Remove dead code

* FailablePattern can no longer be created since ab51bee40c82
  Therefore, Opt_WarnMissingMonadFailInstances has no effect anymore.
* XWrap is no longer used, it was moved to an extension field

8 files changed, 16 insertions, 48 deletions

diff --git a/compiler/GHC/Driver/Session.hs b/compiler/GHC/Driver/Session.hs
index 4eb9ab2597..f20a899086 100644
--- a/compiler/GHC/Driver/Session.hs
+++ b/compiler/GHC/Driver/Session.hs
@@ -875,7 +875,7 @@ data WarningFlag =
    | Opt_WarnRedundantRecordWildcards
    | Opt_WarnWarningsDeprecations
    | Opt_WarnDeprecatedFlags
-   | Opt_WarnMissingMonadFailInstances -- since 8.0
+   | Opt_WarnMissingMonadFailInstances -- since 8.0, has no effect since 8.8
    | Opt_WarnSemigroup -- since 8.0
    | Opt_WarnDodgyExports
    | Opt_WarnDodgyImports
@@ -4918,8 +4918,7 @@ minusWeverythingOpts = [ toEnum 0 .. ]
 -- code future compatible to fix issues before they even generate warnings.
 minusWcompatOpts :: [WarningFlag]
 minusWcompatOpts
-    = [ Opt_WarnMissingMonadFailInstances
-      , Opt_WarnSemigroup
+    = [ Opt_WarnSemigroup
       , Opt_WarnNonCanonicalMonoidInstances
       , Opt_WarnStarIsType
       , Opt_WarnCompatUnqualifiedImports
diff --git a/compiler/GHC/Hs/Expr.hs b/compiler/GHC/Hs/Expr.hs
index a84bc1b240..f6f0541097 100644
--- a/compiler/GHC/Hs/Expr.hs
+++ b/compiler/GHC/Hs/Expr.hs
@@ -666,8 +666,6 @@ type instance XBinTick       (GhcPass _) = NoExtField
 
 type instance XPragE         (GhcPass _) = NoExtField
 
-type instance XWrap          (GhcPass _) = NoExtField
-
 type instance XXExpr         GhcPs       = NoExtCon
 type instance XXExpr         GhcRn       = NoExtCon
 type instance XXExpr         GhcTc       = HsWrap HsExpr
diff --git a/compiler/GHC/Hs/Extension.hs b/compiler/GHC/Hs/Extension.hs
index cde29509c5..31e6a20f5d 100644
--- a/compiler/GHC/Hs/Extension.hs
+++ b/compiler/GHC/Hs/Extension.hs
@@ -522,7 +522,6 @@ type family XStatic         x
 type family XTick           x
 type family XBinTick        x
 type family XPragE          x
-type family XWrap           x
 type family XXExpr          x
 
 type family XSCC            x
diff --git a/compiler/typecheck/TcErrors.hs b/compiler/typecheck/TcErrors.hs
index de38cdfcec..d098edac8a 100644
--- a/compiler/typecheck/TcErrors.hs
+++ b/compiler/typecheck/TcErrors.hs
@@ -810,31 +810,20 @@ cmp_loc ct1 ct2 = ctLocSpan (ctLoc ct1) `compare` ctLocSpan (ctLoc ct2)
 reportGroup :: (ReportErrCtxt -> [Ct] -> TcM ErrMsg) -> ReportErrCtxt
             -> [Ct] -> TcM ()
 reportGroup mk_err ctxt cts =
-  case partition isMonadFailInstanceMissing cts of
-        -- Only warn about missing MonadFail constraint when
-        -- there are no other missing constraints!
-        (monadFailCts, []) ->
-            do { err <- mk_err ctxt monadFailCts
-               ; reportWarning (Reason Opt_WarnMissingMonadFailInstances) err }
-
-        (_, cts') -> do { err <- mk_err ctxt cts'
-                        ; traceTc "About to maybeReportErr" $
-                          vcat [ text "Constraint:"             <+> ppr cts'
-                               , text "cec_suppress ="          <+> ppr (cec_suppress ctxt)
-                               , text "cec_defer_type_errors =" <+> ppr (cec_defer_type_errors ctxt) ]
-                        ; maybeReportError ctxt err
-                            -- But see Note [Always warn with -fdefer-type-errors]
-                        ; traceTc "reportGroup" (ppr cts')
-                        ; mapM_ (addDeferredBinding ctxt err) cts' }
-                            -- Add deferred bindings for all
-                            -- Redundant if we are going to abort compilation,
-                            -- but that's hard to know for sure, and if we don't
-                            -- abort, we need bindings for all (e.g. #12156)
-  where
-    isMonadFailInstanceMissing ct =
-        case ctLocOrigin (ctLoc ct) of
-            FailablePattern _pat -> True
-            _otherwise           -> False
+  ASSERT( not (null cts))
+  do { err <- mk_err ctxt cts
+     ; traceTc "About to maybeReportErr" $
+       vcat [ text "Constraint:"             <+> ppr cts
+            , text "cec_suppress ="          <+> ppr (cec_suppress ctxt)
+            , text "cec_defer_type_errors =" <+> ppr (cec_defer_type_errors ctxt) ]
+     ; maybeReportError ctxt err
+         -- But see Note [Always warn with -fdefer-type-errors]
+     ; traceTc "reportGroup" (ppr cts)
+     ; mapM_ (addDeferredBinding ctxt err) cts }
+         -- Add deferred bindings for all
+         -- Redundant if we are going to abort compilation,
+         -- but that's hard to know for sure, and if we don't
+         -- abort, we need bindings for all (e.g. #12156)
 
