• Simon Peyton Jones's avatar
    Complete work on new OVERLAPPABLE/OVERLAPPING pragmas (Trac #9242) · 1ae5fa45
    Simon Peyton Jones authored
    * Deprecate -XOverlappingInstances
    * Update test suite.  Several tests even had entirely unnecessary
      uses of -XOverlappingInstances
    * Update user manual with a careful description of the instance
      resolution story
    * Fix an outright bug in the handling of duplidate instances in GHCi,
      which are meant to silently overwrite the earlier duplicate. The
      logic was right for family instances but was both more complicated,
      and plain wrong, for class instances.  (If you are interested, the
      bug was that we were eliminating the duplicate from the InstEnv, but
      not from the [ClsInst] held in tcg_insts.)  Test is ghci044a.