From 968ca7b38235bdcae6ec82173e1fe01bcf248eb1 Mon Sep 17 00:00:00 2001
From: "willchan@chromium.org"
 <willchan@chromium.org@0039d316-1c4b-4281-b951-d872f2087c98>
Date: Wed, 15 Dec 2010 09:10:43 +0000
Subject: Reland 69237 - Fix raw_scoped_refptr_mismatch_checker.h.

BUG=28083
TEST=none

Review URL: http://codereview.chromium.org/3549010

TBR=willchan@chromium.org
Review URL: http://codereview.chromium.org/5885001

TBR=phajdan.jr@chromium.org
Review URL: http://codereview.chromium.org/5887001

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@69243 0039d316-1c4b-4281-b951-d872f2087c98
---
 base/callback.h                           |   5 +-
 base/raw_scoped_refptr_mismatch_checker.h | 225 ++++++++++++------------------
 base/task.h                               |  15 +-
 base/template_util.h                      |  47 +++++++
 4 files changed, 151 insertions(+), 141 deletions(-)

(limited to 'base')

diff --git a/base/callback.h b/base/callback.h
index 7f2eb70..e5ea771 100644
--- a/base/callback.h
+++ b/base/callback.h
@@ -206,8 +206,9 @@ template <class T, class Method, class Params>
 class UnboundMethod {
  public:
   UnboundMethod(Method m, const Params& p) : m_(m), p_(p) {
-    COMPILE_ASSERT((MethodUsesScopedRefptrCorrectly<Method, Params>::value),
-                   badunboundmethodparams);
+    COMPILE_ASSERT(
+        (base::internal::ParamsUseScopedRefptrCorrectly<Params>::value),
+        badunboundmethodparams);
   }
   void Run(T* obj) const {
     DispatchToMethod(obj, m_, p_);
diff --git a/base/raw_scoped_refptr_mismatch_checker.h b/base/raw_scoped_refptr_mismatch_checker.h
index d2913e7..b79cfb5 100644
--- a/base/raw_scoped_refptr_mismatch_checker.h
+++ b/base/raw_scoped_refptr_mismatch_checker.h
@@ -7,165 +7,124 @@
 #pragma once
 
 #include "base/ref_counted.h"
+#include "base/template_util.h"
 #include "base/tuple.h"
+#include "build/build_config.h"
 
-// It is dangerous to post a task with a raw pointer argument to a function
-// that expects a scoped_refptr<>.  The compiler will happily accept the
-// situation, but it will not attempt to increase the refcount until the task
-// runs.  Callers expecting the argument to be refcounted up at post time are
-// in for a nasty surprise!  Example: http://crbug.com/27191
+// It is dangerous to post a task with a T* argument where T is a subtype of
+// RefCounted(Base|ThreadSafeBase), since by the time the parameter is used, the
+// object may already have been deleted since it was not held with a
+// scoped_refptr. Example: http://crbug.com/27191
 // The following set of traits are designed to generate a compile error
 // whenever this antipattern is attempted.
-template <class A, class B>
-struct ExpectsScopedRefptrButGetsRawPtr {
+
+namespace base {
+
+// This is a base internal implementation file used by task.h and callback.h.
+// Not for public consumption, so we wrap it in namespace internal.
+namespace internal {
+
+template <typename T>
+struct NeedsScopedRefptrButGetsRawPtr {
+#if defined(OS_WIN)
+  enum {
+    value = base::false_type::value
+  };
+#else
+  enum {
+    // Human readable translation: you needed to be a scoped_refptr if you are a
+    // raw pointer type and are convertible to a RefCounted(Base|ThreadSafeBase)
+    // type.
+    value = (is_pointer<T>::value &&
+             (is_convertible<T, subtle::RefCountedBase*>::value ||
+              is_convertible<T, subtle::RefCountedThreadSafeBase*>::value))
+  };
+#endif
+};
+
+template <typename Params>
+struct ParamsUseScopedRefptrCorrectly {
   enum { value = 0 };
 };
 
