Use mrb_true_or_false_value() / in mrb_f_block_given_p_m().

src/kernel.c

@@ -219,21 +219,28 @@ mrb_f_block_given_p_m(mrb_state *mrb, mrb_value self)
 {
   mrb_callinfo *ci = mrb->ci;
   mrb_value *bp;
+  mrb_bool given_p;
 
   bp = mrb->stbase + ci->stackidx + 1;
   ci--;
-  if (ci <= mrb->cibase) return mrb_false_value();
-  /* block_given? called within block; check upper scope */
-  if (ci->proc->env && ci->proc->env->stack) {
-    if (ci->proc->env->stack == mrb->stbase || mrb_nil_p(ci->proc->env->stack[1]))
-      return mrb_false_value();
-    return mrb_true_value();
+  if (ci <= mrb->cibase) {
+    given_p = 0;
   }
-  if (ci->argc > 0) {
-    bp += ci->argc;
+  else {
+    /* block_given? called within block; check upper scope */
+    if (ci->proc->env && ci->proc->env->stack) {
+      given_p = !(ci->proc->env->stack == mrb->stbase ||
+                  mrb_nil_p(ci->proc->env->stack[1]));
+    }
+    else {
+      if (ci->argc > 0) {
+        bp += ci->argc;
+      }
+      given_p = !mrb_nil_p(*bp);
+    }
   }
-  if (mrb_nil_p(*bp)) return mrb_false_value();
-  return mrb_true_value();
+
+  return mrb_true_or_false_value(given_p);
 }
 
 /* 15.3.1.3.7  */