Implement the 'detection idiom' from LFTS v2

llvm-svn: 287981

5 files changed, 224 insertions, 0 deletions

diff --git a/libcxx/test/std/experimental/utilities/meta/meta.detect/detected_or.pass.cpp b/libcxx/test/std/experimental/utilities/meta/meta.detect/detected_or.pass.cpp
new file mode 100644
index 00000000000..ffce8145947
--- /dev/null
+++ b/libcxx/test/std/experimental/utilities/meta/meta.detect/detected_or.pass.cpp
@@ -0,0 +1,40 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11
+// <experimental/type_traits>
+
+#include <experimental/type_traits>
+#include <string>
+
+#include "test_macros.h"
+
+namespace ex = std::experimental;
+
+template <typename T>
+  using hasFoo = typename T::Foo;
+  
+struct yesFoo {
+    using Foo = int;
+};
+
+struct noFoo {
+};
+
+
+template <typename T, typename Res>
+void test() {
+    static_assert( std::is_same<Res, typename ex::detected_or  <double, hasFoo, T>::type>::value, "" );
+    static_assert( std::is_same<Res, typename ex::detected_or_t<double, hasFoo, T>      >::value, "" );
+}
+
+int main () {
+    test<yesFoo, int>();
+    test<noFoo, double>();
+}
diff --git a/libcxx/test/std/experimental/utilities/meta/meta.detect/detected_t.pass.cpp b/libcxx/test/std/experimental/utilities/meta/meta.detect/detected_t.pass.cpp
new file mode 100644
index 00000000000..136fb068be3
--- /dev/null
+++ b/libcxx/test/std/experimental/utilities/meta/meta.detect/detected_t.pass.cpp
@@ -0,0 +1,48 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11
+// <experimental/type_traits>
+
+#include <experimental/type_traits>
+#include <string>
+
+#include "test_macros.h"
+
+namespace ex = std::experimental;
+
+template <typename T>
+  using callFoo = decltype(std::declval<T&>().Foo());
+  
+struct yesFoo {
+    int Foo() { return 0; }
+};
+
+struct noFoo {
+};
+
+struct wrongFoo {
+    std::string Foo() { return ""; }
+};
+
+struct convertibleFoo {
+    long Foo() { return 0; }
+};
+
+
+template <typename T, typename Res>
+void test() {
+    static_assert( std::is_same<Res, typename ex::detected_t<callFoo, T>>::value, "" );
+}
+
+int main () {
+    test<yesFoo, int>();
+    test<noFoo, ex::nonesuch>();  // lookup failure returns nonesuch
+    test<wrongFoo, std::string>();
+}
diff --git a/libcxx/test/std/experimental/utilities/meta/meta.detect/is_detected.pass.cpp b/libcxx/test/std/experimental/utilities/meta/meta.detect/is_detected.pass.cpp
new file mode 100644
index 00000000000..d8528a25161
--- /dev/null
+++ b/libcxx/test/std/experimental/utilities/meta/meta.detect/is_detected.pass.cpp
@@ -0,0 +1,37 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11
+// <experimental/type_traits>
+
+#include <experimental/type_traits>
+#include <string>
+
+#include "test_macros.h"
+
+namespace ex = std::experimental;
+
+template <typename T>
+  using copy_assign_t = decltype(std::declval<T&>() = std::declval<T const &>());
+  
+struct not_assignable {
+    not_assignable & operator=(const not_assignable&) = delete;
+};
+
+template <typename T, bool b>
+void test() {
+    static_assert( b == ex::is_detected  <copy_assign_t, T>::value, "" );
+    static_assert( b == ex::is_detected_v<copy_assign_t, T>, "" );
+}
+
+int main () {
+    test<int, true>();
+    test<std::string, true>();
+    test<not_assignable, false>();
+}
diff --git a/libcxx/test/std/experimental/utilities/meta/meta.detect/is_detected_convertible.pass.cpp b/libcxx/test/std/experimental/utilities/meta/meta.detect/is_detected_convertible.pass.cpp
new file mode 100644
index 00000000000..8d1e0ae825d
--- /dev/null
+++ b/libcxx/test/std/experimental/utilities/meta/meta.detect/is_detected_convertible.pass.cpp
@@ -0,0 +1,50 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11
+// <experimental/type_traits>
+
+#include <experimental/type_traits>
+#include <string>
+
+#include "test_macros.h"
+
+namespace ex = std::experimental;
+
+template <typename T>
+  using callFoo = decltype(std::declval<T&>().Foo());
+  
+struct yesFoo {
+    int Foo() { return 0; }
+};
+
+struct noFoo {
+};
+
+struct wrongFoo {
+    std::string Foo() { return ""; }
+};
+
+struct convertibleFoo {
+    long Foo() { return 0; }
+};
+
+
+template <typename T, bool b>
+void test() {
+    static_assert( b == ex::is_detected_convertible  <int, callFoo, T>::value, "" );
+    static_assert( b == ex::is_detected_convertible_v<int, callFoo, T>, "" );
+}
+
+int main () {
+    test<yesFoo, true>();
+    test<noFoo, false>();
+    test<wrongFoo, false>();
+    test<convertibleFoo, true>();
+}
diff --git a/libcxx/test/std/experimental/utilities/meta/meta.detect/is_detected_exact.pass.cpp b/libcxx/test/std/experimental/utilities/meta/meta.detect/is_detected_exact.pass.cpp
new file mode 100644
index 00000000000..e9e5d8ce005
--- /dev/null
+++ b/libcxx/test/std/experimental/utilities/meta/meta.detect/is_detected_exact.pass.cpp
@@ -0,0 +1,49 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// UNSUPPORTED: c++98, c++03, c++11
+// <experimental/type_traits>
+
+#include <experimental/type_traits>
+#include <string>
+
+#include "test_macros.h"
+
+namespace ex = std::experimental;
+
+template <typename T>
+  using callFoo = decltype(std::declval<T&>().Foo());
+  
+struct yesFoo {
+    int Foo() { return 0; }
+};
+
+struct noFoo {
+};
+
+struct wrongFoo {
+    std::string Foo() { return ""; }
+};
+
+struct convertibleFoo {
+    long Foo() { return 0; }
+};
+
+template <typename T, bool b>
+void test() {
+    static_assert( b == ex::is_detected_exact  <int, callFoo, T>::value, "" );
+    static_assert( b == ex::is_detected_exact_v<int, callFoo, T>, "" );
+}
+
+int main () {
+    test<yesFoo, true>();
+    test<noFoo, false>();
+    test<wrongFoo, false>();
+    test<convertibleFoo, false>();
+}