#14171: STM causes program to suddenly exit ----------------------------------+---------------------------------------- Reporter: MichaelBurge | Owner: bgamari Type: bug | Status: new Priority: highest | Milestone: Component: libraries/stm | Version: 8.2.1 Resolution: | Keywords: Operating System: Linux | Architecture: Unknown/Multiple Type of failure: Runtime crash | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | ----------------------------------+---------------------------------------- Comment (by bgamari): I think I see what is going on here: `postProcessDmdResult` looks only for `ThrowsExn` `DmdResult` when computing termination, {{{#!hs postProcessDmdResult :: Str () -> DmdResult -> DmdResult postProcessDmdResult Lazy _ = topRes postProcessDmdResult (Str ExnStr _) ThrowsExn = topRes -- Key point! postProcessDmdResult _ res = res }}} However, the demand being analysed here is `Diverges`, not `ThrowsExn` (again, due to the use of `retry#`). One "solution" here is, {{{#!patch diff --git a/compiler/basicTypes/Demand.hs b/compiler/basicTypes/Demand.hs index dfff0a2c92..f56d28c4a9 100644 --- a/compiler/basicTypes/Demand.hs +++ b/compiler/basicTypes/Demand.hs @@ -1440,6 +1441,7 @@ postProcessDmdType du@(JD { sd = ss }) (DmdType fv _ res_ty) postProcessDmdResult :: Str () -> DmdResult -> DmdResult postProcessDmdResult Lazy _ = topRes postProcessDmdResult (Str ExnStr _) ThrowsExn = topRes -- Key point! +postProcessDmdResult (Str ExnStr _) Diverges = topRes -- Key point! postProcessDmdResult _ res = res }}} This allows the program malfunctioning in this ticket to run as expected. However, it's not clear to me that this is correct: the `ThrowsExn`/`Diverges` distinction isn't defined in the original demand analysis paper nor any of the later papers that I have found. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14171#comment:4 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler