Language.C fails doesn't support Mac OS X blocks notation

[ezyang]

This is causing  Bug 29 for c2hs.

Steps to reproduce:

1. Get stdlib.h from Mac OS X 10.6 (Snow Leopard). I've attached the file from my machine here for convenience.
2. Attempt to parse the header file with the default GCC preprocessor as such:

Prelude Language.C Language.C.System.GCC> either show (show . pretty)
  `fmap` parseCFile (newGCC "gcc") Nothing [] "/usr/include/stdlib.h"
"/usr/include/stdlib.h:272: (column 20) [ERROR]  >>> Syntax Error !
  Syntax error !
  The symbol `^' does not fit here.
"

Expected result: parse is successful, possibly just ignoring BLOCKS notation.

Here is the segment of the header file in question:

#ifdef __BLOCKS__
int      atexit_b(void (^)(void));
void    *bsearch_b(const void *, const void *, size_t,
            size_t, int (^)(const void *, const void *));
#endif /* __BLOCKS__ */

[ezyang]

stdlib.h file from Mac OS X

[ezyang]

Investigating further, it seems that the preprocessor is incorrectly assuming BLOCKS support, when Language.C doesn't support it; so this is a question of undef'ing the macro when we run the preprocessor, or adding blocks support to Language.C. I've modified the ticket accordingly.

[benedikt]

To highlight the workaround suggested above by Edward, I'm forwarding this post by aaron to the language-c mailing list (May 2010):
On May 30 2010, Aaron Tomb wrote

Kevin Ballard wrote:
There is a (relatively) new extension for C called Blocks[1] that Apple introduced in Mac OS X 10.6. Block declarations look
similar to function declarations except for using ^{in place of *. Unfortunately Language.C doesn't understand this and ends
up triggering a parse error when processing the system header files (even /usr/include/stdlib.h has this issue). Is there any
way to work around this issue?}

Complete support for blocks would certainly be a big (though
potentially valuable) job. However, if what you want is just to be
able to parse C files that include Mac OS X 10.6 header files, there's
a simpler solution. All of the uses of blocks in the header files are
wrapped in #ifdef __BLOCKS__/#endif. So you can just pass -U__BLOCKS__
to CPP and the parse errors will go away.