Difference between revisions of "User:Dydzio/cpp standard upgrade"
| Line 5: | Line 5: | ||
If we assume GCC 7.3 (GCC 7) as minimal supported GCC version then on GCC part we can use: | If we assume GCC 7.3 (GCC 7) as minimal supported GCC version then on GCC part we can use: | ||
| − | - full C++14 | + | - full C++14 (also in GCC 6 if we do not want GCC 7 for some reason) |
- almost full C++17, with exception of few features listed below, with optional examples of related standard library elements in braces: | - almost full C++17, with exception of few features listed below, with optional examples of related standard library elements in braces: | ||
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* https://en.cppreference.com/w/cpp/compiler_support | * https://en.cppreference.com/w/cpp/compiler_support | ||
* https://gcc.gnu.org/projects/cxx-status.html#cxx1z | * https://gcc.gnu.org/projects/cxx-status.html#cxx1z | ||
| + | |||
| + | |||
| + | If we decide to use Visual Studio 2017 as minimum supported VS version then we can use: | ||
| + | - full C++14 | ||
| + | |||
| + | - vast majority of C++17 (microsoft claims "full comformance but with bugs" in VS 2017) | ||
| + | |||
| + | Apart from cppreference page... full conformance overview for VS 2015/2017/2019 is available on https://docs.microsoft.com/en-us/cpp/overview/visual-cpp-language-conformance?view=vs-2019 | ||
| + | |||
| + | Especially watch out for following stuff in Visual Studio 2017: | ||
| + | |||
| + | * Preprocessor misbehavior, especially usingvariadic macros - last C++11 conformance bug, fixed in VS 2019 | ||
| + | * Some bugs in advanced lambda usage, also fixed in VS 2019 - not directly C++17 related | ||
| + | * std::is_constant_evaluated() not working - C++17 related | ||
| + | |||
| + | Other not working stuff in VS2017 (C++17 related): | ||
| + | * [https://cplusplus.github.io/LWG/issue2221 LWG 2221 Formatted output operator for nullptr] | ||
| + | * [http://open-std.org/JTC1/SC22/WG21/docs/papers/2018/p0961r1.html P0961R1 Relaxing the structured bindings customization point finding rules] | ||
| + | * [http://open-std.org/JTC1/SC22/WG21/docs/papers/2018/p0969r0.pdf P0969R0 Allowing structured bindings to accessible members] | ||
| + | * [http://www.open-std.org/jtc1/sc22/wg21/docs/papers/2017/p0588r1.html P0588R1 Simplifying implicit lambda capture] | ||
| + | * [http://open-std.org/JTC1/SC22/WG21/docs/papers/2018/p0962r1.html P0962R2 Relaxing the range-for loop customization point finding rules] | ||
| + | * [https://wg21.link/P0929R2 P0929R2 Checking for abstract class types] | ||
| + | * [https://wg21.link/P1009R2 P1009R2 Array size deduction in new-expressions] | ||
| + | * [https://wg21.link/P1286R2 P1286R2 Contra CWG DR1778] | ||
Revision as of 19:42, 22 June 2019
As of 22.06.2019 - linux debian will receive next stable version in few version and its GCC will upgrade from 6.3 to 8.3. Ubuntu 18.04 supports GCC 7.4, [AVS] currently uses GCC 7.3.
Scripting branch breaks VS 2015 compatibility by (bug/lack of C++ feature/whatever) in ERM parser. VS 2017 (MSVC 19.1x) has way better C++ support and there is almost no reason to still use 2015.
If we assume GCC 7.3 (GCC 7) as minimal supported GCC version then on GCC part we can use:
- full C++14 (also in GCC 6 if we do not want GCC 7 for some reason)
- almost full C++17, with exception of few features listed below, with optional examples of related standard library elements in braces:
- Polymorphic memory resources (<memory_resource>)
- C++17 should refer to C11 instead of C99
- Elementary string conversions (std::to_chars, std::from_chars, chars_format)
- Standardization of Parallelism TS
- File system library (std::filesystem)
- Template argument deduction for class templates - only partial support, probably conforms to v1 / draft paper?
- std::char_traits<char> and std::char_traits<wchar_t> in constant expressions.
There is no guarantee this is everything, travis CI should help. If somebody uses "not fully supported" feature on purpose he should let others know in PR description / slack etc.
Some sources:
- https://en.cppreference.com/w/cpp/compiler_support
- https://gcc.gnu.org/projects/cxx-status.html#cxx1z
If we decide to use Visual Studio 2017 as minimum supported VS version then we can use:
- full C++14
- vast majority of C++17 (microsoft claims "full comformance but with bugs" in VS 2017)
Apart from cppreference page... full conformance overview for VS 2015/2017/2019 is available on https://docs.microsoft.com/en-us/cpp/overview/visual-cpp-language-conformance?view=vs-2019
Especially watch out for following stuff in Visual Studio 2017:
- Preprocessor misbehavior, especially usingvariadic macros - last C++11 conformance bug, fixed in VS 2019
- Some bugs in advanced lambda usage, also fixed in VS 2019 - not directly C++17 related
- std::is_constant_evaluated() not working - C++17 related
Other not working stuff in VS2017 (C++17 related):
- LWG 2221 Formatted output operator for nullptr
- P0961R1 Relaxing the structured bindings customization point finding rules
- P0969R0 Allowing structured bindings to accessible members
- P0588R1 Simplifying implicit lambda capture
- P0962R2 Relaxing the range-for loop customization point finding rules
- P0929R2 Checking for abstract class types
- P1009R2 Array size deduction in new-expressions
- P1286R2 Contra CWG DR1778
