITH_QCHART=On -DUSE_BUNDLED_TINYXML2=Off -DCMAKE_DISABLE_PRECOMPILE_HEADERS=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
           cmake --build cmake.output.tinyxml2 -- -j$(nproc)
 
       - name: CMake build on macos (with GUI / system tinyxml2)
         if: contains(matrix.os, 'macos')
         run: |
-          cmake -S . -B cmake.output.tinyxml2 -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DWITH_QCHART=On -DUSE_BUNDLED_TINYXML2=Off -DCMAKE_DISABLE_PRECOMPILE_HEADERS=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -DQt5_DIR=$(brew --prefix qt@5)/lib/cmake/Qt5
+          cmake -S . -B cmake.output.tinyxml2 -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DUSE_QT6=On -DWITH_QCHART=On -DUSE_BUNDLED_TINYXML2=Off -DCMAKE_DISABLE_PRECOMPILE_HEADERS=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -DQt6_DIR=$(brew --prefix qt@6)/lib/cmake/Qt6
           cmake --build cmake.output.tinyxml2 -- -j$(nproc)
 
       - name: Run CMake test (system tinyxml2)
@@ -70,6 +82,10 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-20.04, ubuntu-22.04, macos-11, macos-12]
+        include:
+          - use_qt6: On
+          - os: ubuntu-20.04
+            use_qt6: Off
       fail-fast: false # Prefer quick result
 
     runs-on: ${{ matrix.os }}
@@ -87,7 +103,7 @@ jobs:
           key: ${{ github.workflow }}-${{ github.job }}-${{ matrix.os }}
 
       - name: Install missing software on ubuntu
-        if: contains(matrix.os, 'ubuntu')
+        if: contains(matrix.os, 'ubuntu') && matrix.use_qt6 == 'Off'
         run: |
           sudo apt-get update
           sudo apt-get install libxml2-utils qtbase5-dev qttools5-dev libqt5charts5-dev qtchooser
@@ -106,23 +122,31 @@ jobs:
         run: |
           echo "CXX=g++-13" >> $GITHUB_ENV
 
+      - name: Install missing software on ubuntu
+        if: contains(matrix.os, 'ubuntu') && matrix.use_qt6 == 'On'
+        run: |
+          sudo apt-get update
+          # qt6-tools-dev-tools for lprodump
+          # qt6-l10n-tools for lupdate
+          sudo apt-get install libxml2-utils qt6-base-dev libqt6charts6-dev qt6-tools-dev qt6-tools-dev-tools qt6-l10n-tools libglx-dev libgl1-mesa-dev
+
       # coreutils contains "nproc"
       - name: Install missing software on macos
         if: contains(matrix.os, 'macos')
         run: |
           # pcre was removed from runner images in November 2022
-          brew install coreutils qt@5 pcre
+          brew install coreutils qt@6 pcre
 
       - name: CMake build on ubuntu (with GUI)
         if: contains(matrix.os, 'ubuntu')
         run: |
-          cmake -S . -B cmake.output -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DWITH_QCHART=On -DCMAKE_DISABLE_PRECOMPILE_HEADERS=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
+          cmake -S . -B cmake.output -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DUSE_QT6=${{ matrix.use_qt6 }} -DWITH_QCHART=On -DCMAKE_DISABLE_PRECOMPILE_HEADERS=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache
           cmake --build cmake.output -- -j$(nproc)
 
       - name: CMake build on macos (with GUI)
         if: contains(matrix.os, 'macos')
         run: |
-          cmake -S . -B cmake.output -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DWITH_QCHART=On -DCMAKE_DISABLE_PRECOMPILE_HEADERS=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -DQt5_DIR=$(brew --prefix qt@5)/lib/cmake/Qt5
+          cmake -S . -B cmake.output -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DUSE_QT6=On -DWITH_QCHART=On -DCMAKE_DISABLE_PRECOMPILE_HEADERS=On -DCMAKE_C_COMPILER_LAUNCHER=ccache -DCMAKE_CXX_COMPILER_LAUNCHER=ccache -DQt6_DIR=$(brew --prefix qt@6)/lib/cmake/Qt6
           cmake --build cmake.output -- -j$(nproc)
 
       - name: Run CMake test
@@ -452,6 +476,7 @@ jobs:
           # compile with verification and ast matchers
           make -j$(nproc) -s CPPFLAGS="-DCHECK_INTERNAL" CXXFLAGS="-g -O2 -w -DHAVE_BOOST" MATCHCOMPILER=yes VERIFY=1
 
