Stacktrace column numbers and special characters

[jensjoha]

Say I have this code:

main(List<String> args) {
  /*𝄞𝄞𝄞𝄞𝄞𝄞𝄞𝄞𝄞𝄞*/throw "Lalala";
}

'throw' basically starts at column 17, so I would expect the stacktrace to contain "2:17".
"𝄞" is 4-bytes, and it seems to count as 2 characters though, so instead I get the stacktrace "2:27".

This is the case in the dart VM both with and without kernel.

[sivachandra]

I will take this for now as I am in the area.

[jensjoha]

#28404
(which includes links like
https://manishearth.github.io/blog/2017/01/14/stop-ascribing-meaning-to-unicode-code-points/
https://www.mikeash.com/pyblog/friday-qa-2015-11-06-why-is-swifts-string-api-so-hard.html
)

There might be no good solution...