On macOS 26.4, AFL builds were picking up Nix compiler-wrapper
variables and Apple SDK target settings from the shell environment.
That caused afl-cc to drive the wrong linker and target configuration,
which broke even simple fuzz harness builds. Unset the Nix compiler and
linker environment in the fuzz dev shell so AFL++ uses the system or
Homebrew Apple toolchain directly.
Also force afl-cc to link with lld because the newer Apple linker
asserts on the custom sections emitted by AFL's LLVM
instrumentation. Finally, pin fuzz-libghostty to the host target so the
build does not inherit stray SDK targets from the environment.
The terminal.Stream next/nextSlice functions can now no longer fail.
All prior failure modes were fully isolated in the handler `vt`
callbacks. As such, vt callbacks are now required to not return an error
and handle their own errors somehow.
Allowing streams to be fallible before was an incorrect design. It
caused problematic scenarios like in `nextSlice` early terminating
processing due to handler errors. This should not be possible.
There is no safe way to bubble up vt errors through the stream because
if nextSlice is called and multiple errors are returned, we can't
coalesce them. We could modify that to return a partial result but its
just more work for stream that is unnecessary. The handler can do all of
this.
This work was discovered due to cleanups to prepare for more C APIs.
Less errors make C APIs easier to implement! And, it helps clean up our
Zig, too.
