PiotrZSL added a comment.
In D141569#4139290 <https://reviews.llvm.org/D141569#4139290>, @ccotter wrote:
> In
>
> template <int tagValue, typename T>
> struct SomeClass
> {
> public:
> explicit SomeClass(T&& value) : value(std::forward<T>(value)) {}
> T value;
> };
>
> `T` is not a universal reference in the constructor, it's an rvalue reference
> to `T`. There is no deducing context, so universal references are not
> involved here (and, `std::forward` would also be incorrect here). The
> following would be a deducing context with a universal reference:
Wrong:
#include <utility>
template<typename T>
struct Wrap {
Wrap(T&& arg)
: value(arg)
{}
T value;
};
struct Value {};
int main()
{
Value value;
Wrap<Value> v1(std::move(value));
Wrap<Value> v2(std::move(value));
Wrap<Value&> v3(value);
return 0;
}
If you add `std::move` you will get compilation error, if you add std::forward,
everything will work fine. Simply Value& and && will evaluate to Value&, no
rvalue reference here.
Repository:
rG LLVM Github Monorepo
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D141569/new/
https://reviews.llvm.org/D141569
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