[libc++] Add C++17 deduction guides for std::function

Summary: http://llvm.org/PR39606 Reviewers: Quuxplusone Subscribers: christof, dexonsmith, libcxx-commits Differential Revision: https://reviews.llvm.org/D54410 git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@366484 91177308-0d34-0410-b5e6-96231b3b80d8
2025-10-23 10:07:41 +08:00 · 2019-07-18 19:50:56 +00:00
parent 548f2e8e96
commit 56bc01df8f
4 changed files with 337 additions and 0 deletions
--- a/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_ptr.pass.cpp
+++ b/test/std/utilities/function.objects/func.wrap/func.wrap.func/func.wrap.func.con/deduct_ptr.pass.cpp
@@ -0,0 +1,112 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <functional>
+
+// template<class R, class ...Args>
+// function(R(*)(Args...)) -> function<R(Args...)>;
+
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+// UNSUPPORTED: libcpp-no-deduction-guides
+
+#include <functional>
+#include <type_traits>
+
+#include "test_macros.h"
+
+
+struct R { };
+struct A1 { };
+struct A2 { };
+struct A3 { };
+
+R f0() { return {}; }
+R f1(A1) { return {}; }
+R f2(A1, A2) { return {}; }
+R f3(A1, A2, A3) { return {}; }
+R f4(A1 = {}) { return {}; }
+
+int main() {
+  {
+    // implicit
+    std::function a = f0;
+    ASSERT_SAME_TYPE(decltype(a), std::function<R()>);
+
+    std::function b = &f0;
+    ASSERT_SAME_TYPE(decltype(b), std::function<R()>);
+
+    // explicit
+    std::function c{f0};
+    ASSERT_SAME_TYPE(decltype(c), std::function<R()>);
+
+    std::function d{&f0};
+    ASSERT_SAME_TYPE(decltype(d), std::function<R()>);
+  }
+  {
+    // implicit
+    std::function a = f1;
+    ASSERT_SAME_TYPE(decltype(a), std::function<R(A1)>);
+
+    std::function b = &f1;
+    ASSERT_SAME_TYPE(decltype(b), std::function<R(A1)>);
+
+    // explicit
+    std::function c{f1};
+    ASSERT_SAME_TYPE(decltype(c), std::function<R(A1)>);
+
+    std::function d{&f1};
+    ASSERT_SAME_TYPE(decltype(d), std::function<R(A1)>);
+  }
+  {
+    // implicit
+    std::function a = f2;
+    ASSERT_SAME_TYPE(decltype(a), std::function<R(A1, A2)>);
+
+    std::function b = &f2;
+    ASSERT_SAME_TYPE(decltype(b), std::function<R(A1, A2)>);
+
+    // explicit
+    std::function c{f2};
+    ASSERT_SAME_TYPE(decltype(c), std::function<R(A1, A2)>);
+
+    std::function d{&f2};
+    ASSERT_SAME_TYPE(decltype(d), std::function<R(A1, A2)>);
+  }
+  {
+    // implicit
+    std::function a = f3;
+    ASSERT_SAME_TYPE(decltype(a), std::function<R(A1, A2, A3)>);
+
+    std::function b = &f3;
+    ASSERT_SAME_TYPE(decltype(b), std::function<R(A1, A2, A3)>);
+
+    // explicit
+    std::function c{f3};
+    ASSERT_SAME_TYPE(decltype(c), std::function<R(A1, A2, A3)>);
+
+    std::function d{&f3};
+    ASSERT_SAME_TYPE(decltype(d), std::function<R(A1, A2, A3)>);
+  }
+  // Make sure defaulted arguments don't mess up the deduction
+  {
+    // implicit
+    std::function a = f4;
+    ASSERT_SAME_TYPE(decltype(a), std::function<R(A1)>);
+
+    std::function b = &f4;
+    ASSERT_SAME_TYPE(decltype(b), std::function<R(A1)>);
+
+    // explicit
+    std::function c{f4};
+    ASSERT_SAME_TYPE(decltype(c), std::function<R(A1)>);
+
+    std::function d{&f4};
+    ASSERT_SAME_TYPE(decltype(d), std::function<R(A1)>);
+  }
+}