[Cargo run] passing arguments to the binary works unexpectedly

[JanLikar]

I'm trying to pass arguments to a binary that then passes arguments after -- to another binary.

`jan@hp:~/Projekti/rustfmt$ cargo run --bin cargo-fmt -- -- --write-mode=diff
Running `target/debug/cargo-fmt --write-mode=diff`

I would expect cargo to run target/debug/cargo-fmt -- --write-mode

[alexcrichton]

Huh, I thought this was a fixed bug...

cc @BurntSushi

[BurntSushi]

I would have thought so too given this test. There might be something else going on with two uses of --. I'll dig into this soon.

[JanLikar]

I have additional info: If a flag is passed to both binaries, it works just as expected, if a flag is passed only to the "final" binary, it doesn't work.

[carols10cents]

Triage: this is still a problem as far as I can tell.

 $ cargo new --bin foo
     Created binary (application) `foo` project
$ cd foo/
$ mkdir src/bin
$ mv src/main.rs src/bin/
$ cargo run --bin main  -- -- --write-mode=diff
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/main --write-mode=diff`

and the last line should instead say:

     Running `target/debug/main -- --write-mode=diff`

[arcuru]

This appears to be fixed in the latest nightly but not yet in stable.

Using @carols10cents repro steps:

$ cargo --version
cargo 0.26.0 (41480f5cc 2018-02-26)
$ cargo run --bin main  -- -- --write-mode=diff
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
      Running `target/debug/main --write-mode=diff`
$ rustup default nightly
$ cargo --version
cargo 1.27.0-nightly (0a1add2d8 2018-04-20)
$ cargo run --bin main  -- -- --write-mode=diff
    Finished dev [unoptimized + debuginfo] target(s) in 0.0 secs
      Running `target/debug/main -- --write-mode=diff`

[matklad]

@patricksjackson indeed!

I've added a test for this in #5429