The "%S" and "%C" format specifiers are part of POSIX.1-2017 XSI extensions for both printf and scanf. https://pubs.opengroup.org/onlinepubs/9699919799/functions/printf.html https://pubs.opengroup.org/onlinepubs/9699919799/functions/scanf.html
@ibuclaw created dlang/dmd pull request #14317 "fix Issue 23254 - Deprecation: format specifier %S and %C are invalid" fixing this issue: - fix Issue 23254 - Deprecation: format specifier %S and %C are invalid https://github.com/dlang/dmd/pull/14317
dlang/dmd pull request #14317 "fix Issue 23254 - Deprecation: format specifier %S and %C are invalid" was merged into master: - e281a0c01acb353d3b1bc6e06bce18feb4ba8f53 by Iain Buclaw: fix Issue 23254 - Deprecation: format specifier %S and %C are invalid https://github.com/dlang/dmd/pull/14317