+      # TODO: update to Qt6
       - name: Generate UI files
         run: |
           pushd gui
diff --git a/.github/workflows/CI-windows.yml b/.github/workflows/CI-windows.yml
index be203c093..56bf24998 100644
--- a/.github/workflows/CI-windows.yml
+++ b/.github/workflows/CI-windows.yml
@@ -28,7 +28,7 @@ jobs:
     strategy:
       matrix:
         os: [windows-2019, windows-2022]
-        qt_ver: [5.15.2, 6.2.4, 6.5.0]
+        qt_ver: [5.15.2, 6.2.4, 6.5.3]
       fail-fast: false
 
     runs-on: ${{ matrix.os }}
@@ -67,7 +67,7 @@ jobs:
       - name: Build GUI release (CMake)
         if: startsWith(matrix.qt_ver, '6')
         run: |
-          cmake -S . -B build -DBUILD_GUI=On -DWITH_QCHART=On -DUSE_QT6=On || exit /b !errorlevel!
+          cmake -S . -B build -DBUILD_GUI=On -DUSE_QT6=On -DWITH_QCHART=On || exit /b !errorlevel!
           cmake --build build --target cppcheck-gui || exit /b !errorlevel!
 
       # TODO: deploy with CMake/Qt6
diff --git a/.github/workflows/asan.yml b/.github/workflows/asan.yml
index 13c838c33..d0a1c29c3 100644
--- a/.github/workflows/asan.yml
+++ b/.github/workflows/asan.yml
@@ -95,7 +95,7 @@ jobs:
           ec=0
           ./cmake.output/bin/cppcheck $selfcheck_options externals/simplecpp || ec=1
           ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options --addon=naming.json cli lib || ec=1
-          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQT_VERSION=0x050000 -DQ_MOC_OUTPUT_REVISION=67 -DQT_CHARTS_LIB --library=qt --addon=naming.json -Icmake.output/gui -Igui gui/*.cpp cmake.output/gui/*.cpp || ec=1
+          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQT_VERSION=0x060000 -DQ_MOC_OUTPUT_REVISION=68 -DQT_CHARTS_LIB --library=qt --addon=naming.json -Icmake.output/gui -Igui gui/*.cpp cmake.output/gui/*.cpp || ec=1
           ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -Icli test/*.cpp tools/*.cpp || ec=1
-          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQ_MOC_OUTPUT_REVISION=67 -DQT_CHARTS_LIB --library=qt -Icmake.output/tools/triage -Igui tools/triage/*.cpp cmake.output/tools/triage/*.cpp || ec=1
+          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQ_MOC_OUTPUT_REVISION=68 -DQT_CHARTS_LIB --library=qt -Icmake.output/tools/triage -Igui tools/triage/*.cpp cmake.output/tools/triage/*.cpp || ec=1
           exit $ec
diff --git a/.github/workflows/clang-tidy.yml b/.github/workflows/clang-tidy.yml
index 3eda19549..5d50459a0 100644
--- a/.github/workflows/clang-tidy.yml
+++ b/.github/workflows/clang-tidy.yml
@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-22.04
 
     env:
-      QT_VERSION: 5.15.2
+      QT_VERSION: 6.5.3
 
     steps:
       - uses: actions/checkout@v3
@@ -53,7 +53,7 @@ jobs:
 
       - name: Prepare CMake
         run: |
-          cmake -S . -B cmake.output -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DWITH_QCHART=On -DENABLE_CHECK_INTERNAL=On -DCMAKE_GLOBAL_AUTOGEN_TARGET=On -DCPPCHK_GLIBCXX_DEBUG=Off
+          cmake -S . -B cmake.output -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DUSE_QT6=On -DWITH_QCHART=On -DENABLE_CHECK_INTERNAL=On -DCMAKE_GLOBAL_AUTOGEN_TARGET=On -DCPPCHK_GLIBCXX_DEBUG=Off
         env:
           CC: clang-17
           CXX: clang++-17
diff --git a/.github/workflows/iwyu.yml b/.github/workflows/iwyu.yml
index abba6f32b..6dfd0b707 100644
--- a/.github/workflows/iwyu.yml
+++ b/.github/workflows/iwyu.yml
@@ -57,6 +57,7 @@ jobs:
           ln -s iwyu_tool.py /usr/bin/iwyu_tool
           ln -s qt5 /usr/include/qt
 
