[cfe-commits] [libcxx] r124166 - in /libcxx/trunk: include/type_traits test/utilities/meta/meta.rel/is_convertible.pass.cpp

[Douglas Gregor]

Author: dgregor
Date: Mon Jan 24 19:15:41 2011
New Revision: 124166

URL: http://llvm.org/viewvc/llvm-project?rev=124166&view=rev
Log:
Eliminate the C++0x-only is_convertible testing function that accepts
a cv-qualifier rvalue reference to the type, e.g.,

  template <class _Tp> char  __test(const volatile typename remove_reference<_Tp>::type&&);

The use of this function signature rather than the more
straightforward one used in C++98/03 mode, e.g.,

  template <class _Tp> char  __test(_Tp);

is broken in two ways:

  1) An rvalue reference cannot bind to lvalues, so is_convertible<X&,
  X&>::value would be false. This breaks two of the unique_ptr tests
  on Clang and GCC >= 4.5. Prior GCC's seem to have allowed rvalue
  references to bind to lvalues, allowing this bug to slip in.

  2) By adding cv-qualifiers to the type we're converting to, we get
  some incorrect "true" results for, e.g., is_convertible<const X&, X&>::value.




Modified:
    libcxx/trunk/include/type_traits
    libcxx/trunk/test/utilities/meta/meta.rel/is_convertible.pass.cpp

Modified: libcxx/trunk/include/type_traits
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/type_traits?rev=124166&r1=124165&r2=124166&view=diff
==============================================================================
--- libcxx/trunk/include/type_traits (original)
+++ libcxx/trunk/include/type_traits Mon Jan 24 19:15:41 2011
@@ -600,11 +600,7 @@
 
 namespace __is_convertible_imp
 {
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
-template <class _Tp> char  __test(const volatile typename remove_reference<_Tp>::type&&);
-#else
 template <class _Tp> char  __test(_Tp);
-#endif
 template <class _Tp> __two __test(...);
 #ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
 template <class _Tp> _Tp&& __source();

Modified: libcxx/trunk/test/utilities/meta/meta.rel/is_convertible.pass.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/test/utilities/meta/meta.rel/is_convertible.pass.cpp?rev=124166&r1=124165&r2=124166&view=diff
==============================================================================
--- libcxx/trunk/test/utilities/meta/meta.rel/is_convertible.pass.cpp (original)
+++ libcxx/trunk/test/utilities/meta/meta.rel/is_convertible.pass.cpp Mon Jan 24 19:15:41 2011
@@ -16,6 +16,10 @@
 typedef void Function();
 typedef char Array[1];
 
+class NonCopyable {
+  NonCopyable(NonCopyable&);
+};
+
 int main()
 {
     {
@@ -366,4 +370,15 @@
     static_assert((!std::is_convertible<const char*, char*>::value), "");
     static_assert(( std::is_convertible<const char*, const char*>::value), "");
     }
+    {
+    static_assert((std::is_convertible<NonCopyable&, NonCopyable&>::value), "");
+    static_assert((std::is_convertible<NonCopyable&, const NonCopyable&>::value), "");
+    static_assert((std::is_convertible<NonCopyable&, const volatile NonCopyable&>::value), "");
+    static_assert((std::is_convertible<NonCopyable&, volatile NonCopyable&>::value), "");
+    static_assert((std::is_convertible<const NonCopyable&, const NonCopyable&>::value), "");
+    static_assert((std::is_convertible<const NonCopyable&, const volatile NonCopyable&>::value), "");
+    static_assert((std::is_convertible<volatile NonCopyable&, const volatile NonCopyable&>::value), "");
+    static_assert((std::is_convertible<const volatile NonCopyable&, const volatile NonCopyable&>::value), "");
+    static_assert((!std::is_convertible<const NonCopyable&, NonCopyable&>::value), "");
+    }
 }