[ref-counted] Use down_cast for additional safety checks (#35579)

Closes #35579

COPYBARA_INTEGRATE_REVIEW=https://github.com/grpc/grpc/pull/35579 from ctiller:use-downcast 6f11268751
PiperOrigin-RevId: 622981017

BUILD

@@ -3031,6 +3031,7 @@ grpc_cc_library(
         "debug_location",
         "gpr_platform",
         "ref_counted_ptr",
+        "//src/core:down_cast",
         "//src/core:ref_counted",
     ],
 )
@@ -3063,6 +3064,7 @@ grpc_cc_library(
     deps = [
         "debug_location",
         "gpr_platform",
+        "//src/core:down_cast",
     ],
 )
 

CMakeLists.txt

@@ -7345,6 +7345,7 @@ target_include_directories(avl_test
 target_link_libraries(avl_test
   ${_gRPC_ALLTARGETS_LIBRARIES}
   gtest
+  absl::config
   absl::hash
   gpr
 )
@@ -12812,6 +12813,7 @@ target_include_directories(endpoint_config_test
 target_link_libraries(endpoint_config_test
   ${_gRPC_ALLTARGETS_LIBRARIES}
   gtest
+  absl::config
   absl::hash
   absl::type_traits
   absl::statusor
@@ -30509,6 +30511,7 @@ target_include_directories(thread_quota_test
 target_link_libraries(thread_quota_test
   ${_gRPC_ALLTARGETS_LIBRARIES}
   gtest
+  absl::config
   absl::hash
   gpr
 )

build_autogenerated.yaml

@@ -5742,12 +5742,14 @@ targets:
   headers:
   - src/core/lib/avl/avl.h
   - src/core/lib/gprpp/atomic_utils.h
+  - src/core/lib/gprpp/down_cast.h
   - src/core/lib/gprpp/ref_counted.h
   - src/core/lib/gprpp/ref_counted_ptr.h
   src:
   - test/core/avl/avl_test.cc
   deps:
   - gtest
+  - absl/base:config
   - absl/hash:hash
   - gpr
   uses_polling: false
@@ -8944,6 +8946,7 @@ targets:
   - src/core/lib/channel/channel_args.h
   - src/core/lib/event_engine/channel_args_endpoint_config.h
   - src/core/lib/gprpp/atomic_utils.h
+  - src/core/lib/gprpp/down_cast.h
   - src/core/lib/gprpp/dual_ref_counted.h
   - src/core/lib/gprpp/orphanable.h
   - src/core/lib/gprpp/ref_counted.h
@@ -8960,6 +8963,7 @@ targets:
   - test/core/event_engine/endpoint_config_test.cc
   deps:
   - gtest
+  - absl/base:config
   - absl/hash:hash
   - absl/meta:type_traits
   - absl/status:statusor
@@ -19159,6 +19163,7 @@ targets:
   language: c++
   headers:
   - src/core/lib/gprpp/atomic_utils.h
+  - src/core/lib/gprpp/down_cast.h
   - src/core/lib/gprpp/ref_counted.h
   - src/core/lib/gprpp/ref_counted_ptr.h
   - src/core/lib/resource_quota/thread_quota.h
@@ -19167,6 +19172,7 @@ targets:
   - test/core/resource_quota/thread_quota_test.cc
   deps:
   - gtest
+  - absl/base:config
   - absl/hash:hash
   - gpr
   uses_polling: false

src/core/BUILD

@@ -1157,6 +1157,7 @@ grpc_cc_library(
     public_hdrs = ["lib/gprpp/ref_counted.h"],
     deps = [
         "atomic_utils",
+        "down_cast",
         "//:debug_location",
         "//:gpr",
         "//:ref_counted_ptr",
@@ -1168,6 +1169,7 @@ grpc_cc_library(
     language = "c++",
     public_hdrs = ["lib/gprpp/dual_ref_counted.h"],
     deps = [
+        "down_cast",
         "//:debug_location",
         "//:gpr",
         "//:orphanable",

