Expand description
The 128-bit signed integer type.
§ABI compatibility
Rust’s i128 is expected to be ABI-compatible with C’s __int128 on platforms where the type
is available, which includes most 64-bit architectures. If any platforms that do not specify
__int128 are updated to introduce it, the Rust i128 ABI on relevant targets will be changed
to match.
It is important to note that in C, __int128 is not the same as _BitInt(128), and the two
types are allowed to have different ABIs. In particular, on x86, __int128 and _BitInt(128)
do not use the same alignment. i128 is intended to always match __int128 and does not
attempt to match _BitInt(128) on platforms without __int128.