#15043: Expand type synonym -------------------------------------+------------------------------------- Reporter: domenkozar | Owner: (none) Type: bug | Status: new Priority: normal | Milestone: 8.6.1 Component: Compiler (Type | Version: 8.2.2 checker) | 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 RyanGlScott): Is that the entirety of the error message? I ask because if I try using `-fprint-expanded-synonyms` on a smaller program, such as this one: {{{#!hs module Bug where type Foo = Int f :: Maybe Foo f = Just 'a' }}} I get this: {{{ $ ghc Bug.hs -fprint-expanded-synonyms [1 of 1] Compiling Bug ( Bug.hs, Bug.o ) Bug.hs:6:5: error: • Couldn't match type ‘Char’ with ‘Int’ Expected type: Maybe Foo Actual type: Maybe Char Type synonyms expanded: Expected type: Maybe Int Actual type: Maybe Char • In the expression: Just 'a' In an equation for ‘f’: f = Just 'a' | 6 | f = Just 'a' | ^^^^^^^^ }}} Notice that there is a separate `Type synonyms expanded` section which shows `Maybe Int` instead of `Maybe Foo`. Does GHC not show this in your example? -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/15043#comment:2 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler