[GHC] #10490: Missing binder type check in coercion equality test?

5 Jun 2015

      #10490: Missing binder type check in coercion equality test?
-------------------------------------+-------------------------------------
              Reporter:  ezyang      |             Owner:
                  Type:  bug         |            Status:  new
              Priority:  normal      |         Milestone:
             Component:  Compiler    |           Version:  7.11
  (Type checker)                     |  Operating System:  Unknown/Multiple
              Keywords:              |   Type of failure:  None/Unknown
          Architecture:              |        Blocked By:
  Unknown/Multiple                   |   Related Tickets:
             Test Case:              |
              Blocking:              |
Differential Revisions:              |
-------------------------------------+-------------------------------------
 I was reading the equality testing code for coercions and I noticed this
 line:

 {{{
 coreEqCoercion2 env (ForAllCo v1 co1) (ForAllCo v2 co2)
   = coreEqCoercion2 (rnBndr2 env v1 v2) co1 co2
 }}}

 This doesn't test if the types of the binders are equal. Should it? (Or is
 the type always trivially the same?)

--
Ticket URL: http://ghc.haskell.org/trac/ghc/ticket/10490
GHC http://www.haskell.org/ghc/
The Glasgow Haskell Compiler