-template <class A, class B>
-struct ExpectsScopedRefptrButGetsRawPtr<scoped_refptr<A>, B*> {
+template <>
+struct ParamsUseScopedRefptrCorrectly<Tuple0> {
   enum { value = 1 };
 };
 
-template <class Function, class Params>
-struct FunctionUsesScopedRefptrCorrectly {
-  enum { value = 1 };
+template <typename A>
+struct ParamsUseScopedRefptrCorrectly<Tuple1<A> > {
+  enum { value = !NeedsScopedRefptrButGetsRawPtr<A>::value };
 };
 
-template <class A1, class A2>
-struct FunctionUsesScopedRefptrCorrectly<void (*)(A1), Tuple1<A2> > {
-  enum { value = !ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value };
+template <typename A, typename B>
+struct ParamsUseScopedRefptrCorrectly<Tuple2<A, B> > {
+  enum { value = !(NeedsScopedRefptrButGetsRawPtr<A>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<B>::value) };
 };
 
-template <class A1, class B1, class A2, class B2>
-struct FunctionUsesScopedRefptrCorrectly<void (*)(A1, B1), Tuple2<A2, B2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value) };
+template <typename A, typename B, typename C>
+struct ParamsUseScopedRefptrCorrectly<Tuple3<A, B, C> > {
+  enum { value = !(NeedsScopedRefptrButGetsRawPtr<A>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<B>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<C>::value) };
 };
 
-template <class A1, class B1, class C1, class A2, class B2, class C2>
-struct FunctionUsesScopedRefptrCorrectly<void (*)(A1, B1, C1),
-                                         Tuple3<A2, B2, C2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<C1, C2>::value) };
+template <typename A, typename B, typename C, typename D>
+struct ParamsUseScopedRefptrCorrectly<Tuple4<A, B, C, D> > {
+  enum { value = !(NeedsScopedRefptrButGetsRawPtr<A>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<B>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<C>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<D>::value) };
 };
 
-template <class A1, class B1, class C1, class D1,
-          class A2, class B2, class C2, class D2>
-struct FunctionUsesScopedRefptrCorrectly<void (*)(A1, B1, C1, D1),
-                                         Tuple4<A2, B2, C2, D2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<C1, C2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<D1, D2>::value) };
+template <typename A, typename B, typename C, typename D, typename E>
+struct ParamsUseScopedRefptrCorrectly<Tuple5<A, B, C, D, E> > {
+  enum { value = !(NeedsScopedRefptrButGetsRawPtr<A>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<B>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<C>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<D>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<E>::value) };
 };
 
-template <class A1, class B1, class C1, class D1, class E1,
-          class A2, class B2, class C2, class D2, class E2>
-struct FunctionUsesScopedRefptrCorrectly<void (*)(A1, B1, C1, D1, E1),
-                                         Tuple5<A2, B2, C2, D2, E2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<C1, C2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<D1, D2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<E1, E2>::value) };
+template <typename A, typename B, typename C, typename D, typename E,
+          typename F>
+struct ParamsUseScopedRefptrCorrectly<Tuple6<A, B, C, D, E, F> > {
+  enum { value = !(NeedsScopedRefptrButGetsRawPtr<A>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<B>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<C>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<D>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<E>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<F>::value) };
 };
 
-template <class A1, class B1, class C1, class D1, class E1, class F1,
-          class A2, class B2, class C2, class D2, class E2, class F2>
-struct FunctionUsesScopedRefptrCorrectly<void (*)(A1, B1, C1, D1, E1, F1),
-                                         Tuple6<A2, B2, C2, D2, E2, F2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<C1, C2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<D1, D2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<E1, E2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<F1, F2>::value) };
+template <typename A, typename B, typename C, typename D, typename E,
+          typename F, typename G>
+struct ParamsUseScopedRefptrCorrectly<Tuple7<A, B, C, D, E, F, G> > {
+  enum { value = !(NeedsScopedRefptrButGetsRawPtr<A>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<B>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<C>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<D>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<E>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<F>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<G>::value) };
 };
 
