Better error message for incorrect struct construction syntax.

[dylanbraithwaite]

If a type parametrized struct is constructed with the parameter in the type name, the error produced is not relevant to the actual problem:

struct MyStruct<T> { my_field : T}

followed by:

let struct_instance = MyStruct<int> { my_field : 42}

Will produce the error:

error: expected one of `;`, `}` but found `:`
    let struct_instance = MyStruct<int>{my_field : 42};
                                                 ^

Which does not indicate that the error is due to the inclusion of '<int>' after the struct's name.

[jdm]

The problem is that the code is being interpreted like this:
let struct_instance = (MyStruct < int) > { my_field, ie. parsing MyStruct, int, and my_field as expression names, and the : is a parse error while try to parse a { expr } expression.

[bombless]

struct MyStruct<T> { my_field : T}
fn main() {
    let x = MyStruct<i32> { my_field: 42 };
}

<anon>:3:21: 3:26 error: chained comparison operators require parentheses
<anon>:3     let x = MyStruct<i32> { my_field: 42 };
                             ^~~~~
<anon>:3:26: 3:26 help: use `::<...>` instead of `<...>` if you meant to specify type arguments
<anon>:3:37: 3:38 error: expected one of `!`, `.`, `::`, `;`, `{`, `}`, or an operator, found `:`
<anon>:3     let x = MyStruct<i32> { my_field: 42 };
                                             ^

I believe current error message for this is quite good-looking, so I think it's safe to say this issue has been fixed.

[dylanbraithwaite]

Yes, that certainly is a lot better. I guess I can close this now.