+      # TODO: switch to Qt 6 after we enabled the Qt mappings again
       - name: Prepare CMake
         run: |
           cmake -S . -B cmake.output -G "Unix Makefiles" -DCMAKE_BUILD_TYPE=Release -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=On -DWITH_QCHART=On -DENABLE_CHECK_INTERNAL=On -DCMAKE_GLOBAL_AUTOGEN_TARGET=On -DCMAKE_DISABLE_PRECOMPILE_HEADERS=On -DCPPCHK_GLIBCXX_DEBUG=Off -DUSE_MATCHCOMPILER=Off
diff --git a/.github/workflows/selfcheck.yml b/.github/workflows/selfcheck.yml
index 70cc147c4..efaceb367 100644
--- a/.github/workflows/selfcheck.yml
+++ b/.github/workflows/selfcheck.yml
@@ -20,7 +20,7 @@ jobs:
     runs-on: ubuntu-22.04
 
     env:
-      QT_VERSION: 5.15.2
+      QT_VERSION: 6.5.3
 
     steps:
       - uses: actions/checkout@v3
@@ -60,7 +60,7 @@ jobs:
 
       - name: CMake
         run: |
-          cmake -S . -B cmake.output -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=ON -DWITH_QCHART=ON -DENABLE_CHECK_INTERNAL=On -DCMAKE_GLOBAL_AUTOGEN_TARGET=On
+          cmake -S . -B cmake.output -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=On -DBUILD_GUI=ON -DUSE_QT6=On -DWITH_QCHART=ON -DENABLE_CHECK_INTERNAL=On -DCMAKE_GLOBAL_AUTOGEN_TARGET=On
 
       - name: Generate dependencies
         run: |
@@ -75,7 +75,7 @@ jobs:
       - name: Self check (unusedFunction)
         if: false # TODO: fails with preprocessorErrorDirective - see #10667
         run: |
-          ./cppcheck -q --template=selfcheck --error-exitcode=1 --library=cppcheck-lib --library=qt -D__CPPCHECK__ -D__GNUC__ -DQT_VERSION=0x050000 -DQ_MOC_OUTPUT_REVISION=67 -DQT_CHARTS_LIB --enable=unusedFunction --exception-handling -rp=. --project=cmake.output/compile_commands.json --suppressions-list=.selfcheck_unused_suppressions --inline-suppr
+          ./cppcheck -q --template=selfcheck --error-exitcode=1 --library=cppcheck-lib --library=qt -D__CPPCHECK__ -D__GNUC__ -DQT_VERSION=0x060000 -DQ_MOC_OUTPUT_REVISION=68 -DQT_CHARTS_LIB --enable=unusedFunction --exception-handling -rp=. --project=cmake.output/compile_commands.json --suppressions-list=.selfcheck_unused_suppressions --inline-suppr
         env:
           DISABLE_VALUEFLOW: 1
           UNUSEDFUNCTION_ONLY: 1
@@ -83,7 +83,7 @@ jobs:
       # the following steps are duplicated from above since setting up the build node in a parallel step takes longer than the actual steps
       - name: CMake (no test)
         run: |
-          cmake -S . -B cmake.output.notest -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=Off -DBUILD_GUI=ON -DWITH_QCHART=ON -DENABLE_CHECK_INTERNAL=On -DCMAKE_GLOBAL_AUTOGEN_TARGET=On
+          cmake -S . -B cmake.output.notest -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=Off -DBUILD_GUI=ON -DUSE_QT6=On -DWITH_QCHART=ON -DENABLE_CHECK_INTERNAL=On -DCMAKE_GLOBAL_AUTOGEN_TARGET=On
 
       - name: Generate dependencies (no test)
         run: |
@@ -96,7 +96,7 @@ jobs:
       # TODO: find a way to report unmatched suppressions without need to add information checks
       - name: Self check (unusedFunction / no test)
         run: |
-          ./cppcheck -q --template=selfcheck --error-exitcode=1 --library=cppcheck-lib --library=qt -D__CPPCHECK__ -D__GNUC__ -DQT_VERSION=0x050000 -DQ_MOC_OUTPUT_REVISION=67 -DQT_CHARTS_LIB --enable=unusedFunction --exception-handling -rp=. --project=cmake.output.notest/compile_commands.json --suppressions-list=.selfcheck_unused_suppressions --inline-suppr
+          ./cppcheck -q --template=selfcheck --error-exitcode=1 --library=cppcheck-lib --library=qt -D__CPPCHECK__ -D__GNUC__ -DQT_VERSION=0x060000 -DQ_MOC_OUTPUT_REVISION=68 -DQT_CHARTS_LIB --enable=unusedFunction --exception-handling -rp=. --project=cmake.output.notest/compile_commands.json --suppressions-list=.selfcheck_unused_suppressions --inline-suppr
         env:
           DISABLE_VALUEFLOW: 1
           UNUSEDFUNCTION_ONLY: 1
@@ -108,7 +108,7 @@ jobs:
 
