gfortran 11.3 for Monterey (macOS 12)

Standalone installer of GCC 11.3, including gfortran, for macOS Monterey (macOS 12). Two files are available:

• gfortran-ARM-11.3-Monterey.dmg for Apple Silicon computers
• gfortran-Intel-11.3-Monterey.dmg for Intel-based computers

New in this release:

• the Ada compiler (GNAT) is included
• the compilers are built from the maintainer’s branch at https://github.com/iains/gcc-11-branch/ and include some patches over the official release