| Message ID | CAFk2RUZ+MGp69Thr=vVeJn-aqRMHKzG7OfwmT393nK3iwONbuw@mail.gmail.com |
|---|---|
| State | New |
| Headers | show |
On 16/03/17 00:43 +0200, Ville Voutilainen wrote: >On 16 March 2017 at 00:31, Jonathan Wakely <jwakely@redhat.com> wrote: >>> emplace(_Args&&... __args) >>> { >>> __do_emplace<_Decay<_ValueType>> >>> (std::forward<_Args>(__args)...); >>> + return *(std::any_cast<_Decay<_ValueType>>(this)); >> >> >> Can we avoid the branch in any_cast to check the stored type? >> We know it's the right type, because we just stored it. > >While I would hope the compiler to be smart enough to realize some of >that (we are passing in >this), the other branches might not be so easy. But certainly, we can >axe every one of the extraneous >branches, like in the attached amendment. And then we don't need the forward declarations of any and any_ast, right? OK for trunk like that, thanks.
diff --git a/libstdc++-v3/include/std/any b/libstdc++-v3/include/std/any index fff13d9..ef6efa5 100644 --- a/libstdc++-v3/include/std/any +++ b/libstdc++-v3/include/std/any @@ -278,7 +278,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { __do_emplace<_Decay<_ValueType>> (std::forward<_Args>(__args)...); - return *(std::any_cast<_Decay<_ValueType>>(this)); + any::_Arg __arg; + this->_M_manager(any::_Op_access, this, &__arg); + return *static_cast<_Decay<_ValueType>*>(__arg._M_obj); } /// Emplace with an object created from @p __il and @p __args as @@ -292,7 +294,9 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION { __do_emplace<_Decay<_ValueType>, _Up> (__il, std::forward<_Args>(__args)...); - return *(std::any_cast<_Decay<_ValueType>>(this)); + any::_Arg __arg; + this->_M_manager(any::_Op_access, this, &__arg); + return *static_cast<_Decay<_ValueType>*>(__arg._M_obj); } // modifiers diff --git a/libstdc++-v3/testsuite/20_util/any/misc/any_cast_neg.cc b/libstdc++-v3/testsuite/20_util/any/misc/any_cast_neg.cc index 2d2b3d3..8e3ca73 100644 --- a/libstdc++-v3/testsuite/20_util/any/misc/any_cast_neg.cc +++ b/libstdc++-v3/testsuite/20_util/any/misc/any_cast_neg.cc @@ -26,5 +26,5 @@ void test01() using std::any_cast; const any y(1); - any_cast<int&>(y); // { dg-error "invalid static_cast" "" { target { *-*-* } } 461 } + any_cast<int&>(y); // { dg-error "invalid static_cast" "" { target { *-*-* } } 465 } }