On Fri, Feb 17, 2012 at 2:12 PM, Simon Marlow
On 17/02/12 19:36, John Meacham wrote:
It isn't local to a file though because it changes the ABI, for instance
void foo(off_t *x);
it will blow up if called from a file with a differently sized off_t.
But we're talking about Haskell code here, not C code. There's no way for something to "blow up", the typechecker will catch any discrepancies.
Perhaps I don't understand what problem you're thinking of - can you give more detail?
Someone writes a C function that returns an off_t * that is foreign imported by a haskell program using Ptr COff, the haskell program then writes to the output pointer with the COff Storable instance. However the imported function was compiled without 64 bit off_t's so it only allocated 32 bits to be written into so some other memory gets overwritten with garbage. 64 bit off_t's change the ABI of called C functions much like passing -m32 or -mrtd does so should be considered a all-or-nothing sort of thing. In particular, when ghc compiles C code, it should make sure it does it with the same ABI flags as the rest of the thing being compiled. John environment as the rest of the code.