[Git][ghc/ghc][wip/simply-bind-tyvars] Simplify bindLHsTyVarBndrs and bindHsQTyVars
Ryan Scott
gitlab at gitlab.haskell.org
Mon Jun 1 11:09:17 UTC 2020
Ryan Scott pushed to branch wip/simply-bind-tyvars at Glasgow Haskell Compiler / GHC
Commits:
dab29bb9 by Ryan Scott at 2020-06-01T07:08:57-04:00
Simplify bindLHsTyVarBndrs and bindHsQTyVars
Both `bindLHsTyVarBndrs` and `bindHsQTyVars` take two separate
`Maybe` arguments, which I find terribly confusing. Thankfully, it's
possible to remove one `Maybe` argument from each of these functions,
which this patch accomplishes:
* `bindHsQTyVars` takes a `Maybe SDoc` argument, which is `Just` if
GHC should warn about any of the quantified type variables going
unused. However, every call site uses `Nothing` in practice. This
makes sense, since it doesn't really make sense to warn about
unused type variables bound by an `LHsQTyVars`. For instance, you
wouldn't warn about the `a` in `data Proxy a = Proxy` going unused.
As a result, I simply remove this `Maybe SDoc` argument altogether.
* `bindLHsTyVarBndrs` also takes a `Maybe SDoc` argument for the same
reasons that `bindHsQTyVars` took one. To make things more
confusing, however, `bindLHsTyVarBndrs` also takes a separate
`HsDocContext` argument, which is pretty-printed (to an `SDoc`) in
warnings and error messages.
In practice, the `Maybe SDoc` and the `HsDocContext` often contain
the same text. See the call sites for `bindLHsTyVarBndrs` in
`rnFamInstEqn` and `rnConDecl`, for instance. There are only a
handful of call sites where the text differs between the
`Maybe SDoc` and `HsDocContext` arguments:
* In `rnHsRuleDecl`, where the `Maybe SDoc` says "`In the rule`"
and the `HsDocContext` says "`In the transformation rule`".
* In `rnHsTyKi`/`rn_ty`, where the `Maybe SDoc` says
"`In the type`" but the `HsDocContext` is inhereted from the
surrounding context (e.g., if `rnHsTyKi` were called on a
top-level type signature, the `HsDocContext` would be
"`In the type signature`" instead)
In both cases, warnings/error messages arguably _improve_ by
unifying making the `Maybe SDoc`'s text match that of the
`HsDocContext`. As a result, I decided to remove the `Maybe SDoc`
argument to `bindLHsTyVarBndrs` entirely and simply reuse the text
from the `HsDocContext`. (I decided to change the phrase
"transformation rule" to "rewrite rule" while I was in the area.)
The `Maybe SDoc` argument has one other purpose: signaling when to
emit "`Unused quantified type variable`" warnings. To recover this
functionality, I replaced the `Maybe SDoc` argument with a
boolean-like `WarnUnusedForalls` argument. The only
`bindLHsTyVarBndrs` call site that chooses _not_ to emit these
warnings in `bindHsQTyVars`.
- - - - -
17 changed files:
- compiler/GHC/Core.hs
- compiler/GHC/Core/Lint.hs
- compiler/GHC/Core/Opt/Simplify.hs
- compiler/GHC/Core/Rules.hs
- compiler/GHC/Driver/Types.hs
- compiler/GHC/Hs/Decls.hs
- compiler/GHC/HsToCore.hs
- compiler/GHC/Rename/HsType.hs
- compiler/GHC/Rename/Module.hs
- compiler/GHC/Rename/Utils.hs
- compiler/GHC/Tc/Gen/Rule.hs
- testsuite/tests/dependent/should_fail/T16326_Fail10.stderr
- testsuite/tests/rename/should_compile/ExplicitForAllRules1.stderr
- testsuite/tests/rename/should_compile/T5331.stderr
- testsuite/tests/safeHaskell/ghci/p14.stderr
- testsuite/tests/typecheck/should_compile/T10072.stderr
- testsuite/tests/typecheck/should_fail/T5853.stderr
Changes:
=====================================
compiler/GHC/Core.hs
=====================================
@@ -1291,7 +1291,7 @@ Orphan-hood is computed
{-
************************************************************************
* *
-\subsection{Transformation rules}
+\subsection{Rewrite rules}
* *
************************************************************************
=====================================
compiler/GHC/Core/Lint.hs
=====================================
@@ -467,7 +467,7 @@ lintCoreBindings dflags pass local_in_scope binds
where
all_pairs = flattenBinds binds
-- Put all the top-level binders in scope at the start
- -- This is because transformation rules can bring something
+ -- This is because rewrite rules can bring something
-- into use 'unexpectedly'; see Note [Glomming] in OccurAnal
binders = map fst all_pairs
=====================================
compiler/GHC/Core/Opt/Simplify.hs
=====================================
@@ -170,7 +170,7 @@ simplTopBinds :: SimplEnv -> [InBind] -> SimplM (SimplFloats, SimplEnv)
-- See Note [The big picture]
simplTopBinds env0 binds0
= do { -- Put all the top-level binders into scope at the start
- -- so that if a transformation rule has unexpectedly brought
+ -- so that if a rewrite rule has unexpectedly brought
-- anything into scope, then we don't get a complaint about that.
