Validate returned value usage for functions not annotated with @return

[crdev]

Here's the case:

function foo()
{
  // do something
  // do not return any value
}

function bar()
{
  console.log(1 + foo());
}

In this case, the foo() function has no @return annotation, since it does not return anything. However, it used to @return {number}, and bar() contains code relying on this. Now that foo() has been modified to not return anything, the compiler considers its return type as ? (unchecked), and hence does not detect the error in bar().

[nicks]

i think the real bug here is just that 1 + undefined should be a type error. the compiler is pretty good about figuring out when a function doesn't return anything

[crdev]

Yeah, sounds about right, but the compiler seems to skip this check...

[concavelenz]

1 - foo() produces a type error. Clearly it is being to conservation about warning about string concats.