Merging 'develop' into 'master' for 1.7.0

RELEASE_NOTES.md

@@ -1,9 +1,4 @@
-Release notes for Hana 1.6.1
+Release notes for Hana 1.7.0
 ============================
-
-- Official support for Xcode 6, 7 and 8, 9, 10 and LLVM Clang 3.5, 3.6, 3.7,
-  and 3.8 has has been dropped. The library should still work with these
-  compilers, however they are not being tested regularly anymore, so they are
-  not officially supported.
-- The `hana::traits::result_of` trait has been removed. Since `std::result_of`
-  has been removed from the Standard in C++20, users should move away from it.
+- Disable the definition of traits::is_pod in C++20 and later, due to its
+  deprecation.

doc/tutorial.hpp

@@ -3576,41 +3576,41 @@ in pseudo-code, the actual implementation sometimes being slightly hard to
 understand. This section defines terms used in the reference and in the
 pseudo-code used to describe some functions.
 
-@anchor tutorial-glossary-forwarded
-#### `forwarded(x)`
-Means that the object is forwarded optimally. This means that if `x` is a
-parameter, it is `std::forward`ed, and if it is a captured variable, it is
-moved from whenever the enclosing lambda is an rvalue.
-
-Also note that when `x` can be moved from, the statement `return forwarded(x);`
-in a function with `decltype(auto)` does not mean that an rvalue reference to
-`x` will be returned, which would create a dangling reference. Rather, it
-means that `x` is returned by value, the value being constructed with the
-`std::forward`ed `x`.
-
-@anchor tutorial-glossary-perfect_capture
-#### `perfect-capture`
-This is used in lambdas to signify that the captured variables are
-initialized using perfect forwarding, as if `[x(forwarded(x))...]() { }`
-had been used.
-
-@anchor tutorial-glossary-tag_dispatched
-#### `tag-dispatched`
-This means that the documented function uses [tag dispatching]
-(@ref tutorial-core-tag_dispatching), and hence the exact
-implementation depends on the model of the concept associated
-to the function.
-
-@anchor tutorial-glossary-implementation_defined
-#### `implementation-defined`
-This expresses the fact that the exact implementation of an entity (usually a
-type) should not be relied upon by users. In particular, this means that one
-can not assume anything beyond what is written explicitly in the documentation.
-Usually, the concepts satisfied by an implementation-defined entity will be
-documented, because one could otherwise do nothing with it. Concretely,
-assuming too much about an implementation-defined entity will probably
-not kill you, but it will very probably break your code when you update
-to a newer version of Hana.
+- @anchor tutorial-glossary-forwarded `forwarded(x)`
+
+  Means that the object is forwarded optimally. This means that if `x` is a
+  parameter, it is `std::forward`ed, and if it is a captured variable, it is
+  moved from whenever the enclosing lambda is an rvalue.
+
+  Also note that when `x` can be moved from, the statement `return forwarded(x);`
+  in a function with `decltype(auto)` does not mean that an rvalue reference to
+  `x` will be returned, which would create a dangling reference. Rather, it
+  means that `x` is returned by value, the value being constructed with the
+  `std::forward`ed `x`.
+
+- @anchor tutorial-glossary-perfect_capture `perfect-capture`
+
+  This is used in lambdas to signify that the captured variables are
+  initialized using perfect forwarding, as if `[x(forwarded(x))...]() { }`
+  had been used.
+
+- @anchor tutorial-glossary-tag_dispatched `tag-dispatched`
+
+  This means that the documented function uses [tag dispatching]
+  (@ref tutorial-core-tag_dispatching), and hence the exact
+  implementation depends on the model of the concept associated
+  to the function.
+
+- @anchor tutorial-glossary-implementation_defined `implementation-defined`
+
+  This expresses the fact that the exact implementation of an entity (usually a
+  type) should not be relied upon by users. In particular, this means that one
+  can not assume anything beyond what is written explicitly in the documentation.
+  Usually, the concepts satisfied by an implementation-defined entity will be
+  documented, because one could otherwise do nothing with it. Concretely,
+  assuming too much about an implementation-defined entity will probably
+  not kill you, but it will very probably break your code when you update
+  to a newer version of Hana.
 
 
 

include/boost/hana/core/tag_of.hpp

@@ -15,6 +15,8 @@ Distributed under the Boost Software License, Version 1.0.
 #include <boost/hana/config.hpp>
 #include <boost/hana/core/when.hpp>
 
+#include <type_traits>
+
 
 BOOST_HANA_NAMESPACE_BEGIN
     //! @cond
@@ -44,6 +46,14 @@ BOOST_HANA_NAMESPACE_BEGIN
     template <typename T> struct tag_of<T const volatile> : tag_of<T> { };
     template <typename T> struct tag_of<T&> : tag_of<T> { };
     template <typename T> struct tag_of<T&&> : tag_of<T> { };
+
+    namespace detail {
+        template <typename T>
+        struct has_idempotent_tag
+            : std::is_same<hana::tag_of_t<T>,
+                           std::remove_const_t<std::remove_reference_t<T>>>
+        { };
+    }
 BOOST_HANA_NAMESPACE_END
 