-- It's rather as if the top-level binders were imported.
-- See note [Glomming] in OccurAnal.
=====================================
compiler/GHC/Core/Rules.hs
=====================================
@@ -1,7 +1,7 @@
{-
(c) The GRASP/AQUA Project, Glasgow University, 1992-1998
-\section[CoreRules]{Transformation rules}
+\section[CoreRules]{Rewrite rules}
-}
{-# LANGUAGE CPP #-}
=====================================
compiler/GHC/Driver/Types.hs
=====================================
@@ -2486,7 +2486,7 @@ lookupFixity env n = case lookupNameEnv env n of
-- * An instance declaration in a module other than the definition
-- module for one of the type constructors or classes in the instance head
--
--- * A transformation rule in a module other than the one defining
+-- * A rewrite rule in a module other than the one defining
-- the function in the head of the rule
--
type WhetherHasOrphans = Bool
=====================================
compiler/GHC/Hs/Decls.hs
=====================================
@@ -2184,7 +2184,7 @@ instance Outputable ForeignExport where
{-
************************************************************************
* *
-\subsection{Transformation rules}
+\subsection{Rewrite rules}
* *
************************************************************************
-}
=====================================
compiler/GHC/HsToCore.hs
=====================================
@@ -354,7 +354,7 @@ to the binders in the top-level bindings
Reason
- It makes the rules easier to look up
- - It means that transformation rules and specialisations for
+ - It means that rewrite rules and specialisations for
locally defined Ids are handled uniformly
- It keeps alive things that are referred to only from a rule
(the occurrence analyser knows about rules attached to Ids)
@@ -368,7 +368,7 @@ Reason
************************************************************************
* *
-* Desugaring transformation rules
+* Desugaring rewrite rules
* *
************************************************************************
-}
=====================================
compiler/GHC/Rename/HsType.hs
=====================================
@@ -23,8 +23,8 @@ module GHC.Rename.HsType (
checkPrecMatch, checkSectionPrec,
-- Binding related stuff
- bindLHsTyVarBndr, bindLHsTyVarBndrs, rnImplicitBndrs,
- bindSigTyVarsFV, bindHsQTyVars, bindLRdrNames,
+ bindLHsTyVarBndr, bindLHsTyVarBndrs, WarnUnusedForalls(..),
+ rnImplicitBndrs, bindSigTyVarsFV, bindHsQTyVars, bindLRdrNames,
extractHsTyRdrTyVars, extractHsTyRdrTyVarsKindVars,
extractHsTysRdrTyVarsDups,
extractRdrKindSigVars, extractDataDefnKindVars,
@@ -41,9 +41,10 @@ import GHC.Driver.Session
import GHC.Hs
import GHC.Rename.Doc ( rnLHsDoc, rnMbLHsDoc )
import GHC.Rename.Env
-import GHC.Rename.Utils ( HsDocContext(..), withHsDocContext, mapFvRn
- , pprHsDocContext, bindLocalNamesFV, typeAppErr
- , newLocalBndrRn, checkDupRdrNames, checkShadowedRdrNames )
+import GHC.Rename.Utils ( HsDocContext(..), inHsDocContext, withHsDocContext
+ , mapFvRn, pprHsDocContext, bindLocalNamesFV
