#11555: catch _|_ breaks at -O1 -------------------------------------+------------------------------------- Reporter: slyfox | Owner: Type: bug | Status: patch Priority: highest | Milestone: 8.0.1 Component: Compiler | Version: 8.0.1-rc2 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: Incorrect result | Unknown/Multiple at runtime | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D1973 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"4c3a0a4a7b999251cbbee00befbfe32b86e556e2/ghc" 4c3a0a4a/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="4c3a0a4a7b999251cbbee00befbfe32b86e556e2" Fix the implementation of lazyId 'lazy' was doing part of its job, but not all! In particular, an application f (lazy e) where f is strict, was still being compiled using call-by-value in CorePrep. This defeated the purpose of defining catch as catch a b = catch# (lazy a) b See Trac #11555, and Neil Mitchell's test case in comment:14 This patch makes 'lazy' behave properly. I updated Note [lazyId magic] in MkId, but all the action is in CorePrep. I can't say I really like this, but it does the job. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/11555#comment:17> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler