unwind: refer to top-level *stderr* stream.

Exception processing should refer to the original, top-level
value of *stderr* rather than the current dynamic value, even
if unwinding has not yet taken place. Using the dynamic value
can not only cause critical output to disappear, but it leads
to a false positive identification of the "unhandled exception
in early initialization" situation, a diagnostic which is
emitted on the C stderr if the Lisp one is unavailable,
which is assumed to be due to initialization not having
yet completed.

* stream.c (top_stderr): New global variable.
(stream_init): GC-protect top_stderr, and initialize it with
the same object that goes into the *stderr* top-level binding.

* stream.h (top_stderr): Declared.

* unwind.c (uw_unwind_to_exit_point, uw_rthrow): Use
top_stderr instead of std_error macro.

0 files changed, 0 insertions, 0 deletions