py/malloc: Provide a proper malloc-based implementation of realloc_ext.
diff --git a/py/malloc.c b/py/malloc.c
index 0aecbd7..b0493d9 100644
--- a/py/malloc.c
+++ b/py/malloc.c
@@ -59,7 +59,16 @@
#define realloc(ptr, n) gc_realloc(ptr, n, true)
#define realloc_ext(ptr, n, mv) gc_realloc(ptr, n, mv)
#else
-#define realloc_ext(ptr, n, mv) realloc(ptr, n)
+STATIC void *realloc_ext(void *ptr, size_t n_bytes, bool allow_move) {
+ if (allow_move) {
+ return realloc(ptr, n_bytes);
+ } else {
+ // We are asked to resize, but without moving the memory region pointed to
+ // by ptr. Unless the underlying memory manager has special provision for
+ // this behaviour there is nothing we can do except fail to resize.
+ return NULL;
+ }
+}
#endif // MICROPY_ENABLE_GC
void *m_malloc(size_t num_bytes) {