[PATCH] D62829: [clang-tidy] Check for dynamically initialized statics in headers.
Aaron Ballman via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Fri Aug 2 06:26:29 PDT 2019
aaron.ballman added inline comments.
Comment at: clang-tools-extra/test/clang-tidy/bugprone-dynamic-static-initializers.hpp:33-35
+ // This may work fine when optimization is enabled because bar() can
+ // be turned into a constant 7. But without optimization, it can
+ // cause problems. Therefore, we must err on the side of conservatism.
> aaron.ballman wrote:
> > What problems can be caused here? Typically, dynamic init is only problematic when it happens before main() is executed (because of initialization order dependencies), but that doesn't apply to local statics.
> Consider the case when synchronization is disabled for static initialization, and two threads call `foo2` for the first time. It may be the case that they both try and initialize the static variable at the same time with different values (since the dynamic initializer may not be pure), creating a race condition.
> Consider the case when synchronization is disabled for static initialization
This is a compiler bug, though: http://eel.is/c++draft/stmt.dcl#4.sentence-3
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