Make the "matchable-given" check happen first
authorSimon Peyton Jones <simonpj@microsoft.com>
Wed, 13 May 2015 11:49:13 +0000 (12:49 +0100)
committerSimon Peyton Jones <simonpj@microsoft.com>
Mon, 18 May 2015 12:45:04 +0000 (13:45 +0100)
commit228ddb95ee137e7cef02dcfe2521233892dd61e0
treead5437cb8c9d8f5ee3a0f8459c8c56f50e9cd630
parentffc21506894c7887d3620423aaf86bc6113a1071
Make the "matchable-given" check happen first

This change makes the matchable-given check apply uniformly to
     - constraint tuples
     - natural numbers
     - Typeable
as well as to vanilla class constraints.

See Note [Instance and Given overlap] in TcInteract
compiler/typecheck/TcInteract.hs