GSL 4.2.0 Release Notes

New Features

• Added gsl::swap for safely swapping gsl::not_null pointers (#1160)
• Introduced element_type member type to gsl::not_null for better type trait consistency (#1196)
• Added support for strict_not_null with unique_ptr (#1179)
• Added comprehensive test suite for gsl::span including empty span, conversion, and comparison tests (#1189)

Performance Improvements

• Significantly improved span_iterator performance with Clang compiler, reducing overhead by up to 20x (#1166)

Bug Fixes

• Fixed GCC-specific bug with list initialization of const references (#1175)
• Fixed SFINAE implementation in gsl::owner (#1174)
• Fixed issues with std::enable_if usage throughout the codebase (#1177)
• Modified include directives to use explicit "gsl/" prefix to prevent header conflicts (#1184)
• Changed include directives to use relative paths to comply with CppCoreGuideline SF.12 (#1194)

Deprecated Features

• Removed deprecated string_span feature (#1185)
• Marked the following features as deprecated as they are now in the C++ standard:
• gsl::unique_ptr
• gsl::shared_ptr
• gsl::byte (since C++17)
• gsl::joining_thread

Infrastructure Updates

• Updated CI pipeline for Ubuntu 24.04
• Updated compiler support:
• Clang 16, 17, 18
• GCC 12, 13, 14
• Upgraded to GoogleTest v1.14.0
• Added new issue templates
• Updated documentation and badges

Thanks to Contributors

Special thanks to the following contributors who helped make GSL 4.2.0 possible:

• @ajtruckle
• @apenn-msft
• @asartori86
• @beinhaerter
• @daltairwalter
• @DanielJump
• @HenryHu
• @lord-pando
• @mhthies
• @paparodeo
• @tiagomacarios

Your contributions have helped improve GSL's reliability, performance, and usability.