E4115

Cannot auto-fill parameter of this type.

MoonBit supports and auto-filling SourceLoc and ArgsLoc parameters in functions. Leaving the default value of parameter of other types will result in this error.

Erroneous example

fn f(parameter~ : Int = _) -> Unit {
  // ^~~~~~~~~ Error: Cannot auto-fill parameter of type Int
}

Suggestion

Use a default value for the parameter:

fn f(parameter~ : Int = 0) -> Unit {
}