gistfile1

~/src/C-ObjC-Blocks  $ cat t.c 
#include <stdio.h>
#include "blocks_runtime.h"

int main() {
    int x[5] = { 0, 1, 2, 3, 4 };

    for(int i=0; i<5; i++) {
        void (^f)(int) = ^(int y) { printf("v: %d\n", i+y); };

        for(int j=10; j>=1; j--)
            f(j);
        printf("\n");
    }
    return 0;
}
~/src/C-ObjC-Blocks  $ ~/src/llvm/Debug/bin/clang -fblocks -lobjc -framework Foundation -o t t.c blocks_runtime.m 
blocks_runtime.m:397:18: warning: comparison of distinct pointer types ('void *' and 'struct psy_objc_class *')
    if(self->isa == &_NSConcreteStackBlock && self->flags & BLOCK_HAS_DESCRIPTOR)
       ~~~~~~~~~ ^  ~~~~~~~~~~~~~~~~~~~~~~
blocks_runtime.m:416:18: warning: comparison of distinct pointer types ('void *' and 'struct psy_objc_class *')
    if(self->isa == &_NSConcreteStackBlock && // A Global block doesn't need to be released
       ~~~~~~~~~ ^  ~~~~~~~~~~~~~~~~~~~~~~
2 diagnostics generated.
~/src/C-ObjC-Blocks  $ ./t 
v: 10
v: 9
v: 8
v: 7
v: 6
v: 5
v: 4
v: 3
v: 2
v: 1

v: 11
v: 10
v: 9
v: 8
v: 7
v: 6
v: 5
v: 4
v: 3
v: 2

v: 12
v: 11
v: 10
v: 9
v: 8
v: 7
v: 6
v: 5
v: 4
v: 3

v: 13
v: 12
v: 11
v: 10
v: 9
v: 8
v: 7
v: 6
v: 5
v: 4

v: 14
v: 13
v: 12
v: 11
v: 10
v: 9
v: 8
v: 7
v: 6
v: 5

~/src/C-ObjC-Blocks  $