Block label can't be used on switch

[rgreenblatt]

EDITED:

pub fn main() void {
    var k : i32 = 0;
    var s : i32 = 1;
    const v = switch (s) blk: {
        1 => {
            if (k == 0) {
                break :blk 8;
            }
            // some code here...
            //
            break :blk 2;
        },
        // another case
        2 => {
            if (k == 2) {
                break :blk 8;
            }
            // some code here...
            //
            break :blk 2;
        },
        else => 9,
    };
}

https://zig.godbolt.org/z/K76eae

[SpexGuy]

That isn't a normal block, it wouldn't make sense to break it. What do you expect this to do?

[rgreenblatt]

That isn't a normal block, it wouldn't make sense to break it. What do you expect this to do?

I've edited my post to show a better example. It would basically be a shorthand for labeling all of the cases.

[SpexGuy]

Hmm, so this would be a workaround:

    const v = blk: {
      break :blk switch (s) {
        ...
      }
    };

I do think we could potentially allow blk: switch (s) { ... }, similar to labeled for and while expressions. But IMO it's weird to allow labeling the switch scope itself, since it's not an expression. It feels the same to me as allowing one of these things:

const x = switch (y) y;
const T = struct blk: { f: usize };
const v = T blk: { .f = 4 };
fn foo() T blk: {}

[Mouvedia]

I do think we could potentially allow blk: switch (s) { ... },

Are you talking about #8220?

[andrewrk]

Superseded by #8220 which does incorporate this use case.