[libcxx] Fix unqualified call to 'ref' inside shared_ptr(unique_ptr<U, D>)

[logan-5]

Summary

This prevents unintended ADL: https://gcc.godbolt.org/z/EHw3Gy

This issue was mentioned as an addendum in https://bugs.llvm.org/show_bug.cgi?id=44398.

Thanks to @Quuxplusone for the test case and filing the bug.

[ldionne]

Thanks for the patch!

libcxx/include/memory

if (__ptr_ == nullptr)
         __cntrl_ = nullptr;
     else
 #endif
     {
         typedef typename __shared_ptr_default_allocator<_Yp>::type _AllocT;
         typedef __shared_ptr_pointer<_Yp*,
                                      reference_wrapper<typename remove_reference<_Dp>::type>,
                                      _AllocT > _CntrlBlk;
-        __cntrl_ = new _CntrlBlk(__r.get(), ref(__r.get_deleter()), _AllocT());
+        __cntrl_ = new _CntrlBlk(__r.get(), _VSTD::ref(__r.get_deleter()), _AllocT());
         __enable_weak_this(__r.get(), __r.get());
     }
     __r.release();
 }
 
 template<class _Tp>
 template<class _Alloc, class ..._Args>
 shared_ptr<_Tp>

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

 int A::count = 0;
 
 void fn ( const std::shared_ptr<int> &) {}
 void fn ( const std::shared_ptr<B> &) { assert (false); }
 
 template <typename T>
 void assert_deleter ( T * ) { assert(false); }
 
+namespace adl {
+struct D {
+    void operator()(int *) const {}
+};
+void ref(D);
+}
+
 int main(int, char**)
 {
     {
         std::unique_ptr<A> ptr(new A);
         A* raw_ptr = ptr.get();
         std::shared_ptr<B> p(std::move(ptr));
         assert(A::count == 1);
         assert(B::count == 1);
#endif
     }
 #if TEST_STD_VER >= 14
     { // LWG 2415
         std::unique_ptr<int, void (*)(int*)> p(nullptr, assert_deleter<int>);
         std::shared_ptr<int> p2(std::move(p)); // should not call deleter when going out of scope
     }
 #endif
 
+    {
+    adl::D d;
+    std::unique_ptr<int, adl::D&> u(nullptr, d);
+    std::shared_ptr<int> s = std::move(u);
+    }
+
   return 0;
 }