E0005; should all constructors be listed?

[Centril]

See #56362 (comment) for context.

cc @estebank @petrochenkov @varkor

[estebank]

Maybe we could do that with an upper bound, as having more than ~3 listed ranges will get really noisy. Imagine if you had a check for every other integer in u16, you'd have 32K ranges! I'd be fine with it as long as this is handled gracefully.

It'll also be nice to mention when a range between two values involves std::{integer}::MAX or MIN.

[Centril]

@estebank Yeah an upper bound makes sense.

[varkor]

It'll also be nice to mention when a range between two values involves std::{integer}::MAX or MIN.

Yeah, this was a case I was thinking about too — it'll probably be fairly common case, so it'd be good to handle sensibly.

Edit: I've filed #56393 for this specific suggestion.

[estebank]

@Centril is there still work left to do on this front?

[varkor]

The match algorithm still short-circuits and reports only the first unencountered constructor in some cases. You can see this in some of the test cases for #65160, for instance.

[Nadrieril]

Couldn't find an example with missing integer ranges like the one mentioned in the OP; I suspect we've fixed those. Here's a different one (play):

enum Foo {
    A(bool),
    B(bool),
    C(bool),
}
fn main() {
    match Foo::A(true) {
        Foo::A(true) => {},
        Foo::B(true) => {},
        Foo::C(true) => {},
    }
}

This only errors about A(false) not being covered.

I'm adding my favorite label so I can find this later.
@rustbot modify labels: +A-exhaustiveness-checking