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-rw-r--r--compiler/deSugar/DsExpr.lhs2
-rw-r--r--compiler/deSugar/DsListComp.lhs2
-rw-r--r--compiler/ghc.cabal2
-rw-r--r--compiler/main/DynFlags.hs23
-rw-r--r--compiler/rename/RnPat.lhs4
-rw-r--r--compiler/rename/RnSource.lhs4
-rw-r--r--compiler/simplCore/SimplUtils.lhs2
-rw-r--r--compiler/typecheck/TcDeriv.lhs4
-rw-r--r--docs/users_guide/flags.xml6
-rw-r--r--docs/users_guide/glasgow_exts.xml68
10 files changed, 63 insertions, 54 deletions
diff --git a/compiler/deSugar/DsExpr.lhs b/compiler/deSugar/DsExpr.lhs
index eed7f87d8f..f152ff5725 100644
--- a/compiler/deSugar/DsExpr.lhs
+++ b/compiler/deSugar/DsExpr.lhs
@@ -564,7 +564,7 @@ dsExplicitList :: PostTcType -> [LHsExpr Id] -> DsM CoreExpr
dsExplicitList elt_ty xs = do
dflags <- getDOptsDs
xs' <- mapM dsLExpr xs
- if not (dopt Opt_RewriteRules dflags)
+ if not (dopt Opt_EnableRewriteRules dflags)
then return $ mkListExpr elt_ty xs'
else mkBuildExpr elt_ty (mkSplitExplicitList (thisPackage dflags) xs')
where
diff --git a/compiler/deSugar/DsListComp.lhs b/compiler/deSugar/DsListComp.lhs
index 2bd1a6d741..bdbe65ee7e 100644
--- a/compiler/deSugar/DsListComp.lhs
+++ b/compiler/deSugar/DsListComp.lhs
@@ -56,7 +56,7 @@ dsListComp lquals body elt_ty = do
dflags <- getDOptsDs
let quals = map unLoc lquals
- if not (dopt Opt_RewriteRules dflags) || dopt Opt_IgnoreInterfacePragmas dflags
+ if not (dopt Opt_EnableRewriteRules dflags) || dopt Opt_IgnoreInterfacePragmas dflags
-- Either rules are switched off, or we are ignoring what there are;
-- Either way foldr/build won't happen, so use the more efficient
-- Wadler-style desugaring
diff --git a/compiler/ghc.cabal b/compiler/ghc.cabal
index b1de64ef69..437ebc2809 100644
--- a/compiler/ghc.cabal
+++ b/compiler/ghc.cabal
@@ -85,7 +85,7 @@ Library
Extensions: CPP, MagicHash, UnboxedTuples, PatternGuards,
ForeignFunctionInterface, EmptyDataDecls,
TypeSynonymInstances, MultiParamTypeClasses,
- FlexibleInstances, Rank2Types, PatternSignatures
+ FlexibleInstances, Rank2Types, ScopedTypeVariables
Include-Dirs: . parser utils
diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index 062443dde9..a3330e7491 100644
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -229,7 +229,6 @@ data DynFlag
| Opt_MagicHash
| Opt_EmptyDataDecls
| Opt_KindSignatures
- | Opt_PatternSignatures
| Opt_ParallelListComp
| Opt_TransformListComp
| Opt_GeneralizedNewtypeDeriving
@@ -261,7 +260,7 @@ data DynFlag
| Opt_UnboxStrictFields
| Opt_MethodSharing
| Opt_DictsCheap
- | Opt_RewriteRules
+ | Opt_EnableRewriteRules -- Apply rewrite rules during simplification
| Opt_Vectorise
| Opt_RegsGraph -- do graph coloring register allocation
| Opt_RegsIterative -- do iterative coalescing graph coloring register allocation
@@ -794,8 +793,8 @@ optLevelFlags
, ([0], Opt_OmitInterfacePragmas)
, ([1,2], Opt_IgnoreAsserts)
- , ([1,2], Opt_RewriteRules) -- Off for -O0; see Note [Scoping for Builtin rules]
- -- in PrelRules
+ , ([1,2], Opt_EnableRewriteRules) -- Off for -O0; see Note [Scoping for Builtin rules]
+ -- in PrelRules
, ([1,2], Opt_DoEtaReduction)
, ([1,2], Opt_CaseMerge)
, ([1,2], Opt_Strictness)
@@ -1470,6 +1469,12 @@ deprecatedForLanguage lang turn_on
