E4205

Compiler diagnostic name: regex_map_key_not_supported.

Regex literal is not supported as a map key.

Map literals require ordinary key values. A re"..." literal creates a Regex, and regex values are not valid map keys.

Erroneous example

fn build_map() -> Unit {
  let _ = { re"a+": 1, "b": 2 }
}

Suggestion

Use a string key if you want to store the pattern text, or store regex values as map values instead of keys.

fn build_map() -> Unit {
  let _ = { "a+": 1, "b": 2 }
}