src/core/lib/gprpp/down_cast.h

@@ -26,10 +26,10 @@
 namespace grpc_core {
 
 template <typename To, typename From>
-inline To down_cast(From* f) {
+inline To DownCast(From* f) {
   static_assert(
       std::is_base_of<From, typename std::remove_pointer<To>::type>::value,
-      "down_cast requires a base-to-derived relationship");
+      "DownCast requires a base-to-derived relationship");
 // If we have RTTI & we're in debug, assert that the cast is legal.
 #if ABSL_INTERNAL_HAS_RTTI
 #ifndef NDEBUG
@@ -40,8 +40,8 @@ inline To down_cast(From* f) {
 }
 
 template <typename To, typename From>
-inline To down_cast(From& f) {
-  return *down_cast<typename std::remove_reference<To>::type*>(&f);
+inline To DownCast(From& f) {
+  return *DownCast<typename std::remove_reference<To>::type*>(&f);
 }
 
 }  // namespace grpc_core

src/core/lib/gprpp/dual_ref_counted.h

@@ -25,6 +25,7 @@
 #include <grpc/support/log.h>
 
 #include "src/core/lib/gprpp/debug_location.h"
+#include "src/core/lib/gprpp/down_cast.h"
 #include "src/core/lib/gprpp/orphanable.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 
@@ -68,7 +69,8 @@ class DualRefCounted {
       std::enable_if_t<std::is_base_of<Child, Subclass>::value, bool> = true>
   RefCountedPtr<Subclass> RefAsSubclass() {
     IncrementRefCount();
-    return RefCountedPtr<Subclass>(static_cast<Subclass*>(this));
+    return RefCountedPtr<Subclass>(
+        DownCast<Subclass*>(static_cast<Child*>(this)));
   }
   template <
       typename Subclass,
@@ -76,7 +78,8 @@ class DualRefCounted {
   RefCountedPtr<Subclass> RefAsSubclass(const DebugLocation& location,
                                         const char* reason) {
     IncrementRefCount(location, reason);
-    return RefCountedPtr<Subclass>(static_cast<Subclass*>(this));
+    return RefCountedPtr<Subclass>(
+        DownCast<Subclass*>(static_cast<Child*>(this)));
   }
 
   void Unref() {
@@ -179,7 +182,8 @@ class DualRefCounted {
       std::enable_if_t<std::is_base_of<Child, Subclass>::value, bool> = true>
   WeakRefCountedPtr<Subclass> WeakRefAsSubclass() {
     IncrementWeakRefCount();
-    return WeakRefCountedPtr<Subclass>(static_cast<Subclass*>(this));
+    return WeakRefCountedPtr<Subclass>(
+        DownCast<Subclass*>(static_cast<Child*>(this)));
   }
   template <
       typename Subclass,
@@ -187,7 +191,8 @@ class DualRefCounted {
   WeakRefCountedPtr<Subclass> WeakRefAsSubclass(const DebugLocation& location,
                                                 const char* reason) {
     IncrementWeakRefCount(location, reason);
-    return WeakRefCountedPtr<Subclass>(static_cast<Subclass*>(this));
+    return WeakRefCountedPtr<Subclass>(
+        DownCast<Subclass*>(static_cast<Child*>(this)));
   }
 
   void WeakUnref() {

src/core/lib/gprpp/orphanable.h

@@ -26,6 +26,7 @@
 #include <utility>
 
 #include "src/core/lib/gprpp/debug_location.h"
+#include "src/core/lib/gprpp/down_cast.h"
 #include "src/core/lib/gprpp/ref_counted.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 
@@ -102,7 +103,8 @@ class InternallyRefCounted : public Orphanable {
       std::enable_if_t<std::is_base_of<Child, Subclass>::value, bool> = true>
   RefCountedPtr<Subclass> RefAsSubclass() {
     IncrementRefCount();
-    return RefCountedPtr<Subclass>(static_cast<Subclass*>(this));
+    return RefCountedPtr<Subclass>(
+        DownCast<Subclass*>(static_cast<Child*>(this)));
   }
   template <
       typename Subclass,
@@ -110,7 +112,8 @@ class InternallyRefCounted : public Orphanable {
   RefCountedPtr<Subclass> RefAsSubclass(const DebugLocation& location,
                                         const char* reason) {
     IncrementRefCount(location, reason);
-    return RefCountedPtr<Subclass>(static_cast<Subclass*>(this));
+    return RefCountedPtr<Subclass>(
+        DownCast<Subclass*>(static_cast<Child*>(this)));
   }
 
