What I meant is that I implemented rough literal support a decade ago (piggybacking on ms-extensions, where someone had defined the suffixes without an implementation), which led to a bunch of discussion and ultimately this post by Richard Smith concerning interaction with the C and C++ standards of the time: [cfe-dev] MS 128-bit literals don't always have the correct type
I didn’t have bandwidth to do any further work on it then (I had only implemented it because the suffixes were already wired up and it was useful for a couple hobby projects I had), and eventually David Majnemer removed support because “most code in clang expects that
evaluation of an integer constant expression won’t give them something
that ‘long long’ can’t represent” (r243243 - [MS Extensions] Remove support for the i128 integer literal suffix). I don’t know if that’s still the case or not.