int foo()
{
   scope(failure) return 22;
   throw new Exception("E");
}

unittest
{
   assert(foo() == 22);
}

Is this defined behavior? At least in x64 dmd the exception is swallowed and the assert evaluates to true.

In any case what should happen? Should the method return or should the exception be propagated up the callstack?

On Saturday, 28 December 2013 at 20:31:14 UTC, TheFlyingFiddle wrote:
> int foo()
> {
>    scope(failure) return 22;
>    throw new Exception("E");
> }
>
> unittest
> {
>    assert(foo() == 22);
> }
>
> Is this defined behavior? At least in x64 dmd the exception is swallowed and the assert evaluates to true.
>
> In any case what should happen? Should the method return or should the exception be propagated up the callstack?

It's rewritten as follows:

int foo()
{
   try {
      throw new Exception("E");
   } catch (Exception e) { // or whatever the D syntax is, I never used it
      return 22;
   }
}

So yes, it's intended. scope(exit) uses finally instead of catch.

On 12/28/2013 12:50 PM, "Casper Færgemand" <shorttail@hotmail.com>" wrote:

> On Saturday, 28 December 2013 at 20:31:14 UTC, TheFlyingFiddle wrote:
>> int foo()
>> {
>>    scope(failure) return 22;
>>    throw new Exception("E");
>> }
>>
>> unittest
>> {
>>    assert(foo() == 22);
>> }
>>
>> Is this defined behavior? At least in x64 dmd the exception is
>> swallowed and the assert evaluates to true.
>>
>> In any case what should happen? Should the method return or should the
>> exception be propagated up the callstack?
>
> It's rewritten as follows:
>
> int foo()
> {
>     try {
>        throw new Exception("E");
>     } catch (Exception e) { // or whatever the D syntax is, I never used it
>        return 22;

There must also be the re-throwing of the caught exception:

         throw e;

What happens is, the return statement does not allow that to happen.

>     }
> }
>
> So yes, it's intended. scope(exit) uses finally instead of catch.

The spec brings restrictions to scope(exit) and scope(success) but does not say much about scope(failure):

  http://dlang.org/statement.html#ScopeGuardStatement

Yeah, it appears that OP's code is legal.

Ali