folly/detail/ThreadLocalDetail.h: avoid UBSAN-detected memcpy abuse
Summary: [technically, the existing code is probably a no-op on all systems we care about, but since it is officially UB, switching to a more strict platform could cause trouble, so it's worth fixing] Calling memcpy with "nullptr" as 2nd argument is undefined, even when the third argument is zero, and causes a failure when testing with an UBSAN-enabled binary (-fsanitize=undefined). Before this change, the buck-run test below would evoke this failure: [ RUN ] ThreadLocalPtr.BasicDestructor folly/detail/ThreadLocalDetail.h:533:29: runtime error: null pointer passed as argument 2, which is declared to never be null third-party-buck/build/glibc/include/string.h:47:45: note: nonnull attribute specified here Ironically, the failure of the target-determinator-buck_push_blocking test (due to an unrelated proxygen dep problem) would block me from landing this, so I am adding this line to override it. Reviewed By: luciang, alexshap Differential Revision: D2692625 fb-gh-sync-id: 8bdc5cd2899705f39c9565d640921de1f363807d
Showing
Please register or sign in to comment