+ , typeAppErr, newLocalBndrRn, checkDupRdrNames
+ , checkShadowedRdrNames )
import GHC.Rename.Fixity ( lookupFieldFixityRn, lookupFixityRn
, lookupTyFixityRn )
import GHC.Tc.Utils.Monad
@@ -203,9 +204,10 @@ rnWcBody ctxt nwc_rdrs hs_ty
rn_ty :: RnTyKiEnv -> HsType GhcPs -> RnM (HsType GhcRn, FreeVars)
-- A lot of faff just to allow the extra-constraints wildcard to appear
- rn_ty env hs_ty@(HsForAllTy { hst_fvf = fvf, hst_bndrs = tvs
- , hst_body = hs_body })
- = bindLHsTyVarBndrs (rtke_ctxt env) (Just $ inTypeDoc hs_ty) Nothing tvs $ \ tvs' ->
+ rn_ty env (HsForAllTy { hst_fvf = fvf, hst_bndrs = tvs
+ , hst_body = hs_body })
+ = bindLHsTyVarBndrs (rtke_ctxt env) WarnUnusedForalls
+ Nothing tvs $ \ tvs' ->
do { (hs_body', fvs) <- rn_lty env hs_body
; return (HsForAllTy { hst_fvf = fvf, hst_xforall = noExtField
, hst_bndrs = tvs', hst_body = hs_body' }
@@ -534,7 +536,7 @@ rnHsTyKi :: RnTyKiEnv -> HsType GhcPs -> RnM (HsType GhcRn, FreeVars)
rnHsTyKi env ty@(HsForAllTy { hst_fvf = fvf, hst_bndrs = tyvars
, hst_body = tau })
= do { checkPolyKinds env ty
- ; bindLHsTyVarBndrs (rtke_ctxt env) (Just $ inTypeDoc ty)
+ ; bindLHsTyVarBndrs (rtke_ctxt env) WarnUnusedForalls
Nothing tyvars $ \ tyvars' ->
do { (tau', fvs) <- rnLHsTyKi env tau
; return ( HsForAllTy { hst_fvf = fvf, hst_xforall = noExtField
@@ -845,11 +847,9 @@ bindLRdrNames rdrs thing_inside
---------------
bindHsQTyVars :: forall a b.
HsDocContext
- -> Maybe SDoc -- Just d => check for unused tvs
- -- d is a phrase like "in the type ..."
-> Maybe a -- Just _ => an associated type decl
-> [Located RdrName] -- Kind variables from scope, no dups
- -> (LHsQTyVars GhcPs)
+ -> LHsQTyVars GhcPs
-> (LHsQTyVars GhcRn -> Bool -> RnM (b, FreeVars))
-- The Bool is True <=> all kind variables used in the
-- kind signature are bound on the left. Reason:
@@ -863,7 +863,7 @@ bindHsQTyVars :: forall a b.
-- and (ii) mentioned in the kinds of hsq_bndrs
-- (b) Bring type variables into scope
--
-bindHsQTyVars doc mb_in_doc mb_assoc body_kv_occs hsq_bndrs thing_inside
+bindHsQTyVars doc mb_assoc body_kv_occs hsq_bndrs thing_inside
= do { let hs_tv_bndrs = hsQTvExplicit hsq_bndrs
bndr_kv_occs = extractHsTyVarBndrsKVs hs_tv_bndrs
@@ -888,7 +888,10 @@ bindHsQTyVars doc mb_in_doc mb_assoc body_kv_occs hsq_bndrs thing_inside
; implicit_kv_nms <- mapM (newTyVarNameRn mb_assoc) implicit_kvs
; bindLocalNamesFV implicit_kv_nms $
- bindLHsTyVarBndrs doc mb_in_doc mb_assoc hs_tv_bndrs $ \ rn_bndrs ->
+ bindLHsTyVarBndrs doc NoWarnUnusedForalls mb_assoc hs_tv_bndrs $ \ rn_bndrs ->
+ -- This is the only call site for bindLHsTyVarBndrs where we pass
+ -- NoWarnUnusedForalls, which suppresses -Wunused-foralls warnings.
+ -- See Note [Suppress -Wunused-foralls when binding LHsQTyVars].
do { traceRn "bindHsQTyVars" (ppr hsq_bndrs $$ ppr implicit_kv_nms $$ ppr rn_bndrs)
; thing_inside (HsQTvs { hsq_ext = implicit_kv_nms
, hsq_explicit = rn_bndrs })
@@ -990,17 +993,50 @@ variable in (a :: k), later in the binding. (This mistake lead to #14710.)
