From 874026e26b56d10b0bb9540180b564b36e685a17 Mon Sep 17 00:00:00 2001
From: Boris Kolpackov <boris@codesynthesis.com>
Date: Fri, 26 Jun 2020 15:29:41 +0200
Subject: Fix

---
 libbutl/optional.mxx      | 83 +++++++++++++++++++++++++++++++++++++++++++----
 tests/optional/driver.cxx | 16 ++++-----
 2 files changed, 85 insertions(+), 14 deletions(-)

diff --git a/libbutl/optional.mxx b/libbutl/optional.mxx
index fe533c5..d32e14b 100644
--- a/libbutl/optional.mxx
+++ b/libbutl/optional.mxx
@@ -60,7 +60,7 @@
 #else
 #  include <utility>     // move()
 #  include <functional>  // hash
-#  include <type_traits> // is_trivially_destructible
+#  include <type_traits> // is_*
 #endif
 #endif
 
@@ -91,9 +91,6 @@ LIBBUTL_MODEXPORT namespace butl
   // Simple optional class template while waiting for std::optional.
   //
   struct nullopt_t {constexpr explicit nullopt_t (int) {}};
-#if defined(__cpp_modules_ts) && defined(__clang__) //@@ MOD Clang duplicate sym.
-  inline
-#endif
   constexpr nullopt_t nullopt (1);
 
   namespace details
@@ -184,12 +181,86 @@ LIBBUTL_MODEXPORT namespace butl
       optional_data& operator= (const optional_data&);
       optional_data& operator= (optional_data&&);
     };
+
+    template <typename T,
+              bool = std::is_copy_constructible<T>::value,
+              bool = std::is_move_constructible<T>::value>
+    struct optional_ctors: optional_data<T>
+    {
+      using optional_data<T>::optional_data;
+    };
+
+    template <typename T>
+    struct optional_ctors<T, false, true>: optional_ctors<T, true, true>
+    {
+      using optional_ctors<T, true, true>::optional_ctors;
+
+#if !defined(_MSC_VER) || _MSC_VER > 1900
+      constexpr optional_ctors () = default;
+#else
+      optional_ctors () = default;
+#endif
+
+      optional_ctors (const optional_ctors&) = delete;
+
+#if (!defined(_MSC_VER) || _MSC_VER > 1900) &&                  \
+    (!defined(__GNUC__) || __GNUC__ > 4 || defined(__clang__))
+      constexpr optional_ctors (optional_ctors&&) = default;
+#else
+      optional_ctors (optional_ctors&&) = default;
+#endif
+
+      optional_ctors& operator= (const optional_ctors&) = default;
+      optional_ctors& operator= (optional_ctors&&) = default;
+    };
+
+    template <typename T>
+    struct optional_ctors<T, true, false>: optional_ctors<T, true, true>
+    {
+      using optional_ctors<T, true, true>::optional_ctors;
+
+#if !defined(_MSC_VER) || _MSC_VER > 1900
+      constexpr optional_ctors () = default;
+#else
+      optional_ctors () = default;
+#endif
+
+#if (!defined(_MSC_VER) || _MSC_VER > 1900) &&                  \
+    (!defined(__GNUC__) || __GNUC__ > 4 || defined(__clang__))
+      constexpr optional_ctors (const optional_ctors&) = default;
+#else
+      optional_ctors (const optional_ctors&) = default;
+#endif
+
+      optional_ctors (optional_ctors&&) = delete;
+
+      optional_ctors& operator= (const optional_ctors&) = default;
+      optional_ctors& operator= (optional_ctors&&) = default;
+    };
+
+    template <typename T>
+    struct optional_ctors<T, false, false>: optional_ctors<T, true, true>
+    {
+      using optional_ctors<T, true, true>::optional_ctors;
+
+#if !defined(_MSC_VER) || _MSC_VER > 1900
+      constexpr optional_ctors () = default;
+#else
+      optional_ctors () = default;
+#endif
+
+      optional_ctors (const optional_ctors&) = delete;
+      optional_ctors (optional_ctors&&) = delete;
+
+      optional_ctors& operator= (const optional_ctors&) = default;
+      optional_ctors& operator= (optional_ctors&&) = default;
+    };
   }
 
   template <typename T>
-  class optional: private details::optional_data<T>
+  class optional: private details::optional_ctors<T>
   {
-    using base = details::optional_data<T>;
+    using base = details::optional_ctors<T>;
 
   public:
     using value_type = T;
diff --git a/tests/optional/driver.cxx b/tests/optional/driver.cxx
index e63c985..5d72f08 100644
--- a/tests/optional/driver.cxx
+++ b/tests/optional/driver.cxx
@@ -21,15 +21,15 @@ import butl.optional;
 
 using namespace std;
 
-struct redirect
+struct move_only
 {
-  redirect () = default;
+  move_only () = default;
 
-  redirect (redirect&&) = default;
-  redirect& operator= (redirect&&) = default;
+  move_only (move_only&&) = default;
+  move_only& operator= (move_only&&) = default;
 
-  redirect (const redirect&) = delete;
-  redirect& operator= (const redirect&) = delete;
+  move_only (const move_only&) = delete;
+  move_only& operator= (const move_only&) = delete;
 };
 
 int
@@ -37,7 +37,7 @@ main ()
 {
   using butl::optional;
 
-  optional<redirect> r;
-  vector<optional<redirect>> rs;
+  optional<move_only> r;
+  vector<optional<move_only>> rs;
   rs.emplace_back (move (r));
 }
-- 
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