support bazel complie this project and format code.

learn_class/modern_cpp_30/SFINAE/sfinae paper/hana.cpp

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+//
+// Created by light on 20-1-6.
+//
+// https://www.boost.org/doc/libs/1_62_0/libs/hana/doc/html/structboost_1_1hana_1_1type.html#a2d2e7e08e284f7e0bd1bd9c3ad0e0a2b
+#include <boost/hana.hpp>
+#include <vector>
+#include <string>
+
+namespace hana = boost::hana;
+
+
+int main() {
+    // 检查成员
+    struct Person {
+        std::string name;
+    };
+    auto has_name = hana::is_valid([](auto &&p) -> decltype(p.name) {});
+
+    Person joe{"Joe"};
+    static_assert(has_name(joe), "");
+    static_assert(!has_name(1), "");
+    // 检查嵌套类型
+    auto has_value_type = hana::is_valid([](auto t) -> hana::type<typename decltype(t)::type::value_type> {});
+    static_assert(has_value_type(hana::type_c<std::vector<int>>), "");
+    static_assert(!has_value_type(hana::type_c<Person>), "");
+
+    return 0;
+}