flag | turn_on = lang
| otherwise = "No"++lang
+useInstead :: String -> Bool -> Deprecated
+useInstead flag turn_on
+ = Deprecated ("Use -f" ++ no ++ flag ++ " instead")
+ where
+ no = if turn_on then "" else "no-"
+
-- | These @-f\<blah\>@ flags can all be reversed with @-fno-\<blah\>@
fFlags :: [(String, DynFlag, Bool -> Deprecated)]
fFlags = [
@@ -1518,7 +1523,8 @@ fFlags = [
( "print-bind-result", Opt_PrintBindResult, const Supported ),
( "force-recomp", Opt_ForceRecomp, const Supported ),
( "hpc-no-auto", Opt_Hpc_No_Auto, const Supported ),
- ( "rewrite-rules", Opt_RewriteRules, const Supported ),
+ ( "rewrite-rules", Opt_EnableRewriteRules, useInstead "enable-rewrite-rules" ),
+ ( "enable-rewrite-rules", Opt_EnableRewriteRules, const Supported ),
( "break-on-exception", Opt_BreakOnException, const Supported ),
( "break-on-error", Opt_BreakOnError, const Supported ),
( "print-evld-with-show", Opt_PrintEvldWithShow, const Supported ),
@@ -1583,7 +1589,6 @@ xFlags = [
( "PolymorphicComponents", Opt_PolymorphicComponents, const Supported ),
( "ExistentialQuantification", Opt_ExistentialQuantification, const Supported ),
( "KindSignatures", Opt_KindSignatures, const Supported ),
- ( "PatternSignatures", Opt_PatternSignatures, const Supported ),
( "EmptyDataDecls", Opt_EmptyDataDecls, const Supported ),
( "ParallelListComp", Opt_ParallelListComp, const Supported ),
( "TransformListComp", Opt_TransformListComp, const Supported ),
@@ -1620,6 +1625,11 @@ xFlags = [
( "ExtendedDefaultRules", Opt_ExtendedDefaultRules, const Supported ),
( "ImplicitParams", Opt_ImplicitParams, const Supported ),
( "ScopedTypeVariables", Opt_ScopedTypeVariables, const Supported ),
+
+ -- -XPatternSignatures is deprecated; now -XScopedTypeVariables enables pattern signatures
+ ( "PatternSignatures", Opt_ScopedTypeVariables,
+ deprecatedForLanguage "ScopedTypeVariables" ),
+
( "UnboxedTuples", Opt_UnboxedTuples, const Supported ),
( "StandaloneDeriving", Opt_StandaloneDeriving, const Supported ),
( "DeriveDataTypeable", Opt_DeriveDataTypeable, const Supported ),
@@ -1675,7 +1685,6 @@ glasgowExtsFlags = [
, Opt_ParallelListComp
, Opt_EmptyDataDecls
, Opt_KindSignatures
- , Opt_PatternSignatures
, Opt_GeneralizedNewtypeDeriving
, Opt_TypeFamilies ]
diff --git a/compiler/rename/RnPat.lhs b/compiler/rename/RnPat.lhs
index 584c2870cd..18f3dd5d85 100644
--- a/compiler/rename/RnPat.lhs
+++ b/compiler/rename/RnPat.lhs
@@ -212,7 +212,7 @@ rnLPatAndThen var@(NM varf) (L loc p) cont =
-- (e.g. in the pattern (x, x -> y) x needs to be bound in the rhs of the tuple)
SigPatIn pat ty -> do
- patsigs <- doptM Opt_PatternSignatures
+ patsigs <- doptM Opt_ScopedTypeVariables
if patsigs
then rnLPatAndThen var pat
(\ pat' -> do { (ty', fvs1) <- rnHsTypeFVs tvdoc ty
@@ -580,7 +580,7 @@ checkTupSize tup_size
patSigErr :: Outputable a => a -> SDoc
patSigErr ty
= (ptext (sLit "Illegal signature in pattern:") <+> ppr ty)
- $$ nest 4 (ptext (sLit "Use -XPatternSignatures to permit it"))
+ $$ nest 4 (ptext (sLit "Use -XScopedTypeVariables to permit it"))
dupFieldErr :: String -> RdrName -> SDoc
dupFieldErr str dup
diff --git a/compiler/rename/RnSource.lhs b/compiler/rename/RnSource.lhs
