Re: [GHC] #15321: Typed holes in Template Haskell splices produce bewildering error messages

#15321: Typed holes in Template Haskell splices produce bewildering error messages -------------------------------------+------------------------------------- Reporter: RyanGlScott | Owner: (none) Type: bug | Status: patch Priority: normal | Milestone: 8.6.1 Component: Template Haskell | Version: 8.4.3 Resolution: | Keywords: TypedHoles Operating System: Unknown/Multiple | Architecture: Type of failure: Poor/confusing | Unknown/Multiple error message | Test Case: Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Phab:D4909 Wiki Page: | -------------------------------------+------------------------------------- Comment (by Ömer Sinan Ağacan ): In [changeset:"39de4e3d33dd9879398062620ad00b1e3b8481ce/ghc" 39de4e3d/ghc]: {{{ #!CommitTicketReference repository="ghc" revision="39de4e3d33dd9879398062620ad00b1e3b8481ce" Fix errors caused by invalid candidates leaking from hole fits This is a one line fix (and a note) that fixes four tickets, #15007, #15321 and #15202, #15314 The issue was that errors caused by illegal candidates (according to GHC stage or being internal names) were leaking to the user, causing bewildering error messages. If a candidate causes the type checker to error, it is not a valid hole fit, and should be discarded. As mentioned in #15321, this can cause a pattern of omissions, which might be hard to discover. A better approach would be to gather the error messages, and ask users to report them as GHC bugs. This will be implemented in a subsequent change. Reviewers: bgamari, simonpj Reviewed By: simonpj Subscribers: simonpj, rwbarton, thomie, carter GHC Trac Issues: #15007, #15321, #15202, #15314 Differential Revision: https://phabricator.haskell.org/D4909 }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15321#comment:13 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler