Builtin Types

Type	AVR	MSP430	ARM32	Unix ARM32/X86	Unix ARM64/X64	Win ARM64/X64
`unsigned char`	1	1	1	1	1	1
`unsigned short`	2	2	2	2	2	2
`unsigned int`	2	2	4	4	4	4
`unsigned long`	4	4	4	4	8	4
`unsigned long long`	8	8	8	8	8	8
`float`	4	4	4	4	4	4
`double`	4	8	8	8	8	8
`long double`	8	8	8	16	16	8
`char`	1	1	1	1	1	1
`wchar_t`	2	4	4	4	4	2
`char8_t`	1	1	1	1	1	1
`char16_t`	2	2	2	2	2	2
`char32_t`	4	4	4	4	4	4

AVR

Size of double and long double can be changed with -mdouble=bits and -mlong-double=bits. Possible values are 32 and 64.

std::construct_at
- Only way to get constexpr "placement new"
tuple protocol (structured bindings)
- std::tuple_size
- std::tuple_element
three-way comparison
- operator<=> returns a type from std for builtin types