Re: [GHC] #12533: Internal error using redundant forall with default signature

#12533: Internal error using redundant forall with default signature -------------------------------------+------------------------------------- Reporter: dfeuer | Owner: Type: bug | Status: new Priority: normal | Milestone: 8.0.2 Component: Compiler (Type | Version: 8.0.1 checker) | Resolution: | Keywords: Operating System: Unknown/Multiple | Architecture: | Unknown/Multiple Type of failure: Compile-time | Test Case: crash | rename/should_compile/T12533 Blocked By: | Blocking: Related Tickets: | Differential Rev(s): Wiki Page: | -------------------------------------+------------------------------------- Comment (by simonpj): I put the wrong ticket number in the commit message. The full commit is {{{ commit 0050aff22ba04baca732bf5124002417ab667f8a Author: Simon Peyton Jones Date: Fri Aug 26 17:32:42 2016 +0100 Fix scoping of type variables in instances This fixes Trac #12531: class Foo x where foo :: forall a . x a -> x a default foo :: forall b . x b -> x b foo x = go where go :: x b go = undefined We want 'b' to scope over the code for 'foo', but we were using 'a' instead. compiler/hsSyn/HsUtils.hs | 29 ++++++++++++++++++++++++++++- compiler/rename/RnBinds.hs | 31 ++++++++++++++----------------- compiler/typecheck/TcClassDcl.hs | 36 ++++++++++++++++++++++-------------- compiler/typecheck/TcInstDcls.hs | 6 +++--- testsuite/tests/rename/should_compile/T12533.hs | 10 ++++++++++ testsuite/tests/rename/should_compile/all.T | 1 + 6 files changed, 78 insertions(+), 35 deletions(-) }}} -- Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/12533#comment:3 GHC http://www.haskell.org/ghc/ The Glasgow Haskell Compiler