_BitInt(N) for fixed width integer aliases

[messmerd]

C23 introduces _BitInt(N) which is a keyword for specifying bit-precise integer types where N is the number of bits.
See the proposal here: https://open-std.org/JTC1/SC22/WG14/www/docs/n2763.pdf

While C's int*_t/uint*_t aliases are nice, they are (in my opinion) a band-aid over the real problem which is that the entire language was built over a foundation of implementation-defined fundamental types rather than universally understood fixed-width types. C++ inherits this mistake.

One example of a negative consequence that resulted from this decision is the lack of a proper 8-bit integer type. There's int8_t but this is typically implemented as an alias for char, which can cause unexpected issues in C++ such as trying to print an int8_t but it instead being printed as a char would. And std::byte doesn't help because it is an enum which lacks the normal operations integer types have.

Now, if C++ adopts C23's language features including _BitInt(N), Cpp2 may have to opportunity to use it in its shortened aliases for fixed-width integer types. The following would be valid in both C and C++:

typedef _BitInt(8) i8; typedef _BitInt(16) i16; typedef _BitInt(32) i32; typedef _BitInt(64) i64; typedef _BitInt(128) i128; typedef unsigned _BitInt(8) u8; typedef unsigned _BitInt(16) u16; typedef unsigned _BitInt(32) u32; typedef unsigned _BitInt(64) u64; typedef unsigned _BitInt(128) u128;

This could potentially for the first time provide proper fundamental types to C and C++, including an 8-bit integer type which is actually an 8-bit integer type, while also using the optimal shortened names.

These _BitInt(N) types can implicitly convert to and from their fixed-width equivalents in <cstdint> which would help make their usage easier. Unfortunately there would be some unsettled issues regarding their usage in existing generic code which wasn't written with _BitInt(N) in mind, though a cast to its corresponding int*_t/uint*_t type could be used where needed.

_BitInt(N) also carries the property that they do not follow integer promotion rules, which may be desirable. Or not? I do not know.

There are likely other issues with this proposal that I haven't thought of yet, but I'd like to see what people think of it. Could it actually work?