#14218: GHC.Stack.HasCallStack not compatible with constraint synonyms -------------------------------------+------------------------------------- Reporter: ntc2 | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 8.2.1 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 gridaphobe): Oh dear.. Ben's explanation sounds plausible to me, though I didn't realize constraint synonyms worked this way. I would have expected them to be transparent to GHC like regular type synonyms, i.e. the `C` constraint would be expanded and we'd get two separate dictionaries rather than a compound dictionary. If this is actually how constraint synonyms work, a simple fix could be to expand them and treat the member constraints individually. But maybe there's a good reason for the current behavior? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/14218#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler