[PATCH] D57058: Implement LWG3101 - span's Container constructors need another constraint

[Marshall Clow via Phabricator]

mclow.lists marked 2 inline comments as done.
mclow.lists added inline comments.


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Comment at: test/std/containers/views/span.cons/container.fail.cpp:72
     {
     std::span<int>    s1{IsAContainer<int>()};          // expected-error {{no matching constructor for initialization of 'std::span<int>'}}
     std::span<int>    s3{NotAContainerNoData<int>()};   // expected-error {{no matching constructor for initialization of 'std::span<int>'}}
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ldionne wrote:
> mclow.lists wrote:
> > ldionne wrote:
> > > Why does this fail? Shouldn't this use `std::span<int, std::dynamic_extent>::span(Container const&)`?
> > Because it's an rvalue?  Dunno; but if so, that makes all the other tests useless. I will investigate.
> > 
> I think it should compile because the `Container const&` will bind to a rvalue (and then the `std::span` contains a dangling reference).
If I was creating a `span<const int>`, then yes, but not a `span<int>`



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