tree 3813dbfab4e672443fecab2671df6949744692b8
parent 5b10c0a64d090b09ab4309f40951e1574d1660eb
author Louis Dionne <ldionne@apple.com> 1593798401 -0400
committer Copybara-Service <copybara-worker@google.com> 1598602021 -0700

[libc++/libc++abi] Automatically detect whether exceptions are enabled

Instead of detecting it automatically (in libc++) and relying on
_LIBCXXABI_NO_EXCEPTIONS being set explicitly (in libc++abi), always
detect whether exceptions are enabled automatically.

This commit also removes support for specifying -D_LIBCPP_NO_EXCEPTIONS
and -D_LIBCXXABI_NO_EXCEPTIONS explicitly -- those should just be inferred
from using -fno-exceptions (or an equivalent flag).

Allowing both -D_FOO_NO_EXCEPTIONS to be provided explicitly and trying
to detect it automatically is just confusing, especially since we did
specify it explicitly when building libc++abi. We should have only one
way to detect whether exceptions are enabled, but it should be robust.

GitOrigin-RevId: 71d88cebfb42c8c5ac2d54b42afdcca956e55660