It really shouldn’t, but could you share how the options are set and a workflow log? Maybe there is some odd twist. 🙂

Thanks for your answer. I just discovered that my ‘windows’ run on Microsoft Windows Server 2019 but compile with GNU 8.1.0. How is it possible ? GNU is only Linux compiler, no ?
This is my workflow:

unit_tests.yml

name: Unit tests Linux/Windows
on: [push]
jobs:

unit-tests:

name: Build and run unit tests

runs-on: ${{ matrix.os }}

strategy:

matrix:

os: [ubuntu-latest, windows-latest]
steps:
- name: Checkout
  uses: actions/checkout@v2
- name: CMake
  run: |
    cd ./build
    cmake -G"Unix Makefiles" ./..
- name: Make
  run: |
    cd ./build
    make
- name: Execute unit tests
  run: |
    cd ./build
    ./tests/unit_tests/UnitTests.out --gtest_also_run_disabled_tests

How can I change my workflow to compile with MSVC on Windows and with GCC on Linux ?

Thanks for information. Do I need to configure a preference in CMake or just configure the compiler in the workflow ? I will check it soon as possible.
Also for compile GCC on windows GitHub must use something like MinGW or Cywin ?

Do I need to configure a preference in CMake or just configure the compiler in the workflow ?

I’m not sure about CMake specifically, but a common thing on Linux is to set the C compiler via the CC environment variable, so setting that in the CMake run might be worth a try.

Also for compile GCC on windows GitHub must use something like MinGW or Cywin ?

The current version of the windows-2019 environment description lists Mingw-w64, so I assume that’s what it is. 😉