https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103639
--- Comment #8 from Iain Sandoe <iains at gcc dot gnu.org> --- Here's a version using the testsuite object etc. it does not need Foundation (it needs CoreFoundation on Darwin for NSString, but only libobjc on Linux) the issue repeats equally with gnu-runtime on Linux. gcc pr103639.m -I path/to/gcc-sources/gcc/testsuite/objc-obj-c++-shared -o t -lobjc ===== #import "TestsuiteObject.m" #ifndef __NEXT_RUNTIME__ #include <objc/NXConstStr.h> #else #include "nsconstantstring-class.h" #endif extern int printf (const char *, ...); #include <stdlib.h> /* A mini-array implementation that can be used to test fast enumeration. You create the array with some objects; you can mutate the array, and you can fast-enumerate it. */ @interface MyArray : TestsuiteObject { unsigned int length; id *objects; unsigned long mutated; } - (id) initWithLength: (unsigned int)l objects: (id *)o; - (void) mutate; - (unsigned long)countByEnumeratingWithState: (struct __objcFastEnumerationState *)state objects:(id *)stackbuf count:(unsigned long)len; @end @implementation MyArray : TestsuiteObject - (id) initWithLength: (unsigned int)l objects: (id *)o { length = l; objects = o; mutated = 0; return self; } - (void) mutate { mutated = 1; } - (unsigned long)countByEnumeratingWithState: (struct __objcFastEnumerationState*)state objects: (id*)stackbuf count: (unsigned long)len { unsigned long i, batch_size; /* We keep how many objects we served in the state->state counter. So the next batch will contain up to length - state->state objects. */ batch_size = length - state->state; /* Make obvious adjustments. */ if (batch_size < 0) batch_size = 0; if (batch_size > len) batch_size = len; /* Copy the objects. */ for (i = 0; i < batch_size; i++) stackbuf[i] = objects[i]; state->state += batch_size; state->itemsPtr = stackbuf; state->mutationsPtr = &mutated; return batch_size; } @end int main() { id *objects = malloc (sizeof (id) * 2); objects[0] = @"a"; objects[1] = @"b"; MyArray *array = [[MyArray alloc] initWithLength: 2 objects: objects]; // NSArray *array = [NSArray arrayWithObjects: @"a", @"b", nil]; int someVar = 0; for (id object in array) { switch (someVar) { case 0: printf ("case 0: %s\n", [object cString]); break; } printf ("foo\n"); } return 0; }