Fix PR27538. Remove __is_convertible specializations for array and function types.

This patch fixes a bunch of bugs in the fallback implementation of
is_convertible, which is used by GCC. Removing the "__is_convertible"
specializations for array/function types we fallback on the SFINAE test,
which is more correct.

See https://llvm.org/bugs/show_bug.cgi?id=27538

llvm-svn: 268359

diff --git a/libcxx/include/type_traits b/libcxx/include/type_traits
index 99dd679..2b14160 100644 (file)
--- a/libcxx/include/type_traits
+++ b/libcxx/include/type_traits
@@ -1423,41 +1423,6 @@ struct __is_convertible
     >
 {};
 
-template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 0> : false_type {};
-
-template <class _T1> struct __is_convertible<_T1, const _T1&, 1, 0> : true_type {};
-template <class _T1> struct __is_convertible<const _T1, const _T1&, 1, 0> : true_type {};
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
-template <class _T1> struct __is_convertible<_T1, _T1&&, 1, 0> : true_type {};
-template <class _T1> struct __is_convertible<_T1, const _T1&&, 1, 0> : true_type {};
-template <class _T1> struct __is_convertible<_T1, volatile _T1&&, 1, 0> : true_type {};
-template <class _T1> struct __is_convertible<_T1, const volatile _T1&&, 1, 0> : true_type {};
-#endif  // _LIBCPP_HAS_NO_RVALUE_REFERENCES
-
-template <class _T1, class _T2> struct __is_convertible<_T1, _T2*, 1, 0>
-    : public integral_constant<bool, __is_convertible<typename remove_all_extents<_T1>::type*, _T2*>::value> {};
-
-template <class _T1, class _T2> struct __is_convertible<_T1, _T2* const, 1, 0>
-    : public integral_constant<bool, __is_convertible<typename remove_all_extents<_T1>::type*, _T2*const>::value> {};
-
-template <class _T1, class _T2> struct __is_convertible<_T1, _T2* volatile, 1, 0>
-    : public integral_constant<bool, __is_convertible<typename remove_all_extents<_T1>::type*, _T2*volatile>::value> {};
-
-template <class _T1, class _T2> struct __is_convertible<_T1, _T2* const volatile, 1, 0>
-    : public integral_constant<bool, __is_convertible<typename remove_all_extents<_T1>::type*, _T2*const volatile>::value> {};
-
-template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 0>                : public false_type {};
-#ifndef _LIBCPP_HAS_NO_RVALUE_REFERENCES
-template <class _T1>            struct __is_convertible<_T1, _T1&&, 2, 0>               : public true_type {};
-#endif
-template <class _T1>            struct __is_convertible<_T1, _T1&, 2, 0>               : public true_type {};
-template <class _T1>            struct __is_convertible<_T1, _T1*, 2, 0>               : public true_type {};
-template <class _T1>            struct __is_convertible<_T1, _T1*const, 2, 0>          : public true_type {};
-template <class _T1>            struct __is_convertible<_T1, _T1*volatile, 2, 0>       : public true_type {};
-template <class _T1>            struct __is_convertible<_T1, _T1*const volatile, 2, 0> : public true_type {};
-
-template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 3, 0> : public false_type {};
-
 template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 0, 1> : public false_type {};
 template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 1, 1> : public false_type {};
 template <class _T1, class _T2> struct __is_convertible<_T1, _T2, 2, 1> : public false_type {};

diff --git a/libcxx/test/std/utilities/meta/meta.rel/is_convertible.pass.cpp b/libcxx/test/std/utilities/meta/meta.rel/is_convertible.pass.cpp
index 144c292..92f7a5d 100644 (file)
--- a/libcxx/test/std/utilities/meta/meta.rel/is_convertible.pass.cpp
+++ b/libcxx/test/std/utilities/meta/meta.rel/is_convertible.pass.cpp
@@ -12,7 +12,6 @@
 // is_convertible
 
 #include <type_traits>
-
 #include "test_macros.h"
 
 template <class T, class U>
@@ -46,8 +45,13 @@ void test_is_not_convertible()
 }
 
 typedef void Function();
+typedef void ConstFunction() const;
 typedef char Array[1];
 
+struct StringType {
+  StringType(const char*) {}
+};
+
 class NonCopyable {
   NonCopyable(NonCopyable&);
 };
@@ -69,12 +73,19 @@ int main()
     test_is_not_convertible<void,char> ();
     test_is_not_convertible<void,char&> ();
     test_is_not_convertible<void,char*> ();
+    test_is_not_convertible<char, void>();
 
