Found the following significant warnings:
  ../inst/include/nlohmann/json_cran.h:16830:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:18166:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:18203:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:18213:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:18223:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:18269:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:18313:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:23135:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:23173:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:23185:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:23241:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:23959:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:23976:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:23990:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24001:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24102:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24118:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24132:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24141:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24218:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24234:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24247:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24256:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24331:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24347:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24360:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24369:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  ../inst/include/nlohmann/json_cran.h:24957:5: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
See ‘/data/gannet/ripley/R/packages/tests-clang/jsonStrings.Rcheck/00install.out’ for details.