`slice()` with `String[N]` fails if the sliced region exceeds the underlying string’s actual length

[benber86]

Version Information

• vyper Version (output of vyper --version): 0.4.1
• OS: linux
• Python Version (output of python --version): 3.12

What's your issue about?

Using slice with a String[N] variable uses the string's actual length rather than the specified N.
For instance:

@view
@external
def foo() -> String[5]:
    id_label: String[78] = uint2str(123)
    short_id: String[5] = slice(id_label, 0, 5)
    return short_id

Will revert, but:

@view
@external
def foo() -> String[5]:
    id_label: String[78] = uint2str(123456)
    short_id: String[5] = slice(id_label, 0, 5)
    return short_id

will work fine.

Both use String[78] for id_label. The only difference is the runtime length: "123" vs "123456".
I'd expect in both cases slice(id_label, 0, 5) should succeed.

You could check the length and use convert but it's not great UX

[cyberthirst]

related #4345 (comment)