So tvs is {k,a} and kvs is {k}.
NB: we do this only at the binding site of 'tvs'.
+
+Note [Suppress -Wunused-foralls when binding LHsQTyVars]
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+The WarnUnusedForalls flag controls whether bindLHsTyVarBndrs should warn about
+explicit type variable binders that go unused (e.g., the `a` in
+`forall a. Int`). We almost always want to warn about these, since unused type
+variables can usually be deleted without any repercussions. There is one
+exception to this rule, however: binding LHsQTyVars. Consider this example:
+
+ data Proxy a = Proxy
+
+The `a` in `Proxy a` is bound by an LHsQTyVars, and the code which brings it
+into scope, bindHsQTyVars, will invoke bindLHsTyVarBndrs in turn. As such, it
+has a choice to make about whether to emit -Wunused-foralls warnings or not.
+If it /did/ emit warnings, then the `a` would be flagged as unused. However,
+this is not what we want! Removing the `a` in `Proxy a` would change its kind
+entirely, which is a huge price to pay for fixing a warning.
+
+Unlike other forms of type variable binders, dropping "unused" variables in
+an LHsQTyVars can be semantically significant. As a result, we suppress
+-Wunused-foralls warnings in exactly one place: in bindHsQTyVars.
-}
+-- | Should GHC warn if a quantified type variable goes unused? Usually, the
+-- answer is \"yes\", but in the particular case of binding 'LHsQTyVars', we
+-- avoid emitting warnings.
+-- See @Note [Suppress -Wunused-foralls when binding LHsQTyVars]@.
+data WarnUnusedForalls
+ = WarnUnusedForalls
+ | NoWarnUnusedForalls
+
+instance Outputable WarnUnusedForalls where
+ ppr wuf = text $ case wuf of
+ WarnUnusedForalls -> "WarnUnusedForalls"
+ NoWarnUnusedForalls -> "NoWarnUnusedForalls"
+
bindLHsTyVarBndrs :: (OutputableBndrFlag flag)
=> HsDocContext
- -> Maybe SDoc -- Just d => check for unused tvs
- -- d is a phrase like "in the type ..."
+ -> WarnUnusedForalls
-> Maybe a -- Just _ => an associated type decl
-> [LHsTyVarBndr flag GhcPs] -- User-written tyvars
-> ([LHsTyVarBndr flag GhcRn] -> RnM (b, FreeVars))
-> RnM (b, FreeVars)
-bindLHsTyVarBndrs doc mb_in_doc mb_assoc tv_bndrs thing_inside
+bindLHsTyVarBndrs doc wuf mb_assoc tv_bndrs thing_inside
= do { when (isNothing mb_assoc) (checkShadowedRdrNames tv_names_w_loc)
; checkDupRdrNames tv_names_w_loc
; go tv_bndrs thing_inside }
@@ -1014,9 +1050,9 @@ bindLHsTyVarBndrs doc mb_in_doc mb_assoc tv_bndrs thing_inside
; warn_unused b' fvs
; return (res, fvs) }
- warn_unused tv_bndr fvs = case mb_in_doc of
- Just in_doc -> warnUnusedForAll in_doc tv_bndr fvs
- Nothing -> return ()
+ warn_unused tv_bndr fvs = case wuf of
+ WarnUnusedForalls -> warnUnusedForAll doc tv_bndr fvs
+ NoWarnUnusedForalls -> return ()
bindLHsTyVarBndr :: HsDocContext
-> Maybe a -- associated class
@@ -1456,16 +1492,14 @@ dataKindsErr env thing
pp_what | isRnKindLevel env = text "kind"
| otherwise = text "type"
-inTypeDoc :: HsType GhcPs -> SDoc
-inTypeDoc ty = text "In the type" <+> quotes (ppr ty)
-
-warnUnusedForAll :: (OutputableBndrFlag flag) => SDoc -> LHsTyVarBndr flag GhcRn -> FreeVars -> TcM ()
