STL_MSFT created this revision.
STL_MSFT added reviewers: mclow.lists, EricWF.
STL_MSFT added a subscriber: cfe-commits.
In test/support/test_allocator.h, fix construct() to avoid moving immovable
types.
This improves the allocator's conformance, and fixes compiler errors with
MSVC's STL. The scenario is when the allocator is asked to construct an object
of type X that's immovable (deleted copy/move ctors), but implicitly
constructible from an argument type A. When perfectly forwarded, X can be
(explicitly) constructed from A, and everything is fine. That's
std::allocator's behavior, and the Standard's default when a user allocator's
construct() doesn't exist. The previous implementation of construct() here
mishandled this scenario. Passing A to this construct() would implicitly
construct an X temporary, bound to (non-templated) T&&. Then construct() would
attempt to move-construct X from that X temporary, but X is immovable, boom.
http://reviews.llvm.org/D21094
Files:
test/support/test_allocator.h
Index: test/support/test_allocator.h
===================================================================
--- test/support/test_allocator.h
+++ test/support/test_allocator.h
@@ -80,11 +80,12 @@
{assert(data_ >= 0); --alloc_count; ::operator delete((void*)p);}
size_type max_size() const throw()
{return UINT_MAX / sizeof(T);}
+#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
void construct(pointer p, const T& val)
{::new(p) T(val);}
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
- void construct(pointer p, T&& val)
- {::new(p) T(std::move(val));}
+#else // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+ template <class U> void construct(pointer p, U&& val)
+ {::new(p) T(std::forward<U>(val));}
#endif // _LIBCPP_HAS_NO_RVALUE_REFERENCES
void destroy(pointer p) {p->~T();}
@@ -140,11 +141,12 @@
{assert(data_ >= 0); --alloc_count; ::operator delete((void*)p); }
size_type max_size() const throw()
{return UINT_MAX / sizeof(T);}
+#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
void construct(pointer p, const T& val)
{::new(p) T(val);}
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
- void construct(pointer p, T&& val)
- {::new(p) T(std::move(val));}
+#else // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+ template <class U> void construct(pointer p, U&& val)
+ {::new(p) T(std::forward<U>(val));}
#endif // _LIBCPP_HAS_NO_RVALUE_REFERENCES
void destroy(pointer p) {p->~T();}
Index: test/support/test_allocator.h
===================================================================
--- test/support/test_allocator.h
+++ test/support/test_allocator.h
@@ -80,11 +80,12 @@
{assert(data_ >= 0); --alloc_count; ::operator delete((void*)p);}
size_type max_size() const throw()
{return UINT_MAX / sizeof(T);}
+#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
void construct(pointer p, const T& val)
{::new(p) T(val);}
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
- void construct(pointer p, T&& val)
- {::new(p) T(std::move(val));}
+#else // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+ template <class U> void construct(pointer p, U&& val)
+ {::new(p) T(std::forward<U>(val));}
#endif // _LIBCPP_HAS_NO_RVALUE_REFERENCES
void destroy(pointer p) {p->~T();}
@@ -140,11 +141,12 @@
{assert(data_ >= 0); --alloc_count; ::operator delete((void*)p); }
size_type max_size() const throw()
{return UINT_MAX / sizeof(T);}
+#ifdef _LIBCPP_HAS_NO_RVALUE_REFERENCES
void construct(pointer p, const T& val)
{::new(p) T(val);}
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
- void construct(pointer p, T&& val)
- {::new(p) T(std::move(val));}
+#else // _LIBCPP_HAS_NO_RVALUE_REFERENCES
+ template <class U> void construct(pointer p, U&& val)
+ {::new(p) T(std::forward<U>(val));}
#endif // _LIBCPP_HAS_NO_RVALUE_REFERENCES
void destroy(pointer p) {p->~T();}
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