Squashed 'external/entt/entt/' content from commit fef92113

git-subtree-dir: external/entt/entt
git-subtree-split: fef921132cae7588213d0f9bcd2fb9c8ffd8b7fc

test/entt/core/utility.cpp

@@ -0,0 +1,61 @@
+#include <utility>
+#include <gtest/gtest.h>
+#include <entt/core/type_traits.hpp>
+#include <entt/core/utility.hpp>
+
+struct functions {
+    static void foo(int) {}
+    static void foo() {}
+
+    void bar(int) {}
+    void bar() {}
+};
+
+TEST(Identity, Functionalities) {
+    entt::identity identity;
+    int value = 42;
+
+    ASSERT_TRUE(entt::is_transparent_v<entt::identity>);
+    ASSERT_EQ(identity(value), value);
+    ASSERT_EQ(&identity(value), &value);
+}
+
+TEST(Overload, Functionalities) {
+    ASSERT_EQ(entt::overload<void(int)>(&functions::foo), static_cast<void (*)(int)>(&functions::foo));
+    ASSERT_EQ(entt::overload<void()>(&functions::foo), static_cast<void (*)()>(&functions::foo));
+
+    ASSERT_EQ(entt::overload<void(int)>(&functions::bar), static_cast<void (functions::*)(int)>(&functions::bar));
+    ASSERT_EQ(entt::overload<void()>(&functions::bar), static_cast<void (functions::*)()>(&functions::bar));
+
+    functions instance;
+
+    ASSERT_NO_FATAL_FAILURE(entt::overload<void(int)>(&functions::foo)(0));
+    ASSERT_NO_FATAL_FAILURE(entt::overload<void()>(&functions::foo)());
+
+    ASSERT_NO_FATAL_FAILURE((instance.*entt::overload<void(int)>(&functions::bar))(0));
+    ASSERT_NO_FATAL_FAILURE((instance.*entt::overload<void()>(&functions::bar))());
+}
+
+TEST(Overloaded, Functionalities) {
+    int iv = 0;
+    char cv = '\0';
+
+    entt::overloaded func{
+        [&iv](int value) { iv = value; },
+        [&cv](char value) { cv = value; }};
+
+    func(42);
+    func('c');
+
+    ASSERT_EQ(iv, 42);
+    ASSERT_EQ(cv, 'c');
+}
+
+TEST(YCombinator, Functionalities) {
+    entt::y_combinator gauss([](const auto &self, auto value) -> unsigned int {
+        return value ? (value + self(value - 1u)) : 0;
+    });
+
+    ASSERT_EQ(gauss(3u), 3u * 4u / 2u);
+    ASSERT_EQ(std::as_const(gauss)(7u), 7u * 8u / 2u);
+}