Control can reach the end of non-void functions

[elliottt]

There's not currently a way to enforce that code paths terminate in a use of ret or retVoid in a proc. It's not clear if there's a way to do this, but a good example of the problem is this:

test = proc "test" $ body $ (ifte_ false (ret true) (return ()))

This will typecheck and generate code, though the generated C will include a path that would return no value, and generate a warning.

[leepike]

The type-checking pass over the AST now catches this. The following warnings and errors are produced from compiling the above function:

*** procedure/area test WARNING: One branch of an if-then-else statement contains a return statement. Statements after the if-the-else block are not reachable on all control paths.
*** procedure/area test ERROR: No return statement and procedure has a non-void type.
*** Exception: There were type-checking errors.