my_hat_stinks

Compiler optimisations don’t apply when you’re breaking the rules of the language. It won’t compile.

That’s because they’re not necessarily mutually exclusive. The function is being called twice so there’s no way to guarantee the result will be the same both times without knowing what it does under the hood.

Consider a case where isalpha performs a coin flip, 50% chance each call to return true. The first call returns false so the first condition fails, then the second call returns true so the second condition fails; in 25% of cases neither code block executes.

You could store the result of the first call in a local variable and reuse it if you really wanted to, but the smart solution is to either use if/else properly or switch to early returns instead.