https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94990
--- Comment #1 from joseph at codesourcery dot com <joseph at codesourcery dot com> --- Note that ISO C references ISO 10646, not Unicode, so normalization forms are not part of the C notion of identifier characters and differently normalized forms are different identifiers as far as C is concerned. The reason the -Wnormalized= options prefer NFC and don't have an option -Wnormalized=nfd is that many characters were only valid in C99 in the precomposed forms (C11 added more combining characters to the set allowed in identifiers). Any Unicode character sequence can of course be converted to an NFC form if desired; some characters there may use precomposed forms and some may use combining characters. If you wish to use NFD in your code, you should probably set your editor to generate NFD source files and compile with -Wno-normalized. (A separate issue is that the Unicode data used in GCC for -Wnormalized= was last updated in 2013 and needs updating to a newer version of Unicode. Since the update I did in 2013 introduced automated generation of the relevant code from Unicode data, such an update to use newer Unicode data should be straightforward.)
