Can't use where clauses with tuple structs

[japaric]

STR

// OK
struct Bar<T> where T: Copy {
    inner: T,
}

// Is this the right syntax?
struct Foo<T>(T) where T: Copy;  //~ error: expected `;`, found `where`

fn main() {}

Version

rustc 0.12.0-dev (10fc25a39 2014-10-09 16:04:25 -0500)

(PR 17669 on top of b08ecf7)

[ftxqxd]

struct Foo<T> where T: Copy, (T);

seems to work. However, the syntax is awful, and requires a comma for disambiguation.

[japaric]

struct Foo<T> where T: Copy, (T);  //~ error: unexpected token in `where` clause

@P1start As of today nightly, that doesn't work anymore.

@nikomatsakis It seems that where clauses don't work with tuple structs anymore. Any plans to support them in the future?

[jroesch]

@nikomatsakis is this the desired syntax? I'm assuming it was chosen in order to do some kind of parsing disambiguation. I am willing to submit a small patch for this, just want clarification on the syntax.

[nikomatsakis]

hmm afaik they should work, and I would expect the syntax to be struct Foo<...>(...) where ...

[jroesch]

I will track this one down and follow up with a PR.

[sfackler]

You can get the current syntax to compile if the generic type bound uses the Fn trait sugar:

struct Foo<T> where T: Fn() (T);

Nominating, since we won't be able to move the where clause to after the tuple after 1.0 without breakage.