Trim unused imports detected by new unused-import code

[ghc-hetmet.git] / compiler / typecheck / TcType.lhs

diff --git a/compiler/typecheck/TcType.lhs b/compiler/typecheck/TcType.lhs
index 2d45334..ce42def 100644 (file)
--- a/compiler/typecheck/TcType.lhs
+++ b/compiler/typecheck/TcType.lhs
@@ -84,6 +84,8 @@ module TcType (
   isFFIExternalTy,     -- :: Type -> Bool
   isFFIDynArgumentTy,  -- :: Type -> Bool
   isFFIDynResultTy,    -- :: Type -> Bool
+  isFFIPrimArgumentTy, -- :: DynFlags -> Type -> Bool
+  isFFIPrimResultTy,   -- :: DynFlags -> Type -> Bool
   isFFILabelTy,        -- :: Type -> Bool
   isFFIDotnetTy,       -- :: DynFlags -> Type -> Bool
   isFFIDotnetObjTy,    -- :: Type -> Bool
@@ -151,7 +153,6 @@ import DynFlags
 import Name
 import NameSet
 import VarEnv
-import OccName
 import PrelNames
 import TysWiredIn
 import BasicTypes
@@ -161,7 +162,6 @@ import ListSetOps
 import Outputable
 import FastString
 
-import Data.List
 import Data.IORef
 \end{code}
 
@@ -353,6 +353,7 @@ data UserTypeCtxt
   | ForSigCtxt Name    -- Foreign inport or export signature
   | DefaultDeclCtxt    -- Types in a default declaration
   | SpecInstCtxt       -- SPECIALISE instance pragma
+  | ThBrackCtxt                -- Template Haskell type brackets [t| ... |]
 
 -- Notes re TySynCtxt
 -- We allow type synonyms that aren't types; e.g.  type List = []
@@ -410,6 +411,7 @@ pprUserTypeCtxt ExprSigCtxt     = ptext (sLit "an expression type signature")
 pprUserTypeCtxt (ConArgCtxt c)  = ptext (sLit "the type of the constructor") <+> quotes (ppr c)
 pprUserTypeCtxt (TySynCtxt c)   = ptext (sLit "the RHS of the type synonym") <+> quotes (ppr c)
 pprUserTypeCtxt GenPatCtxt      = ptext (sLit "the type pattern of a generic definition")
+pprUserTypeCtxt ThBrackCtxt     = ptext (sLit "a Template Haskell quotation [t|...|]")
 pprUserTypeCtxt LamPatSigCtxt   = ptext (sLit "a pattern type signature")
 pprUserTypeCtxt BindPatSigCtxt  = ptext (sLit "a pattern type signature")
 pprUserTypeCtxt ResSigCtxt      = ptext (sLit "a result type signature")
@@ -1226,6 +1228,18 @@ isFFILabelTy :: Type -> Bool
 -- or a newtype of either.
 isFFILabelTy = checkRepTyConKey [ptrTyConKey, funPtrTyConKey]
 
+isFFIPrimArgumentTy :: DynFlags -> Type -> Bool
+-- Checks for valid argument type for a 'foreign import prim'
+-- Currently they must all be simple unlifted types.
+isFFIPrimArgumentTy dflags ty
+   = checkRepTyCon (legalFIPrimArgTyCon dflags) ty
+
+isFFIPrimResultTy :: DynFlags -> Type -> Bool
+-- Checks for valid result type for a 'foreign import prim'
+-- Currently it must be an unlifted type, including unboxed tuples.
+isFFIPrimResultTy dflags ty
+   = checkRepTyCon (legalFIPrimResultTyCon dflags) ty
+
 isFFIDotnetTy :: DynFlags -> Type -> Bool
 isFFIDotnetTy dflags ty
   = checkRepTyCon (\ tc -> (legalFIResultTyCon dflags tc || 
@@ -1351,6 +1365,26 @@ boxedMarshalableTyCon tc
                         , stablePtrTyConKey
                         , boolTyConKey
                         ]
+
+legalFIPrimArgTyCon :: DynFlags -> TyCon -> Bool
+-- Check args of 'foreign import prim', only allow simple unlifted types.
+-- Strictly speaking it is unnecessary to ban unboxed tuples here since
+-- currently they're of the wrong kind to use in function args anyway.
+legalFIPrimArgTyCon dflags tc
+  = dopt Opt_UnliftedFFITypes dflags
+    && isUnLiftedTyCon tc
+    && not (isUnboxedTupleTyCon tc)
+
+legalFIPrimResultTyCon :: DynFlags -> TyCon -> Bool
+-- Check result type of 'foreign import prim'. Allow simple unlifted
+-- types and also unboxed tuple result types '... -> (# , , #)'
+legalFIPrimResultTyCon dflags tc
+  = dopt Opt_UnliftedFFITypes dflags
+    && isUnLiftedTyCon tc
+    && (isUnboxedTupleTyCon tc
+        || case tyConPrimRep tc of     -- Note [Marshalling VoidRep]
+          VoidRep -> False
+          _       -> True)
 \end{code}
 
 Note [Marshalling VoidRep]