#12489: undefined in view pattern inside pattern synonym causes GHC to panic -------------------------------------+------------------------------------- Reporter: pkmx | Owner: Type: bug | Status: merge Priority: normal | Milestone: Component: Compiler | Version: 8.1 Resolution: | Keywords: | PatternSynonyms Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Compile-time | Test Case: crash | patsyn/should_compile/T12489 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ben Gamari <ben@…>): In [changeset:"829b9682969a5dabd3a75b82864c48c2e6a19ee8/ghc" 829b9682/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="829b9682969a5dabd3a75b82864c48c2e6a19ee8" Keep the bindings local during defaultCallStacks defaultCallStacks generates evidence bindings for call stacks, but wasn't setting the binding site correctly. As a result they were simply discarded in the case of pattern synonyms, giving rise to Trac #12489. The fix is easy; and I added an ASSERT to catch the error earlier. (cherry picked from commit f352e5cd7bb629fe0ca3b913bfbe7bee43d62f3a) }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12489#comment:5> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler