diff options
Diffstat (limited to 'compiler/GHC/Tc/Errors.hs')
| -rw-r--r-- | compiler/GHC/Tc/Errors.hs | 31 |
1 files changed, 1 insertions, 30 deletions
diff --git a/compiler/GHC/Tc/Errors.hs b/compiler/GHC/Tc/Errors.hs index 61caa2e456..c22ab6a2e5 100644 --- a/compiler/GHC/Tc/Errors.hs +++ b/compiler/GHC/Tc/Errors.hs @@ -391,7 +391,7 @@ reportImplic ctxt implic@(Implic { ic_skols = tvs warnRedundantConstraints :: SolverReportErrCtxt -> TcLclEnv -> SkolemInfoAnon -> [EvVar] -> TcM () -- See Note [Tracking redundant constraints] in GHC.Tc.Solver -warnRedundantConstraints ctxt env info ev_vars +warnRedundantConstraints ctxt env info redundant_evs | null redundant_evs = return () @@ -423,18 +423,6 @@ warnRedundantConstraints ctxt env info ev_vars [] ; reportDiagnostic msg } - redundant_evs = - filterOut is_type_error $ - case info of -- See Note [Redundant constraints in instance decls] - InstSkol -> filterOut (improving . idType) ev_vars - _ -> ev_vars - - -- See #15232 - is_type_error = isJust . userTypeError_maybe . idType - - improving pred -- (transSuperClasses p) does not include p - = any isImprovementPred (pred : transSuperClasses pred) - reportBadTelescope :: SolverReportErrCtxt -> TcLclEnv -> SkolemInfoAnon -> [TcTyVar] -> TcM () reportBadTelescope ctxt env (ForAllSkol telescope) skols = do { msg <- mkErrorReport @@ -449,23 +437,6 @@ reportBadTelescope ctxt env (ForAllSkol telescope) skols reportBadTelescope _ _ skol_info skols = pprPanic "reportBadTelescope" (ppr skol_info $$ ppr skols) -{- Note [Redundant constraints in instance decls] -~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ -For instance declarations, we don't report unused givens if -they can give rise to improvement. Example (#10100): - class Add a b ab | a b -> ab, a ab -> b - instance Add Zero b b - instance Add a b ab => Add (Succ a) b (Succ ab) -The context (Add a b ab) for the instance is clearly unused in terms -of evidence, since the dictionary has no fields. But it is still -needed! With the context, a wanted constraint - Add (Succ Zero) beta (Succ Zero) -we will reduce to (Add Zero beta Zero), and thence we get beta := Zero. -But without the context we won't find beta := Zero. - -This only matters in instance declarations.. --} - -- | Should we completely ignore this constraint in error reporting? -- It *must* be the case that any constraint for which this returns True -- somehow causes an error to be reported elsewhere. |