On Thu, Nov 8, 2012 at 5:49 PM, Ryan Molden <[email protected]> wrote: > This is a re-submission of an older proposed patch > (http://www.mail-archive.com/[email protected]/msg55616/0001-Added-support-for-MSVC-2012-type-traits-used-in-stan.patch) > that João hadn't had time to write tests for (which were requested with the > original submission review). > > The only changes I made from the original (apart from adding tests) was to > take out the bail-out for hasTrivialMoveAssignment from > UTT_HasNothrowMoveAssign in EvaluateUnaryTypeTrait (in > lib\Sema\SemaExprCXX.cpp). > > My reasoning was that trivial move assignment operators (which I understand > to be implicitly generated ones, please correct me if this is mistaken) can > actually have non-empty exception specifiers if any of the member > move-assignment operators they invoke have such non-empty exception > specifiers. > > Specifically: > > n3376 15.4 [except.spec]/14 > > An inheriting constructor (12.9) and an implicitly declared special member > function (Clause 12) have an exception-specification. If f is an inheriting > constructor or an implicitly declared default constructor, copy constructor, > move constructor, destructor, copy assignment operator, or move assignment > operator, its implicit exception-specification specifies the type-id T if > and only if T is allowed by the exception-specification of a function > directly invoked by f’s implicit definition; f allows all exceptions if any > function it directly invokes allows all exceptions, and f has the > exception-specification noexcept(true) if every function it directly invokes > allows no exceptions. [ Note: An instantiation of an inheriting constructor > template has an implied exception-specification as if it were a non-template > inheriting constructor.] > > so I would expect this class (HasMemberThrowMoveAssign) to fail for > std::is_nothrow_move_assignable: > > struct NonPOD { NonPOD(int); }; enum Enum { EV }; struct POD { Enum e; int > i; float f; NonPOD* p; }; > > struct HasThrowMoveAssign { HasThrowMoveAssign& operator =(const > HasThrowMoveAssign&&) throw(POD); }; > struct HasMemberThrowMoveAssign { HasThrowMoveAssign member; }; > > even though it should have a trivial move-assignment operator generated. > Please correct me if I am mistaken here as my standards reading FU is...not > strong.
You are mistaken here ;-) HasMemberThrowMoveAssign's move assignment is not trivial because it calls a non-trivial move assignment operator. It is possible to have a throwing trivial move assignment operator, but only if it is deleted. In that case, the trait should presumbly return false. _______________________________________________ cfe-commits mailing list [email protected] http://lists.cs.uiuc.edu/mailman/listinfo/cfe-commits
