Doesn't solve the problem. The same function can get called a 1000 times and take different paths each time. Which method is your hypothetical rewinding debugg

Doesn't solve the problem. The same function can get called a 1000 times and take different paths each time. Which method is your hypothetical rewinding debugger going to show? (Leaving aside the big gaping hole of how your program is executing while you are typing it out). The problem of deciding which method actually gets called by static analysis in a text editor (and it would have to be static analysis) is literally impossible for dynamic languages - pretty much by definition.