From 1c816ef5425fa4e3ba13c3757f25afbd7d223f6c Mon Sep 17 00:00:00 2001
From: Eric Wong <e@80x24.org>
Date: Sat, 15 Apr 2017 00:28:41 +0000
Subject: [PATCH] fix RSTRUCT_LEN macro in public C-API

rb_struct_size returns an Integer VALUE, so it must be converted
to a `long` for compatibility with previous Ruby C-API versions.

* ext/-test-/struct/len.c: new
* test/-ext-/struct/test_len.rb: new
* include/ruby/ruby.h (RSTRUCT_LEN): use NUM2LONG
---
 ext/-test-/struct/len.c       | 13 +++++++++++++
 include/ruby/ruby.h           |  2 +-
 test/-ext-/struct/test_len.rb | 10 ++++++++++
 3 files changed, 24 insertions(+), 1 deletion(-)
 create mode 100644 ext/-test-/struct/len.c
 create mode 100644 test/-ext-/struct/test_len.rb

diff --git a/ext/-test-/struct/len.c b/ext/-test-/struct/len.c
new file mode 100644
index 0000000000..6153c720b2
--- /dev/null
+++ b/ext/-test-/struct/len.c
@@ -0,0 +1,13 @@
+#include "ruby.h"
+
+static VALUE
+bug_struct_len(VALUE obj)
+{
+    return LONG2NUM(RSTRUCT_LEN(obj));
+}
+
+void
+Init_len(VALUE klass)
+{
+    rb_define_method(klass, "rstruct_len", bug_struct_len, 0);
+}
diff --git a/include/ruby/ruby.h b/include/ruby/ruby.h
index 01ab9e55cd..9cf0b4c6b0 100644
--- a/include/ruby/ruby.h
+++ b/include/ruby/ruby.h
@@ -1183,7 +1183,7 @@ void *rb_check_typeddata(VALUE, const rb_data_type_t *);
 #define TypedData_Get_Struct(obj,type,data_type,sval) \
     ((sval) = (type*)rb_check_typeddata((obj), (data_type)))
 
-#define RSTRUCT_LEN(st)         rb_struct_size(st)
+#define RSTRUCT_LEN(st)         NUM2LONG(rb_struct_size(st))
 #define RSTRUCT_PTR(st)         rb_struct_ptr(st)
 #define RSTRUCT_SET(st, idx, v) rb_struct_aset(st, INT2NUM(idx), (v))
 #define RSTRUCT_GET(st, idx)    rb_struct_aref(st, INT2NUM(idx))
diff --git a/test/-ext-/struct/test_len.rb b/test/-ext-/struct/test_len.rb
new file mode 100644
index 0000000000..2358e340e5
--- /dev/null
+++ b/test/-ext-/struct/test_len.rb
@@ -0,0 +1,10 @@
+# frozen_string_literal: false
+require 'test/unit'
+require "-test-/struct"
+
+class Bug::Struct::Test_Len < Test::Unit::TestCase
+  def test_rstruct_len
+    klass = Bug::Struct.new(:a, :b, :c)
+    assert_equal 3, klass.new.rstruct_len
+  end
+end
-- 
EW