index 27de40f662..cebc6746c6 100644
--- a/compiler/rename/RnSource.lhs
+++ b/compiler/rename/RnSource.lhs
@@ -174,7 +174,9 @@ rnSrcDecls shadowP group@(HsGroup {hs_valds = val_decls,
-- (H) Rename Everything else
(rn_inst_decls, src_fvs2) <- rnList rnSrcInstDecl inst_decls ;
- (rn_rule_decls, src_fvs3) <- rnList rnHsRuleDecl rule_decls ;
+ (rn_rule_decls, src_fvs3) <- setOptM Opt_ScopedTypeVariables $
+ rnList rnHsRuleDecl rule_decls ;
+ -- Inside RULES, scoped type variables are on
(rn_foreign_decls, src_fvs4) <- rnList rnHsForeignDecl foreign_decls ;
(rn_default_decls, src_fvs5) <- rnList rnDefaultDecl default_decls ;
(rn_deriv_decls, src_fvs6) <- rnList rnSrcDerivDecl deriv_decls ;
diff --git a/compiler/simplCore/SimplUtils.lhs b/compiler/simplCore/SimplUtils.lhs
index be5c4b3e6a..1fdde7f209 100644
--- a/compiler/simplCore/SimplUtils.lhs
+++ b/compiler/simplCore/SimplUtils.lhs
@@ -797,7 +797,7 @@ activeInline env id
activeRule :: DynFlags -> SimplEnv -> Maybe (Activation -> Bool)
-- Nothing => No rules at all
activeRule dflags env
- | not (dopt Opt_RewriteRules dflags)
+ | not (dopt Opt_EnableRewriteRules dflags)
= Nothing -- Rewriting is off
| otherwise
= case getMode env of
diff --git a/compiler/typecheck/TcDeriv.lhs b/compiler/typecheck/TcDeriv.lhs
index efc46cd34f..ea38b34d04 100644
--- a/compiler/typecheck/TcDeriv.lhs
+++ b/compiler/typecheck/TcDeriv.lhs
@@ -308,8 +308,8 @@ renameDeriv is_boot gen_binds insts
| otherwise
= discardWarnings $ -- Discard warnings about unused bindings etc
- do { (rn_gen, dus_gen) <- setOptM Opt_PatternSignatures $ -- Type signatures in patterns
- -- are used in the generic binds
+ do { (rn_gen, dus_gen) <- setOptM Opt_ScopedTypeVariables $ -- Type signatures in patterns
+ -- are used in the generic binds
rnTopBinds (ValBindsIn gen_binds [])
; keepAliveSetTc (duDefs dus_gen) -- Mark these guys to be kept alive
diff --git a/docs/users_guide/flags.xml b/docs/users_guide/flags.xml
index 32eb56548c..5e52d61d30 100644
--- a/docs/users_guide/flags.xml
+++ b/docs/users_guide/flags.xml
@@ -828,12 +828,6 @@
<entry><option>-XNoKindSignatures</option></entry>
</row>
<row>
- <entry><option>-XPatternSignatures</option></entry>
- <entry>Enable <link linkend="pattern-type-sigs">pattern type signatures</link>.</entry>
- <entry>dynamic</entry>
- <entry><option>-XNoPatternSignatures</option></entry>
- </row>
- <row>
<entry><option>-XEmptyDataDecls</option></entry>
<entry>Enable empty data declarations.</entry>
<entry>dynamic</entry>
diff --git a/docs/users_guide/glasgow_exts.xml b/docs/users_guide/glasgow_exts.xml
index 14848159a4..0bccb9e7f7 100644
--- a/docs/users_guide/glasgow_exts.xml
+++ b/docs/users_guide/glasgow_exts.xml
@@ -6674,15 +6674,7 @@ data S = S {-# UNPACK #-} !Int {-# UNPACK #-} !Int
<para>
The programmer can specify rewrite rules as part of the source program
-(in a pragma). GHC applies these rewrite rules wherever it can, provided (a)
-the <option>-O</option> flag (<xref linkend="options-optimise"/>) is on,
-and (b) the <option>-fno-rewrite-rules</option> flag
-(<xref linkend="options-f"/>) is not specified, and (c) the
-<option>-fglasgow-exts</option> (<xref linkend="options-language"/>)
-flag is active.
