llvm/llvm-project • PR #219236Score: 8/10
[libc++] Implement P3798R1: The unexpected in `std::expected`
Language: C+++109 -7feature
The Issue & Context
The C++ standard library's std::expected implementation lacked support for the proposal P3798R1, which introduces the 'unexpected' type to better handle error states.
Root Cause Analysis
Prior versions of libc++ did not implement the 'unexpected' type as specified in P3798R1, limiting the expressiveness and correctness of error handling in std::expected.
Solution Strategy & Architectural Pattern
This PR re-applies a previous change to implement P3798R1, adding the 'unexpected' type and associated functionality along with comprehensive tests across 11 files, improving error state representation in std::expected.
Key Takeaway for Contributors
Incorporating P3798R1 enhances libc++'s std::expected by aligning it with the latest C++ proposals, providing developers with more robust and standardized error handling patterns.