Rust does not allow trailing commas in a fn signature

[Kimundi]

I think this can be considered a bug, seeing how trailing commas generally are allowed at other places:

foo.rs:5:33: 5:34 error: unexpected token: `)`
foo.rs:5          fn foo(a: uint, b: uint,) -> uint { a + b }
                                          ^

[brson]

Yeah, it would be consistent, maybe it could useful in macros, but ... ew.

[catamorphism]

I agree with @brson 's "ew", and I would much rather declare that commas are always element separators, but I guess we should discuss. Nominating for milestone 1, well-defined.

[catamorphism]

Accepted for well-defined

[nikomatsakis]

I think it ought to be consistent. It looks ugly in that example but it is useful for macros and, if you put a and b on their own lines, for generating better diffs

[sanxiyn]

Triage. This was discussed in the meeting, and the decision was to allow trailing commas.