Found the following significant warnings:
  ../inst/include/cpp11/R.hpp../inst/include/cpp11/R.hpp::5454::3131::  warning: warning: identifier '_xl' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]identifier '_xl' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/include/cpp11/R.hpp:54:31: warning: identifier '_xl' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/include/cpp11/named_arg.hpp:44:29: warning: identifier '_nm' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  duckdb/third_party/httplib/httplib.hpp:3422:43: warning: identifier '_t' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  duckdb/third_party/httplib/httplib.hpp:3437:26: warning: identifier '_t' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  duckdb/third_party/httplib/httplib.hpp:3495:26: warning: identifier '_t' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  duckdb/third_party/fmt/include/fmt/format.h:551:33: warning: identifier '_u' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  duckdb/third_party/fmt/include/fmt/format.h:3345:56: warning: identifier '_format' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  duckdb/third_party/fmt/include/fmt/format.h:3349:59: warning: identifier '_format' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  duckdb/third_party/fmt/include/fmt/format.h:3365:50: warning: identifier '_a' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  duckdb/third_party/fmt/include/fmt/format.h:3369:53: warning: identifier '_a' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
See ‘/data/gannet/ripley/R/packages/tests-clang/duckdb.Rcheck/00install.out’ for details.
* used C++ compiler: ‘clang version 20.1.0-rc3’