stabilize build system: depends, installer, boost/bdb fixes, cross targets groundwork

2026-02-24 18:38:47 +00:00
parent da8c28aaeb
commit 65cb2619a7
13106 changed files with 2484322 additions and 1804 deletions
@@ -0,0 +1,48 @@
+/*!
+@file
+Defines a replacement for `std::decay`, which is sometimes too slow at
+compile-time.
+
+@copyright Louis Dionne 2013-2017
+Distributed under the Boost Software License, Version 1.0.
+(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
+ */
+
+#ifndef BOOST_HANA_DETAIL_DECAY_HPP
+#define BOOST_HANA_DETAIL_DECAY_HPP
+
+#include <boost/hana/config.hpp>
+
+#include <type_traits>
+
+
+BOOST_HANA_NAMESPACE_BEGIN namespace detail {
+    //! @ingroup group-details
+    //! Equivalent to `std::decay`, except faster.
+    //!
+    //! `std::decay` in libc++ is implemented in a suboptimal way. Since
+    //! this is used literally everywhere by the `make<...>` functions, it
+    //! is very important to keep this as efficient as possible.
+    //!
+    //! @note
+    //! `std::decay` is still being used in some places in the library.
+    //! Indeed, this is a peephole optimization and it would not be wise
+    //! to clutter the code with our own implementation of `std::decay`,
+    //! except when this actually makes a difference in compile-times.
+    template <typename T, typename U = typename std::remove_reference<T>::type>
+    struct decay {
+        using type = typename std::remove_cv<U>::type;
+    };
+
+    template <typename T, typename U>
+    struct decay<T, U[]> { using type = U*; };
+    template <typename T, typename U, std::size_t N>
+    struct decay<T, U[N]> { using type = U*; };
+
+    template <typename T, typename R, typename ...A>
+    struct decay<T, R(A...)> { using type = R(*)(A...); };
+    template <typename T, typename R, typename ...A>
+    struct decay<T, R(A..., ...)> { using type = R(*)(A..., ...); };
+} BOOST_HANA_NAMESPACE_END
+
+#endif // !BOOST_HANA_DETAIL_DECAY_HPP