 maybeReportHoleError :: ReportErrCtxt -> Ct -> ErrMsg -> TcM ()
 -- Unlike maybeReportError, these "hole" errors are
diff --git a/compiler/typecheck/TcOrigin.hs b/compiler/typecheck/TcOrigin.hs
index c69013917c..4137939135 100644
--- a/compiler/typecheck/TcOrigin.hs
+++ b/compiler/typecheck/TcOrigin.hs
@@ -437,10 +437,6 @@ data CtOrigin
   | ListOrigin          -- An overloaded list
   | BracketOrigin       -- An overloaded quotation bracket
   | StaticOrigin        -- A static form
-  | FailablePattern (LPat GhcTcId) -- A failable pattern in do-notation for the
-                                   -- MonadFail Proposal (MFP). Obsolete when
-                                   -- actual desugaring to MonadFail.fail is
-                                   -- live.
   | Shouldn'tHappenOrigin String
                             -- the user should never see this one,
                             -- unless ImpredicativeTypes is on, where all
@@ -601,10 +597,6 @@ pprCtOrigin (MCompPatOrigin pat)
     = ctoHerald <+> hsep [ text "the failable pattern"
            , quotes (ppr pat)
            , text "in a statement in a monad comprehension" ]
-pprCtOrigin (FailablePattern pat)
-    = ctoHerald <+> text "the failable pattern" <+> quotes (ppr pat)
-      $$
-      text "(this will become an error in a future GHC release)"
 
 pprCtOrigin (Shouldn'tHappenOrigin note)
   = sdocOption sdocImpredicativeTypes $ \case
diff --git a/testsuite/tests/ghci/scripts/T9293.stdout b/testsuite/tests/ghci/scripts/T9293.stdout
index 57820fc4ed..12f5958925 100644
--- a/testsuite/tests/ghci/scripts/T9293.stdout
+++ b/testsuite/tests/ghci/scripts/T9293.stdout
@@ -13,7 +13,6 @@ other dynamic, non-language, flag settings:
   -fimplicit-import-qualified
   -fshow-warning-groups
 warning settings:
-  -Wmissing-monadfail-instances
   -Wsemigroup
   -Wnoncanonical-monoid-instances
   -Wstar-is-type
@@ -37,7 +36,6 @@ other dynamic, non-language, flag settings:
   -fimplicit-import-qualified
   -fshow-warning-groups
 warning settings:
-  -Wmissing-monadfail-instances
   -Wsemigroup
   -Wnoncanonical-monoid-instances
   -Wstar-is-type
@@ -60,7 +58,6 @@ other dynamic, non-language, flag settings:
   -fimplicit-import-qualified
   -fshow-warning-groups
 warning settings:
-  -Wmissing-monadfail-instances
   -Wsemigroup
   -Wnoncanonical-monoid-instances
   -Wstar-is-type
@@ -85,7 +82,6 @@ other dynamic, non-language, flag settings:
   -fimplicit-import-qualified
   -fshow-warning-groups
 warning settings:
-  -Wmissing-monadfail-instances
   -Wsemigroup
   -Wnoncanonical-monoid-instances
   -Wstar-is-type
diff --git a/testsuite/tests/ghci/scripts/ghci024.stdout b/testsuite/tests/ghci/scripts/ghci024.stdout
index e4e664ada9..c2efd4e68f 100644
--- a/testsuite/tests/ghci/scripts/ghci024.stdout
+++ b/testsuite/tests/ghci/scripts/ghci024.stdout
@@ -14,7 +14,6 @@ other dynamic, non-language, flag settings:
   -fimplicit-import-qualified
   -fshow-warning-groups
 warning settings:
-  -Wmissing-monadfail-instances
   -Wsemigroup
   -Wnoncanonical-monoid-instances
   -Wstar-is-type
diff --git a/testsuite/tests/ghci/scripts/ghci057.stdout b/testsuite/tests/ghci/scripts/ghci057.stdout
index 57820fc4ed..12f5958925 100644
--- a/testsuite/tests/ghci/scripts/ghci057.stdout
+++ b/testsuite/tests/ghci/scripts/ghci057.stdout
@@ -13,7 +13,6 @@ other dynamic, non-language, flag settings:
   -fimplicit-import-qualified
   -fshow-warning-groups
 warning settings:
-  -Wmissing-monadfail-instances
   -Wsemigroup
   -Wnoncanonical-monoid-instances
   -Wstar-is-type
@@ -37,7 +36,6 @@ other dynamic, non-language, flag settings:
   -fimplicit-import-qualified
   -fshow-warning-groups
 warning settings:
-  -Wmissing-monadfail-instances
   -Wsemigroup
   -Wnoncanonical-monoid-instances
   -Wstar-is-type
@@ -60,7 +58,6 @@ other dynamic, non-language, flag settings:
   -fimplicit-import-qualified
   -fshow-warning-groups
 warning settings:
-  -Wmissing-monadfail-instances
   -Wsemigroup
   -Wnoncanonical-monoid-instances
   -Wstar-is-type
@@ -85,7 +82,6 @@ other dynamic, non-language, flag settings:
   -fimplicit-import-qualified
   -fshow-warning-groups
 warning settings:
-  -Wmissing-monadfail-instances
   -Wsemigroup
   -Wnoncanonical-monoid-instances
   -Wstar-is-type