Integer overflow with custom integer in Zig

integer_overflow.zig

//! Integer overflow with custom int in Zig
//! build and run with:
//! zig build-exe integer_overflow.zig && ./integer_overflow
const std = @import("std");

pub fn main() void {
    std.log.info("unsigned int (primitive type) [0, 7)", .{});
    // usize is an unsigned pointer sized integer. See also: https://github.com/ziglang/zig/issues/5185
    // usize is a primitive type:
    // https://ziglang.org/documentation/master/#Primitive-Types
    for (0..8) |i| {
        std.log.debug("i: {}", .{i});
    }

    std.log.info("unsigned int (custom type) [0, 7)", .{});
    // u3 is NOT a primitive type. It is a custom type.
    var j: u3 = 0;
    while (j < 7) : (j += 1) {
        std.log.debug("j: {}", .{j});
    }

    std.log.info("unsigned int (custom type, overflow) [0, 7)", .{});
    // overflow when k is 7 (111) and gets incremented to 8
    var k: u3 = 0;
    while (k < 8) : (k += 1) {
        std.log.debug("k: {}", .{k});
    }
}