Setup Fortran

Set up a Fortran compiler on Ubuntu, macOS and Windows runners.

• Usage
• Options
• Outputs
• Environment variables
• Runner compatibility
• License

Usage

jobs:
  test:
    runs-on: ${{ matrix.os }}
    strategy:
      fail-fast: false
      matrix:
        os: [ubuntu-latest, macos-latest, windows-latest]
        toolchain:
          - {compiler: gcc, version: 'latest'}
          - {compiler: intel, version: '2025.0'}
          - {compiler: intel-classic, version: '2021.10'}
          - {compiler: nvidia-hpc, version: 'latest'}
          - {compiler: lfortran, version: '0.45.0'}
          - {compiler: aocc, version: '5.1.0'}
        exclude:
          - os: macos-latest
            toolchain: {compiler: intel}
          - os: macos-latest
            toolchain: {compiler: intel-classic}
          - os: macos-latest
            toolchain: {compiler: nvidia-hpc}
          - os: windows-latest
            toolchain: {compiler: nvidia-hpc}
          - os: macos-latest
            toolchain: {compiler: aocc}
          - os: windows-latest
            toolchain: {compiler: aocc}

    steps:
      - uses: fortran-lang/setup-fortran@v1
        id: setup-fortran
        with:
          compiler: ${{ matrix.toolchain.compiler }}
          version: ${{ matrix.toolchain.version }}

      - run: |
          ${{ env.FC }} ... # environment vars FC, CC, and CXX are set
          ${{ steps.setup-fortran.outputs.fc }} ... # outputs work too

Options

• compiler: Compiler toolchain to setup, available options are
  • gcc for gfortran
  • intel for ifx
  • intel-classic for ifort
  • lfortran for lfortran
  • nvidia-hpc for nvfortran
  • aocc for flang (AMD Optimizing C/C++ and Fortran Compilers)
  • flang for flang (LLVM Flang, from apt.llvm.org on Linux and Homebrew on Apple Silicon macOS)
• version: Version of the compiler toolchain. See runner compatibility charts below.
• update-environment: Whether to set environment variables (FC etc, defaults true).

Outputs

The action sets the following outputs:

• fc: Fortran compiler executable, e.g. gfortran
• cc: C compiler executable, e.g. gcc
• cxx: C++ compiler executable, e.g. g++

C/C++ compilers of the same toolchain/version are provided where available. If a standalone Fortran compiler is selected, the action will attempt to configure compatible C/C++ compilers (typically GCC, or MSVC on Windows), but this is not guaranteed — use at your own risk.

With the intel and intel-classic toolchains on Windows, CC and CXX are set to MSVC's cl, which is ABI-compatible with the Intel Fortran compilers. Intel's Fortran-only Windows installers do not include a working icx, so it is not used. To use Intel's C/C++ compilers instead, install the oneAPI Base Toolkit yourself and set CC and CXX in your workflow.

Environment variables

The same values are also set as environment variables:

• FC
• CC
• CXX

Corresponding FPM environment variables are also set:

• FPM_FC
• FPM_CC
• FPM_CXX

These are made available to subsequent workflow steps via the GITHUB_ENV environment file mechanism.

Runner compatibility

Toolchain support varies across GitHub-hosted runner images.

runner	aocc 5.1.0	aocc 5.2.0	flang 20	flang 21	flang 22	flang 23	gcc 13	gcc 14	gcc 15	gcc 16	intel 2021.1	intel 2021.1.2	intel 2021.2	intel 2021.4	intel 2022.0	intel 2022.1	intel 2022.2	intel 2022.2.1	intel 2023.0	intel 2023.1	intel 2023.2	intel 2024.0	intel 2024.1	intel 2025.0	intel 2025.2	intel 2025.3	intel 2026.0	intel 2026.1	intel-classic 2021.1	intel-classic 2021.1.2	intel-classic 2021.2	intel-classic 2021.3	intel-classic 2021.4	intel-classic 2021.5	intel-classic 2021.6	intel-classic 2021.7.1	intel-classic 2021.8	intel-classic 2021.9	intel-classic 2021.10	intel-classic 2021.11	intel-classic 2021.12	lfortran 0.57.0	lfortran 0.58.0	nvidia-hpc 23.3	nvidia-hpc 23.5	nvidia-hpc 23.7	nvidia-hpc 23.9	nvidia-hpc 23.11	nvidia-hpc 24.1	nvidia-hpc 24.3	nvidia-hpc 24.5	nvidia-hpc 25.1	nvidia-hpc 25.3	nvidia-hpc 25.5	nvidia-hpc 25.7	nvidia-hpc 25.9	nvidia-hpc 26.1
macos-14							✓	✓	✓	✓																			✓		✓	✓		✓	✓		✓	✓	✓			✓	✓
macos-15						✓	✓	✓	✓	✓																			✓		✓	✓		✓	✓		✓	✓	✓			✓	✓
macos-15-intel							✓	✓	✓		✓		✓																✓		✓	✓		✓	✓		✓	✓	✓			✓	✓
macos-26						✓	✓	✓	✓	✓																			✓		✓	✓		✓	✓		✓	✓	✓			✓	✓
macos-26-intel							✓	✓	✓		✓		✓																✓		✓	✓		✓	✓		✓	✓	✓			✓	✓
ubuntu-22.04			✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓		✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓
ubuntu-24.04	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓		✓	✓	✓	✓	✓	✓	✓	✓	✓	✓	✓								✓	✓	✓	✓	✓	✓	✓
windows-2022							✓	✓	✓	✓						✓	✓			✓	✓	✓	✓	✓	✓	✓	✓	✓							✓			✓	✓	✓	✓	✓	✓
windows-2025							✓	✓	✓	✓																✓	✓	✓														✓	✓
windows-2025-vs2026							✓	✓	✓	✓																✓	✓	✓														✓	✓

Note: Intel's ifx compiler is not supported on macOS, so the intel option redirects to intel-classic (ifort).

Note: LFortran is currently only discoverable by name with bash on Windows, see here for context.

License

Licensed under the Apache License, Version 2.0 (the “License”); you may not use this file except in compliance with the License. You may obtain a copy of the License at http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on an “as is” basis, without warranties or conditions of any kind, either express or implied. See the License for the specific language governing permissions and limitations under the License.

Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this project by you, as defined in the Apache-2.0 license, shall be licensed as above, without any additional terms or conditions.