Declaration of non-local variable in 'for' loop

#include <stdio.h>
int main() {


    /***Declaration of non-local variable in 'for' loop***/
    for (struct {
             int i;
         } s = {0}; s.i < 25; ++s.i) {
        printf("-----------
");
    }

    /**等价方式**/
    {
        struct {
            int i;
        } s = {0};
        for (; s.i < 25; ++s.i) {
            printf("-----------
");
        }
    }


    return 0;
}

参考自：https://stackoverflow.com/questions/53468223/declare-structure-within-for

这是我在使用一份代码[https://github.com/DavidLeeds/hashmap]的时候发现的问题：

#define __HASHMAP_FOREACH(x, key, data, h)                              
    for (HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); 
        ((key) = hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it))) &&     
            ((data) = hashmap_iter_get_data(&__HASHMAP_UNIQUE(x, it))); 
        hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)))
#define __HASHMAP_FOREACH_SAFE(x, key, data, h, temp_ptr)               
    for (HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); 
        ((temp_ptr) = (void *)((key) = hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it)))) && 
            ((data) = hashmap_iter_get_data(&__HASHMAP_UNIQUE(x, it)));           
        ((temp_ptr) == (void *)hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it))) ?  
            hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)) : __HASHMAP_ITER_RESET(&__HASHMAP_UNIQUE(x, it)))
#define __HASHMAP_FOREACH_KEY(x, key, h)                                
    for (HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); 
        (key = hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it)));                   
        hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)))
#define __HASHMAP_FOREACH_KEY_SAFE(x, key, h, temp_ptr)                 
    for (HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); 
        ((temp_ptr) = (void *)((key) = hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it)))); 
        ((temp_ptr) == (void *)hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it))) ?  
            hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)) : __HASHMAP_ITER_RESET(&__HASHMAP_UNIQUE(x, it)))
#define __HASHMAP_FOREACH_DATA(x, data, h)                              
    for (HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); 
        (data = hashmap_iter_get_data(&__HASHMAP_UNIQUE(x, it)));                 
        hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)))
#define __HASHMAP_FOREACH_DATA_SAFE(x, data, h, temp_ptr)               
    for (HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); 
        ((temp_ptr) = (void *)hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it))) &&  
            ((data) = hashmap_iter_get_data(&__HASHMAP_UNIQUE(x, it)));           
        ((temp_ptr) == (void *)hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it))) ?  
            hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)) : __HASHMAP_ITER_RESET(&__HASHMAP_UNIQUE(x, it)))

更正：

#define __HASHMAP_FOREACH(x, key, data, h)                              
   HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); for (; 
        ((key) = hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it))) &&     
            ((data) = hashmap_iter_get_data(&__HASHMAP_UNIQUE(x, it))); 
        hashmap_iter_next(&__HASHMAP_UNIQUE(x, it))) 

#define __HASHMAP_FOREACH_SAFE(x, key, data, h, temp_ptr)               
  HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); for (; 
        ((temp_ptr) = (void *)((key) = hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it)))) && 
            ((data) = hashmap_iter_get_data(&__HASHMAP_UNIQUE(x, it)));           
        ((temp_ptr) == (void *)hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it))) ?  
            hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)) : __HASHMAP_ITER_RESET(&__HASHMAP_UNIQUE(x, it)))
#define __HASHMAP_FOREACH_KEY(x, key, h)                                
  HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); for (; 
        (key = hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it)));                   
        hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)))
#define __HASHMAP_FOREACH_KEY_SAFE(x, key, h, temp_ptr)                 
   HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); for (; 
        ((temp_ptr) = (void *)((key) = hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it)))); 
        ((temp_ptr) == (void *)hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it))) ?  
            hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)) : __HASHMAP_ITER_RESET(&__HASHMAP_UNIQUE(x, it)))
#define __HASHMAP_FOREACH_DATA(x, data, h)                              
   HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it)); for (; 
        (data = hashmap_iter_get_data(&__HASHMAP_UNIQUE(x, it)));                 
        hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)))
#define __HASHMAP_FOREACH_DATA_SAFE(x, data, h, temp_ptr)               
   HASHMAP_ITER(*(h)) __HASHMAP_UNIQUE(x, it) = hashmap_iter(h, &__HASHMAP_UNIQUE(x, it));  for (; 
        ((temp_ptr) = (void *)hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it))) &&  
            ((data) = hashmap_iter_get_data(&__HASHMAP_UNIQUE(x, it)));           
        ((temp_ptr) == (void *)hashmap_iter_get_key(&__HASHMAP_UNIQUE(x, it))) ?  
            hashmap_iter_next(&__HASHMAP_UNIQUE(x, it)) : __HASHMAP_ITER_RESET(&__HASHMAP_UNIQUE(x, it)))