Renaming a struct field should rename variables that destructure the field

[jyn514]

The title is not as clear as it could be - here's an example:

        let Item { attrs, name, source, visibility, def_id, inner, stability, deprecation } = item;

When I rename inner to kind, I expect this to be changed to

        let Item { attrs, name, source, visibility, def_id, kind, stability, deprecation } = item;

and all usages of inner in this scope updated. Instead, rust-analyzer changes it to

        let Item { attrs, name, source, visibility, def_id, kind: inner, stability, deprecation } = item;

which is not super helpful and messes up rustfmt.

[bjorn3]

This may not be the best idea in the general case. For example:

enum Foo {
    A { bar: u8 },
    B { bar: u8 },
}

let a: Foo = todo!();
match a {
    Foo::A { bar } | Foo::B { bar } => {
        std::mem::drop(bar);
    }
}

If you were to rename the bar in Foo::A { bar } then this would cause the result to be:

enum Foo {
    A { baz: u8 },
    B { bar: u8 },
}

let a: Foo = todo!();
match a {
    Foo::A { baz } | Foo::B { bar: baz } => {
        std::mem::drop(baz);
    }
}

[jyn514]

Sure - maybe 'rename variables that destructure the field when all types/variants in the match are the same'? I think the common case is useful though.