1fn foo() [:0]u8 {
 2    const x: []u8 = undefined;
 3    return x;
 4}
 5comptime {
 6    _ = &foo;
 7}
 8
 9// error
10//
11// :3:12: error: expected type '[:0]u8', found '[]u8'
12// :3:12: note: destination pointer requires '0' sentinel
13// :1:10: note: function return type declared here