Found the following significant warnings:
  /usr/local/clang/include/google/protobuf/io/coded_stream.h:695:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/arenastring.h:246:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/arenastring.h:248:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/repeated_ptr_field.h:281:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/repeated_ptr_field.h:295:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/repeated_ptr_field.h:667:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/repeated_ptr_field.h:738:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/inlined_string_field.h:205:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/inlined_string_field.h:207:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:128:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:139:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:148:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:154:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:162:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:171:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:176:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:181:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:184:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:365:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:408:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:411:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:431:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:527:1: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:661:1: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:790:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:795:1: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:841:1: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:862:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:864:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:866:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:868:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:870:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:872:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:874:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:878:1: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:894:1: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:908:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:910:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:912:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:914:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:916:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:918:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:920:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:924:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/parse_context.h:929:17: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/message.h:503:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/message.h:658:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/extension_set.h:292:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/extension_set.h:297:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/extension_set.h:367:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/extension_set.h:587:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/extension_set.h:1381:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:786:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:804:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:822:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:837:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:855:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:1031:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:1560:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:1575:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:1847:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:2208:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:2226:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:2244:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:2262:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:2280:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:2295:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:2537:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:2552:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:2958:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:2973:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3145:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3160:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3361:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3376:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3549:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3567:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3585:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3600:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3867:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3885:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3903:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3921:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3939:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3957:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3975:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:3993:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:4011:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:4029:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:4256:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:4687:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:5194:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:5555:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:5937:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:6308:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:6678:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:7094:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:7355:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:7561:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:7579:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:7597:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:7877:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:7895:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:8253:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/any.pb.h:232:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/any.pb.h:246:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/source_context.pb.h:198:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:376:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:391:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:684:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:698:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:712:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:726:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:971:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:986:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:1173:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:1336:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /usr/local/clang/include/google/protobuf/type.pb.h:1351:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  init.c:109:41: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  init.c:153:36: warning: a function declaration without a prototype is deprecated in all versions of C [-Wstrict-prototypes]
  3In file included from :/usr/local/clang/include/google/protobuf/descriptor.pb.h :warning: 26use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]:
   warning: /usr/local/clang/include/google/protobuf/port_def.incuse of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]:
  3In file included from :/usr/local/clang/include/google/protobuf/generated_message_table_driven.h :warning: 34use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]:
  3:/usr/local/clang/include/google/protobuf/port_def.inc :warning: 463use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]:
  warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]/usr/local/clang/include/google/protobuf/port_def.inc
  /usr/local/clang/include/google/protobuf/type.pb.h:391:3: In file included from warning: mutators.cppuse of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]:
  /usr/local/clang/include/google/protobuf/descriptor.pb.h:/usr/local/clang/include/google/protobuf/port_def.inc2295::4633::30 :warning:  use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]note: 
  :In file included from  ./rprotobuf.hwarning: :use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]37
  :297:3: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  : warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
See ‘/data/gannet/ripley/R/packages/tests-clang/RProtoBuf.Rcheck/00install.out’ for details.