[GitHub] [incubator-kvrocks] PragmaTwice edited a discussion: Update the C++ standard used by kvrocks to a newer version

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GitHub user PragmaTwice edited a discussion: Update the C++ standard used by kvrocks to a newer version

C++ is an evolving language led by WG21 ([ISO/IEC JTC1/SC22/WG21](https://www.open-std.org/jtc1/sc22/wg21/)), which has been significantly modified over the years to improve ease of use and expressiveness while maintaining the zero-overhead principle.

The latest experimental standard for C++ is C++23 (also known as C++2b), and the latest stable standard is C++20. After C++11, WG21 has made a number of sweeping improvements to make modern C++ even more exciting. Among them, C++14 [1] can be regarded as a series of small patches to C++11, which complemented the unsatisfactory parts of C++11, such as lifting some of the restrictions on constexpr functions, supporting variable templates and polymorphic lambdas; while C++17 [2] is a relatively big change, it supports constexpr if, guarantees more copy elision to improve efficiency and specifies a more explicit execution order to eliminate undefined behaviors, and brings several new library components such as filesystem, basic_string_view, any, optional, variant, and other class templates.

Industry has gradually become more comfortable with the new C++ standard, and here are some notable open source projects and the C++ standard they are using (in the main branch):

- clickhouse: c++20
- bitcoin: c++20
- mongodb: c++17 or c++20
- godot: c++17
- llvm: c++17
- taichi: c++17
- mysql: c++17
- rocksdb: c++17
- grpc: c++14
- tensorflow: c++14
- pytorch: c++14

I want kvrocks to use a newer C++ standard to apply rich new features to improve code quality and maintainability and have the ability to use the current rocksdb rather than stucking into an old version, and in particular, I want to update the standard to at least C++17. It is important to note that the new C++ standard will have significant breaking changes in only a few cases, but we can sort out later whether these changes will affect kvrocks. Also, all developers' experience with c++11 can continue to be used in the new standard.

C++17 requires a newer version of the compiler. In fact, this can be a compiler version from a few years ago (e.g., gcc7, 2017), but not an antique compiler from a decade old (e.g., gcc 4.8, 2013). As with the very new version of go 1.18 that we are currently using, I see no harm in encouraging users to use as newer versions of the compiler as possible, as long as they are not unstable versions. We do place restrictions on the compiler versions that users can use, and these restrictions are as follows:

gcc: 7 or above
clang: 5 or above

I'm not quite sure what expectations, concerns and questions people have about updating the standards at this point, and I look forward to everyone expressing their views on this issue!

[1] https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2018/p1319r0.html
[2] https://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0636r2.html



GitHub link: https://github.com/apache/incubator-kvrocks/discussions/970

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