[project @ 2000-11-10 15:12:50 by simonpj]

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

diff --git a/ghc/compiler/typecheck/TcInstDcls.lhs b/ghc/compiler/typecheck/TcInstDcls.lhs
index 8b145d5..f8ec304 100644 (file)
--- a/ghc/compiler/typecheck/TcInstDcls.lhs
+++ b/ghc/compiler/typecheck/TcInstDcls.lhs
@@ -580,7 +580,7 @@ tcInstDecl2 (InstInfo { iLocal = is_local, iDFunId = dfun_id,
         methods_lie = plusLIEs insts_needed_s
     in
 
-       -- Ditto method bindings
+       -- Simplify the constraints from methods
     tcAddErrCtxt methodCtxt (
       tcSimplifyAndCheck
                 (ptext SLIT("instance declaration context"))
@@ -589,11 +589,9 @@ tcInstDecl2 (InstInfo { iLocal = is_local, iDFunId = dfun_id,
                 methods_lie
     )                                           `thenTc` \ (const_lie1, lie_binds1) ->
     
-       -- Now do the simplification again, this time to get the
-       -- bindings; this time we use an enhanced "avails"
-       -- Ignore errors because they come from the *previous* tcSimplify
-    discardErrsTc (
-       tcSimplifyAndCheck
+       -- Figure out bindings for the superclass context
+    tcAddErrCtxt superClassCtxt (
+      tcSimplifyAndCheck
                 (ptext SLIT("instance declaration context"))
                 inst_tyvars_set
                 dfun_arg_dicts         -- NB! Don't include this_dict here, else the sc_dicts
@@ -788,6 +786,5 @@ nonBoxedPrimCCallErr clas inst_ty
                        ppr inst_ty])
 
 methodCtxt     = ptext SLIT("When checking the methods of an instance declaration")
+superClassCtxt = ptext SLIT("When checking the super-classes of an instance declaration")
 \end{code}
-
-