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.
* The WASI targets deal with the `main` symbol a bit differently than
native so some `codegen` and `assembly` tests have been ignored.
* All `ignore-emscripten` directives have been updated to
`ignore-wasm32` to be more clear that all wasm targets are ignored and
it's not just Emscripten.
* Most `ignore-wasm32-bare` directives are now gone.
* Some ignore directives for wasm were switched to `needs-unwind`
instead.
* Many `ignore-wasm32*` directives are removed as the tests work with
WASI as opposed to `wasm32-unknown-unknown`.
Replace `yes` command by `while-echo` in test `tests/ui/process/process-sigpipe.rs`
The `yes` command is not available on all platforms.
Fixes#108596.
Inviting `@mvf` as he contributed to this patch. Thanks! This issue has been discussed in https://github.com/rust-lang/rust/pull/106673 but was moved to #108596 to get going.
CC `@gh-tr`
r? `@workingjubilee`
`@rustbot` label +O-neutrino
Notes about the comments https://github.com/rust-lang/rust/pull/106673#discussion_r1117324265:
- The `echo` command is `/proc/boot/echo` (not built-in)
- `/bin/sh` is a symlink to `/proc/boot/ksh`
```sh
# ls -l /bin/sh /proc/boot/ksh /proc/boot/echo
lrwxrwxrwx 1 root root 14 Mar 20 07:52 /bin/sh -> /proc/boot/ksh
-r-xr-xr-x 1 root root 9390 Sep 12 2022 /proc/boot/echo
-r-xr-xr-x 1 root root 308114 Sep 12 2022 /proc/boot/ksh
```
