preprocessor + CI cleanup

also:
- minor refactors in path
- updated conformance tests

.github/workflows/ci.yaml

@@ -29,6 +29,10 @@ concurrency:
   group: ${{ github.workflow }}-${{ github.ref }}
   cancel-in-progress: true
 
+env:
+  clang_version: '14'
+  gcc_version: '11'
+
 jobs:
   linux:
     strategy:
@@ -48,22 +52,56 @@ jobs:
 
     runs-on: ubuntu-latest
 
+    defaults:
+      run:
+        shell: bash
+
     steps:
-    - name: Install dependencies
+    - name: Install base dependencies
       run: |
         sudo apt -y update
-        if [ ${{ matrix.compiler }} = clang++ ]; then compiler=clang; else compiler=${{ matrix.compiler }}; fi
-        sudo apt -y install --no-install-recommends $compiler ${{ matrix.linker }} pkgconf git ca-certificates locales-all python3 python3-pip python3-setuptools python3-wheel ninja-build
-        sudo pip3 install --upgrade meson
+        sudo apt -y install --no-install-recommends ${{ matrix.linker }} git python3 python3-pip ninja-build locales-all
+        sudo -H pip3 install --no-cache-dir --upgrade meson
 
     - uses: actions/checkout@v3
 
     - name: Check toml.hpp
       run: |
-        sudo pip3 install --upgrade --requirement tools/requirements.txt
         cd tools
+        sudo -H pip3 install --upgrade --requirement ./requirements.txt
         python3 ci_single_header_check.py
 
+    - name: Update LLVM package repository
+      if: ${{ startsWith(matrix.compiler, 'clang') || startsWith(matrix.linker, 'lld') }}
+      run: |
+        sudo apt -y install --no-install-recommends software-properties-common wget
+        wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | sudo apt-key add -
+        codename=$(lsb_release -sc)
+        sudo add-apt-repository --yes --no-update "deb http://apt.llvm.org/${codename}/ llvm-toolchain-${codename}-${{ env.clang_version }} main"
+        sudo apt -y update
+
+    - name: Install clang
+      if: ${{ startsWith(matrix.compiler, 'clang')  }}
+      run: |
+        sudo apt -y install --no-install-recommends clang-${{ env.clang_version }}
+        sudo update-alternatives --install /usr/bin/clang++ clang++ /usr/bin/clang++-${{ env.clang_version }} 1000
+
+    - name: Install g++
+      if: ${{ startsWith(matrix.compiler, 'g++') }}
+      run: |
+        sudo apt -y install --no-install-recommends g++-${{ env.gcc_version }}
+        sudo update-alternatives --install /usr/bin/g++ g++ /usr/bin/g++-${{ env.gcc_version }} 1000
+
+    - name: Install lld
+      if: ${{ startsWith(matrix.linker, 'lld')  }}
+      run: |
+        sudo apt -y install --no-install-recommends lld-${{ env.clang_version }}
+        sudo update-alternatives --install /usr/bin/ld.lld ld.lld /usr/bin/ld.lld-${{ env.clang_version }} 1000
+
+    - name: Configure locales
+      run: |
+        sudo locale-gen 'en_US.utf8' 'ja_JP.utf8' 'de_DE.utf8' 'it_IT.utf8' 'tr_TR.utf8' 'fi_FI.utf8' 'fr_FR.utf8' 'zh_CN.utf8'
+
     - name: Configure Meson
       run: |
         CXX=${{ matrix.compiler }} CXX_LD=${{ matrix.linker }} meson setup build --buildtype=${{ matrix.type }} -Dcompile_library=${{ matrix.compile_library }} -Dpedantic=true -Dbuild_tests=true -Dbuild_examples=true -Dgenerate_cmake_config=false -Db_lto=false -Dubsan_examples=true -Dasan_examples=true
@@ -97,7 +135,7 @@ jobs:
         python3 -m pip install -U pip==21.3.1
         pip3 install meson ninja
 
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v3
 
     - uses: ilammy/msvc-dev-cmd@v1
 
@@ -114,13 +152,14 @@ jobs:
   tipi-build-linux:
     name: tipi.build project build and dependency resolution 
     runs-on: ubuntu-latest
+    if: github.ref == 'refs/heads/master'
     container: tipibuild/tipi-ubuntu
 
     env:
       HOME: /root
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - run: mkdir -p ~/.tipi
 
       # checking if the tomlplusplus project builds and passes tests