Python _scproxy build fails on Yosemite

[vbraun]

This Python module is required by Cython, so its not an option to let it fail

In file included from /usr/include/dispatch/dispatch.h:51:0,
                 from /System/Library/Frameworks/CoreFoundation.framework/Headers/CFStream.h:15,
                 from /System/Library/Frameworks/CoreFoundation.framework/Headers/CFPropertyList.h:13,
                 from /System/Library/Frameworks/CoreFoundation.framework/Headers/CoreFoundation.h:55,
                 from /System/Library/Frameworks/SystemConfiguration.framework/Headers/SystemConfiguration.h:29,
                 from ./Mac/Modules/_scproxy.c:6:
/usr/include/dispatch/object.h:143:15: error: expected identifier or '(' before '^' token
 typedef void (^dispatch_block_t)(void);
               ^
/usr/include/dispatch/object.h:362:3: error: unknown type name 'dispatch_block_t'
   dispatch_block_t notification_block);
   ^
./Mac/Modules/_scproxy.c: In function 'get_proxy_settings':
./Mac/Modules/_scproxy.c:67:50: warning: the comparison will always evaluate as 'true' for the address of 'kSCPropNetProxiesExcludeSimpleHostnames' will never be NULL [-Waddress]
     if (&kSCPropNetProxiesExcludeSimpleHostnames != NULL) {
                                                  ^

Python build finished, but the necessary bits to build these modules were not found:
_bsddb             dl                 gdbm            
imageop            linuxaudiodev      ossaudiodev     
spwd               sunaudiodev                        
To find the necessary bits, look in setup.py in detect_modules() for the module's name.


Failed to build these modules:
_scproxy                                              

[vbraun]

Offending line:

typedef void (^dispatch_block_t)(void);

Other objc bits are in #if blocks, but this (and some following stuff) is not.

[vbraun]

Simply replacing it with typedef dispatch_block_t void; works for Python, but then R blows up when it tries to build its OSX interface.

[vbraun]

Using void* works, I have added that as a hack at #17169. This at least fixes compilation.

[vbraun]

Fixed by the C header hack in #17169, propose to close as duplicate

[kcrisman]

Just for reference, apparently at least one person ​has been hit with this in Sage 6.7, though I assume they were not using the Sage gcc (?).