[2025-11 CWG Motion 2b] P3921R0 issue 1670

[jensmaurer]

https://wiki.edg.com/pub/Wg21kona2025/StrawPolls/p3921r0.html

issue 1670

[eisenwave]

Remember to fix the example in https://eel.is/c++draft/class.conv.fct#8; this fix is not included in CWG1670.