Found the following significant warnings:
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:16830:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:18166:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:18203:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:18213:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:18223:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:18269:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:18313:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:23135:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:23173:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:23185:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:23241:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:23959:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:23976:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:23990:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24001:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24102:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24118:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24132:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24141:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24218:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24234:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24247:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24256:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24331:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24347:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24360:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24369:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
  /home/hornik/tmp/R.check/r-devel-clang/Work/build/Packages/rvinecopulib/include/vinecopulib/misc/nlohmann_json.hpp:24957:13: warning: use of the 'nodiscard' attribute is a C++17 extension [-Wc++17-attribute-extensions]
See '/home/hornik/tmp/R.check/r-devel-clang/Work/PKGS/svines.Rcheck/00install.out' for details.