Assigning break to a variable hits type checking errors even outside a loop

[huonw]

fn main() { let x = { break }; }

error: cannot determine a type for this local variable: unconstrained type
fn main() { let x = { break }; }
                ^~~~~~~~~~~~~

I would think this should just emit the same error as

fn main() { break }

error: `break` outside of loop

[edwardw]

This is a bit tricky. The same error is actually sensible if there is an outer loop:

fn main() { loop { let x = { break }; } }

But if rustc is to report error eagerly, it is quite the same as:

fn main() { let x = { break }; }

[alexcrichton]

Closing as working as intended.

Loop checking occurs after typechecking (and this is caught by loop checking), and typechecking is hitting the legitimate error that it's doesn't have the type of the local variable.

[huonw]

I filed this because I think that we can/should move loop checking earlier, since it gives the information about how to fix things in cases like these (a type error is useless in comparision, it's obviously 100% correct, but it doesn't pin-point the issue like the loop error does).

Is there some fundamental problem with moving error checking passes as early as is reasonable? (since this is just an AST visit with no need for any other information it move whereever.)

[alexcrichton]

Ah, ok. In that case, I do believe that loop checking can move up the chain of passes, it was quite a small file.