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, 4 insertions, 1 deletions

diff --git a/src/rustc/rustc.rs b/src/rustc/rustc.rs
index a888838ce43..ab5a7c3f747 100644
--- a/src/rustc/rustc.rs
+++ b/src/rustc/rustc.rs
@@ -23,4 +23,7 @@ extern {}
 
 extern crate rustc_driver;
 
-fn main() { rustc_driver::main() }
+fn main() {
+    rustc_driver::set_sigpipe_handler();
+    rustc_driver::main()
+}