https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71399
--- Comment #12 from Ludovic Courtès <ludo at gnu dot org> --- (In reply to Ludovic Courtès from comment #10) > In fact, the revert only needs to be done on the initial > pseudo-cross-compiler that is used to build the native compiler (I'm > attaching a PDF of the dependency graph, where the initial > pseudo-cross-compiler as described at > http://linuxfromscratch.org/lfs/view/stable/chapter05/gcc-pass1.html is > marked as "gcc-cross-boot0", and the final native compiler is simply "gcc"). > > To summarize, if we build 4.9.4 with a cross-4.9.3, that's fine; if we build > 4.9.4 with a cross-4.9.4, we get the bootstrap comparison failure. The faulty commit is r231177 (commit f6ab85b7049a03962ea98924d00802da357a1ad3 in the Git mirror). If we take 4.9.4 and revert r231177 in the "gcc-cross-boot0" compiler, then the final gcc builds fine (no bootstrap comparison failure). Note that the revert needs not be applied to the final gcc, only to gcc-cross-boot0. (For reference, we applied the revert here: http://git.savannah.gnu.org/cgit/guix.git/commit/?id=e7e43727ce7b3426a31b2f50b035a5b0aba61d52 .) Any idea what's going on here?
