Launder dereferencing type-punned address #4892
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This is a small patch to avoid strict aliasing issues manifested in GCC I came across a while ago. The test case was complex and the failing assertion with a matcher was present only with `-O3`, so I don't have a standalone test. However, I manually confirmed adding `-fno-strict-aliasing` fixed the issue before this patch, and `-O3` behaved as intended after this patch without turning strict-aliasing off. There is a similar previous change in google@50ce520. For the relevant clause from the C++17 standard, refer to below note from https://timsong-cpp.github.io/cppwp/n4659/basic.life#8: > [ Note: If these conditions are not met, a pointer to the new object can be obtained from a pointer that represents the address of its storage by calling std::launder ([support.dynamic]). — end note ]
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This is a small patch to avoid strict aliasing issues manifested in GCC I came across a while ago.
The test case was complex and the failing assertion with a matcher was present only with
-O3, so I don't have a standalone test. However, I manually confirmed adding-fno-strict-aliasingfixed the issue before this patch, and-O3behaved as intended after this patch without turning strict-aliasing off.There is a similar previous change in 50ce520.
For the relevant clause from the C++17 standard, refer to below note from https://timsong-cpp.github.io/cppwp/n4659/basic.life#8: