Tracking issue for reverting `cargo check` in Rust 1.15

[alexcrichton]

This is a tracking issue for the tasks to revert cargo check and --crate-type=metadata in the Rust 1.15 release branch. currently --crate-type=metadata is on the beta branch of this repository and cargo check is itself in the rust-1.15.0 branch of the Cargo repository.

Unfortunately there have been a number of bugs associated with cargo check since first implemented:

• Cargo check gives error where cargo build does not cargo#3461
• Cargo check on nightly seems to have problems with re-exported types cargo#3464
• cargo check compiles library object code if a binary exists cargo#3418
• cargo check recompiles dependencies when checking lib and bin separately cargo#3421
• cargo check fails oddly on binaries cargo#3419
• --crate-type metadata overrides binary-ness of crates #38273

All of these issues, however, should be fixed by these two changes:

• Change --crate-type metadata to --emit=metadata #38571
• Test for #3419 cargo#3426

We need to fix the issues on beta in one way or another, and today the tools team decided to go ahead and revert the changes on beta and let the bug fixes ride the trains to stable in the Rust 1.16 release. There's two things that need to happen to close out this issue:

• Don't accept --crate-type=metadata in the compiler - Remove --crate-type=metadata from beta #38668
• Remove the cargo check command from Cargo - Remove the cargo check subcommand from Rust 1.15 cargo#3465

[alexcrichton]

I'm tagging this as a regression to make sure we don't lose track of it, but to be clear there's not actually a regression here. Just want to piggy back off the processes that triage beta regressions!

[alexcrichton]

cc @nrc

[alexcrichton]

Ok, this should be done now, so closing.