diff options
Diffstat (limited to 'compiler/GHC/HsToCore/Match.hs')
| -rw-r--r-- | compiler/GHC/HsToCore/Match.hs | 14 |
1 files changed, 11 insertions, 3 deletions
diff --git a/compiler/GHC/HsToCore/Match.hs b/compiler/GHC/HsToCore/Match.hs index 86095b8e3f..8576197d4d 100644 --- a/compiler/GHC/HsToCore/Match.hs +++ b/compiler/GHC/HsToCore/Match.hs @@ -1063,7 +1063,6 @@ viewLExprEq (e1,_) (e2,_) = lexp e1 e2 -- the instance for IPName derives using the id, so this works if the -- above does exp (HsIPVar _ i) (HsIPVar _ i') = i == i' - exp (HsOverLabel _ l x) (HsOverLabel _ l' x') = l == l' && x == x' exp (HsOverLit _ l) (HsOverLit _ l') = -- Overloaded lits are equal if they have the same type -- and the data is the same. @@ -1133,8 +1132,17 @@ viewLExprEq (e1,_) (e2,_) = lexp e1 e2 --------- ev_term :: EvTerm -> EvTerm -> Bool - ev_term (EvExpr (Var a)) (EvExpr (Var b)) = a==b - ev_term (EvExpr (Coercion a)) (EvExpr (Coercion b)) = a `eqCoercion` b + ev_term (EvExpr (Var a)) (EvExpr (Var b)) + = idType a `eqType` idType b + -- The /type/ of the evidence matters, not its precise proof term. + -- Caveat: conceivably a sufficiently exotic use of incoherent instances + -- could make a difference, but remember this is only used within the + -- pattern matches for a single function, so it's hard to see how that + -- could really happen. And we don't want accidentally different proofs + -- to prevent spotting equalities, and hence degrade pattern-match + -- overlap checking. + ev_term (EvExpr (Coercion a)) (EvExpr (Coercion b)) + = a `eqCoercion` b ev_term _ _ = False --------- |