Issue Description:

Writing a loop like this:

repeat {
}

...will trigger a diagnostic message for the missing "while", but that message has no location:
"<unknown>:0: error: expected 'while' after body of 'repeat' statement"

In Xcode, that means the first message you see is located at the end of the scope repeat is located in, and it says: "Consecutive declarations on a line must be separated by ';'". This makes no sense to the user unless the <unknown>:0 message is seen.

I would argue that this is the most intuitive infinite loop syntax ever, so if illegal the compiler should complain properly.