       - name: CMake (corpus / no test)
         run: |
-          cmake -S cppcheck-2.8 -B cmake.output.corpus -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=Off -DBUILD_GUI=ON -DWITH_QCHART=ON -DENABLE_CHECK_INTERNAL=On -DCMAKE_GLOBAL_AUTOGEN_TARGET=On
+          cmake -S cppcheck-2.8 -B cmake.output.corpus -G "Unix Makefiles" -DHAVE_RULES=On -DBUILD_TESTS=Off -DBUILD_GUI=ON -DUSE_QT6=On -DWITH_QCHART=ON -DENABLE_CHECK_INTERNAL=On -DCMAKE_GLOBAL_AUTOGEN_TARGET=On
 
       - name: Generate dependencies (corpus)
         run: |
@@ -122,7 +122,7 @@ jobs:
       - name: Self check (unusedFunction / corpus / no test / callgrind)
         run: |
           # TODO: fix -rp so the suppressions actually work
-          valgrind --tool=callgrind ./cppcheck --template=selfcheck --error-exitcode=0 --library=cppcheck-lib --library=qt -D__GNUC__ -DQT_VERSION=0x050000 -DQ_MOC_OUTPUT_REVISION=67 -DQT_CHARTS_LIB --enable=unusedFunction --exception-handling -rp=. --project=cmake.output.corpus/compile_commands.json --suppressions-list=.selfcheck_unused_suppressions --inline-suppr 2>callgrind.log || (cat callgrind.log && false)
+          valgrind --tool=callgrind ./cppcheck --template=selfcheck --error-exitcode=0 --library=cppcheck-lib --library=qt -D__GNUC__ -DQT_VERSION=0x060000 -DQ_MOC_OUTPUT_REVISION=68 -DQT_CHARTS_LIB --enable=unusedFunction --exception-handling -rp=. --project=cmake.output.corpus/compile_commands.json --suppressions-list=.selfcheck_unused_suppressions --inline-suppr 2>callgrind.log || (cat callgrind.log && false)
           cat callgrind.log
           callgrind_annotate --auto=no > callgrind.annotated.log
           head -50 callgrind.annotated.log
diff --git a/.github/workflows/tsan.yml b/.github/workflows/tsan.yml
index c841da9c3..fdb17dae7 100644
--- a/.github/workflows/tsan.yml
+++ b/.github/workflows/tsan.yml
@@ -94,7 +94,7 @@ jobs:
           ec=0
           ./cmake.output/bin/cppcheck $selfcheck_options externals/simplecpp || ec=1
           ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options --addon=naming.json -DCHECK_INTERNAL cli lib || ec=1
-          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQT_VERSION=0x050000 -DQ_MOC_OUTPUT_REVISION=67 -DQT_CHARTS_LIB --library=qt --addon=naming.json -Icmake.output/gui -Igui gui/*.cpp cmake.output/gui/*.cpp || ec=1
+          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQT_VERSION=0x060000 -DQ_MOC_OUTPUT_REVISION=68 -DQT_CHARTS_LIB --library=qt --addon=naming.json -Icmake.output/gui -Igui gui/*.cpp cmake.output/gui/*.cpp || ec=1
           ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -Icli test/*.cpp tools/*.cpp || ec=1
-          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQ_MOC_OUTPUT_REVISION=67 -DQT_CHARTS_LIB --library=qt -Icmake.output/tools/triage -Igui tools/triage/*.cpp cmake.output/tools/triage/*.cpp || ec=1
+          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQ_MOC_OUTPUT_REVISION=68 -DQT_CHARTS_LIB --library=qt -Icmake.output/tools/triage -Igui tools/triage/*.cpp cmake.output/tools/triage/*.cpp || ec=1
           exit $ec
diff --git a/.github/workflows/ubsan.yml b/.github/workflows/ubsan.yml
index 8596f3009..654448987 100644
--- a/.github/workflows/ubsan.yml
+++ b/.github/workflows/ubsan.yml
@@ -91,7 +91,7 @@ jobs:
           ec=0
           ./cmake.output/bin/cppcheck $selfcheck_options externals/simplecpp || ec=1
           ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options --addon=naming.json cli lib || ec=1
-          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQT_VERSION=0x050000 -DQ_MOC_OUTPUT_REVISION=67 -DQT_CHARTS_LIB --library=qt --addon=naming.json -Icmake.output/gui -Igui gui/*.cpp cmake.output/gui/*.cpp || ec=1
+          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQT_VERSION=0x060000 -DQ_MOC_OUTPUT_REVISION=68 -DQT_CHARTS_LIB --library=qt --addon=naming.json -Icmake.output/gui -Igui gui/*.cpp cmake.output/gui/*.cpp || ec=1
           ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -Icli test/*.cpp tools/*.cpp || ec=1
-          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQ_MOC_OUTPUT_REVISION=67 -DQT_CHARTS_LIB --library=qt -Icmake.output/tools/triage -Igui tools/triage/*.cpp cmake.output/tools/triage/*.cpp || ec=1
+          ./cmake.output/bin/cppcheck $selfcheck_options $cppcheck_options -DQ_MOC_OUTPUT_REVISION=68 -DQT_CHARTS_LIB --library=qt -Icmake.output/tools/triage -Igui tools/triage/*.cpp cmake.output/tools/triage/*.cpp || ec=1
           exit $ec
diff --git a/clang-tidy.md b/clang-tidy.md
index ba7c7d611..4bc5c5954 100644
--- a/clang-tidy.md
+++ b/clang-tidy.md
@@ -155,6 +155,11 @@ To be evaluated (need to remove exclusion).
 
