SourceKit get 2D character indices (instead of byte indices)

[taylorswift]

@akyrtzi

This is not how it works, the swift compiler internally accepts a UTF8 string for the source buffer and then only deals with byte offsets. For example, even the (line:column) pairs you see in the diagnostics that the compiler emits are actually (line:"UTF8 byte offset from the start of the line") pairs. The notion of character indices doesn't exist internally.

hmm. that’s discouraging. I guess we have to do grapheme breaking in the highlighter then.