#14163: Stack Overflow with ApplicativeDo -------------------------------------+------------------------------------- Reporter: lippling | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 Keywords: | Operating System: MacOS X Architecture: x86_64 | Type of failure: Compile-time (amd64) | crash or panic Test Case: | Blocked By: Blocking: | Related Tickets: Differential Rev(s): | Wiki Page: -------------------------------------+------------------------------------- I tried to compile one of our server applications with 8.2.1 (which compiles fine with 8.0.2). The compilation runs smooth, but when it reaches a specific file, the RAM usage goes up to > 20GB pretty fast on my 16GB machine and the GHC process gets terminated with a stack overflow error. I tried to find a minimal example that causes this behavior: {{{ #!/usr/bin/env stack -- stack --resolver nightly-2017-08-25 script {-# LANGUAGE ApplicativeDo #-} x = do (a, _) <- undefined (b, _) <- undefined (c, _) <- undefined undefined main = undefined }}} It only happens with at least 3 of these pattern matches. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14163 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler