Nim: Bad line info in async code

[dom96]

import asyncdispatch

proc bar(): Future[string] {.async.} =
  await sleepAsync(100)
  if true:

    raise newException(OSError, "hall")

proc foo(): Future[string] {.async.} = return await bar()

echo waitFor(foo())

Results in:

a2.nim(11)               a2
asyncdispatch.nim(1204)  waitFor
asyncdispatch.nim(1253)  poll
asyncdispatch.nim(181)   processPendingCallbacks
asyncmacro.nim(34)       cb0
a2.nim(7)                barIter
[[reraised from:
a2.nim(11)               a2
asyncdispatch.nim(1204)  waitFor
asyncdispatch.nim(1253)  poll
asyncdispatch.nim(181)   processPendingCallbacks
asyncmacro.nim(34)       cb0
asyncmacro.nim           fooIter
asyncfutures.nim(311)    read
]]
[[reraised from:
a2.nim(11)               a2
asyncdispatch.nim(1612)  waitFor
asyncfutures.nim(311)    read
]]
Error: unhandled exception:
Async traceback
---------------
a2.nim(11)              a2
asyncdispatch.nim(1204) waitFor
asyncdispatch.nim(1253) poll
asyncdispatch.nim(181)  processPendingCallbacks
asyncmacro.nim(34)      cb0
a2.nim(7)               barIter
Exception message: hall

Definitely different on devel (I'm working on improving async stack traces).

Note the asyncdispatch.nim(1204) waitFor, it points to the proc poll definition.

This is likely related to #5617.

[endragor]

This issue makes it very hard to dig into problems we encounter in production logs. Is it hard to fix?

[yglukhov]

I was planning to look into async stack traces after #7770 is merged, asyncmacro is simplified and await turned to a template.