When checking the GCC 14.2 implementation of C++23 fixed width floating-point types in the header <stdfloat> [1]:
The page [2] says that one should be able to write std::float128_t using std::formatter as it is using std::to_chars which is required to support all arithmetic type, but it does not work with GCC. But the wording suggests it has been working with GCC.
Then using std::to_chars directly, I found what may be a error in the conversion from float to std::std::float64_t: I modify the code at [3] by adding to “main”
show_to_chars(+3.14159f64);
show_to_chars(std::float64_t{+3.14159F});
and increasing, in “show_to_chars”, the bufsize to 20, I get the output:
"3.14159"
"3.141590118408203"
These extra decimals do not appear when using std::float32_t{+3.14159F}.
Also, this code does not work with GCC when using, in “main”, any of
show_to_chars(+3.14159f128);
show_to_chars(std::float128_t{+3.14159F});
1. https://en.cppreference.com/w/cpp/types/floating-point
2. https://stackoverflow.com/questions/76500128/cant-use-operator-with-stdfloat128-t-how-do-i-print-it
3. https://en.cppreference.com/w/cpp/utility/to_chars
