> This library is designed to be used for binaries that are already compiled against glibc. It does not contain any headers, and cannot be used to build software that requires glibc. It is instead recommended that any software that requires glibc APIs be modified to become more portable.

This is exactly the opposite that I was talking about. What I was talking is a library that expose glibc compatible headers to compile software that uses Glibc-isms with minor or zero modifications, but this instead is a compatibility layer for binaries and doesn't expose headers (probably for proprietary software that can't be recompiled).

FWIW, that is an unofficial mirror repo and very old. gcompat lives at https://git.adelielinux.org/adelie/gcompat.