[libcxx-commits] [libcxx] [libcxx] Handle windows system error code mapping in std::error_code. (PR #93101)

[James Y Knight via libcxx-commits]

jyknight wrote:

> Is there a possibility that this would break user code that is relying on the previous mapping, or does that previous mapping never escape out of libc++ implementation details?

Yes, there is: user could could be expecting that `std::error_code(ENOSYS, std::system_category()) == std::errc::function_not_supported`, but will no longer work on Windows. They will need to switch to `std::error_code(ENOSYS, std::generic_category())`. This needs a release note.

https://github.com/llvm/llvm-project/pull/93101