Use named union in JanetGCObject

src/core/abstract.c

@@ -63,8 +63,8 @@ void *janet_abstract_begin_threaded(const JanetAbstractType *atype, size_t size)
     }
     janet_vm.next_collection += size + sizeof(JanetAbstractHead);
     header->gc.flags = JANET_MEMORY_THREADED_ABSTRACT;
-    header->gc.next = NULL; /* Clear memory for address sanitizers */
-    header->gc.refcount = 1;
+    header->gc.data.next = NULL; /* Clear memory for address sanitizers */
+    header->gc.data.refcount = 1;
     header->size = size;
     header->type = atype;
     void *abstract = (void *) & (header->data);
@@ -86,11 +86,11 @@ void *janet_abstract_threaded(const JanetAbstractType *atype, size_t size) {
 #ifdef JANET_WINDOWS
 
 static int32_t janet_incref(JanetAbstractHead *ab) {
-    return InterlockedIncrement(&ab->gc.refcount);
+    return InterlockedIncrement(&ab->gc.data.refcount);
 }
 
 static int32_t janet_decref(JanetAbstractHead *ab) {
-    return InterlockedDecrement(&ab->gc.refcount);
+    return InterlockedDecrement(&ab->gc.data.refcount);
 }
 
 void janet_os_mutex_init(JanetOSMutex *mutex) {
@@ -112,11 +112,11 @@ void janet_os_mutex_unlock(JanetOSMutex *mutex) {
 #else
 
 static int32_t janet_incref(JanetAbstractHead *ab) {
-    return __atomic_add_fetch(&ab->gc.refcount, 1, __ATOMIC_RELAXED);
+    return __atomic_add_fetch(&ab->gc.data.refcount, 1, __ATOMIC_RELAXED);
 }
 
 static int32_t janet_decref(JanetAbstractHead *ab) {
-    return __atomic_add_fetch(&ab->gc.refcount, -1, __ATOMIC_RELAXED);
+    return __atomic_add_fetch(&ab->gc.data.refcount, -1, __ATOMIC_RELAXED);
 }
 
 void janet_os_mutex_init(JanetOSMutex *mutex) {

src/core/debug.c

@@ -86,7 +86,7 @@ void janet_debug_find(
                 }
             }
         }
-        current = current->next;
+        current = current->data.next;
     }
     if (best_def) {
         *def_out = best_def;

src/core/gc.c

@@ -323,7 +323,7 @@ void janet_sweep() {
     JanetGCObject *current = janet_vm.blocks;
     JanetGCObject *next;
     while (NULL != current) {
-        next = current->next;
+        next = current->data.next;
         if (current->flags & (JANET_MEM_REACHABLE | JANET_MEM_DISABLED)) {
             previous = current;
             current->flags &= ~JANET_MEM_REACHABLE;
@@ -331,7 +331,7 @@ void janet_sweep() {
             janet_vm.block_count--;
             janet_deinit_block(current);
             if (NULL != previous) {
-                previous->next = next;
+                previous->data.next = next;
             } else {
                 janet_vm.blocks = next;
             }
@@ -395,7 +395,7 @@ void *janet_gcalloc(enum JanetMemoryType type, size_t size) {
 
     /* Prepend block to heap list */
     janet_vm.next_collection += size;
-    mem->next = janet_vm.blocks;
+    mem->data.next = janet_vm.blocks;
     janet_vm.blocks = mem;
     janet_vm.block_count++;
 
@@ -532,7 +532,7 @@ void janet_clear_memory(void) {
     JanetGCObject *current = janet_vm.blocks;
     while (NULL != current) {
         janet_deinit_block(current);
-        JanetGCObject *next = current->next;
+        JanetGCObject *next = current->data.next;
         janet_free(current);
         current = next;
     }

src/include/janet.h

@@ -866,7 +866,7 @@ struct JanetGCObject {
     union {
         JanetGCObject *next;
         int32_t refcount; /* For threaded abstract types */
-    };
+    } data;
 };
 
 /* A lightweight green thread in janet. Does not correspond to