build: downgrade GCC support to experimental

Update the configure script to select Clang by default.
V8 no longer officially supports GCC and we often have problems because
of it.
Also bump the expected version to 13.2 because version 12 can't compile
newer V8.

Signed-Off-By: Michaël Zasso <targos@protonmail.com>

Author: targos

.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))