tree 40bee7585c64f87b825218e8df1f09badee0ef7d
parent 90f8d9b44700c4c4017355cab97788f262e7f9fd
author Patrick Williams <patrick@stwcx.xyz> 1683581549 -0500
committer Patrick Williams <patrick@stwcx.xyz> 1683658604 +0000

async: scope: forward exception correctly

There were test cases to cover an unhandled exception thrown by a
spawned task in the async::context, but I observed some cases where
this exception was silently dropped.  The test cases only covered
spawned Senders and not spawned Coroutines.  The underlying cause
of this was that in some cases the exception was deleted prior to
it being forwarded along to the async::context's scope.

When a task completes in the async::scope, the operational state
holding the task has to be deleted.  There needs to be a careful
handshake to be able to trigger the scope while at the same time
deleting the object which is being executed (the scope_receiver),
so that there is not a memory leak.  As part of this, if the task
completed with an unhandled exception, the complete function is
suppose to forward the exception to the scope.  It is quite likely
that the exception is actually held by the operational state of the
task, which is going to be deleted prior to triggering the scope, so
we need to save this exception prior to the deletion.

Add a specific test case to cover the throwing coroutine, which
failed prior to this fix.

Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
Change-Id: I7e24529a724c3338b6e155ba0a9b4220e1d2fa50