-warnUnusedForAll in_doc (L loc tv) used_names
+warnUnusedForAll :: OutputableBndrFlag flag
+ => HsDocContext -> LHsTyVarBndr flag GhcRn -> FreeVars -> TcM ()
+warnUnusedForAll doc (L loc tv) used_names
= whenWOptM Opt_WarnUnusedForalls $
unless (hsTyVarName tv `elemNameSet` used_names) $
addWarnAt (Reason Opt_WarnUnusedForalls) loc $
vcat [ text "Unused quantified type variable" <+> quotes (ppr tv)
- , in_doc ]
+ , inHsDocContext doc ]
opTyErr :: Outputable a => RdrName -> a -> SDoc
opTyErr op overall_ty
=====================================
compiler/GHC/Rename/Module.hs
=====================================
@@ -31,7 +31,7 @@ import GHC.Rename.HsType
import GHC.Rename.Bind
import GHC.Rename.Env
import GHC.Rename.Utils ( HsDocContext(..), mapFvRn, bindLocalNames
- , checkDupRdrNames, inHsDocContext, bindLocalNamesFV
+ , checkDupRdrNames, bindLocalNamesFV
, checkShadowedRdrNames, warnUnusedTypePatterns
, extendTyVarEnvFVRn, newLocalBndrsRn
, withHsDocContext )
@@ -720,7 +720,7 @@ rnFamInstEqn doc atfi rhs_kvars
-- with a sensible binding location
; ((bndrs', pats', payload'), fvs)
<- bindLocalNamesFV all_imp_var_names $
- bindLHsTyVarBndrs doc (Just $ inHsDocContext doc)
+ bindLHsTyVarBndrs doc WarnUnusedForalls
Nothing bndrs $ \bndrs' ->
-- Note: If we pass mb_cls instead of Nothing here,
-- bindLHsTyVarBndrs will use class variables for any names
@@ -1017,7 +1017,7 @@ rnHsRuleDecl (HsRule { rd_name = rule_name
; checkShadowedRdrNames rdr_names_w_loc
; names <- newLocalBndrsRn rdr_names_w_loc
; let doc = RuleCtx (snd $ unLoc rule_name)
- ; bindRuleTyVars doc in_rule tyvs $ \ tyvs' ->
+ ; bindRuleTyVars doc tyvs $ \ tyvs' ->
bindRuleTmVars doc tyvs' tmvs names $ \ tmvs' ->
do { (lhs', fv_lhs') <- rnLExpr lhs
; (rhs', fv_rhs') <- rnLExpr rhs
@@ -1033,7 +1033,6 @@ rnHsRuleDecl (HsRule { rd_name = rule_name
get_var :: RuleBndr GhcPs -> Located RdrName
get_var (RuleBndrSig _ v _) = v
get_var (RuleBndr _ v) = v
- in_rule = text "in the rule" <+> pprFullRuleName rule_name
bindRuleTmVars :: HsDocContext -> Maybe ty_bndrs
-> [LRuleBndr GhcPs] -> [Name]
@@ -1059,17 +1058,17 @@ bindRuleTmVars doc tyvs vars names thing_inside
bind_free_tvs = case tyvs of Nothing -> AlwaysBind
Just _ -> NeverBind
-bindRuleTyVars :: HsDocContext -> SDoc -> Maybe [LHsTyVarBndr () GhcPs]
+bindRuleTyVars :: HsDocContext -> Maybe [LHsTyVarBndr () GhcPs]
-> (Maybe [LHsTyVarBndr () GhcRn] -> RnM (b, FreeVars))
-> RnM (b, FreeVars)
-bindRuleTyVars doc in_doc (Just bndrs) thing_inside
- = bindLHsTyVarBndrs doc (Just in_doc) Nothing bndrs (thing_inside . Just)
-bindRuleTyVars _ _ _ thing_inside = thing_inside Nothing
+bindRuleTyVars doc (Just bndrs) thing_inside
+ = bindLHsTyVarBndrs doc WarnUnusedForalls Nothing bndrs (thing_inside . Just)
+bindRuleTyVars _ _ thing_inside = thing_inside Nothing
{-
Note [Rule LHS validity checking]
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-Check the shape of a transformation rule LHS. Currently we only allow
+Check the shape of a rewrite rule LHS. Currently we only allow
LHSs of the form @(f e1 .. en)@, where @f@ is not one of the
@forall@'d variables.
