[libcxx] Fix LWG 2874: Constructor shared_ptr::shared_ptr(Y*) should be constrained.

[zoecarver]

Summary

Fix LWG 2874.

[ldionne]

Nitpick: You've got the wrong LWG number in your commit message.

Also, can you please mark the LWG issue as complete in the docs?

libcxx/include/memory

3565

You are eagerly instantiating all templates here, and I don't think that's what you want. For example, you'll instantiate __well_formed_delete_op<_Yp*> even when is_array<_Tp>::value is true.

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/shared_ptr_Y.pass.cpp

122

STD_TEST_VERSION doesn't exist, it's TEST_STD_VER.

To catch these sorts of errors, it can be good to add tests and witness their failure before actually fixing them.

[zoecarver]

libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.shared/util.smartptr.shared.const/shared_ptr_Y.pass.cpp

122

Oops, you're right. Somehow that got suck in my clipboard history.

[zoecarver]

• Update status.
• Use TEST_STD_VER instead of the non-existant STD_TEST_VERSION.
• Use std::conditional (instead of logical and/or).