This makes rustc simply return an exit code from main rather than calling `std::process::exit` with an exit code. This means that drops run normally and the process exits cleanly.
Also instead of hard coding success and failure codes this uses `ExitCode::SUCCESS` and `ExitCode::FAILURE`, which in turn effectively uses `libc::EXIT_SUCCESS` and `libc::EXIT_FAILURE` (via std). These are `0` and `1` respectively for all currently supported host platforms so it doesn't actually change the exit code.
In the stabilization attempt of `#[unix_sigpipe = "sig_dfl"]`, a concern
was raised related to using a language attribute for the feature: Long
term, we want `fn lang_start()` to be definable by any crate, not just
libstd. Having a special language attribute in that case becomes
awkward.
So as a first step towards towards the next stabilization attempt, this
PR changes the `#[unix_sigpipe = "..."]` attribute to a compiler flag
`-Zon-broken-pipe=...` to remove that concern, since now the language
is not "contaminated" by this feature.
Another point was also raised, namely that the ui should not leak
**how** it does things, but rather what the **end effect** is. The new
flag uses the proposed naming. This is of course something that can be
iterated on further before stabilization.
Before, it said "global_allocator does nothing". Now it gives you
suggestions for what to do if you want to change the global allocator
(which is likely the main reason you'd be reading the comment).
This is the first (known) step towards starting to use `unix_sigpipe` in
the wild. Eventually, `rustc_driver::set_sigpipe_handler` can be removed
and all clients can use `unix_sigpipe` instead.
For now we just start using `unix_sigpipe` in once place: `rustc`
itself.
It is easy to manually verify this change. If you remove
`#[unix_sigpipe = "sig_dfl"]` and run `./x.py build` you will get an ICE
when you do `./build/x86_64-unknown-linux-gnu/stage1/bin/rustc --help |
false`. Add back `#[unix_sigpipe = "sig_dfl"]` and the ICE disappears
again.
Chris Denton