Quuxplusone added inline comments.
================ Comment at: test/std/language.support/support.types/byteops/and.assign.pass.cpp:30 - static_assert(noexcept(b &= b), "" ); + static_assert(noexcept(b &= (std::byte &)b), "" ); ---------------- lebedev.ri wrote: > EricWF wrote: > > Should Clang really be warning when the expression is in an unevaluated > > context? > At least that is what it currently already does: > https://godbolt.org/g/RpcgBi > Clang already warns on `noexcept(b = b)` that "expression with side effects has no effect in an unevaluated context [-Wunevaluated-expression]", so adding one more warning should be acceptable, I think. Both warnings are (IMO correctly) disabled if the expression `b = b` is dependently typed, e.g. in a template, where expressions like `noexcept(b = b)` are practically unavoidable. Personally I think the warnings are acceptable, but these proposed fixes (inserting C-style casts to `T&`) are not good. The cast hides the intent of the code (especially in the self-assignment tests for `function` and `any`). We shouldn't be encouraging that particular workaround in user code. And besides, a good static analyzer (or even Clang itself) should be able to see that "casting `a` to the type of `a`" doesn't change the object referred to, and so the self-assignment is still happening, regardless. How do the `std::byte` tests avoid the existing warning for `-Wunevaluated-expression`? Could we use the same mechanism to avoid the new warning for `-Wself-assign`? Could we reuse that mechanism in the tests for `byte`'s `-=` and `/=` and `%=` and `^=` operators, which may one day start complaining as loudly as `&=` and `|=` when you have the same thing on the left and right hand sides? Could we reuse that mechanism in the tests for `function` and `any`? Repository: rCXX libc++ https://reviews.llvm.org/D45128 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