 To be evaluated (need to enable explicitly).
 
+`modernize-type-traits`</br>
+`modernize-use-nodiscard`</br>
+
+These apply to codebases which use later standards then C++11 (C++17 is used when building with Qt6) so we cannot simply apply them.
+
 `portability-std-allocator-const`<br/>
 
 Only necessary for code which is exclusively compiled with `libc++`. Also disabled for performance reasons - see https://github.com/llvm/llvm-project/issues/57527#issuecomment-1237935132.
diff --git a/cmake/findDependencies.cmake b/cmake/findDependencies.cmake
index 90b7c137e..5cab7009e 100644
--- a/cmake/findDependencies.cmake
+++ b/cmake/findDependencies.cmake
@@ -24,6 +24,7 @@ if (BUILD_GUI)
             set(DISABLE_CRTDBG_MAP_ALLOC ON)
         endif()
     else()
+        message(WARNING "Building with Qt5 is deprecated (it went EOL in May 2023) and will be removed in a future release - please use Qt6 instead")
         find_package(Qt5 COMPONENTS ${qt_components} REQUIRED)
         set(QT_VERSION "${Qt5Core_VERSION_STRING}")
     endif()
diff --git a/gui/codeeditorstyle.cpp b/gui/codeeditorstyle.cpp
index 509a9570b..8ec1b1345 100644
--- a/gui/codeeditorstyle.cpp
+++ b/gui/codeeditorstyle.cpp
@@ -43,21 +43,21 @@ CodeEditorStyle::CodeEditorStyle(
     QColor SymbFGColor, QColor SymbBGColor,
     // cppcheck-suppress naming-varname - TODO: fix this
     QFont::Weight SymbWeight) :
-    widgetFGColor(std::move(CtrlFGColor)),
-    widgetBGColor(std::move(CtrlBGColor)),
-    highlightBGColor(std::move(HiLiBGColor)),
-    lineNumFGColor(std::move(LnNumFGColor)),
-    lineNumBGColor(std::move(LnNumBGColor)),
-    keywordColor(std::move(KeyWdFGColor)),
+    widgetFGColor(CtrlFGColor),
+    widgetBGColor(CtrlBGColor),
+    highlightBGColor(HiLiBGColor),
+    lineNumFGColor(LnNumFGColor),
+    lineNumBGColor(LnNumBGColor),
+    keywordColor(KeyWdFGColor),
     keywordWeight(KeyWdWeight),
-    classColor(std::move(ClsFGColor)),
+    classColor(ClsFGColor),
     classWeight(ClsWeight),
-    quoteColor(std::move(QteFGColor)),
+    quoteColor(QteFGColor),
     quoteWeight(QteWeight),
-    commentColor(std::move(CmtFGColor)),
+    commentColor(CmtFGColor),
     commentWeight(CmtWeight),
-    symbolFGColor(std::move(SymbFGColor)),
-    symbolBGColor(std::move(SymbBGColor)),
+    symbolFGColor(SymbFGColor),
+    symbolBGColor(SymbBGColor),
     symbolWeight(SymbWeight)
 {}
 