-</para>
-
-<para>
+(in a pragma).
Here is an example:
<programlisting>
@@ -6802,17 +6794,40 @@ variables it mentions, though of course they need to be in scope.
<listitem>
<para>
- Rules are automatically exported from a module, just as instance declarations are.
+ All rules are implicitly exported from the module, and are therefore
+in force in any module that imports the module that defined the rule, directly
+or indirectly. (That is, if A imports B, which imports C, then C's rules are
+in force when compiling A.) The situation is very similar to that for instance
+declarations.
</para>
</listitem>
+<listitem>
+
+<para>
+Inside a RULE "<literal>forall</literal>" is treated as a keyword, regardless of
+any other flag settings. Furthermore, inside a RULE, the language extension
+<option>-XScopedTypeVariables</option> is automatically enabled; see
+<xref linkend="scoped-type-variables"/>.
+</para>
+</listitem>
+<listitem>
+
+<para>
+Like other pragmas, RULE pragmas are always checked for scope errors, and
+are typechecked. Typechecking means that the LHS and RHS of a rule are typechecked,
+and must have the same type. However, rules are only <emphasis>enabled</emphasis>
+if the <option>-fenable-rewrite-rules</option> flag is
+on (see <xref linkend="rule-semantics"/>).
+</para>
+</listitem>
</itemizedlist>
</para>
</sect2>
-<sect2>
+<sect2 id="rule-semantics">
<title>Semantics</title>
<para>
@@ -6820,9 +6835,17 @@ From a semantic point of view:
<itemizedlist>
<listitem>
-
<para>
-Rules are only applied if you use the <option>-O</option> flag.
+Rules are enabled (that is, used during optimisation)
+by the <option>-fenable-rewrite-rules</option> flag.
+This flag is implied by <option>-O</option>, and may be switched
+off (as usual) by <option>-fno-enable-rewrite-rules</option>.
+(NB: enabling <option>-fenable-rewrite-rules</option> without <option>-O</option>
+may not do what you expect, though, because without <option>-O</option> GHC
+ignores all optimisation information in interface files;
+see <option>-fignore-interface-pragmas</option>, <xref linkend="options-f"/>.)
+Note that <option>-fenable-rewrite-rules</option> is an <emphasis>optimisation</emphasis> flag, and
+has no effect on parsing or typechecking.
</para>
</listitem>
@@ -6839,14 +6862,6 @@ expression by substituting for the pattern variables.
<listitem>
<para>
- The LHS and RHS of a rule are typechecked, and must have the
-same type.
-
-</para>
-</listitem>
-<listitem>
-
-<para>
GHC makes absolutely no attempt to verify that the LHS and RHS
of a rule have the same meaning. That is undecidable in general, and
infeasible in most interesting cases. The responsibility is entirely the programmer's!
@@ -6939,17 +6954,6 @@ pragma on <literal>f</literal>, to ensure
that it is not inlined until its RULEs have had a chance to fire.
</para>
</listitem>
-<listitem>
-
-<para>
- All rules are implicitly exported from the module, and are therefore
-in force in any module that imports the module that defined the rule, directly
-or indirectly. (That is, if A imports B, which imports C, then C's rules are
-in force when compiling A.) The situation is very similar to that for instance
-declarations.
-</para>
-</listitem>
-
</itemizedlist>
</para>
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