Found the following significant warnings:
  ../inst/i/b/multiprecision/cpp_int/literals.hpp:239:166: warning: identifier '_cppi' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/i/b/multiprecision/cpp_int/literals.hpp:246:168: warning: identifier '_cppui' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/i/b/multiprecision/cpp_int/literals.hpp:270:1: warning: identifier '_cppi128' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/i/b/multiprecision/cpp_int/literals.hpp:270:1: warning: identifier '_cppui128' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/i/b/multiprecision/cpp_int/literals.hpp:271:1: warning: identifier '_cppi256' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/i/b/multiprecision/cpp_int/literals.hpp:271:1: warning: identifier '_cppui256' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/i/b/multiprecision/cpp_int/literals.hpp:272:1: warning: identifier '_cppi512' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/i/b/multiprecision/cpp_int/literals.hpp:272:1: warning: identifier '_cppui512' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/i/b/multiprecision/cpp_int/literals.hpp:273:1: warning: identifier '_cppi1024' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
  ../inst/i/b/multiprecision/cpp_int/literals.hpp:273:1: warning: identifier '_cppui1024' preceded by whitespace in a literal operator declaration is deprecated [-Wdeprecated-literal-operator]
See ‘/data/gannet/ripley/R/packages/tests-clang/googlePolylines.Rcheck/00install.out’ for details.
* used C++ compiler: ‘clang version 20.1.0-rc2’