https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105238
--- Comment #5 from Esger Abbink <esgergn at hotmail dot com> --- Cherry picking https://github.com/gcc-mirror/gcc/commit/cde87638bf5cf6aafffb590986b6a890da0ba06c on top of releases-9.4.0 allowed me to apply the patch to get a patched gcc9.4 supporting -fprofile-prefix-map and that leads to the same (desired) behavior as described in the previous comment for patched gcc11, plus gcovr is now able to produce coverage reports. However, all is still not well, because ccache does not know the -fprofile-prefix-map option and therefore marks files compiled with it as uncacheable.. :(
