Rollup merge of #49606 - varkor:pipe-repair, r=alexcrichton

Prevent broken pipes causing ICEs

As the private `std::io::print_to` panics if there is an I/O error, which is used by `println!`, the compiler would ICE if one attempted to use a broken pipe (e.g. `rustc --help | false`). This introduces a new (private) macro `try_println!` which allows us to avoid this.

As a side note, it seems this macro might be useful publicly (and actually there seems to be [a crate specifically for this purpose](https://crates.io/crates/try_print/)), though that can probably be left for a future discussion.

One slight alternative approach would be to simply early exit without an error (i.e. exit code `0`), which [this comment](https://github.com/rust-lang/rust/issues/34376#issuecomment-377822526) suggests is the usual approach. I've opted not to take that approach initially, because I think it's more helpful to know when there is a broken pipe.

Fixes #34376.

1 files changed, 2 insertions, 2 deletions

diff --git a/src/libstd/sys/unix/mod.rs b/src/libstd/sys/unix/mod.rs
index 9bdea945ea4..c1298e5040d 100644
--- a/src/libstd/sys/unix/mod.rs
+++ b/src/libstd/sys/unix/mod.rs
@@ -80,11 +80,11 @@ pub fn init() {
         reset_sigpipe();
     }
 
-    #[cfg(not(any(target_os = "emscripten", target_os="fuchsia")))]
+    #[cfg(not(any(target_os = "emscripten", target_os = "fuchsia")))]
     unsafe fn reset_sigpipe() {
         assert!(signal(libc::SIGPIPE, libc::SIG_IGN) != libc::SIG_ERR);
     }
-    #[cfg(any(target_os = "emscripten", target_os="fuchsia"))]
+    #[cfg(any(target_os = "emscripten", target_os = "fuchsia"))]
     unsafe fn reset_sigpipe() {}
 }