use Enum::* confuses type inference

[kornelski]

enum Enum {
    Bar(u32)
}

fn main() {
    let e = Enum::Bar(1);
    use Enum::*;
    match e {
        Bar(_i_am_unknown) => {}
        Enum::Bar(_works_fine) => {}
    }
}

In vscode hint for _i_am_unknown is {unknown} | u32. The _works_fine variable gets u32 | u32 hint. The {unknown} variable doesn't get type-based autocomplete, etc.

[lnicola]

Duplicate of #1165.