#8556: Invalid constructor names are accepted in data declarations ------------------------------------+------------------------------------- Reporter: dolio | Owner: Type: bug | Status: new Priority: normal | Milestone: Component: Compiler | Version: 7.6.3 Keywords: | Operating System: Unknown/Multiple Architecture: Unknown/Multiple | Type of failure: None/Unknown Difficulty: Unknown | Test Case: Blocked By: | Blocking: Related Tickets: | ------------------------------------+------------------------------------- Earlier today, someone was asking on #haskell why the constructor name {{{(^)}}} wouldn't work in GADT definitions. My response was that {{{(^)}}} isn't a constructor name, but much to my surprise, GHC accepts such names in a regular data declaration: {{{ data Foo = F | (^^^^) Int Int }}} This creates a {{{Foo}}} type and value constructor {{{F}}}, but no value constructor {{{(^^^^)}}}. However, in 7.6.3, if DataKinds are enabled, both constructors appear at the type level. In HEAD, the same definition is accepted, with only {{{F}}} existing at the value level, as before. But at the type level, both {{{F}}} and {{{(^^^^)}}} just generate errors that {{{Foo}}} is not a promotable type. At that point, I think there's no question that the declaration should just be ruled out. -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/8556 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler