Underlying type for std::uint8_t

Question

Question:
Is there any c++ toolchain, where std::uint8_t exists, but is not a typedef for unsigned char (or char, if it is unsigned)?

EDIT: Conversely: Is such a thing even possible in a standards conforming implementation?

Background / Motivation:
I'm mainly asking because I want to know if std::uint8_t* can be used portably to access individual bytes (just like unsigned char*). And yes, I'm aware of std::byte, but thats not relevant here. I'm mainly interested in toolchains for x86, arm and mips, but out of curiosity I'd also like to hear about other examples.

Answer 1

1. char is not an unsigned integer type, even if it is, in fact, unsigned. Since uint8_t must be a unsigned integer type, it never can be char.
2. CHAR_BIT must be at least 8, while the next smallest standard unsigned integer type, unsigned short, must have at least 16 bits. If uint8_t exists, then it must be "an unsigned integer type with width 8 and no padding bits." If uint8_t denotes a standard unsigned integer type, then it can only be unsigned char.
3. However, nothing in the wording prevents uint8_t from denoting an implementation-defined extended unsigned integer type. I don't know of any implementations that do this, however.