id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	os	architecture	failure	difficulty	testcase	blockedby	blocking	related
5931	Allow 'Any' to be passed to a foreign prim function.	nomeata	simonmar	"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 there as well, and the attached patch does that.

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.

I am working on code that helps investigating the heap, similar to vacuum, and unwrapClosure was not sufficient. With this patch in GHC I do not have to modify the compiler further to create an improved version.

If applied, the documentation at wiki:Commentary/PrimOps#Foreignout-of-linePrimOps needs to be updated. I did not find any documentation in the GHC tree to updated accordingly."	feature request	closed	normal	7.6.2	Compiler (FFI)	7.4.1	fixed			Unknown/Multiple	Unknown/Multiple	None/Unknown	Unknown