Support `#[unix_sigpipe = "inherit|sig_dfl|sig_ign"]` on `fn main()`

This makes it possible to instruct libstd to never touch the signal
handler for `SIGPIPE`, which makes programs pipeable by default (e.g.
with `./your-program | head -n 1`) without `ErrorKind::BrokenPipe`
errors.

1 files changed, 6 insertions, 0 deletions

diff --git a/src/test/ui/attributes/unix_sigpipe/unix_sigpipe-struct.rs b/src/test/ui/attributes/unix_sigpipe/unix_sigpipe-struct.rs
new file mode 100644
index 00000000000..a5e47cfebc8
--- /dev/null
+++ b/src/test/ui/attributes/unix_sigpipe/unix_sigpipe-struct.rs
@@ -0,0 +1,6 @@
+#![feature(unix_sigpipe)]
+
+#[unix_sigpipe = "inherit"] //~ error: `unix_sigpipe` attribute can only be used on `fn main()`
+struct S;
+
+fn main() {}