Why does libc++ still not have full C++17 support?
The question of why libc++, a popular open-source implementation of the C++ Standard Library, still lacks full support for C++17, despite being released over five years ago, has sparked a lively discussion among C++ enthusiasts. This documentation aims to provide insight into the reasons behind this phenomenon, drawing from expert opinions and real-world experiences.
libc++ is widely used, particularly with the Clang compiler, and its development is closely tied to the LLVM project. Despite this, it seems that the library has not yet caught up with the latest C++17 features, leaving many developers wondering why.
The State of libc++ Support
A quick glance at the C++ compiler support page reveals that libc++ is still missing some essential C++17 library features. This includes, but is not limited to, parallel algorithms and math operations. These omissions can be a significant hindrance for developers seeking to leverage the full power of C++17 in their projects.
The Role of Apple and Swift
One commentator, equeim, attributes the slow development of libc++ to Apple's shifting priorities towards Swift, which utilizes LLVM only as a backend. This may have led to a decrease in resources and focus on Clang and libc++ development. While this is speculative, it's essential to consider the role of corporate priorities in open-source development.
Importance of C++17 Features
blipman17 argues that certain C++17 features, such as parallel algorithms and math operations, are not crucial for many projects. They suggest that, for performance-critical projects, developers often opt for specialized libraries or custom implementations, making the lack of these features in the STL less pressing. However, this perspective overlooks the importance of standardization and the benefits of having these features readily available in the STL.
Resource Constraints
pjf_cpp points to a more fundamental issue: the lack of developers and resources dedicated to working on libc++. This is a common problem in open-source development, where projects often rely on volunteer contributions and may struggle to attract and retain talent.
Real-World Experiences
serenetomato shares their personal experience with libc++ limitations, having encountered issues while compiling libpqxx. Although they found a workaround, this anecdote highlights the practical implications of libc++'s incomplete C++17 support.
In conclusion, the reasons behind libc++'s incomplete C++17 support are complex and multifaceted. While it's essential to acknowledge the importance of standardization and the benefits of having a comprehensive STL, resource constraints and shifting priorities may be contributing factors. As the C++ community continues to grow and evolve, it's crucial to address these gaps and ensure that libc++ remains a reliable and up-to-date implementation of the C++ Standard Library.