confusing left shift error

[nektro]

Zig Version

0.11.0-dev.1+841235b3f

Steps to Reproduce and Observed Behavior

const std = @import("std");

test {
    try std.testing.expect(init(.constructed, .context) == 0b10100000);
}

fn init(pc: enum(u1) { primitive, constructed }, class: enum(u2) { universal, application, context, private }) u8 {
    var res: u8 = 0;
    res |= (@enumToInt(pc) << 5);
    res |= (@enumToInt(class) << 6);
    return res;
}

a.zig:9:31: error: type 'u0' cannot represent integer value '5'
    res |= (@enumToInt(pc) << 5);
                              ^

Expected Behavior

successful compile or error about u1/u2 not having enough space to shift 5/6 spaces respectively