[Add an extension to disable n+k patterns
Ian Lynagh <igloo@earth.li>**20090725134703] {
hunk ./compiler/main/DynFlags.hs 229
+   | Opt_NPlusKPatterns
hunk ./compiler/main/DynFlags.hs 697
+            Opt_NPlusKPatterns,
hunk ./compiler/main/DynFlags.hs 1813
+  -- On by default:
+  ( "NPlusKPatterns",                   Opt_NPlusKPatterns, const Supported ),
hunk ./compiler/parser/Lexer.x 49
+   getPState,
hunk ./compiler/parser/Lexer.x 1519
+getPState :: P PState
+getPState = P $ \s -> POk s s
+
hunk ./compiler/parser/RdrHsSyn.lhs 66
-import Lexer		( P, failSpanMsgP, extension, standaloneDerivingEnabled, bangPatEnabled )
+import Lexer
hunk ./compiler/parser/RdrHsSyn.lhs 73
+import DynFlags
hunk ./compiler/parser/RdrHsSyn.lhs 729
-  = do { p <- checkAPat loc e; return (L loc p) }
+  = do { pState <- getPState
+       ; p <- checkAPat (dflags pState) loc e
+       ; return (L loc p) }
hunk ./compiler/parser/RdrHsSyn.lhs 735
-checkAPat :: SrcSpan -> HsExpr RdrName -> P (Pat RdrName)
-checkAPat loc e = case e of
+checkAPat :: DynFlags -> SrcSpan -> HsExpr RdrName -> P (Pat RdrName)
+checkAPat dynflags loc e = case e of
hunk ./compiler/parser/RdrHsSyn.lhs 772
-   		      | plus == plus_RDR
+   		      | dopt Opt_NPlusKPatterns dynflags && (plus == plus_RDR)
hunk ./docs/users_guide/flags.xml 708
+	    <row>
+	      <entry><option>-XNoNPlusKPatterns</option></entry>
+	      <entry>Disable support for <literal>n+k</literal> patterns</entry>
+	      <entry>dynamic</entry>
+	      <entry><option>-XNPlusKPatterns</option></entry>
+	    </row>
hunk ./docs/users_guide/glasgow_exts.xml 842
+
+    <!-- ===================== n+k patterns ===================  -->
+
+<sect2 id="n-k-patterns">
+<title>n+k patterns</title>
+<indexterm><primary><option>-XNoNPlusKPatterns</option></primary></indexterm>
+
+<para>
+<literal>n+k</literal> pattern support is enabled by default. To disable
+it, you can use the <option>-XNoNPlusKPatterns</option> flag.
+</para>
+
+</sect2>
}