Upgrading macOS broke my C compiler... so I* fixed it!
*with the indispensable help and guidance of the conda-forge core team! Patient zero Yesterday, disaster struck — after upgrading my main machine to macOS 26 (thinking what could possibly go wrong?), I was suddenly unable to build SciPy. Reviewing pull requests certainly becomes a bit more difficult when you are faced with this error whenever you try to test changes on your machine: ❯ pixi run build ✨ Pixi task (build in build): spin build --setup-args=-Dblas=blas --setup-args=-Dlapack=lapack --setup-args=-Duse-g77-abi=true: (Build SciPy (default settings)) $ meson setup build --prefix=/usr -Dblas=blas -Dlapack=lapack -Duse-g77-abi=true The Meson build system Version: 1.9.0 Source dir: /path/to/scipy/scipy Build dir: /path/to/scipy/scipy/build Build type: native build Project name: scipy Project version: 1.17.0.dev0+git20250925.e4d0fa1 meson.build:1:0: ERROR: Executables created by c compiler ccache arm64-apple-darwin20.0.0-clang are not runnable. At a glance, the error seemed to be telling me that my C compiler (clang, from conda-forge) was creating executables which cannot run on my machine. Since this was the first time I had tried compiling C code since upgrading to macOS 26, I figured that the upgrade was probably the cause of the problem. Now the tricky part: figure out how to fix it! ...