-template <class A1, class B1, class C1, class D1, class E1, class F1, class G1,
-          class A2, class B2, class C2, class D2, class E2, class F2, class G2>
-struct FunctionUsesScopedRefptrCorrectly<void (*)(A1, B1, C1, D1, E1, F1, G1),
-                                         Tuple7<A2, B2, C2, D2, E2, F2, G2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<C1, C2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<D1, D2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<E1, E2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<F1, F2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<G1, G2>::value) };
+template <typename A, typename B, typename C, typename D, typename E,
+          typename F, typename G, typename H>
+struct ParamsUseScopedRefptrCorrectly<Tuple8<A, B, C, D, E, F, G, H> > {
+  enum { value = !(NeedsScopedRefptrButGetsRawPtr<A>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<B>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<C>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<D>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<E>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<F>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<G>::value ||
+                   NeedsScopedRefptrButGetsRawPtr<H>::value) };
 };
 
-template <class Method, class Params>
-struct MethodUsesScopedRefptrCorrectly {
-  enum { value = 1 };
-};
+}  // namespace internal
 
-template <class T, class A1, class A2>
-struct MethodUsesScopedRefptrCorrectly<void (T::*)(A1), Tuple1<A2> > {
-  enum { value = !ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value };
-};
-
-template <class T, class A1, class B1, class A2, class B2>
-struct MethodUsesScopedRefptrCorrectly<void (T::*)(A1, B1), Tuple2<A2, B2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value) };
-};
-
-template <class T, class A1, class B1, class C1,
-                   class A2, class B2, class C2>
-struct MethodUsesScopedRefptrCorrectly<void (T::*)(A1, B1, C1),
-                                       Tuple3<A2, B2, C2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<C1, C2>::value) };
-};
-
-template <class T, class A1, class B1, class C1, class D1,
-          class A2, class B2, class C2, class D2>
-struct MethodUsesScopedRefptrCorrectly<void (T::*)(A1, B1, C1, D1),
-                                       Tuple4<A2, B2, C2, D2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<C1, C2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<D1, D2>::value) };
-};
-
-template <class T, class A1, class B1, class C1, class D1, class E1,
-                   class A2, class B2, class C2, class D2, class E2>
-struct MethodUsesScopedRefptrCorrectly<void (T::*)(A1, B1, C1, D1, E1),
-                                       Tuple5<A2, B2, C2, D2, E2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<C1, C2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<D1, D2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<E1, E2>::value) };
-};
-
-template <class T, class A1, class B1, class C1, class D1, class E1, class F1,
-                   class A2, class B2, class C2, class D2, class E2, class F2>
-struct MethodUsesScopedRefptrCorrectly<void (T::*)(A1, B1, C1, D1, E1, F1),
-                                       Tuple6<A2, B2, C2, D2, E2, F2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<C1, C2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<D1, D2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<E1, E2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<F1, F2>::value) };
-};
-
-template <class T,
-          class A1, class B1, class C1, class D1, class E1, class F1, class G1,
-          class A2, class B2, class C2, class D2, class E2, class F2, class G2>
-struct MethodUsesScopedRefptrCorrectly<void (T::*)(A1, B1, C1, D1, E1, F1, G1),
-                                       Tuple7<A2, B2, C2, D2, E2, F2, G2> > {
-  enum { value = !(ExpectsScopedRefptrButGetsRawPtr<A1, A2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<B1, B2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<C1, C2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<D1, D2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<E1, E2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<F1, F2>::value ||
-                   ExpectsScopedRefptrButGetsRawPtr<G1, G2>::value) };
-};
+}  // namespace base
 
