[GHC] #12096: Attach stacktrace information to SomeException

[GHC]

#12096: Attach stacktrace information to SomeException
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        Reporter:  ndtimofeev        |                Owner:  (none)
            Type:  feature request   |               Status:  new
        Priority:  normal            |            Milestone:
       Component:  Core Libraries    |              Version:  8.0.1
      Resolution:                    |             Keywords:
Operating System:  Unknown/Multiple  |         Architecture:
                                     |  Unknown/Multiple
 Type of failure:  None/Unknown      |            Test Case:
      Blocked By:                    |             Blocking:
 Related Tickets:                    |  Differential Rev(s):
       Wiki Page:                    |
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Comment (by ezyang):

 So, in my head, I want to minimize the amount of changes to code necessary
 to take advantage of call stacks. Adding CallStacks to each of the
 exception types individually means that you have to modify each exception
 type to contain a CallStack (so, linear in the number of exception types.)
 Creating a new `SomeExceptionWithCallStack` means that we have to modify
 all occurrences of catch-rethrow to preserve call stacks (so, linear in
 the number of catch-rethrows in code everywhere.)

 I admit that there is a tradeoff here, but the benefits of
 `SomeExceptionWithCallStack` don't make sense to me. I imagine there are a
 lot more catch-rethrows than there are exception types, and you will have
 to go through and fix each one of them. Admittedly, if you get a call
 stack that is missing info you need, it shouldn't be hard to track down
 (since the error will have the call stack of the bad rethrow attached :)
 Perhaps I am not seeing some other hidden costs?

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Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12096#comment:8>
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