#14434: GHC 8.2.1 picks wrong instances with -O in a presence of an OVERLAPPABLE instance -------------------------------------+------------------------------------- Reporter: dredozubov | Owner: (none) Type: bug | Status: merge Priority: high | Milestone: 8.2.3 Component: Compiler | Version: 8.2.1 Resolution: | Keywords: Operating System: Linux | Architecture: x86_64 | (amd64) Type of failure: Incorrect result | Test Case: at runtime | typecheck/should_compile/T14434 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Changes (by simonpj): * testcase: => typecheck/should_compile/T14434 * status: new => merge Comment: Thank you for such a small repro case. Can you confirm that this patch fixes your actual application? Merge to 8.2.3 -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14434#comment:6 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler