Fix -Wdeprecated-copy warnings in the boringssl project: Source/third_party/boringssl/src/include/openssl/bytestring.h:53:3: error: definition of implicit copy assignment operator for 'cbs_st' is deprecated because it has a user-declared copy constructor [-Werror,-Wdeprecated-copy] cbs_st(const cbs_st &) = default; ^ Source/ThirdParty/libwebrtc/Source/third_party/boringssl/src/ssl/t1_lib.cc:183:14: note: in implicit copy assignment operator for 'cbs_st' first required here extensions = *cbs; ^ Source/third_party/boringssl/src/include/openssl/bytestring.h:53:3: error: definition of implicit copy assignment operator for 'cbs_st' is deprecated because it has a user-declared copy constructor [-Werror,-Wdeprecated-copy] cbs_st(const cbs_st &) = default; ^ Source/ThirdParty/libwebrtc/Source/third_party/boringssl/src/ssl/handshake_server.cc:452:18: note: in implicit copy assignment operator for 'cbs_st' first required here extensions = copy; ^ Source/third_party/boringssl/src/include/openssl/bytestring.h:53:3: error: definition of implicit copy assignment operator for 'cbs_st' is deprecated because it has a user-declared copy constructor [-Werror,-Wdeprecated-copy] cbs_st(const cbs_st &) = default; ^ Source/ThirdParty/libwebrtc/Source/third_party/boringssl/src/ssl/handshake.cc:176:18: note: in implicit copy assignment operator for 'cbs_st' first required here out_msg->raw = CBS(ech_client_hello_buf); ^ Fixed by upstream commit: Fix a -Wdeprecated-copy warning. https://github.com/google/boringssl/commit/f315a86df3d5cd51135db996c9d5747ec2641331