     // Function
     test_is_not_convertible<Function, void> ();
     test_is_not_convertible<Function, Function> ();
     test_is_convertible<Function, Function&> ();
     test_is_convertible<Function, Function*> ();
+    test_is_convertible<Function, Function*const> ();
+
+#if TEST_STD_VER >= 11
+    static_assert(( std::is_convertible<Function, Function&&>::value), "");
+#endif
+
     test_is_not_convertible<Function, Array> ();
     test_is_not_convertible<Function, Array&> ();
     test_is_not_convertible<Function, char> ();
@@ -105,6 +116,16 @@ int main()
     test_is_not_convertible<Function*, char&> ();
     test_is_not_convertible<Function*, char*> ();
 
+    // Non-referencable function type
+    static_assert((!std::is_convertible<ConstFunction, Function>::value), "");
+    static_assert((!std::is_convertible<ConstFunction, Function*>::value), "");
+    static_assert((!std::is_convertible<ConstFunction, Function&>::value), "");
+    static_assert((!std::is_convertible<ConstFunction, Function>::value), "");
+    static_assert((!std::is_convertible<Function*, ConstFunction>::value), "");
+    static_assert((!std::is_convertible<Function&, ConstFunction>::value), "");
+    static_assert((!std::is_convertible<ConstFunction, ConstFunction>::value), "");
+    static_assert((!std::is_convertible<ConstFunction, void>::value), "");
+
     // Array
     test_is_not_convertible<Array, void> ();
     test_is_not_convertible<Array, Function> ();
@@ -114,17 +135,37 @@ int main()
 
     static_assert((!std::is_convertible<Array, Array&>::value), "");
     static_assert(( std::is_convertible<Array, const Array&>::value), "");
+    static_assert((!std::is_convertible<Array, const volatile Array&>::value), "");
+
     static_assert((!std::is_convertible<const Array, Array&>::value), "");
     static_assert(( std::is_convertible<const Array, const Array&>::value), "");
+    static_assert((!std::is_convertible<Array, volatile Array&>::value), "");
+    static_assert((!std::is_convertible<Array, const volatile Array&>::value), "");
+
+#if TEST_STD_VER >= 11
+    static_assert(( std::is_convertible<Array, Array&&>::value), "");
+    static_assert(( std::is_convertible<Array, const Array&&>::value), "");
+    static_assert(( std::is_convertible<Array, volatile Array&&>::value), "");
+    static_assert(( std::is_convertible<Array, const volatile Array&&>::value), "");
+    static_assert(( std::is_convertible<const Array, const Array&&>::value), "");
+    static_assert((!std::is_convertible<Array&, Array&&>::value), "");
+    static_assert((!std::is_convertible<Array&&, Array&>::value), "");
+#endif
 
     test_is_not_convertible<Array, char> ();
     test_is_not_convertible<Array, char&> ();
 
     static_assert(( std::is_convertible<Array, char*>::value), "");
     static_assert(( std::is_convertible<Array, const char*>::value), "");
+    static_assert(( std::is_convertible<Array, char* const>::value), "");
+    static_assert(( std::is_convertible<Array, char* const volatile>::value), "");
+
     static_assert((!std::is_convertible<const Array, char*>::value), "");
     static_assert(( std::is_convertible<const Array, const char*>::value), "");
 
+    static_assert((!std::is_convertible<char[42][42], char*>::value), "");
+    static_assert((!std::is_convertible<char[][1], char*>::value), "");
+
     // Array&
     test_is_not_convertible<Array&, void> ();
     test_is_not_convertible<Array&, Function> ();
@@ -145,6 +186,9 @@ int main()
     static_assert((!std::is_convertible<const Array&, char*>::value), "");
     static_assert(( std::is_convertible<const Array&, const char*>::value), "");
 
+    static_assert((std::is_convertible<Array, StringType>::value), "");
+    static_assert((std::is_convertible<char(&)[], StringType>::value), "");
+
     // char
     test_is_not_convertible<char, void> ();
     test_is_not_convertible<char, Function> ();
@@ -207,7 +251,7 @@ int main()
     static_assert((!std::is_convertible<const NonCopyable&, NonCopyable&>::value), "");
 // This test requires Access control SFINAE which we only have in C++11 or when
 // we are using the compiler builtin for is_convertible.
-#if __cplusplus >= 201103L || !defined(_LIBCPP_USE_IS_CONVERTIBLE_FALLBACK)
+#if TEST_STD_VER >= 11 || !defined(_LIBCPP_USE_IS_CONVERTIBLE_FALLBACK)
     test_is_not_convertible<NonCopyable&, NonCopyable>();
 #endif