From 89465dce7c16d2108fdf0b64fe6b3e7388c3a24e Mon Sep 17 00:00:00 2001 From: Eric Fiselier Date: Wed, 18 Feb 2015 16:31:46 +0000 Subject: [PATCH] [libc++] Fix PR20084 - std::is_function failed. Summary: This patch introduces some black magic to detect const and volatile qualified function types such as `void () const`. The patch works in the following way: We first rule out any type that satisfies on of the following. These restrictions are important so that the test below works properly. * `is_class<_Tp>::value` * `is_union<_Tp>::value` * `is_void<_Tp>::value` * `is_reference<_Tp>::value` * `__is_nullptr_t<_Tp>::value` If none of the above is true we perform overload resolution on `__source<_Tp>(0)` to determine the return type. * If `_Tp&` is well-formed we select `_Tp& __source(int)`. `_Tp&` is only ill formed for cv void types and cv/ref qualified function types. * Otherwise we select `__dummy_type __source(...)`. Since we know `_Tp` cannot be void then it must be a function type. let `R` be the returned from `__source<_Tp>(0)`. We perform overload resolution on `__test<_Tp>(R)`. * If `R` is `__dummy_type` we call `true_type __test(__dummy_type)`. * if `R` is `_Tp&` and `_Tp&` decays to `_Tp*` we call `true_type __test(_Tp*)`. Only references to function types decay to a pointer of the same type. * In all other cases we call `false_type __test(...)`. `__source<_Tp>(0)` will try and form `_Tp&` in the return type. if `_Tp&` is not well formed the return type of `__source<_Tp>(0)` will be dummy type. `_Tp&` is only ill-formed for cv/ref qualified function types (and void which is dealt with elsewhere). This fixes PR20084 - http://llvm.org/bugs/show_bug.cgi?id=20084 Reviewers: rsmith, K-ballo, mclow.lists Reviewed By: mclow.lists Subscribers: cfe-commits Differential Revision: http://reviews.llvm.org/D7573 git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@229696 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/type_traits | 7 ++- .../meta.unary.cat/function.pass.cpp | 62 +++++++++++++++---- 2 files changed, 54 insertions(+), 15 deletions(-) diff --git a/include/type_traits b/include/type_traits index c44cae639..52fb59024 100644 --- a/include/type_traits +++ b/include/type_traits @@ -430,9 +430,12 @@ template struct _LIBCPP_TYPE_VIS_ONLY is_same<_Tp, _Tp> : namespace __libcpp_is_function_imp { +struct __dummy_type {}; template char __test(_Tp*); +template char __test(__dummy_type); template __two __test(...); -template _Tp& __source(); +template _Tp& __source(int); +template __dummy_type __source(...); } template ::value || @@ -441,7 +444,7 @@ template ::value || is_reference<_Tp>::value || __is_nullptr_t<_Tp>::value > struct __libcpp_is_function - : public integral_constant(__libcpp_is_function_imp::__source<_Tp>())) == 1> + : public integral_constant(__libcpp_is_function_imp::__source<_Tp>(0))) == 1> {}; template struct __libcpp_is_function<_Tp, true> : public false_type {}; diff --git a/test/std/utilities/meta/meta.unary/meta.unary.cat/function.pass.cpp b/test/std/utilities/meta/meta.unary/meta.unary.cat/function.pass.cpp index 82757f503..b1df4f2d3 100644 --- a/test/std/utilities/meta/meta.unary/meta.unary.cat/function.pass.cpp +++ b/test/std/utilities/meta/meta.unary/meta.unary.cat/function.pass.cpp @@ -13,8 +13,19 @@ #include +using namespace std; + +class Class {}; + +enum Enum1 {}; +#if __cplusplus >= 201103L +enum class Enum2 : int {}; +#else +enum Enum2 {}; +#endif + template -void test_function_imp() +void test() { static_assert(!std::is_void::value, ""); #if _LIBCPP_STD_VER > 11 @@ -34,19 +45,44 @@ void test_function_imp() static_assert( std::is_function::value, ""); } -template -void test_function() -{ - test_function_imp(); - test_function_imp(); - test_function_imp(); - test_function_imp(); -} +// Since we can't actually add the const volatile and ref qualifiers once +// later let's use a macro to do it. +#define TEST_REGULAR(...) \ + test<__VA_ARGS__>(); \ + test<__VA_ARGS__ const>(); \ + test<__VA_ARGS__ volatile>(); \ + test<__VA_ARGS__ const volatile>() + + +#define TEST_REF_QUALIFIED(...) \ + test<__VA_ARGS__ &>(); \ + test<__VA_ARGS__ const &>(); \ + test<__VA_ARGS__ volatile &>(); \ + test<__VA_ARGS__ const volatile &>(); \ + test<__VA_ARGS__ &&>(); \ + test<__VA_ARGS__ const &&>(); \ + test<__VA_ARGS__ volatile &&>(); \ + test<__VA_ARGS__ const volatile &&>() + int main() { - test_function(); - test_function(); - test_function(); - test_function(); + TEST_REGULAR( void () ); + TEST_REGULAR( void (int) ); + TEST_REGULAR( int (double) ); + TEST_REGULAR( int (double, char) ); + TEST_REGULAR( void (...) ); + TEST_REGULAR( void (int, ...) ); + TEST_REGULAR( int (double, ...) ); + TEST_REGULAR( int (double, char, ...) ); +#if __cplusplus >= 201103L + TEST_REF_QUALIFIED( void () ); + TEST_REF_QUALIFIED( void (int) ); + TEST_REF_QUALIFIED( int (double) ); + TEST_REF_QUALIFIED( int (double, char) ); + TEST_REF_QUALIFIED( void (...) ); + TEST_REF_QUALIFIED( void (int, ...) ); + TEST_REF_QUALIFIED( int (double, ...) ); + TEST_REF_QUALIFIED( int (double, char, ...) ); +#endif }