include/fmt/format-inl.h:707:23: error: implicit conversion changes
signedness: 'typename std::make_unsigned<int>::type' (aka 'unsigned
int') to 'int' [-Werror,-Wsign-conversion]
  params.num_digits = to_unsigned(num_digits);
                    ~ ^~~~~~~~~~~~~~~~~~~~~~~
include/fmt/format-inl.h:755:33: error: implicit conversion changes
signedness: 'int' to 'size_t' (aka 'unsigned long')
[-Werror,-Wsign-conversion]
  params.num_digits)) {
  ~~~~~~~^~~~~~~~~~}