@@ -1581,7 +1580,7 @@ rnTyClDecl (SynDecl { tcdLName = tycon, tcdTyVars = tyvars,
; let kvs = extractHsTyRdrTyVarsKindVars rhs
doc = TySynCtx tycon
; traceRn "rntycl-ty" (ppr tycon <+> ppr kvs)
- ; bindHsQTyVars doc Nothing Nothing kvs tyvars $ \ tyvars' _ ->
+ ; bindHsQTyVars doc Nothing kvs tyvars $ \ tyvars' _ ->
do { (rhs', fvs) <- rnTySyn doc rhs
; return (SynDecl { tcdLName = tycon', tcdTyVars = tyvars'
, tcdFixity = fixity
@@ -1597,7 +1596,7 @@ rnTyClDecl (DataDecl
; let kvs = extractDataDefnKindVars defn
doc = TyDataCtx tycon
; traceRn "rntycl-data" (ppr tycon <+> ppr kvs)
- ; bindHsQTyVars doc Nothing Nothing kvs tyvars $ \ tyvars' no_rhs_kvs ->
+ ; bindHsQTyVars doc Nothing kvs tyvars $ \ tyvars' no_rhs_kvs ->
do { (defn', fvs) <- rnDataDefn doc defn
; cusk <- data_decl_has_cusk tyvars' new_or_data no_rhs_kvs kind_sig
; let rn_info = DataDeclRn { tcdDataCusk = cusk
@@ -1621,7 +1620,7 @@ rnTyClDecl (ClassDecl { tcdCtxt = context, tcdLName = lcls,
-- Tyvars scope over superclass context and method signatures
; ((tyvars', context', fds', ats'), stuff_fvs)
- <- bindHsQTyVars cls_doc Nothing Nothing kvs tyvars $ \ tyvars' _ -> do
+ <- bindHsQTyVars cls_doc Nothing kvs tyvars $ \ tyvars' _ -> do
-- Checks for distinct tyvars
{ (context', cxt_fvs) <- rnContext cls_doc context
; fds' <- rnFds fds
@@ -1878,7 +1877,7 @@ rnFamDecl mb_cls (FamilyDecl { fdLName = tycon, fdTyVars = tyvars
, fdInjectivityAnn = injectivity })
= do { tycon' <- lookupLocatedTopBndrRn tycon
; ((tyvars', res_sig', injectivity'), fv1) <-
- bindHsQTyVars doc Nothing mb_cls kvs tyvars $ \ tyvars' _ ->
+ bindHsQTyVars doc mb_cls kvs tyvars $ \ tyvars' _ ->
do { let rn_sig = rnFamResultSig doc
; (res_sig', fv_kind) <- wrapLocFstM rn_sig res_sig
; injectivity' <- traverse (rnInjectivityAnn tyvars' res_sig')
@@ -2080,7 +2079,7 @@ rnConDecl decl@(ConDeclH98 { con_name = name, con_ex_tvs = ex_tvs
-- scoping we get. So no implicit binders at the existential forall
; let ctxt = ConDeclCtx [new_name]
- ; bindLHsTyVarBndrs ctxt (Just (inHsDocContext ctxt))
+ ; bindLHsTyVarBndrs ctxt WarnUnusedForalls
Nothing ex_tvs $ \ new_ex_tvs ->
do { (new_context, fvs1) <- rnMbContext ctxt mcxt
; (new_args, fvs2) <- rnConDeclDetails (unLoc new_name) ctxt args
@@ -2118,11 +2117,11 @@ rnConDecl decl@(ConDeclGADT { con_names = names
$ extractHsTvBndrs explicit_tkvs
$ extractHsTysRdrTyVarsDups (theta ++ arg_tys ++ [res_ty])
- ; let ctxt = ConDeclCtx new_names
- mb_ctxt = Just (inHsDocContext ctxt)
+ ; let ctxt = ConDeclCtx new_names
; rnImplicitBndrs implicit_bndrs $ \ implicit_tkvs ->
- bindLHsTyVarBndrs ctxt mb_ctxt Nothing explicit_tkvs $ \ explicit_tkvs ->
+ bindLHsTyVarBndrs ctxt WarnUnusedForalls
+ Nothing explicit_tkvs $ \ explicit_tkvs ->
do { (new_cxt, fvs1) <- rnMbContext ctxt mcxt
; (new_args, fvs2) <- rnConDeclDetails (unLoc (head new_names)) ctxt args
; (new_res_ty, fvs3) <- rnLHsType ctxt res_ty
=====================================
compiler/GHC/Rename/Utils.hs
=====================================
@@ -495,7 +495,7 @@ pprHsDocContext PatCtx = text "a pattern type-signature"
pprHsDocContext SpecInstSigCtx = text "a SPECIALISE instance pragma"
pprHsDocContext DefaultDeclCtx = text "a `default' declaration"
pprHsDocContext DerivDeclCtx = text "a deriving declaration"
-pprHsDocContext (RuleCtx name) = text "the transformation rule" <+> ftext name
+pprHsDocContext (RuleCtx name) = text "the rewrite rule" <+> doubleQuotes (ftext name)
pprHsDocContext (TyDataCtx tycon) = text "the data type declaration for" <+> quotes (ppr tycon)
