I don't know how old this regression is, but [a thread on Discourse](https://discourse.cmake.org/t/autorcc/2179) brought up a regression in autogen somewhere between 3.10 and 3.18 (bisection needed). Apparently, interactions with AUTOGEN_BUILD_DIR is involved. Minimal test case attached (repackaged from .7z as provided on Discourse). [autorcctest.tar.bz2](/uploads/babc2d521972b561977a4c7e43f51354/autorcctest.tar.bz2) Cc: @brad.king