For single-method classes use newtypes

[ghc-hetmet.git] / compiler / basicTypes / MkId.lhs

diff --git a/compiler/basicTypes/MkId.lhs b/compiler/basicTypes/MkId.lhs
index 4bfb53b..7bd9910 100644 (file)
--- a/compiler/basicTypes/MkId.lhs
+++ b/compiler/basicTypes/MkId.lhs
@@ -433,19 +433,21 @@ mkDictSelId no_unf name clas
 
     base_info = noCafIdInfo
                 `setArityInfo`      1
-                `setStrictnessInfo`  Just strict_sig
+                `setStrictnessInfo` Just strict_sig
                 `setUnfoldingInfo`  (if no_unf then noUnfolding
-                                    else mkImplicitUnfolding rhs)
+                                    else mkImplicitUnfolding rhs)
                   -- In module where class op is defined, we must add
                   -- the unfolding, even though it'll never be inlined
                   -- becuase we use that to generate a top-level binding
                   -- for the ClassOp
 
-    info = base_info    `setSpecInfo`       mkSpecInfo [rule]
-                       `setInlinePragInfo` neverInlinePragma
-               -- Add a magic BuiltinRule, and never inline it
-               -- so that the rule is always available to fire.
-               -- See Note [ClassOp/DFun selection] in TcInstDcls
+    info | new_tycon = base_info `setInlinePragInfo` alwaysInlinePragma
+                  -- See Note [Single-method classes] for why alwaysInlinePragma
+         | otherwise = base_info  `setSpecInfo`       mkSpecInfo [rule]
+                                 `setInlinePragInfo` neverInlinePragma
+                  -- Add a magic BuiltinRule, and never inline it
+                  -- so that the rule is always available to fire.
+                  -- See Note [ClassOp/DFun selection] in TcInstDcls
 
     n_ty_args = length tyvars