Avoid use-after-move warning for PendingRemote::InitWithNewPipe...

This CL annotates mojo::PendingRemote::InitWithNewPipeAndPassReceiver
with clang's [[clang::reinitializes]] attribute to suppress the
use-after-move lint warning - see the example here:
https://crrev.com/c/2824128/2..4/content/browser/renderer_host/render_frame_host_impl.cc#b7754

Bug: 1198689
Change-Id: Ic451e5fd126ff43b36314dda55492902cc72becd
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2824016
Reviewed-by: Daniel Cheng <dcheng@chromium.org>
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Cr-Commit-Position: refs/heads/master@{#872568}

base/compiler_specific.h

@@ -373,4 +373,13 @@ inline constexpr bool AnalyzerAssumeTrue(bool arg) {
 #define TRIVIAL_ABI
 #endif
 
+// Marks a member function as reinitializing a moved-from variable.
+// See also
+// https://clang.llvm.org/extra/clang-tidy/checks/bugprone-use-after-move.html#reinitialization
+#if defined(__clang__) && __has_attribute(reinitializes)
+#define REINITIALIZES_AFTER_MOVE [[clang::reinitializes]]
+#else
+#define REINITIALIZES_AFTER_MOVE
+#endif
+
 #endif  // BASE_COMPILER_SPECIFIC_H_

mojo/public/cpp/bindings/pending_associated_receiver.h

@@ -9,6 +9,7 @@
 
 #include <utility>
 
+#include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "build/build_config.h"
 #include "mojo/public/cpp/bindings/associated_interface_request.h"
@@ -90,8 +91,8 @@ class PendingAssociatedReceiver {
     handle_.ResetWithReason(custom_reason, description);
   }
 
-  PendingAssociatedRemote<Interface> InitWithNewEndpointAndPassRemote()
+  REINITIALIZES_AFTER_MOVE PendingAssociatedRemote<Interface>
-      WARN_UNUSED_RESULT;
+  InitWithNewEndpointAndPassRemote() WARN_UNUSED_RESULT;
 
   // Associates this endpoint with a dedicated message pipe. This allows the
   // entangled AssociatedReceiver/AssociatedRemote endpoints to be used without

mojo/public/cpp/bindings/pending_associated_remote.h

@@ -87,8 +87,8 @@ class PendingAssociatedRemote {
   uint32_t version() const { return version_; }
   void set_version(uint32_t version) { version_ = version; }
 
-  PendingAssociatedReceiver<Interface> InitWithNewEndpointAndPassReceiver()
+  REINITIALIZES_AFTER_MOVE PendingAssociatedReceiver<Interface>
-      WARN_UNUSED_RESULT;
+  InitWithNewEndpointAndPassReceiver() WARN_UNUSED_RESULT;
 
   // Associates this endpoint with a dedicated message pipe. This allows the
   // entangled AssociatedReceiver/AssociatedRemote endpoints to be used

mojo/public/cpp/bindings/pending_receiver.h

@@ -136,7 +136,8 @@ class PendingReceiver {
   // Creates a new message pipe, retaining one end in the PendingReceiver
   // (making it valid) and returning the other end as its entangled
   // PendingRemote. May only be called on an invalid PendingReceiver.
-  PendingRemote<Interface> InitWithNewPipeAndPassRemote() WARN_UNUSED_RESULT;
+  REINITIALIZES_AFTER_MOVE PendingRemote<Interface>
+  InitWithNewPipeAndPassRemote() WARN_UNUSED_RESULT;
 
   // For internal Mojo use only.
   internal::PendingReceiverState* internal_state() { return &state_; }

mojo/public/cpp/bindings/pending_remote.h

@@ -121,8 +121,8 @@ class PendingRemote {
   // Creates a new message pipe, retaining one end in the PendingRemote (making
   // it valid) and returning the other end as its entangled PendingReceiver. May
   // only be called on an invalid PendingRemote.
-  PendingReceiver<Interface> InitWithNewPipeAndPassReceiver()
+  REINITIALIZES_AFTER_MOVE PendingReceiver<Interface>
-      WARN_UNUSED_RESULT;
+  InitWithNewPipeAndPassReceiver() WARN_UNUSED_RESULT;
 
   // For internal Mojo use only.
   internal::PendingRemoteState* internal_state() { return &state_; }