https://gcc.gnu.org/bugzilla/show_bug.cgi?id=123868
--- Comment #2 from Andrew Benson <abensonca at gcc dot gnu.org> --- The regression appears to have been caused by commit 9636d90e4326003e6da1ea86df7c730852629920 - which implemented deep copy semantics: https://github.com/gcc-mirror/gcc/commit/9636d90e4326003e6da1ea86df7c730852629920
