You're not wrong about the halting problem, but the reality is that most people do simple things that the IDE can extract a lot of information about. I.e. it do

You're not wrong about the halting problem, but the reality is that most people do simple things that the IDE can extract a lot of information about. I.e. it doesn't have to understand a function to make the function fireable from a GUI button, and that is still actually quite useful.