Slice notation with negative indices

[lovasoa]

fn main() {
    let a = "haha";
    println!("Nope. {}", a[1..-1]);
}

Compilation succeeds without any warning.
-1 is silently converted to an unsigned int, and I get an executable that panics with index 1 and/or 18446744073709551615 inhahado not lie on character boundary

I think there should be a compilation warning or error.

[thestinger]

-1 is not silently converted to an unsigned integer. Rust's integer literals are generic and - is not included in the literal grammar. The 1 is inferred as a uint literal, and our unsigned integers provide an implementation of the - operator. Removing the - operator or warning when it's used with unsigned integers would need to go through the RFC process.

[thestinger]

I don't think it's a great idea to have an - implementation for unsigned integers, but that isn't the existing consensus.

[lovasoa]

OK, I did not understand that.
But still, in this case, the compiler knows the size of the string. Couldn't we get a warning?

[xor2k]

I use this feature in Python a lot. The difference is: does one want to write the name of a variable a second time just to access it's tail? For short demos, it's okay, but for meaningful, not super-short variable names it gets annoying. Example: instead of

    let some_array_with_non_short_name = [1, 2, 3, 4, 5];

    let nice_slice = &some_array_with_non_short_name[1..some_array_with_non_short_name.len()-1];

one would have

    let some_array_with_non_short_name = [1, 2, 3, 4, 5];

    let nice_slice = &some_array_with_non_short_name[1..-1];

Is there something I'm missing out on? Can this be implemented without a great runtime impact?