#11970: Simplify Parent for patten synonyms -------------------------------------+------------------------------------- Reporter: simonpj | Owner: mpickering Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.10.3 Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: None/Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by mpickering): I have looked a bit at this. The problem from last time is that when renaming exports we need to reject data constructors if they are exported with a type constructor which is not their parent. This is how the code was structured before my changes. 1. `tcg_rdr_env` is converted into a `kids_env` which is a map from `NameEnv [GlobalRdrElt]`. The intention of this map that we can lookup a type constructor and find which data constructors are allowed to be bundled with it. 2. `lookupChildren` uses this map to check that all bundled constructors are with the correct type constructor. The problem which I ran into was that as we only have `GlobalRdrElt`s, at this stage I couldn't see a way of telling whether a certain `GlobalRdrElt` arose from a data constructor or a pattern synonym. It seemed to me that the sole purpose of the `Parent` datatype was to indicate when it should be allowed to export an identifier with a certain type constructor (its parent). Because of this, I made the necessary changes to `Parent` to indicate whether a `GRE` arose from a pattern synonyn. Do you see a better way of structuring this? Unless it is possible to distinguish between a pattern synonym and a data constructor at this point then it isn't safe to ignore an entry in the export list as it might be a data constructor which we are not allowed to export with that type constructor. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/11970#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler