Remove -fwarn-simple-patterns, and make -fwarn-incomplete-patterns include lambdas

This makes
     \(x:xs) -> e
want when you have -fwarn-incomplete-patterns, which is consistent.

diff --git a/compiler/deSugar/Match.lhs b/compiler/deSugar/Match.lhs
index 2c9aa0b..4bc0c4b 100644 (file)
--- a/compiler/deSugar/Match.lhs
+++ b/compiler/deSugar/Match.lhs
@@ -700,21 +700,14 @@ matchEquations  :: HsMatchContext Name
                -> [Id] -> [EquationInfo] -> Type
                -> DsM CoreExpr
 matchEquations ctxt vars eqns_info rhs_ty
-  = do { dflags <- getDOptsDs
-       ; locn   <- getSrcSpanDs
-       ; let   ds_ctxt      = DsMatchContext ctxt locn
+  = do { locn <- getSrcSpanDs
+       ; let   ds_ctxt   = DsMatchContext ctxt locn
                error_doc = matchContextErrString ctxt
 
-       ; match_result <- match_fun dflags ds_ctxt vars rhs_ty eqns_info
+       ; match_result <- matchCheck ds_ctxt vars rhs_ty eqns_info
 
        ; fail_expr <- mkErrorAppDs pAT_ERROR_ID rhs_ty error_doc
        ; extractMatchResult match_result fail_expr }
-  where 
-    match_fun dflags ds_ctxt
-       = case ctxt of 
-           LambdaExpr | dopt Opt_WarnSimplePatterns dflags -> matchCheck ds_ctxt
-                      | otherwise                          -> match
-           _                                               -> matchCheck ds_ctxt
 \end{code}
 
 %************************************************************************
@@ -734,7 +727,7 @@ matchSimply :: CoreExpr                     -- Scrutinee
            -> CoreExpr                 -- Return this if it matches
            -> CoreExpr                 -- Return this if it doesn't
            -> DsM CoreExpr
-
+-- Do not warn about incomplete patterns; see matchSinglePat comments
 matchSimply scrut hs_ctx pat result_expr fail_expr = do
     let
       match_result = cantFailMatchResult result_expr
@@ -746,16 +739,11 @@ matchSimply scrut hs_ctx pat result_expr fail_expr = do
 
 matchSinglePat :: CoreExpr -> HsMatchContext Name -> LPat Id
               -> Type -> MatchResult -> DsM MatchResult
-matchSinglePat (Var var) hs_ctx (L _ pat) ty match_result = do
-    dflags <- getDOptsDs
-    locn <- getSrcSpanDs
-    let
-        match_fn dflags
-           | dopt Opt_WarnSimplePatterns dflags = matchCheck ds_ctx
-           | otherwise                          = match
-           where
-             ds_ctx = DsMatchContext hs_ctx locn
-    match_fn dflags [var] ty [EqnInfo { eqn_pats = [pat], eqn_rhs  = match_result }]
+-- Do not warn about incomplete patterns
+-- Used for things like [ e | pat <- stuff ], where 
+-- incomplete patterns are just fine
+matchSinglePat (Var var) _ (L _ pat) ty match_result 
+  = match [var] ty [EqnInfo { eqn_pats = [pat], eqn_rhs  = match_result }]
 
 matchSinglePat scrut hs_ctx pat ty match_result = do
     var <- selectSimpleMatchVarL pat

