[libcxx-commits] [libcxx] [libc++] mark `std::expected` as `nodiscard` (PR #130820)

[Nicole Mazzuca via libcxx-commits]

strega-nil-re wrote:

It seems like it's pretty much always a bug to not check an `expected`. I certainly have my opinions from MS-STL (`[[nodiscard]]` all the things!) but I don't see why anyone would ever want to implicitly ignore an `expected`.

https://github.com/llvm/llvm-project/pull/130820