EricWF marked 6 inline comments as done. EricWF added inline comments.
================ Comment at: include/clang/Basic/DiagnosticSemaKinds.td:2129 +def warn_class_template_argument_deduction_no_user_defined_guides : Warning< + "class template argument deduction for %0 that has no user defined deduction guides" >, + InGroup<ImplicitCTADUsage>, DefaultIgnore; ---------------- lebedev.ri wrote: > Quuxplusone wrote: > > `s/user defined/user-defined/`, and perhaps `s/that has/with/` for brevity. > `class template argument deduction <was used? happened?> for %0 that has no > user` > the sentence looks incomplete to me. How about `using class template argument deduction for %0 that has no user-defined deduction guides`? ================ Comment at: test/SemaCXX/cxx1z-class-template-argument-deduction.cpp:426 +// expected-warning@+1 {{class template argument deduction for 'NoExplicit' that has no user defined deduction guides}} +NoExplicit ne(42); + ---------------- Quuxplusone wrote: > I suggest that additional (more realistic) motivating examples can be found > in STL's CppCon 2018 talk. E.g. > > ``` > template<class T, class U> > struct Pair { > T first; U second; > explicit Pair(const T& t, const U& u) : first(t), second(u) {} > }; > Pair p(42, "hello world"); // constructs a Pair<int, char[12]> > > template<class T, class U> > struct Pair2 { > T first; U second; > explicit Pair2(T t, U u) : first(t), second(u) {} > }; > Pair2 p(42, "hello world"); // constructs a Pair2<int, const char*> > ``` > > I would expect (and, with your patch, receive) diagnostics for both of these. > > But for something like `Vector("a", "b")` your patch gives no diagnostic: > https://godbolt.org/z/_9zhav > And for something like [`std::optional o(x);` in generic > context](https://quuxplusone.github.io/blog/2018/12/11/dont-inherit-from-std-types/) > your patch gives no diagnostic. > > I do have a patch out for a general-purpose `-Wctad` that would give warnings > on those latter cases as well: D54565 > I think `-Wimplicit-ctad` is a good start, but it doesn't solve all the cases > I'd like to see solved. I'll add the tests you described. And indeed, this solution is incomplete. Can you expand on you `std::optional` example? I don't understand it. Repository: rC Clang CHANGES SINCE LAST ACTION https://reviews.llvm.org/D56731/new/ https://reviews.llvm.org/D56731 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org http://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits