Skip array embedding if `MRB_NO_BOXING` and `MRB_32BIT`; fix #4382

On some platforms, `sizeof(mrb_value) > sizeof(void*)*3`, which makes
`MRB_ARY_EMBED_LEN_MAX` zero. And zero sized array cause compile errors.

include/mruby/array.h

@@ -21,7 +21,14 @@ typedef struct mrb_shared_array {
   mrb_value *ptr;
 } mrb_shared_array;
 
-#define MRB_ARY_EMBED_LEN_MAX ((mrb_int)(sizeof(void*)*3/sizeof(mrb_value)))
+#if defined(MRB_32BIT) && defined(MRB_NO_BOXING)
+# define MRB_ARY_NO_EMBED
+# define MRB_ARY_EMBED_LEN_MAX 0
+#else
+# define MRB_ARY_EMBED_LEN_MAX ((mrb_int)(sizeof(void*)*3/sizeof(mrb_value)))
+mrb_static_assert(MRB_ARY_EMBED_LEN_MAX > 0, "MRB_ARY_EMBED_LEN_MAX > 0");
+#endif
+
 struct RArray {
   MRB_OBJECT_HEADER;
   union {
@@ -33,7 +40,9 @@ struct RArray {
       } aux;
       mrb_value *ptr;
     } heap;
+#ifndef MRB_ARY_NO_EMBED
     mrb_value ary[MRB_ARY_EMBED_LEN_MAX];
+#endif
   } as;
 };
 
@@ -41,13 +50,21 @@ struct RArray {
 #define mrb_ary_value(p)  mrb_obj_value((void*)(p))
 #define RARRAY(v)  ((struct RArray*)(mrb_ptr(v)))
 
+#ifdef MRB_ARY_NO_EMBED
+#define ARY_EMBED_P(a) 0
+#define ARY_UNSET_EMBED_FLAG(a) (void)0
+#define ARY_EMBED_LEN(a) 0
+#define ARY_SET_EMBED_LEN(a,len) (void)0
+#define ARY_EMBED_PTR(a) 0
+#else
 #define MRB_ARY_EMBED_MASK  7
 #define ARY_EMBED_P(a) ((a)->flags & MRB_ARY_EMBED_MASK)
 #define ARY_UNSET_EMBED_FLAG(a) ((a)->flags &= ~(MRB_ARY_EMBED_MASK))
 #define ARY_EMBED_LEN(a) ((mrb_int)(((a)->flags & MRB_ARY_EMBED_MASK) - 1))
 #define ARY_SET_EMBED_LEN(a,len) ((a)->flags = ((a)->flags&~MRB_ARY_EMBED_MASK) | ((uint32_t)(len) + 1))
 #define ARY_EMBED_PTR(a) ((a)->as.ary)
-
+#endif
+  
 #define ARY_LEN(a) (ARY_EMBED_P(a)?ARY_EMBED_LEN(a):(a)->as.heap.len)
 #define ARY_PTR(a) (ARY_EMBED_P(a)?ARY_EMBED_PTR(a):(a)->as.heap.ptr)
 #define RARRAY_LEN(a) ARY_LEN(RARRAY(a))

src/array.c

@@ -1123,8 +1123,14 @@ mrb_ary_clear(mrb_state *mrb, mrb_value self)
   else if (!ARY_EMBED_P(a)){
     mrb_free(mrb, a->as.heap.ptr);
   }
-  ARY_SET_EMBED_LEN(a, 0);
-
+  if (MRB_ARY_EMBED_LEN_MAX > 0) {
+    ARY_SET_EMBED_LEN(a, 0);
+  }
+  else {
+    a->as.heap.ptr = NULL;
+    a->as.heap.aux.capa = 0;
+    ARY_SET_LEN(a, 0);
+  }
   return self;
 }
 

src/value_array.h

@@ -6,6 +6,7 @@
 static inline void
 value_move(mrb_value *s1, const mrb_value *s2, size_t n)
 {
+  if (n == 0) return;
   if (s1 > s2 && s1 < s2 + n)
   {
     s1 += n;

src/vm.c

@@ -1823,7 +1823,7 @@ RETRY_TRY_BLOCK:
         if (kd) regs[len + 1] = kdict;
 
         /* copy mandatory and optional arguments */
-        if (argv0 != argv) {
+        if (argv0 != argv && argv) {
           value_move(&regs[1], argv, argc-mlen); /* m1 + o */
         }
         if (argc < m1) {