Thank you for your solution. I downgraded the driver with the command below, and the game now starts.
sudo pacman -U /var/cache/pacman/pkg/mesa-19.2.7-1-x86_64.pkg.tar.xz

Mesa 19.3.0-1 is the current version used by my distro (as of today), and it was installed this morning on my machine by an ...

0.000 2019-12-14 16:32:20; Factorio 0.17.79 (build 47865, linux64, steam)
0.066 Operating system: Linux (Arch rolling)
0.066 Program arguments: "/home/anthony/.local/share/Steam/steamapps/common/Factorio/bin/x64/factorio"
0.066 Read data path: /home/anthony/.local/share/Steam/steamapps/common ...