Cargo not passing arguments to binary

[jhod0]

The cargo run command passes arguments like 1 2 3 or <filename> to the binary, but sees flags as arguments to cargo itself.

I have a crate which produces an executable which takes flags in the form of ./<mybinary> -r 4. Executing cargo run --bin <targetname> 4 works fine, but cargo run --bin <targetname> -r 4 gives the error:

Unknown flag: '-r'

Usage
    cargo run [options] [--] [<args>...]

So, it looks like Cargo is trying to parse arguments intended for my binary. I think all arguments after --bin <targetname> should be passed straight to the executable. Arguments to cargo would then have to be before --bin.

My version info:

$ cargo --version
cargo 0.4.0-nightly (84ef25d 2015-07-23) (built 2015-07-23)

[alexcrichton]

This is part of our option parsing, you need to pass -- as a separator between the flags to your binary and the flags to Cargo. cargo run --bin foo -- -r 4 should do the trick!

[jhod0]

Ahh great that works fine. Thanks!
That might be worth an explanation in cargo help run :)

[alexcrichton]

Sounds like a reasonable idea! reopening as a docs bug to add info about -- to the cargo help page.

[ProtectedMode]

Shouldn't the usage just be changed from:
cargo run [options] [--] [<args>...]
to
cargo run [options] [-- <args>...]?

[alexcrichton]

Unfortunately that would require -- be passed 100% of the time, which we don't want to do. It's just required for flags, not necessarily for positional arguments (e.g. cargo run foo)