diff --git a/gui/threadresult.cpp b/gui/threadresult.cpp
index 52d683414..8eb625e2e 100644
--- a/gui/threadresult.cpp
+++ b/gui/threadresult.cpp
@@ -35,7 +35,7 @@ void ThreadResult::reportOut(const std::string &outmsg, Color /*c*/)
 
 void ThreadResult::fileChecked(const QString &file)
 {
-    QMutexLocker locker(&mutex);
+    std::lock_guard<std::mutex> locker(mutex);
 
     mProgress += QFile(file).size();
     mFilesChecked++;
@@ -50,7 +50,7 @@ void ThreadResult::fileChecked(const QString &file)
 
 void ThreadResult::reportErr(const ErrorMessage &msg)
 {
-    QMutexLocker locker(&mutex);
+    std::lock_guard<std::mutex> locker(mutex);
     const ErrorItem item(msg);
     if (msg.severity != Severity::debug)
         emit error(item);
@@ -60,7 +60,7 @@ void ThreadResult::reportErr(const ErrorMessage &msg)
 
 QString ThreadResult::getNextFile()
 {
-    QMutexLocker locker(&mutex);
+    std::lock_guard<std::mutex> locker(mutex);
     if (mFiles.isEmpty()) {
         return QString();
     }
@@ -70,7 +70,7 @@ QString ThreadResult::getNextFile()
 
 ImportProject::FileSettings ThreadResult::getNextFileSettings()
 {
-    QMutexLocker locker(&mutex);
+    std::lock_guard<std::mutex> locker(mutex);
     if (mFileSettings.empty()) {
         return ImportProject::FileSettings();
     }
@@ -81,7 +81,7 @@ ImportProject::FileSettings ThreadResult::getNextFileSettings()
 
 void ThreadResult::setFiles(const QStringList &files)
 {
-    QMutexLocker locker(&mutex);
+    std::lock_guard<std::mutex> locker(mutex);
     mFiles = files;
     mProgress = 0;
     mFilesChecked = 0;
@@ -97,7 +97,7 @@ void ThreadResult::setFiles(const QStringList &files)
 
 void ThreadResult::setProject(const ImportProject &prj)
 {
-    QMutexLocker locker(&mutex);
+    std::lock_guard<std::mutex> locker(mutex);
     mFiles.clear();
     mFileSettings = prj.fileSettings;
     mProgress = 0;
@@ -113,7 +113,7 @@ void ThreadResult::setProject(const ImportProject &prj)
 
 void ThreadResult::clearFiles()
 {
-    QMutexLocker locker(&mutex);
+    std::lock_guard<std::mutex> locker(mutex);
     mFiles.clear();
     mFileSettings.clear();
     mFilesChecked = 0;
@@ -122,6 +122,6 @@ void ThreadResult::clearFiles()
 
 int ThreadResult::getFileCount() const
 {
-    QMutexLocker locker(&mutex);
+    std::lock_guard<std::mutex> locker(mutex);
     return mFiles.size() + mFileSettings.size();
 }
diff --git a/gui/threadresult.h b/gui/threadresult.h
index 4e32a1cbe..80ef39b63 100644
--- a/gui/threadresult.h
+++ b/gui/threadresult.h
@@ -25,9 +25,9 @@
 #include "importproject.h"
 
 #include <list>
+#include <mutex>
 #include <string>
 
-#include <QMutex>
 #include <QObject>
 #include <QString>
 #include <QStringList>
@@ -127,7 +127,7 @@ protected:
      * @brief Mutex
      *
      */
-    mutable QMutex mutex;
+    mutable std::mutex mutex;
 
     /**
      * @brief List of files to check
diff --git a/releasenotes.txt b/releasenotes.txt
index 99fa49afd..51ee1d681 100644
--- a/releasenotes.txt
+++ b/releasenotes.txt
@@ -14,6 +14,7 @@ Changed interface:
 
 Deprecations:
 - "--showtime=top5" has been deprecated and will be removed in Cppcheck 2.14. Please use --showtime=top5_file or --showtime=top5_summary instead.
+- Building with Qt5 has been deprecated (it went EOL in May 2023) and will be removed in a future version - please use Qt6 instead.
 
 Other:
 - Windows builds now default to the `native` platform instead of `win32A` or `win64`. Please specify it explicitly if you depend on it.