rustc on error always prints the same two "task failed" lines

[ben0x539]

task '<unnamed>' failed at 'explicit failure', /build/rust-git/src/rust/src/libsyntax/diagnostic.rs:101
task '<unnamed>' failed at 'explicit failure', /build/rust-git/src/rust/src/librustc/rustc.rs:395

It's more messy than informative, isn't it?

This might go away when rustc stops unwinding and just aborts, but I wonder whether we oughtn't have some way to suppress those messages, since I imagine a lot of commandliney programs that use unwinding won't want to expose their internal task failures to the console, unless they're tearing down the entire runtime with linked failure.

[alexcrichton]

This is actually a general problem in that when a task fails it will forcibly log the error to the task's logger. With #9967 coming down the pipe soon, I believe that the way forward with this is to have the message get propagated to the parent who then decides what to do with it.

For rustc specifically, all of the monitored tasks wouldn't print their failure, the parents would receive the failure and then just ignore it (or print the ICE message).

[ben0x539]

I don't think this is an issue anymore.