abs doesn't work on tuple with implicit i32 element

[RazerM]

I asked a question on #rust-beginners and it was suggested to make a bug report.

fn main() {
    let implicit = (3, 4);
    let explicit: (i32, i32) = (3, 4);
    let _ = implicit.0.abs(); // fails
    let _ = explicit.0.abs(); // works
}

Playground

[Havvy]

The reference currently states in tokens:

• If an integer type can be uniquely determined from the surrounding program context, the unsuffixed integer literal has that type.
• If the program context under-constrains the type, it defaults to the signed 32-bit integer i32.
• If the program context over-constrains the type, it is considered a static type error.

Whereas this example shows that even though it must be i32 by default, the abs method cannot figure it out. This may also be a part of the method call operator — does it happen anywhere else?

[madsmtm]

This is not tied to tuples:

fn main() {
    let implicit = 3;
    let explicit: i32 = 3;
    let _ = implicit.abs(); // fails
    let _ = explicit.abs(); // works
}

And the error is considered a bug in rustc, see rust-lang/rust#24124, so I don't think the reference has to document anything here.