pprHsDocContext (FamPatCtx tycon) = text "a type pattern of family instance for" <+> quotes (ppr tycon)
pprHsDocContext (TySynCtx name) = text "the declaration for type synonym" <+> quotes (ppr name)
=====================================
compiler/GHC/Tc/Gen/Rule.hs
=====================================
@@ -7,7 +7,7 @@
{-# LANGUAGE ViewPatterns #-}
{-# LANGUAGE TypeFamilies #-}
--- | Typechecking transformation rules
+-- | Typechecking rewrite rules
module GHC.Tc.Gen.Rule ( tcRules ) where
import GHC.Prelude
@@ -239,7 +239,7 @@ tcRuleTmBndrs (L _ (RuleBndrSig _ (L _ name) rn_ty) : rule_bndrs)
; return (map snd tvs ++ tyvars, id : tmvars) }
ruleCtxt :: FastString -> SDoc
-ruleCtxt name = text "When checking the transformation rule" <+>
+ruleCtxt name = text "When checking the rewrite rule" <+>
doubleQuotes (ftext name)
=====================================
testsuite/tests/dependent/should_fail/T16326_Fail10.stderr
=====================================
@@ -4,4 +4,4 @@ T16326_Fail10.hs:12:18: error:
forall a -> a -> a
(GHC does not yet support this)
• In a RULE for ‘x’: forall a -> a -> a
- When checking the transformation rule "flurmp"
+ When checking the rewrite rule "flurmp"
=====================================
testsuite/tests/rename/should_compile/ExplicitForAllRules1.stderr
=====================================
@@ -1,4 +1,4 @@
ExplicitForAllRules1.hs:49:31: warning: [-Wunused-foralls (in -Wextra)]
Unused quantified type variable ‘b’
- in the rule "example7"
+ In the rewrite rule "example7"
=====================================
testsuite/tests/rename/should_compile/T5331.stderr
=====================================
@@ -9,4 +9,4 @@ T5331.hs:11:16: warning: [-Wunused-foralls (in -Wextra)]
T5331.hs:13:13: warning: [-Wunused-foralls (in -Wextra)]
Unused quantified type variable ‘a’
- In the type ‘forall a. Int’
+ In the type signature for ‘f’
=====================================
testsuite/tests/safeHaskell/ghci/p14.stderr
=====================================
@@ -1,6 +1,6 @@
<interactive>:9:25: error:
- No instance for (Num a) arising from a use of ‘f’
- Possible fix: add (Num a) to the context of the RULE "id/Int"
- In the expression: f
- When checking the transformation rule "id/Int"
+ • No instance for (Num a) arising from a use of ‘f’
+ Possible fix: add (Num a) to the context of the RULE "id/Int"
+ • In the expression: f
+ When checking the rewrite rule "id/Int"
=====================================
testsuite/tests/typecheck/should_compile/T10072.stderr
=====================================
@@ -7,4 +7,4 @@ T10072.hs:3:31: error:
To use the inferred type, enable PartialTypeSignatures
• In the type ‘a -> _’
In a RULE for ‘f’: a -> _
- When checking the transformation rule "map/empty"
+ When checking the rewrite rule "map/empty"
=====================================
testsuite/tests/typecheck/should_fail/T5853.stderr
=====================================
@@ -9,7 +9,7 @@ T5853.hs:15:52: error:
bound by the RULE "map/map" at T5853.hs:15:2-57
NB: ‘Subst’ is a non-injective type family
• In the expression: (f . g) <$> xs
- When checking the transformation rule "map/map"
+ When checking the rewrite rule "map/map"
• Relevant bindings include
f :: Elem fa -> b (bound at T5853.hs:15:19)
g :: a -> Elem fa (bound at T5853.hs:15:21)
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/dab29bb953aee1f60b6124e83502aeb91bb73e02
--
View it on GitLab: https://gitlab.haskell.org/ghc/ghc/-/commit/dab29bb953aee1f60b6124e83502aeb91bb73e02
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