Library defs don't bind to each other; fix #479

compile.c

@@ -290,16 +290,30 @@ block block_bind(block binder, block body, int bindflags) {
 block block_bind_referenced(block binder, block body, int bindflags) {
   assert(block_has_only_binders(binder, bindflags));
   bindflags |= OP_HAS_BINDING;
-  block refd = gen_noop();
+
+  // Repeatedly bind until there's no remaining references to any of the
+  // binders in binder.
+  block unrefd = gen_noop();
+  int unref_count = 0, last = -1;
+loop:
   for (inst* curr; (curr = block_take(&binder));) {
     block b = inst_block(curr);
     if (block_bind_subblock(b, body, bindflags)) {
-      refd = BLOCK(refd, b);
+      body = BLOCK(b, body);
     } else {
-      block_free(b);
+      unrefd = BLOCK(unrefd, b);
+      unref_count++;
     }
   }
-  return block_join(refd, body);
+  if (unref_count == 0 || unref_count == last) {
+    block_free(unrefd);
+    return body;
+  }
+  last = unref_count;
+  unref_count = 0;
+  binder = unrefd;
+  unrefd = gen_noop();
+  goto loop;
 }
 
 block gen_function(const char* name, block formals, block body) {