Extract libcore benchmarks to a separate crate

[phungleson]

When looking though libcore I saw this

https://github.com/rust-lang/rust/blob/master/src/libcore/Cargo.toml#L16-L19

So just want to check if the task is about:

1. Create libcorebench in src
2. Move all #[bench] from libcoretest to libcorebench like this one

https://github.com/rust-lang/rust/blob/master/src/libcoretest/any.rs#L128

If it is I can give it a try, thanks

[alexcrichton]

@phungleson yeah that should do the trick! I think that you can avoid a whole new directory even, but could have something like src/libcore/bench/*.rs and then that could get pulled in the Cargo.toml

The same thing applies to libcollections, too: benchmarks should be moved into libcollectionsbench (or libcollections/bench).

[est31]

I've recently been wondering what the reason behind that was. Any ideas? Any links to previous discussion?

[alexcrichton]

@est31 in general compiling libcore with --test literally is a huge PITA because there's so many intermixed types. The "foreign" libcore (one linked by libtest) duplicates the local libcore (the one being compiled with --test) and it's very difficult to keep the types straight, especially for standard traits.

It ended up being easier to do everything out of the library

[est31]

@alexcrichton thanks!