Philipp <p.stephani2@gmail.com> schrieb am Mi., 3. Okt. 2018 um 22:12 Uhr:

>
> ./globals.h:1075:1: error: arithmetic on a null pointer treated as a cast
> from integer to pointer is a GNU extension
> [-Werror,-Wnull-pointer-arithmetic]
> ./lisp.h:835:53: note: expanded from macro 'TAG_PTR'
>   LISP_INITIALLY ((Lisp_Word) ((untagged_ptr) (ptr) + LISP_WORD_TAG (tag)))
>

Some discussion around this topic:
http://releases.llvm.org/6.0.0/tools/clang/docs/ReleaseNotes.html#improvements-to-clang-s-diagnostics
, https://reviews.llvm.org/D37042,
http://lists.llvm.org/pipermail/llvm-dev/2017-July/115053.html. Given that
the TAG_PTR implementation is technically undefined behavior, would it be
possible to change the definition (e.g. to use intptr_t instead of char*)?