Extended integer types are decidedly not just aliases to other types - the C standard has separate "standard integer types" which are the regular char/short/int

Extended integer types are decidedly not just aliases to other types - the C standard has separate "standard integer types" which are the regular char/short/int/long/long long, and "extended integer types" which are any additional implementation-specific types. stdint.h-defined types can be either of those categories (and on regular clang/gcc they're all standard integer types and not extended ones). So you could have a system with char/short/int/long/long long being 8/16/64/64/64-bit respectively and still be able to provide an int32_t that's none of those; just, noone does.