build: downgrade GCC support to experimental

.github/workflows/build-tarball.yml

@@ -77,6 +77,10 @@ jobs:
       - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd  # v6.0.2
         with:
           persist-credentials: false
+      - name: Install Clang ${{ env.CLANG_VERSION }}
+        uses: ./.github/actions/install-clang
+        with:
+          clang-version: ${{ env.CLANG_VERSION }}
       - name: Set up Python ${{ env.PYTHON_VERSION }}
         uses: actions/setup-python@a309ff8b426b58ec0e2a45f0f869d46889d02405  # v6.2.0
         with:
@@ -90,6 +94,9 @@ jobs:
           export DATESTRING=$(date "+%Y-%m-%d")
           export COMMIT=$(git rev-parse --short=10 "$GITHUB_SHA")
           ./configure && make tar -j4 SKIP_XZ=1
+        env:
+          CC: clang-19
+          CXX: clang++-19
       - name: Upload tarball artifact
         uses: actions/upload-artifact@bbbca2ddaa5d8feaa63e36b76fdaad77386f024f  # v7.0.0
         with:

.github/workflows/test-macos.yml

@@ -78,8 +78,8 @@ jobs:
       fail-fast: false
     runs-on: macos-15
     env:
-      CC: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache' || '' }} gcc
-      CXX: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache' || '' }} g++
+      CC: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache' || '' }} clang
+      CXX: ${{ (github.base_ref == 'main' || github.ref_name == 'main') && 'sccache' || '' }} clang++
       SCCACHE_GHA_ENABLED: ${{ github.base_ref == 'main' || github.ref_name == 'main' }}
       SCCACHE_IDLE_TIMEOUT: '0'
     steps:

.github/workflows/test-shared.yml

@@ -104,6 +104,7 @@ concurrency:
 
 env:
   FLAKY_TESTS: keep_retrying
+  CLANG_VERSION: '19'
 
 permissions:
   contents: read
@@ -119,6 +120,11 @@ jobs:
         with:
           persist-credentials: false
 
+      - name: Install Clang ${{ env.CLANG_VERSION }}
+        uses: ./.github/actions/install-clang
+        with:
+          clang-version: ${{ env.CLANG_VERSION }}
+
       - name: Make tarball
         if: ${{ github.event_name != 'workflow_dispatch' }}
         run: |
@@ -127,6 +133,8 @@ jobs:
           ./configure && make tar -j4 SKIP_XZ=1 SKIP_SHARED_DEPS=1
         env:
           DISTTYPE: nightly
+          CC: clang-19
+          CXX: clang++-19
 
       - name: Upload tarball artifact
         if: ${{ github.event_name != 'workflow_dispatch' }}

BUILDING.md

@@ -156,7 +156,7 @@ Depending on the host platform, the selection of toolchains may vary.
 
 | Operating System | Compiler Versions                                                   |
 | ---------------- | ------------------------------------------------------------------- |
-| Linux            | GCC >= 12.2 or Clang >= 19.1                                        |
+| Linux            | Clang >= 19.1 or GCC >= 13.2 (experimental)                         |
 | Windows          | Visual Studio 2022 or 2026 with the Windows 11 SDK on a 64-bit host |
 | macOS            | Xcode >= 16.4 (Apple LLVM >= 19)                                    |
 
@@ -238,19 +238,19 @@ Consult previous versions of this document for older versions of Node.js:
 
 #### Unix prerequisites
 
-* `gcc` and `g++` >= 12.2 or `clang` and `clang++` >= 19.1
+* `clang` and `clang++` >= 19.1 or `gcc` and `g++` >= 13.2 (experimental)
 * GNU Make 3.81 or newer
 * [A supported version of Python][Python versions]
   * For test coverage, your Python installation must include pip.
 
 Installation via Linux package manager can be achieved with:
 
 * Nix, NixOS: `nix-shell`
-* Ubuntu, Debian: `sudo apt-get install python3 g++-12 gcc-12 make python3-pip`
-* Fedora: `sudo dnf install python3 gcc-c++ make python3-pip`
-* CentOS and RHEL: `sudo yum install python3 gcc-c++ make python3-pip`
-* OpenSUSE: `sudo zypper install python3 gcc-c++ make python3-pip`
-* Arch Linux, Manjaro: `sudo pacman -S python gcc make python-pip`
+* Ubuntu, Debian: `sudo apt-get install python3 clang-19 make python3-pip`
+* Fedora: `sudo dnf install python3 clang make python3-pip`
+* CentOS and RHEL: `sudo yum install python3 clang make python3-pip`
+* OpenSUSE: `sudo zypper install python3 clang make python3-pip`
+* Arch Linux, Manjaro: `sudo pacman -S python clang make python-pip`
 
 FreeBSD and OpenBSD users may also need to install `libexecinfo`.
 
@@ -660,8 +660,8 @@ need to install the latest version but not the apt version.
 
 ```bash
 sudo apt install ccache mold   # for Debian/Ubuntu, included in most Linux distros
-export CC="ccache gcc"         # add to your .profile
-export CXX="ccache g++"        # add to your .profile
+export CC="ccache clang"       # add to your .profile
+export CXX="ccache clang++"    # add to your .profile
 export LDFLAGS="-fuse-ld=mold" # add to your .profile
 ```
 

configure.py

@@ -19,10 +19,8 @@
 
 original_argv = sys.argv[1:]
 
-# gcc and g++ as defaults matches what GYP's Makefile generator does,
-# except on macOS and Windows.
-CC = os.environ.get('CC', 'cc' if sys.platform == 'darwin' else 'clang' if sys.platform == 'win32' else 'gcc')
-CXX = os.environ.get('CXX', 'c++' if sys.platform == 'darwin' else 'clang' if sys.platform == 'win32' else 'g++')
+CC = os.environ.get('CC', 'clang')
+CXX = os.environ.get('CXX', 'clang' if sys.platform == 'win32' else 'clang++')
 
 tools_path = Path('tools')
 
@@ -1521,8 +1519,8 @@ def check_compiler(o):
   print_verbose(f"Detected {'Apple ' if is_apple else ''}{'clang ' if is_clang else ''}C++ compiler (CXX={CXX}) version: {version_str}")
   if not ok:
     warn(f'failed to autodetect C++ compiler version (CXX={CXX})')
-  elif ((is_apple and clang_version < (17, 0, 0)) or (not is_apple and clang_version < (19, 1, 0))) if is_clang else gcc_version < (12, 2, 0):
-    warn(f"C++ compiler (CXX={CXX}, {version_str}) too old, need g++ 12.2.0 or clang++ 19.1.0{' or Apple clang++ 17.0.0' if is_apple else ''}")
+  elif ((is_apple and clang_version < (17, 0, 0)) or (not is_apple and clang_version < (19, 1, 0))) if is_clang else gcc_version < (13, 2, 0):
+    warn(f"C++ compiler (CXX={CXX}, {version_str}) too old, need g++ 13.2.0 or clang++ 19.1.0{' or Apple clang++ 17.0.0' if is_apple else ''}")
 
   ok, is_clang, clang_version, gcc_version, is_apple = try_check_compiler(CC, 'c')
   version_str = ".".join(map(str, clang_version if is_clang else gcc_version))