[commit: ghc] master: Allow Any as an argument type to foreign prim functions (e29001c)

[Simon Marlow]

Repository : ssh://darcs.haskell.org//srv/darcs/ghc

On branch  : master

http://hackage.haskell.org/trac/ghc/changeset/e29001c9e0f73885c0b85d86c3a854519448013a

>---------------------------------------------------------------

commit e29001c9e0f73885c0b85d86c3a854519448013a
Author: Joachim Breitner <mail at joachim-breitner.de>
Date:   Mon Mar 12 09:20:12 2012 +0100

    Allow Any as an argument type to foreign prim functions
    
    Real primops can take boxed arguments, and the Cmm code will receive the
    pointer to the object on the Haskell heap, e.g. for unpackClosure#. To
    be able to implement such a function in a "foreign prim" call, this
    needs to be allowed as well. By only allowing Any here (instead of
    arbitrary types), it is clearer that the function will not receive the
    value in any marshalled form, but just the raw pointer. Haskell code
    using such functions are likely to use unsafeCoerce# to turn a haskell
    value into a value of type Any.

>---------------------------------------------------------------

 compiler/typecheck/TcType.lhs |    9 ++++++---
 1 files changed, 6 insertions(+), 3 deletions(-)

diff --git a/compiler/typecheck/TcType.lhs b/compiler/typecheck/TcType.lhs
index 669545a..ea134ed 100644
--- a/compiler/typecheck/TcType.lhs
+++ b/compiler/typecheck/TcType.lhs
@@ -1166,7 +1166,7 @@ isOverloadedTy _               = False
 
 \begin{code}
 isFloatTy, isDoubleTy, isIntegerTy, isIntTy, isWordTy, isBoolTy,
-    isUnitTy, isCharTy :: Type -> Bool
+    isUnitTy, isCharTy, isAnyTy :: Type -> Bool
 isFloatTy      = is_tc floatTyConKey
 isDoubleTy     = is_tc doubleTyConKey
 isIntegerTy    = is_tc integerTyConKey
@@ -1175,6 +1175,7 @@ isWordTy       = is_tc wordTyConKey
 isBoolTy       = is_tc boolTyConKey
 isUnitTy       = is_tc unitTyConKey
 isCharTy       = is_tc charTyConKey
+isAnyTy        = is_tc anyTyConKey
 
 isStringTy :: Type -> Bool
 isStringTy ty
@@ -1342,9 +1343,11 @@ 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.
+-- Currently they must all be simple unlifted types, or the well-known type
+-- Any, which can be used to pass the address to a Haskell object on the heap to
+-- the foreign function.
 isFFIPrimArgumentTy dflags ty
-   = checkRepTyCon (legalFIPrimArgTyCon dflags) ty
+   = isAnyTy ty || checkRepTyCon (legalFIPrimArgTyCon dflags) ty
 
 isFFIPrimResultTy :: DynFlags -> Type -> Bool
 -- Checks for valid result type for a 'foreign import prim'