Unable to upgrade binaries installed via cargo

[keyneston]

I noticed there was a new version of rustfmt out and decided to upgrade. When I ran cargo install to update it I got an error about rustfmt already being installed. So I start looking through the --help output and can't find a --upgrade flag of any sort.

I was able to fix my issue by running cargo install cargo to get to cargo 0.8 and then ~/.cargo/bin/cargo uninstall rustfmt && cargo install rustfmt but it should be easier than this. If no one objects I'd like to add an --upgrade flag to cargo. Does adding new flags require an RFC?

Output

[I] Aldgate ~$ cargo install rustfmt
    Updating registry `https://github.com/rust-lang/crates.io-index`
 Downloading rustfmt v0.3.0
binary `cargo-fmt` already exists in destination as part of `rustfmt v0.2.1`

Cargo Version

[I] Aldgate ~$ which cargo && cargo version
/usr/local/bin/cargo
cargo 0.7.0 (1af03be 2015-12-08)

[steveklabnik]

Yes, you have to uninstall and then install.

I think there's another bug for this open...

[alexcrichton]

We do indeed have an issue for this! I'm gonna close this as a dupe of #2082, but as @steveklabnik you'll just need to uninstall and then reinstall for now