E3021

Compiler diagnostic name: invalid_warn_list.

Invalid warning list.

MoonBit warning lists are strings that enable or disable warnings by name or number. They are accepted in places such as the warnings field in moon.pkg and the #warnings attribute. This error happens when the warning list cannot be parsed, for example because it contains an unknown warning name or malformed syntax.

Erroneous example

#warnings("-does_not_exist")
fn f() -> Unit {
  ()
}

does_not_exist is not a known warning name.

Suggestion

Use a valid warning name or warning number. Warning names are the identifiers shown in compiler diagnostics, such as unused_value.

#warnings("-unused_value")
fn f() -> Unit {
  ()
}