Fix cache validity check of require

* array.c (rb_ary_shared_with_p): fix cache validity check.
  If #pop or #shift has been called against $: or $", the array will
  be still shared with the snapshot. We check array length for cache
  validity.
  [ruby-core:49518] [Bug #7383]

* test/ruby/test_require.rb
  (TestRequire#test_require_with_array_pop,
   TestRequire#test_require_with_array_shift): add tests for above.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@37808 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ChangeLog

@@ -1,3 +1,15 @@
+Thu Nov 22 23:45:18 2012  Hiroshi Shirosaki  <h.shirosaki@gmail.com>
+
+	* array.c (rb_ary_shared_with_p): fix cache validity check.
+	  If #pop or #shift has been called against $: or $", the array will
+	  be still shared with the snapshot. We check array length for cache
+	  validity.
+	  [ruby-core:49518] [Bug #7383]
+
+	* test/ruby/test_require.rb
+	  (TestRequire#test_require_with_array_pop,
+	   TestRequire#test_require_with_array_shift): add tests for above.
+
 Thu Nov 22 21:48:48 2012  NAKAMURA Usaku  <usa@ruby-lang.org>
 
 	* common.mk, win32/Makefile.sub (probes.dmyh): now be made in current

array.c

@@ -351,13 +351,16 @@ rb_ary_frozen_p(VALUE ary)
    e.g. rb_ary_replace) and check later whether the array has been
    modified from the snapshot.  The snapshot is cheap, though if
    something does modify the array it will pay the cost of copying
-   it. */
+   it.  If Array#pop or Array#shift has been called, the array will
+   be still shared with the snapshot, but the array length will
+   differ. */
 VALUE
 rb_ary_shared_with_p(VALUE ary1, VALUE ary2)
 {
-    if (!ARY_EMBED_P(ary1) && ARY_SHARED_P(ary1)
-     && !ARY_EMBED_P(ary2) && ARY_SHARED_P(ary2)
-     && RARRAY(ary1)->as.heap.aux.shared == RARRAY(ary2)->as.heap.aux.shared) {
+    if (!ARY_EMBED_P(ary1) && ARY_SHARED_P(ary1) &&
+	!ARY_EMBED_P(ary2) && ARY_SHARED_P(ary2) &&
+	RARRAY(ary1)->as.heap.aux.shared == RARRAY(ary2)->as.heap.aux.shared &&
+	RARRAY(ary1)->as.heap.len == RARRAY(ary2)->as.heap.len) {
 	return Qtrue;
     }
     return Qfalse;

test/ruby/test_require.rb

@@ -545,4 +545,35 @@ class TestRequire < Test::Unit::TestCase
       }
     }
   end
+
+  def assert_require_with_shared_array_modified(add, del)
+    bug7383 = '[ruby-core:49518]'
+    Dir.mktmpdir {|tmp|
+      Dir.chdir(tmp) {
+        open("foo.rb", "w") {}
+        Dir.mkdir("a")
+        open(File.join("a", "bar.rb"), "w") {}
+        assert_in_out_err([], <<-INPUT, %w(:ok), [], bug7383)
+          $:.#{add} "#{tmp}"
+          $:.#{add} "#{tmp}/a"
+          require "foo"
+          $:.#{del}
+          # Expanded load path cache should be rebuilt.
+          begin
+            require "bar"
+          rescue LoadError
+            p :ok
+          end
+        INPUT
+      }
+    }
+  end
+
+  def test_require_with_array_pop
+    assert_require_with_shared_array_modified("push", "pop")
+  end
+
+  def test_require_with_array_shift
+    assert_require_with_shared_array_modified("unshift", "shift")
+  end
 end