Why is char considered a distinct type from signed char and unsigned char in C Templates?

char!=(signed char), char!=(unsigned char)

This question explores the behavior of the char data type in C compared to other integer types like int. Specifically, it addresses the observation that char is treated as a distinct type from both signed char and unsigned char.

The C standard defines char, signed char, and unsigned char as three separate types. While they share the same amount of storage and alignment requirements, their value representations and bit patterns are distinct. For unsigned character types, all bit patterns represent numbers. However, this is not necessarily true for char or signed char.

The example code in the question demonstrates this difference in behavior. When template specializations are created for int8 (signed char), uint8 (unsigned char), and char, three separate instantiations are generated. This is because the compiler treats char as a distinct type from the other two.

In contrast, when template specializations are created for int, int32, and uint32, only one instantiation is generated for int and int32 because they are considered the same type. Signed int, however, is treated as a separate type and generates its own template specialization.

This behavior is consistent with the C standard, which states that char, signed char, and unsigned char are three different types. Therefore, it is correct to treat them as distinct types in template specializations.

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