Fix compile

include/grpc++/impl/codegen/call.h

@@ -528,7 +528,7 @@ class CallOpClientRecvStatus {
   void ClientRecvStatus(ClientContext* context, Status* status) {
     metadata_map_ = &context->trailing_metadata_;
     recv_status_ = status;
-    status_details_ = grpc_empty_slice();
+    status_details_ = g_core_codegen_interface->grpc_empty_slice();
   }
 
  protected:

include/grpc++/impl/codegen/core_codegen.h

@@ -76,6 +76,7 @@ class CoreCodegen : public CoreCodegenInterface {
   grpc_byte_buffer* grpc_raw_byte_buffer_create(grpc_slice* slice,
                                                 size_t nslices) override;
 
+  grpc_slice grpc_empty_slice() override;
   grpc_slice grpc_slice_malloc(size_t length) override;
   void grpc_slice_unref(grpc_slice slice) override;
   grpc_slice grpc_slice_split_tail(grpc_slice* s, size_t split) override;

include/grpc++/impl/codegen/core_codegen_interface.h

@@ -94,6 +94,7 @@ class CoreCodegenInterface {
   virtual grpc_byte_buffer* grpc_raw_byte_buffer_create(grpc_slice* slice,
                                                         size_t nslices) = 0;
 
+  virtual grpc_slice grpc_empty_slice() = 0;
   virtual grpc_slice grpc_slice_malloc(size_t length) = 0;
   virtual void grpc_slice_unref(grpc_slice slice) = 0;
   virtual grpc_slice grpc_slice_split_tail(grpc_slice* s, size_t split) = 0;

src/cpp/common/core_codegen.cc

@@ -111,6 +111,8 @@ grpc_byte_buffer* CoreCodegen::grpc_raw_byte_buffer_create(grpc_slice* slice,
   return ::grpc_raw_byte_buffer_create(slice, nslices);
 }
 
+grpc_slice CoreCodegen::grpc_empty_slice() { return ::grpc_empty_slice(); }
+
 grpc_slice CoreCodegen::grpc_slice_malloc(size_t length) {
   return ::grpc_slice_malloc(length);
 }