Default to C++20, pin embedded backends to C++17#20438
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PyTorch has moved to C++20 and ExecuTorch's PyTorch-facing targets (_portable_lib, util, wheel config) are already built as C++20. Raise the repo-wide default in the top-level CMakeLists and .buckconfig to match. The embedded backends build the portable runtime without PyTorch, so their constraint is the cross-toolchain, not the standard the host uses. Pin cadence, cortex_m, arm, nxp, and mediatek to C++17 so they keep building on toolchains (e.g. Xtensa) that lack full C++20 support, regardless of the new default.
🔗 Helpful Links🧪 See artifacts and rendered test results at hud.pytorch.org/pr/pytorch/executorch/20438
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I think we'd rather keep one C++ standard level. I've opened #20468 to discuss raising the standard to C++20. |
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@rascani We can not move all code to cpp 20 due to device environment limits. |
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Summary
PyTorch has moved to C++20 and ExecuTorch's PyTorch-facing targets (_portable_lib, util, wheel config) are already built as C++20. Raise the repo-wide default in the top-level CMakeLists and .buckconfig to match.
The embedded backends build the portable runtime without PyTorch, so their constraint is the cross-toolchain, not the standard the host uses. Pin cadence, cortex_m, arm, nxp, and mediatek to C++17 so they keep building on toolchains (e.g. Xtensa) that lack full C++20 support, regardless of the new default.
Test plan
No new test is required.
cc @digantdesai @freddan80 @per @zingo @oscarandersson8218 @mansnils @Sebastian-Larsson @robell @rascani