 #endif // !BOOST_HANA_CORE_TAG_OF_HPP

include/boost/hana/detail/operators/comparable.hpp

@@ -26,15 +26,23 @@ BOOST_HANA_NAMESPACE_BEGIN namespace detail {
 
     namespace operators {
         template <typename X, typename Y, typename = typename std::enable_if<
-            detail::comparable_operators<typename hana::tag_of<X>::type>::value ||
-            detail::comparable_operators<typename hana::tag_of<Y>::type>::value
+            !detail::has_idempotent_tag<X>::value &&
+            !detail::has_idempotent_tag<Y>::value &&
+            (detail::comparable_operators<
+                typename hana::tag_of<X>::type>::value ||
+             detail::comparable_operators<
+                typename hana::tag_of<Y>::type>::value)
         >::type>
         constexpr auto operator==(X&& x, Y&& y)
         { return hana::equal(static_cast<X&&>(x), static_cast<Y&&>(y)); }
 
         template <typename X, typename Y, typename = typename std::enable_if<
-            detail::comparable_operators<typename hana::tag_of<X>::type>::value ||
-            detail::comparable_operators<typename hana::tag_of<Y>::type>::value
+            !detail::has_idempotent_tag<X>::value &&
+            !detail::has_idempotent_tag<Y>::value &&
+            (detail::comparable_operators<
+                typename hana::tag_of<X>::type>::value ||
+             detail::comparable_operators<
+                typename hana::tag_of<Y>::type>::value)
         >::type>
         constexpr auto operator!=(X&& x, Y&& y)
         { return hana::not_equal(static_cast<X&&>(x), static_cast<Y&&>(y)); }

include/boost/hana/equal.hpp

@@ -191,7 +191,10 @@ BOOST_HANA_NAMESPACE_BEGIN
     }
 
     template <typename S>
-    struct equal_impl<S, S, when<hana::Struct<S>::value>> {
+    struct equal_impl<S, S, when<
+        hana::Struct<S>::value &&
+        !detail::EqualityComparable<S, S>::value
+    >> {
         template <typename X, typename Y>
         static constexpr auto apply(X const& x, Y const& y) {
             return hana::all_of(hana::accessors<S>(),

include/boost/hana/traits.hpp

@@ -67,7 +67,9 @@ BOOST_HANA_NAMESPACE_BEGIN namespace traits {
     constexpr auto is_trivial = detail::hana_trait<std::is_trivial>{};
     constexpr auto is_trivially_copyable = detail::hana_trait<std::is_trivially_copyable>{};
     constexpr auto is_standard_layout = detail::hana_trait<std::is_standard_layout>{};
+#if __cplusplus < 202002L
     constexpr auto is_pod = detail::hana_trait<std::is_pod>{};
+#endif
     constexpr auto is_literal_type = detail::hana_trait<std::is_literal_type>{};
     constexpr auto is_empty = detail::hana_trait<std::is_empty>{};
     constexpr auto is_polymorphic = detail::hana_trait<std::is_polymorphic>{};

include/boost/hana/version.hpp

@@ -24,11 +24,11 @@ Distributed under the Boost Software License, Version 1.0.
 
 //! @ingroup group-config
 //! Macro expanding to the minor version of the library, i.e. the `y` in `x.y.z`.
-#define BOOST_HANA_MINOR_VERSION 6
+#define BOOST_HANA_MINOR_VERSION 7
 
 //! @ingroup group-config
 //! Macro expanding to the patch level of the library, i.e. the `z` in `x.y.z`.
-#define BOOST_HANA_PATCH_VERSION 1
+#define BOOST_HANA_PATCH_VERSION 0
 
 //! @ingroup group-config
 //! Macro expanding to the full version of the library, in hexadecimal

test/issues/github_460.cpp

@@ -0,0 +1,27 @@
+// Copyright Jason Rice 2020
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+
+#include <boost/hana/define_struct.hpp>
+#include <boost/hana/equal.hpp>
+#include <boost/hana/members.hpp>
+#include <boost/hana/not_equal.hpp>
+namespace hana = boost::hana;
+
+
+struct SomeStruct {
+    BOOST_HANA_DEFINE_STRUCT(SomeStruct, (int, x));
+
+    constexpr bool operator==(SomeStruct const& other) {
+        return hana::equal(hana::members(*this), hana::members(other));
+    }
+
+    constexpr bool operator!=(SomeStruct const& other) {
+        return hana::not_equal(hana::members(*this), hana::members(other));
+    }
+};
+
+int main() {
+    static_assert(SomeStruct{5} == SomeStruct{5}, "");
+    static_assert(hana::equal(SomeStruct{5}, SomeStruct{5}), "");
+}

test/issues/github_470.cpp

@@ -0,0 +1,39 @@
+// Copyright Jason Rice 2020
+// Distributed under the Boost Software License, Version 1.0.
+// (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+
+#include <boost/hana/equal.hpp>
+#include <boost/hana/not_equal.hpp>
+#include <boost/hana/tuple.hpp>
+#include <cassert>
+namespace hana = boost::hana;
+
+namespace {
+    template <typename T>
+    struct optional {
+        T t;
+    };
+
+    template <typename T>
+    constexpr bool operator==(optional<T> const& o, T const& t) {
+        return o.t == t;
+    }
+    template <typename T>
+    constexpr bool operator==(T const& t, optional<T> const& o) {
+        return o.t == t;
+    }
+    template <typename T>
+    constexpr bool operator!=(optional<T> const& o, T const& t) {
+        return o.t != t;
+    }
+    template <typename T>
+    constexpr bool operator!=(T const& t, optional<T> const& o) {
+        return o.t != t;
+    }
+}
+
+int main() {
+    boost::hana::tuple<int> x{};
+    optional<boost::hana::tuple<int>> attr{x};
+    assert(attr == x);  // <-- Kablooey!
+}

test/type/traits.cpp

@@ -53,7 +53,9 @@ int main() {
     hana::traits::is_trivial(s);
     hana::traits::is_trivially_copyable(s);
     hana::traits::is_standard_layout(s);
+#if __cplusplus < 202002L
     hana::traits::is_pod(s);
+#endif
     hana::traits::is_literal_type(s);
     hana::traits::is_empty(s);
     hana::traits::is_polymorphic(s);