Is rustc --emit=<type>=<path> supported?

[pnkfelix]

There seems to be code hanging around to support a variant of --emit of the form --emit=<type>=<path>.

Its not clear what it is supposed to do.

I suspect it was meant to be a way to indicate a specific file name to use for an output (so that one could do e.g. rustc --emit asm=bar.s --emit obj foo.rs to get machine code in foo.o (inferred) and assembly in bar.s (explicitly specified).

But if that's the intention, it does not seem to work currently. (Which is fine because the option is undocumented anyway.)

[pnkfelix]

(or is it somehow meant to be used as an input filename? )

[pnkfelix]

cc @alexcrichton

[alexcrichton]

Yeah this was added recently to make dep-info emission more customizable and I tried to add some docs for it but our man pages are actually pretty rarely read I think...

We've also got what I was hoping was a pretty exhaustive test for this sort of functionality, and when I run rustc --emit asm=bar.s --emit obj foo.rs it works for me? (nightly channel right now)

When you say that it doesn't work, what sort of behavior did you see?

[pnkfelix]

@alexcrichton oh maybe I wasn't testing against nightly; let me double check

[pnkfelix]

@alexcrichton I think I know the problem: I'm using --emit=asm=bar, not --emit asm=bar

Update: /me goes off to review what getopts is specified to do in such cases

[alexcrichton]

Oh weird, I would expect getopts to consider those two equivalent... I wonder if there's a bug in getopts?

[pnkfelix]

@alexcrichton yes I think it is, I just saw something suspicious; look here:

https://github.com/rust-lang/rust/blob/master/src/libgetopts/lib.rs#L605

(I bet the split above it should be a splitn...)

---

Update:

Yeah, compare it against the version that is hosted on crates.io, which does use splitn at the analogous spot:

https://github.com/rust-lang-nursery/getopts/blob/master/src/lib.rs#L338

[alexcrichton]

Ah yep that'd do it!

[pnkfelix]

I'm cherry-picking rust-lang/getopts@8ec916b as we speak. :)