Found the following significant warnings:
  ../inst/include/nlohmann/json.hpp:24392:35: warning: identifier '_json' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/include/nlohmann/json.hpp:24400:49: warning: identifier '_json_pointer' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/include/nlohmann/json.hpp:24464:58: warning: identifier '_json' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/include/nlohmann/json.hpp:24465:58: warning: identifier '_json_pointer' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
See ‘/home/hornik/tmp/R.check/r-devel-clang/Work/PKGS/rflashtext.Rcheck/00install.out’ for details.
* used C++ compiler: ‘Debian clang version 19.1.7 (1+b1)’
Found the following significant warnings:
  ../inst/include/nlohmann/json.hpp:24392:35: warning: identifier '_json' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/include/nlohmann/json.hpp:24400:49: warning: identifier '_json_pointer' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/include/nlohmann/json.hpp:24464:58: warning: identifier '_json' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/include/nlohmann/json.hpp:24465:58: warning: identifier '_json_pointer' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
See ‘/data/gannet/ripley/R/packages/tests-clang/rflashtext.Rcheck/00install.out’ for details.
* used C++ compiler: ‘clang version 20.1.0’