#12175: Instance resolution regression -------------------------------------+------------------------------------- Reporter: crockeea | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.0.1 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: Type of failure: GHC rejects | Unknown/Multiple valid program | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by Simon Peyton Jones <simonpj@…>): In [changeset:"ce97b7298d54bdfccd9dcf366a69c5617b4eb43f/ghc" ce97b72/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="ce97b7298d54bdfccd9dcf366a69c5617b4eb43f" Expand given superclasses more eagerly This patch fixes Trac #12175, another delicate corner case of Note [Instance and Given overlap] in TcInteract. In #12175 we were not expanding given superclasses eagerly enough. It was easy to fix, and is actually rather neater than before. See Note [Eagerly expand given superclasses] in TcCanonical. The main change is to move the eager expansion of given superclasses to canClassNC. }}} -- Ticket URL: <http://ghc.haskell.org/trac/ghc/ticket/12175#comment:1> GHC <http://www.haskell.org/ghc/> The Glasgow Haskell Compiler