Author: mpark
Date: Thu May 11 02:17:12 2017
New Revision: 302773
URL: http://llvm.org/viewvc/llvm-project?rev=302773&view=rev
Log:
Fix `std::visit` for the zero variants case.
Summary:
The following code is broken:
```
std::visit([]{});
```
Reviewers: EricWF
Reviewed By: EricWF
Differential Revision: https://reviews.llvm.org/D33090
Modified:
libcxx/trunk/include/variant
libcxx/trunk/test/std/utilities/variant/variant.visit/visit.pass.cpp
Modified: libcxx/trunk/include/variant
URL:
http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/variant?rev=302773&r1=302772&r2=302773&view=diff
==============================================================================
--- libcxx/trunk/include/variant (original)
+++ libcxx/trunk/include/variant Thu May 11 02:17:12 2017
@@ -425,30 +425,21 @@ struct __base {
constexpr auto __fmatrix =
__make_fmatrix<_Visitor&&,
decltype(_VSTD::forward<_Vs>(__vs).__as_base())...>();
- const size_t __indices[] = {__vs.index()...};
- return __at(__fmatrix, __indices)(_VSTD::forward<_Visitor>(__visitor),
-
_VSTD::forward<_Vs>(__vs).__as_base()...);
+ return __at(__fmatrix, __vs.index()...)(
+ _VSTD::forward<_Visitor>(__visitor),
+ _VSTD::forward<_Vs>(__vs).__as_base()...);
}
private:
template <class _Tp>
inline _LIBCPP_INLINE_VISIBILITY
- static constexpr const _Tp& __at_impl(const _Tp& __elem, const size_t*) {
- return __elem;
- }
-
- template <class _Tp, size_t _Np>
- inline _LIBCPP_INLINE_VISIBILITY
- static constexpr auto&& __at_impl(const array<_Tp, _Np>& __elems,
- const size_t* __index) {
- return __at_impl(__elems[*__index], __index + 1);
- }
+ static constexpr const _Tp& __at(const _Tp& __elem) { return __elem; }
- template <class _Tp, size_t _Np, size_t _Ip>
+ template <class _Tp, size_t _Np, typename... _Indices>
inline _LIBCPP_INLINE_VISIBILITY
static constexpr auto&& __at(const array<_Tp, _Np>& __elems,
- const size_t (&__indices)[_Ip]) {
- return __at_impl(__elems, begin(__indices));
+ size_t __index, _Indices... __indices) {
+ return __at(__elems[__index], __indices...);
}
template <class _Fp, class... _Fs>
Modified: libcxx/trunk/test/std/utilities/variant/variant.visit/visit.pass.cpp
URL:
http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/std/utilities/variant/variant.visit/visit.pass.cpp?rev=302773&r1=302772&r2=302773&view=diff
==============================================================================
--- libcxx/trunk/test/std/utilities/variant/variant.visit/visit.pass.cpp
(original)
+++ libcxx/trunk/test/std/utilities/variant/variant.visit/visit.pass.cpp Thu
May 11 02:17:12 2017
@@ -94,6 +94,16 @@ void test_call_operator_forwarding() {
using Fn = ForwardingCallObject;
Fn obj{};
const Fn &cobj = obj;
+ { // test call operator forwarding - no variant
+ std::visit(obj);
+ assert(Fn::check_call<>(CT_NonConst | CT_LValue));
+ std::visit(cobj);
+ assert(Fn::check_call<>(CT_Const | CT_LValue));
+ std::visit(std::move(obj));
+ assert(Fn::check_call<>(CT_NonConst | CT_RValue));
+ std::visit(std::move(cobj));
+ assert(Fn::check_call<>(CT_Const | CT_RValue));
+ }
{ // test call operator forwarding - single variant, single arg
using V = std::variant<int>;
V v(42);
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