[libcxx-commits] [libcxx] Implement P1885R12: `<text_encoding>` header (PR #141312)

[William Tran-Viet via libcxx-commits]

smallp-o-p wrote:

The issue with `text_encoding::environment()` is that the `text_encoding` class isn't visible in C++23, and I don't see how it would be possible to make it visible prior to C++26 other than:

1. Backport <text_encoding> to earlier versions of the library
2. Wait until libcxx is built with `-std=c++26` by default 

I'll have to dig in more with the availability macros, how `<filesystem>` was implemented seems promising. 

https://github.com/llvm/llvm-project/pull/141312