Does anyone know which upstream boehm-gc release FSF gcc's copy was last synchronized against? The system libunwinder.dylib (providing the compatibility unwinder on darwin) has been recompiled, without source changes, in OS X 10.11 El Capitan. This recompilation with the newer Apple clang 7.0 compiler has broken the boehm-gc test suite on darwin15...
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66848 as demonstrated by the fact that substituting the libunwind.dylib from darwin14 on darwin15 eliminates the boehm-gc test suite failures. Apple considers the optimization changes made by the Clang 7.0 compiler to the compatibility unwinder in libunwind.dylib to be safe and believes that it tickles a latent bug in FSF gcc's boehm-gc. The upstream release for boehm-gc 7.2 through 7.4.2 all build fine and pass their test suite on darwin15. Looking at the sources, it seems that the current boehm-gc is based on upstream gc 7.1 or earlier so perhaps updating the FSF gcc's boehm-gc to 7.2 or later may help resolve this issue. Jack
