From 220cf9c2000f23fb47e817ff0b6c20b5061a4a89 Mon Sep 17 00:00:00 2001 From: Nick Gerleman Date: Wed, 13 Sep 2023 21:50:26 -0700 Subject: [PATCH] Breaking: Use C++ 20 (#39437) MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Summary: X-link: https://github.com/facebook/yoga/pull/1382 Have been running into places where C++ 20 makes life easier for use like `std::bit_cast` (that one is easy to polyfill), in-class member initializer support for bitfields, designated initializers, defaulted comparison operator, concepts instead of SFINAE, and probably more. Our other infra is in the process of making this jump, or already has. This tests it out everywhere, across the various reference builds, to see if we have any issues. This is a bit more aggressive than I had previously communicated, but n - 1 is going to be a better long term place than n - 2. If we wanted to use `std::bit_cast` we would need one of: 1. GCC 11+ (~2.5 years old) 1. Clang 14 (~2.5 years old) 1. VS 16.11 (~2 years old) For mobile this means: 1. NDK 26 (still in Beta 😭) 1. XCode 14.3.0 (~6 months old) https://en.cppreference.com/w/cpp/compiler_support/20 That isn't quite doable yet, but we can start taking advantage of language features in the meantime. More of these will be supported in older toolchains. Anyone needing support for older C++ versions can lag behind on more recent changes. E.g. Yoga 2.0 supports C++ 14. Differential Revision: D49261607 --- packages/react-native/ReactCommon/yoga/Yoga.podspec | 2 +- .../react-native/ReactCommon/yoga/cmake/project-defaults.cmake | 2 +- packages/react-native/ReactCommon/yoga/yoga/bits/BitCast.h | 1 + 3 files changed, 3 insertions(+), 2 deletions(-) diff --git a/packages/react-native/ReactCommon/yoga/Yoga.podspec b/packages/react-native/ReactCommon/yoga/Yoga.podspec index 8a3d88bca902a5..74d3895301fdc3 100644 --- a/packages/react-native/ReactCommon/yoga/Yoga.podspec +++ b/packages/react-native/ReactCommon/yoga/Yoga.podspec @@ -38,7 +38,7 @@ Pod::Spec.new do |spec| '-fexceptions', '-Wall', '-Werror', - '-std=c++17', + '-std=c++20', '-fPIC' ] diff --git a/packages/react-native/ReactCommon/yoga/cmake/project-defaults.cmake b/packages/react-native/ReactCommon/yoga/cmake/project-defaults.cmake index 8868ce93d9a3ba..08f50a4eced8f5 100644 --- a/packages/react-native/ReactCommon/yoga/cmake/project-defaults.cmake +++ b/packages/react-native/ReactCommon/yoga/cmake/project-defaults.cmake @@ -3,7 +3,7 @@ # This source code is licensed under the MIT license found in the # LICENSE file in the root directory of this source tree. -set(CMAKE_CXX_STANDARD 17) +set(CMAKE_CXX_STANDARD 20) set(CMAKE_CXX_VISIBILITY_PRESET hidden) set(CMAKE_POSITION_INDEPENDENT_CODE ON) diff --git a/packages/react-native/ReactCommon/yoga/yoga/bits/BitCast.h b/packages/react-native/ReactCommon/yoga/yoga/bits/BitCast.h index eaca348c8c4c5d..13fb0e41f2d39b 100644 --- a/packages/react-native/ReactCommon/yoga/yoga/bits/BitCast.h +++ b/packages/react-native/ReactCommon/yoga/yoga/bits/BitCast.h @@ -14,6 +14,7 @@ namespace facebook::yoga { // Polyfill for std::bit_cast() from C++20, to allow safe type punning // https://en.cppreference.com/w/cpp/numeric/bit_cast +// TODO: Remove when we upgrade to NDK 26+ template std::enable_if_t< sizeof(To) == sizeof(From) && std::is_trivially_copyable_v &&