diff --git a/compiler/main/DynFlags.hs b/compiler/main/DynFlags.hs
index 6af63fe..467ebcb 100644 (file)
--- a/compiler/main/DynFlags.hs
+++ b/compiler/main/DynFlags.hs
@@ -192,7 +192,6 @@ data DynFlag
    | Opt_WarnMissingLocalSigs
    | Opt_WarnNameShadowing
    | Opt_WarnOverlappingPatterns
-   | Opt_WarnSimplePatterns
    | Opt_WarnTypeDefaults
    | Opt_WarnMonomorphism
    | Opt_WarnUnusedBinds
@@ -1432,7 +1431,6 @@ fFlags = [
   ( "warn-missing-local-sigs",          Opt_WarnMissingLocalSigs, nop ),
   ( "warn-name-shadowing",              Opt_WarnNameShadowing, nop ),
   ( "warn-overlapping-patterns",        Opt_WarnOverlappingPatterns, nop ),
-  ( "warn-simple-patterns",             Opt_WarnSimplePatterns, nop ),
   ( "warn-type-defaults",               Opt_WarnTypeDefaults, nop ),
   ( "warn-monomorphism-restriction",    Opt_WarnMonomorphism, nop ),
   ( "warn-unused-binds",                Opt_WarnUnusedBinds, nop ),
@@ -1760,7 +1758,6 @@ minuswRemovesOpts
     = minusWallOpts ++
       [Opt_WarnImplicitPrelude,
        Opt_WarnIncompletePatternsRecUpd,
-       Opt_WarnSimplePatterns,
        Opt_WarnMonomorphism,
        Opt_WarnUnrecognisedPragmas,
        Opt_WarnTabs

diff --git a/docs/users_guide/flags.xml b/docs/users_guide/flags.xml
index 9b26e49..5a3458a 100644 (file)
--- a/docs/users_guide/flags.xml
+++ b/docs/users_guide/flags.xml
@@ -1179,13 +1179,6 @@
          </row>
 
          <row>
-           <entry><option>-fwarn-simple-patterns</option></entry>
-           <entry>warn about lambda-patterns that can fail</entry>
-           <entry>dynamic</entry>
-           <entry><option>-fno-warn-simple-patterns</option></entry>
-         </row>
-
-         <row>
            <entry><option>-fwarn-tabs</option></entry>
            <entry>warn if there are tabs in the source file</entry>
            <entry>dynamic</entry>

diff --git a/docs/users_guide/using.xml b/docs/users_guide/using.xml
index 593781f..7ef2f2f 100644 (file)
--- a/docs/users_guide/using.xml
+++ b/docs/users_guide/using.xml
@@ -989,7 +989,6 @@ ghc -c Foo.hs</screen>
          suspicious code.  The warnings that are
          <emphasis>not</emphasis> enabled by <option>-Wall</option>
          are
-            <option>-fwarn-simple-patterns</option>,
             <option>-fwarn-tabs</option>,
             <option>-fwarn-incomplete-record-updates</option>,
             <option>-fwarn-monomorphism-restriction</option>,
@@ -1376,28 +1375,6 @@ f "2"    = 2
       </varlistentry>
 
       <varlistentry>
-       <term><option>-fwarn-simple-patterns</option>:</term>
-       <listitem>
-         <indexterm><primary><option>-fwarn-simple-patterns</option></primary>
-         </indexterm>
-         <para>Causes the compiler to warn about lambda-bound
-         patterns that can fail, eg. <literal>\(x:xs)->...</literal>.
-         Normally, these aren't treated as incomplete patterns by
-         <option>-fwarn-incomplete-patterns</option>.</para>
-         <para>&ldquo;Lambda-bound patterns&rdquo; includes all places where there is a single pattern,
-           including list comprehensions and do-notation.  In these cases, a pattern-match 
-           failure is quite legitimate, and triggers filtering (list comprehensions) or
-           the monad <literal>fail</literal> operation (monads). For example:
-           <programlisting>
-             f :: [Maybe a] -> [a]
-             f xs = [y | Just y &lt;- xs]
-             </programlisting>
-           Switching on <option>-fwarn-simple-patterns</option> will elicit warnings about
-           these probably-innocent cases, which is why the flag is off by default. </para>
-       </listitem>
-      </varlistentry>
-
-      <varlistentry>
        <term><option>-fwarn-tabs</option>:</term>
        <listitem>
          <indexterm><primary><option>-fwarn-tabs</option></primary></indexterm>