Fix bugprone unhandled self assignment (#25667)

* Add bugprone-unhandled-self-assignment

* Fix bugprone-unhandled-self-assignment

.clang-tidy

@@ -24,7 +24,6 @@
 # - bugprone-signed-char-misuse
 # - bugprone-sizeof-expression
 # - bugprone-too-small-loop-variable
-# - bugprone-unhandled-self-assignment
 # - clang-diagnostic-deprecated-declarations
 # - clang-diagnostic-unused-function
 # - google-readability-avoid-underscore-in-googletest-name
@@ -62,7 +61,6 @@ Checks: '-*,
   -bugprone-signed-char-misuse,
   -bugprone-sizeof-expression,
   -bugprone-too-small-loop-variable,
-  -bugprone-unhandled-self-assignment,
   google-*,
   -google-readability-avoid-underscore-in-googletest-name,
   -google-runtime-int,

include/grpcpp/impl/codegen/call_op_set.h

@@ -878,6 +878,9 @@ class CallOpSet : public CallOpSetInterface,
         interceptor_methods_(InterceptorBatchMethodsImpl()) {}
 
   CallOpSet& operator=(const CallOpSet& other) {
+    if (&other == this) {
+      return *this;
+    }
     core_cq_tag_ = this;
     return_tag_ = this;
     call_ = other.call_;

include/grpcpp/impl/codegen/string_ref.h

@@ -51,6 +51,7 @@ class string_ref {
   string_ref() : data_(nullptr), length_(0) {}
   string_ref(const string_ref& other)
       : data_(other.data_), length_(other.length_) {}
+  // NOLINTNEXTLINE(bugprone-unhandled-self-assignment)
   string_ref& operator=(const string_ref& rhs) {
     data_ = rhs.data_;
     length_ = rhs.length_;

src/core/ext/filters/client_channel/lb_policy.cc

@@ -70,6 +70,9 @@ LoadBalancingPolicy::UpdateArgs::UpdateArgs(UpdateArgs&& other) noexcept {
 
 LoadBalancingPolicy::UpdateArgs& LoadBalancingPolicy::UpdateArgs::operator=(
     const UpdateArgs& other) {
+  if (&other == this) {
+    return *this;
+  }
   addresses = other.addresses;
   config = other.config;
   grpc_channel_args_destroy(args);

src/core/ext/filters/client_channel/resolver.cc

@@ -60,6 +60,9 @@ Resolver::Result::Result(Result&& other) noexcept {
 }
 
 Resolver::Result& Resolver::Result::operator=(const Result& other) {
+  if (&other == this) {
+    return *this;
+  }
   addresses = other.addresses;
   service_config = other.service_config;
   GRPC_ERROR_UNREF(service_config_error);

src/core/ext/filters/client_channel/server_address.cc

@@ -61,6 +61,9 @@ ServerAddress::ServerAddress(const ServerAddress& other)
   }
 }
 ServerAddress& ServerAddress::operator=(const ServerAddress& other) {
+  if (&other == this) {
+    return *this;
+  }
   address_ = other.address_;
   grpc_channel_args_destroy(args_);
   args_ = grpc_channel_args_copy(other.args_);

src/core/ext/filters/client_channel/subchannel_pool_interface.cc

@@ -44,6 +44,9 @@ SubchannelKey::SubchannelKey(const SubchannelKey& other) {
 }
 
 SubchannelKey& SubchannelKey::operator=(const SubchannelKey& other) {
+  if (&other == this) {
+    return *this;
+  }
   grpc_channel_args_destroy(const_cast<grpc_channel_args*>(args_));
   Init(other.args_, grpc_channel_args_copy);
   return *this;

src/core/lib/gprpp/ref_counted_ptr.h

@@ -83,6 +83,7 @@ class RefCountedPtr {
   }
 
   // Copy assignment.
+  // NOLINTNEXTLINE(bugprone-unhandled-self-assignment)
   RefCountedPtr& operator=(const RefCountedPtr& other) {
     // Note: Order of reffing and unreffing is important here in case value_
     // and other.value_ are the same object.
@@ -235,6 +236,7 @@ class WeakRefCountedPtr {
   }
 
   // Copy assignment.
+  // NOLINTNEXTLINE(bugprone-unhandled-self-assignment)
   WeakRefCountedPtr& operator=(const WeakRefCountedPtr& other) {
     // Note: Order of reffing and unreffing is important here in case value_
     // and other.value_ are the same object.