aaronpuchert wrote: > > On a related note, do we emit `-Wthread-safety-negative` for reentrant > > locks? I don't remember that we carved out an exception for that, and we > > probably should. > > We do - and it's deliberate on my part as I've been trying to indicate that > there might be valid use cases for that. While conceptually contradictory, > there might be cases where developers want to ensure a reentrant mutex is NOT > held before entering a function.
Correct me if I'm wrong, but in my understanding, `-Wthread-safety-negative` is not a prerequisite for using negative capabilities in the manner you describe. The [only warning message under that flag](https://clang.llvm.org/docs/DiagnosticsReference.html#wthread-safety-negative) is "acquiring _A_ ‘_B_’ requires negative capability ‘_C_’", which warns when we're _acquiring_ the mutex without holding the negative capability: ```c++ class Foo { Mutex mu; public: void direct() { mu.Lock(); // warning: acquiring mutex 'mu' requires negative capability '!mu' [-Wthread-safety-negative] mu.Unlock(); } void indirect() { requireNegative(); // warning: calling function 'require_neg' requires holding '!mu' [-Wthread-safety-analysis] } void requireNegative() REQUIRES(!mu); }; ``` Note that the warnings are under different flags. You seem to want the second one, which is under `-Wthread-safety-analysis`. But do we want the first one? That would seem contradictory. https://github.com/llvm/llvm-project/pull/141599 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
