Make comparison on equalities work right (ie look at the types)

[ghc-hetmet.git] / compiler / typecheck / TcRnTypes.lhs

diff --git a/compiler/typecheck/TcRnTypes.lhs b/compiler/typecheck/TcRnTypes.lhs
index 3e63827..ebf4101 100644 (file)
--- a/compiler/typecheck/TcRnTypes.lhs
+++ b/compiler/typecheck/TcRnTypes.lhs
@@ -730,7 +730,8 @@ than with the Avails handling stuff in TcSimplify
 
 \begin{code}
 instance Ord Inst where
 
 \begin{code}
 instance Ord Inst where

-  compare = cmpInst
+   compare = cmpInst
+       -- Used *only* for AvailEnv in TcSimplify

 
 instance Eq Inst where
   (==) i1 i2 = case i1 `cmpInst` i2 of
 
 instance Eq Inst where
   (==) i1 i2 = case i1 `cmpInst` i2 of

@@ -761,11 +762,12 @@ cmpInst i1@(ImplicInst {}) i2@(ImplicInst {}) = tci_name i1 `compare` tci_name i
 cmpInst (ImplicInst {})    _                  = LT
 
        -- same for Equality constraints
 cmpInst (ImplicInst {})    _                  = LT
 
        -- same for Equality constraints

-cmpInst (EqInst {})    (Dict {})             = GT
-cmpInst (EqInst {})    (Method {})           = GT
-cmpInst (EqInst {})    (LitInst {})          = GT
-cmpInst (EqInst {})    (ImplicInst {})       = GT
-cmpInst i1@(EqInst {}) i2@(EqInst {})         = tci_name i1 `compare` tci_name i2
+cmpInst (EqInst {})    (Dict {})       = GT
+cmpInst (EqInst {})    (Method {})     = GT
+cmpInst (EqInst {})    (LitInst {})    = GT
+cmpInst (EqInst {})    (ImplicInst {}) = GT
+cmpInst i1@(EqInst {}) i2@(EqInst {})  = (tci_left  i1 `tcCmpType` tci_left  i2) `thenCmp`
+                                         (tci_right i1 `tcCmpType` tci_right i2)

 \end{code}
 
 
 \end{code}