C FFI Compilation bug

[dfordivam]

For this code (from bytestring) clang gives error

foreign import ccall unsafe "static stdlib.h &free" c_free_finalizer
    :: FunPtr (Ptr Word8 -> IO ())


./ghc25458_0/ghc_4.hc:153:42: error: use of undeclared identifier 'free'
(W_)&base_GHCziPtr_FunPtr_con_info, (W_)&free

It is solved by adding the appropriate includes in ghc_4.hc

 #include <stdlib.h>

[ElvishJerricco]

Yes, the C FFI in Haskell supports using & to indicate you want a reference to the symbol instead of calling it. This does not work in ccall (EDIT: on wasm, that is), and AFAICT, there's no general way to make it work on wasm due to the strict type requirements. This does work with the capi FFI though. In fact, I believe the capi FFI should be preferred virtually always on wasm.

[ElvishJerricco]

See e.g.: 7f1605d#diff-79ec7cacd18d11f92a5069572e68989d

[dfordivam]

Ok.. this ought to be documented somewhere..
But for the time being lets keep this issue open..