Add regression test for rustc/rustdoc broken pipe ICEs

src/bootstrap/src/bin/rustc.rs

@@ -136,10 +136,8 @@ fn main() {
         cmd.args(lint_flags.split_whitespace());
     }
 
-    // Conditionally pass `-Zon-broken-pipe=kill` to rustc bin shim when this shim is *not* used to
-    // build cargo itself, i.e. set `-Zon-broken-pipe=kill` only when building non-cargo tools.
-    //
-    // See <https://github.com/rust-lang/rust/issues/131059> for more context.
+    // Conditionally pass `-Zon-broken-pipe=kill` to underlying rustc. Not all binaries want
+    // `-Zon-broken-pipe=kill`, which includes cargo itself.
     if env::var_os("FORCE_ON_BROKEN_PIPE_KILL").is_some() {
         cmd.arg("-Z").arg("on-broken-pipe=kill");
     }

tests/run-make/broken-pipe-no-ice/rmake.rs

@@ -0,0 +1,42 @@
+//! Check that `rustc` and `rustdoc` does not ICE upon encountering a broken pipe due to unhandled
+//! panics from raw std `println!` usages.
+//!
+//! Regression test for <https://github.com/rust-lang/rust/issues/34376>.
+
+//@ ignore-cross-compile (needs to run test binary)
+
+#![feature(anonymous_pipe)]
+
+use std::io::Read;
+use std::process::{Command, Stdio};
+
+use run_make_support::env_var;
+
+fn check_broken_pipe_handled_gracefully(name: &str, mut cmd: Command) {
+    let (reader, writer) = std::pipe::pipe().unwrap();
+    drop(reader); // close read-end
+    cmd.stdout(writer).stderr(Stdio::piped());
+
+    let mut child = cmd.spawn().unwrap();
+
+    let mut stderr = String::new();
+    child.stderr.as_mut().unwrap().read_to_string(&mut stderr).unwrap();
+    let status = child.wait().unwrap();
+
+    assert!(!status.success(), "{name}");
+
+    const PANIC_ICE_EXIT_STATUS: i32 = 101;
+    assert_ne!(status.code(), Some(101), "{name}");
+
+    assert!(stderr.is_empty(), "{name} stderr:\n{}", stderr);
+}
+
+fn main() {
+    let mut rustc = Command::new(env_var("RUSTC"));
+    rustc.arg("--print=sysroot");
+    check_broken_pipe_handled_gracefully("rustc", rustc);
+
+    let mut rustdoc = Command::new(env_var("RUSTDOC"));
+    rustdoc.arg("--version");
+    check_broken_pipe_handled_gracefully("rustdoc", rustdoc);
+}