Retry 114494 - Remove BindStateHolder and have Bind() return a Callback<> object directly."

This removes some complexity and also fixes a bug where if you call Bind() with the result of Bind(), the resulting Callback would only be valid during the first call. Ouch.

Also makes the static type checking a bit more strict when assigning into a Callback<>.

BUG=none
TEST=new unittests

Review URL: http://codereview.chromium.org/8915024

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@115045 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 27 insertions, 0 deletions

diff --git a/base/bind_unittest.cc b/base/bind_unittest.cc
index 654a277..372523b 100644
--- a/base/bind_unittest.cc
+++ b/base/bind_unittest.cc
@@ -199,10 +199,18 @@ void RefArgSet(int &n) {
   n = 2;
 }
 
+void PtrArgSet(int *n) {
+  *n = 2;
+}
+
 int FunctionWithWeakFirstParam(WeakPtr<NoRef> o, int n) {
   return n;
 }
 
+void TakesACallback(const Closure& callback) {
+  callback.Run();
+}
+
 class BindTest : public ::testing::Test {
  public:
   BindTest() {
@@ -284,6 +292,25 @@ TEST_F(BindTest, CurryingTest) {
   EXPECT_EQ(63, c0.Run());
 }
 
+// Test that currying the rvalue result of another Bind() works correctly.
+//   - rvalue should be usable as argument to Bind().
+//   - multiple runs of resulting Callback remain valid.
+TEST_F(BindTest, CurryingRvalueResultOfBind) {
+  int n = 0;
+  Closure cb = base::Bind(&TakesACallback, base::Bind(&PtrArgSet, &n));
+
+  // If we implement Bind() such that the return value has auto_ptr-like
+  // semantics, the second call here will fail because ownership of
+  // the internal BindState<> would have been transfered to a *temporary*
+  // constructon of a Callback object on the first call.
+  cb.Run();
+  EXPECT_EQ(2, n);
+
+  n = 0;
+  cb.Run();
+  EXPECT_EQ(2, n);
+}
+
 // Function type support.
 //   - Normal function.
 //   - Normal function bound with non-refcounted first argument.