Fix PR27115 - enable_shared_from_this does not work as a virtual base class.

See https://llvm.org/bugs/show_bug.cgi?id=27115

The problem was that the conversion from
'const enable_shared_from_this<T>*' to 'const T*' didn't work if
T inherited enable_shared_from_this as a virtual base class. The fix
is to take the original pointer passed to shared_ptr's constructor in the
__enable_weak_this method and perform an upcast to 'const T*' instead of
performing a downcast from the enable_shared_from_this base.

llvm-svn: 273835

1 files changed, 16 insertions, 0 deletions

diff --git a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.enab/enable_shared_from_this.pass.cpp b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.enab/enable_shared_from_this.pass.cpp
index 6661e831ab8..baee66e123e 100644
--- a/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.enab/enable_shared_from_this.pass.cpp
+++ b/libcxx/test/std/utilities/memory/util.smartptr/util.smartptr.enab/enable_shared_from_this.pass.cpp
@@ -39,12 +39,28 @@ struct Z : Y {};
 
 void nullDeleter(void*) {}
 
+struct Foo : virtual public std::enable_shared_from_this<Foo>
+{
+	virtual ~Foo() {}
+};
+
+struct Bar : public Foo {
+    Bar(int) {}
+};
+
+
 int main()
 {
     {  // https://llvm.org/bugs/show_bug.cgi?id=18843
     std::shared_ptr<T const> t1(new T);
     std::shared_ptr<T const> t2(std::make_shared<T>());
     }
+    { // https://llvm.org/bugs/show_bug.cgi?id=27115
+    std::shared_ptr<Bar> t1(new Bar(42));
+    assert(t1->shared_from_this() == t1);
+    std::shared_ptr<Bar> t2(std::make_shared<Bar>(42));
+    assert(t2->shared_from_this() == t2);
+    }
     {
     std::shared_ptr<Y> p(new Z);
     std::shared_ptr<T> q = p->shared_from_this();