 #endif  // BASE_RAW_SCOPED_REFPTR_MISMATCH_CHECKER_H_
diff --git a/base/task.h b/base/task.h
index b21ccd8..1949e74 100644
--- a/base/task.h
+++ b/base/task.h
@@ -149,8 +149,9 @@ class ScopedRunnableMethodFactory {
         : obj_(obj),
           meth_(meth),
           params_(params) {
-      COMPILE_ASSERT((MethodUsesScopedRefptrCorrectly<Method, Params>::value),
-                     badscopedrunnablemethodparams);
+      COMPILE_ASSERT(
+          (base::internal::ParamsUseScopedRefptrCorrectly<Params>::value),
+          badscopedrunnablemethodparams);
     }
 
     virtual void Run() {
@@ -317,8 +318,9 @@ class RunnableMethod : public CancelableTask {
   RunnableMethod(T* obj, Method meth, const Params& params)
       : obj_(obj), meth_(meth), params_(params) {
     traits_.RetainCallee(obj_);
-    COMPILE_ASSERT((MethodUsesScopedRefptrCorrectly<Method, Params>::value),
-                   badrunnablemethodparams);
+    COMPILE_ASSERT(
+        (base::internal::ParamsUseScopedRefptrCorrectly<Params>::value),
+        badrunnablemethodparams);
   }
 
   ~RunnableMethod() {
@@ -429,8 +431,9 @@ class RunnableFunction : public CancelableTask {
  public:
   RunnableFunction(Function function, const Params& params)
       : function_(function), params_(params) {
-    COMPILE_ASSERT((FunctionUsesScopedRefptrCorrectly<Function, Params>::value),
-                   badrunnablefunctionparams);
+    COMPILE_ASSERT(
+        (base::internal::ParamsUseScopedRefptrCorrectly<Params>::value),
+        badrunnablefunctionparams);
   }
 
   ~RunnableFunction() {
diff --git a/base/template_util.h b/base/template_util.h
index 2cfe04c..27bdb73 100644
--- a/base/template_util.h
+++ b/base/template_util.h
@@ -6,6 +6,8 @@
 #define BASE_TEMPLATE_UTIL_H_
 #pragma once
 
+#include "build/build_config.h"
+
 namespace base {
 
 // template definitions from tr1
@@ -25,6 +27,51 @@ typedef integral_constant<bool, false> false_type;
 template <class T> struct is_pointer : false_type {};
 template <class T> struct is_pointer<T*> : true_type {};
 
+namespace internal {
+
+// Types small_ and big_ are guaranteed such that sizeof(small_) <
+// sizeof(big_)
+typedef char small_;
+
+struct big_ {
+  small_ dummy[2];
+};
+
+#if !defined(OS_WIN)
+
+// This class is an implementation detail for is_convertible, and you
+// don't need to know how it works to use is_convertible. For those
+// who care: we declare two different functions, one whose argument is
+// of type To and one with a variadic argument list. We give them
+// return types of different size, so we can use sizeof to trick the
+// compiler into telling us which function it would have chosen if we
+// had called it with an argument of type From.  See Alexandrescu's
+// _Modern C++ Design_ for more details on this sort of trick.
+
+template <typename From, typename To>
+struct ConvertHelper {
+  static small_ Test(To);
+  static big_ Test(...);
+  static From Create();
+};
+
+#endif  // !defined(OS_WIN)
+
+}  // namespace internal
+
+#if !defined(OS_WIN)
+
+// Inherits from true_type if From is convertible to To, false_type otherwise.
+template <typename From, typename To>
+struct is_convertible
+    : integral_constant<bool,
+                        sizeof(internal::ConvertHelper<From, To>::Test(
+                                  internal::ConvertHelper<From, To>::Create()))
+                        == sizeof(internal::small_)> {
+};
+
+#endif  // !defined(OS_WIN)
+
 }  // namespace base
 
 #endif  // BASE_TEMPLATE_UTIL_H_
-- 
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