Use UB impl of launder on when using clang < 8 and c++17 #1448
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derekmauro
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May 17, 2023
| @@ -197,7 +197,8 @@ union TypeErasedState { | |||
| template <class T> | |||
| T& ObjectInLocalStorage(TypeErasedState* const state) { | |||
| // We launder here because the storage may be reused with the same type. | |||
| #if ABSL_INTERNAL_CPLUSPLUS_LANG >= 201703L | |||
| #if ABSL_INTERNAL_CPLUSPLUS_LANG >= 201703L && \ | |||
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The proposed patch works in my testing, but I think I more principled thing to do would be to use #if __cpp_lib_launder >= 201606L. This seems to produce the same result when I try it on godbolt.
libstdc++'s definition of std::launder places it behind a check for __builtin_launder, which is not available before clang 8. Fixes: abseil#1309
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…ebrtc-reviewers,ng Sent upstream at abseil/abseil-cpp#1448 Differential Revision: https://phabricator.services.mozilla.com/D178274
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…ebrtc-reviewers,ng Sent upstream at abseil/abseil-cpp#1448 Differential Revision: https://phabricator.services.mozilla.com/D178274
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…ebrtc-reviewers,ng Sent upstream at abseil/abseil-cpp#1448 Differential Revision: https://phabricator.services.mozilla.com/D178274 Mercurial Revision: https://hg.mozilla.org/mozilla-central/rev/d976369464663a9147b82c82436afcaab1f61aec
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…ebrtc-reviewers,ng Sent upstream at abseil/abseil-cpp#1448 Differential Revision: https://phabricator.services.mozilla.com/D178274 Mercurial Revision: https://hg.mozilla.org/mozilla-central/rev/d976369464663a9147b82c82436afcaab1f61aec
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libstdc++'s definition of std::launder places it behind a check for __builtin_launder, which is not available before clang 8.
Fixes: #1309