It's only necessary in edge cases of super-hot code, avoiding argument adaptation "because performance" is a bad idea.
It's also a v8 specific weakness, it's not hard to imagine a small fix getting rid of the performance penalty.
It's also a v8 specific weakness, it's not hard to imagine a small fix getting rid of the performance penalty.
So in Rust you would be forced to write it the way you consider to be "bad idea".
Many people think that default function arguments are a bad idea and languages like Rust or C or Go or Java don't even have them.