   GRPC_MUST_USE_RESULT RefCountedPtr<Child> RefIfNonZero() {

src/core/lib/gprpp/ref_counted.h

@@ -29,6 +29,7 @@
 
 #include "src/core/lib/gprpp/atomic_utils.h"
 #include "src/core/lib/gprpp/debug_location.h"
+#include "src/core/lib/gprpp/down_cast.h"
 #include "src/core/lib/gprpp/ref_counted_ptr.h"
 
 namespace grpc_core {
@@ -310,7 +311,8 @@ class RefCounted : public Impl {
       std::enable_if_t<std::is_base_of<Child, Subclass>::value, bool> = true>
   RefCountedPtr<Subclass> RefAsSubclass() {
     IncrementRefCount();
-    return RefCountedPtr<Subclass>(static_cast<Subclass*>(this));
+    return RefCountedPtr<Subclass>(
+        DownCast<Subclass*>(static_cast<Child*>(this)));
   }
   template <
       typename Subclass,
@@ -318,7 +320,8 @@ class RefCounted : public Impl {
   RefCountedPtr<Subclass> RefAsSubclass(const DebugLocation& location,
                                         const char* reason) {
     IncrementRefCount(location, reason);
-    return RefCountedPtr<Subclass>(static_cast<Subclass*>(this));
+    return RefCountedPtr<Subclass>(
+        DownCast<Subclass*>(static_cast<Child*>(this)));
   }
 
   // RefIfNonZero() for mutable types.

src/core/lib/gprpp/ref_counted_ptr.h

@@ -30,6 +30,7 @@
 #include "absl/hash/hash.h"
 
 #include "src/core/lib/gprpp/debug_location.h"
+#include "src/core/lib/gprpp/down_cast.h"
 
 namespace grpc_core {
 
@@ -159,7 +160,7 @@ class RefCountedPtr {
   template <typename Y,
             std::enable_if_t<std::is_base_of<T, Y>::value, bool> = true>
   RefCountedPtr<Y> TakeAsSubclass() {
-    return RefCountedPtr<Y>(static_cast<Y*>(release()));
+    return RefCountedPtr<Y>(DownCast<Y*>(release()));
   }
 
   template <typename Y,

src/core/lib/promise/context.h

@@ -36,7 +36,7 @@ struct ContextType;
 
 // Some contexts can be subclassed. If the subclass is set as that context
 // then GetContext<Base>() will return the base, and GetContext<Derived>() will
-// down_cast to the derived type.
+// DownCast to the derived type.
 // Specializations of this type should be created for each derived type, and
 // should have a single using statement Base pointing to the derived base class.
 // Example:
@@ -84,7 +84,7 @@ class Context<T, absl::void_t<typename ContextSubclass<T>::Base>>
  public:
   using Context<typename ContextSubclass<T>::Base>::Context;
   static T* get() {
-    return down_cast<T*>(Context<typename ContextSubclass<T>::Base>::get());
+    return DownCast<T*>(Context<typename ContextSubclass<T>::Base>::get());
   }
 };
 

test/core/gprpp/down_cast_test.cc

@@ -32,8 +32,8 @@ class Derived : public Base {
 TEST(DownCastTest, DownCast) {
   Derived d;
   Base* b = &d;
-  EXPECT_EQ(down_cast<Derived*>(b)->i, 3);
-  EXPECT_EQ(down_cast<Derived&>(*b).i, 3);
+  EXPECT_EQ(DownCast<Derived*>(b)->i, 3);
+  EXPECT_EQ(DownCast<Derived&>(*b).i, 3);
 }
 
 }  // namespace