Merge branch 'feature/issue-26-nofix' into feature/issue-26

.travis.yml

@@ -1,4 +1,4 @@
-# Copyright 2016-2019 Peter Dimov
+# Copyright 2016-2021 Peter Dimov
 # Distributed under the Boost Software License, Version 1.0.
 # (See accompanying file LICENSE_1_0.txt or copy at http://boost.org/LICENSE_1_0.txt)
 
@@ -95,7 +95,7 @@ matrix:
     - os: linux
       dist: bionic
       compiler: g++-10
-      env: TOOLSET=gcc COMPILER=g++-10 CXXSTD=11,14,17,2a
+      env: UBSAN=1 TOOLSET=gcc COMPILER=g++-10 CXXSTD=11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1 LINKFLAGS=-fuse-ld=gold
       addons:
         apt:
           packages:
@@ -103,21 +103,6 @@ matrix:
           sources:
             - ubuntu-toolchain-r-test
 
-    - os: linux
-      compiler: g++-8
-      env: UBSAN=1 TOOLSET=gcc COMPILER=g++-8 CXXSTD=11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1 LINKFLAGS=-fuse-ld=gold
-      addons:
-        apt:
-          packages:
-            - g++-8
-          sources:
-            - ubuntu-toolchain-r-test
-
-    - os: linux
-      dist: trusty
-      compiler: clang++
-      env: DIST=trusty TOOLSET=clang COMPILER=clang++ CXXSTD=11,14,1z
-
     - os: linux
       compiler: clang++-3.5
       env: TOOLSET=clang COMPILER=clang++-3.5 CXXSTD=11,14,1z
@@ -180,6 +165,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      dist: bionic
       compiler: clang++-5.0
       env: TOOLSET=clang COMPILER=clang++-5.0 CXXSTD=11,14,1z
       addons:
@@ -190,6 +176,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      dist: bionic
       compiler: clang++-6.0
       env: TOOLSET=clang COMPILER=clang++-6.0 CXXSTD=11,14,17
       addons:
@@ -200,6 +187,7 @@ matrix:
             - ubuntu-toolchain-r-test
 
     - os: linux
+      dist: bionic
       compiler: clang++-7
       env: TOOLSET=clang COMPILER=clang++-7 CXXSTD=11,14,17,2a
       addons:
@@ -208,9 +196,10 @@ matrix:
             - clang-7
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-xenial-7
+            - llvm-toolchain-bionic-7
 
     - os: linux
+      dist: bionic
       compiler: clang++-8
       env: TOOLSET=clang COMPILER=clang++-8 CXXSTD=11,14,17,2a
       addons:
@@ -219,10 +208,10 @@ matrix:
             - clang-8
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-xenial-8
+            - llvm-toolchain-bionic-8
 
     - os: linux
-      dist: xenial
+      dist: bionic
       compiler: clang++-9
       env: TOOLSET=clang COMPILER=clang++-9 CXXSTD=11,14,17,2a
       addons:
@@ -231,11 +220,11 @@ matrix:
             - clang-9
           sources:
             - ubuntu-toolchain-r-test
-            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-9 main'
+            - sourceline: 'deb https://apt.llvm.org/bionic/ llvm-toolchain-bionic-9 main'
               key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
 
     - os: linux
-      dist: xenial
+      dist: bionic
       compiler: clang++-10
       env: TOOLSET=clang COMPILER=clang++-10 CXXSTD=11,14,17,2a
       addons:
@@ -244,19 +233,34 @@ matrix:
             - clang-10
           sources:
             - ubuntu-toolchain-r-test
-            - sourceline: 'deb https://apt.llvm.org/xenial/ llvm-toolchain-xenial-10 main'
+            - sourceline: 'deb https://apt.llvm.org/bionic/ llvm-toolchain-bionic-10 main'
               key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
 
     - os: linux
-      compiler: clang++-8
-      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-8 CXXSTD=11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1
+      dist: bionic
+      compiler: clang++-11
+      env: TOOLSET=clang COMPILER=clang++-11 CXXSTD=11,14,17,2a
       addons:
         apt:
           packages:
-            - clang-8
+            - clang-11
           sources:
             - ubuntu-toolchain-r-test
-            - llvm-toolchain-xenial-8
+            - sourceline: 'deb https://apt.llvm.org/bionic/ llvm-toolchain-bionic-11 main'
+              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
+
+    - os: linux
+      dist: bionic
+      compiler: clang++-12
+      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-12 CXXSTD=11,14,17,2a UBSAN_OPTIONS=print_stacktrace=1
+      addons:
+        apt:
+          packages:
+            - clang-12
+          sources:
+            - ubuntu-toolchain-r-test
+            - sourceline: 'deb https://apt.llvm.org/bionic/ llvm-toolchain-bionic-12 main'
+              key_url: 'https://apt.llvm.org/llvm-snapshot.gpg.key'
 
     - os: linux
       dist: trusty
@@ -268,18 +272,14 @@ matrix:
             - libc++-dev
 
     - os: linux
-      dist: trusty
+      dist: bionic
       compiler: clang++-libc++
-      env: UBSAN=1 TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=11,14,1z UBSAN_OPTIONS=print_stacktrace=1
+      env: TOOLSET=clang COMPILER=clang++-libc++ CXXSTD=11,14,17,2a
       addons:
         apt:
           packages:
             - libc++-dev
 
-    - os: osx
-      compiler: clang++
-      env: TOOLSET=clang COMPILER=clang++ CXXSTD=11,14,1z
-
     - os: osx
       compiler: clang++
       env: UBSAN=1 TOOLSET=clang COMPILER=clang++ CXXSTD=11,14,1z UBSAN_OPTIONS=print_stacktrace=1

appveyor.yml

@@ -20,15 +20,15 @@ environment:
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       TOOLSET: msvc-14.1
       ADDRMD: 32,64
-      CXXSTD: 14,17
+      CXXSTD: 14,17,latest
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2017
       TOOLSET: clang-win
       ADDRMD: 64
-      CXXSTD: 14,17
+      CXXSTD: 14,17,latest
     - APPVEYOR_BUILD_WORKER_IMAGE: Visual Studio 2019
       TOOLSET: msvc-14.2
       ADDRMD: 32,64
-      CXXSTD: 14,17
+      CXXSTD: 14,17,latest
 
 install:
   - set BOOST_BRANCH=develop

doc/variant2/changelog.adoc

@@ -1,5 +1,5 @@
 ////
-Copyright 2019, 2020 Peter Dimov
+Copyright 2019-2021 Peter Dimov
 
 Distributed under the Boost Software License, Version 1.0.
 
@@ -11,6 +11,10 @@ http://www.boost.org/LICENSE_1_0.txt
 # Revision History
 :idprefix: changelog_
 
+## Changes in 1.76.0
+
+* Improved generated code for the double buffered case.
+
 ## Changes in 1.74.0
 
 * Added support for derived types in `visit`

doc/variant2/reference.adoc

@@ -490,8 +490,8 @@ template<size_t I, class... A>
 +
 Requires: :: `I < sizeof...(T)`.
 Effects:  ::
-  Destroys the currently contained value, then initializes a new contained
-  value as if using the expression `Ti(std::forward<A>(a)...)`.
+  Initializes a new contained value as if using the expression
+  `Ti(std::forward<A>(a)...)`, then destroys the currently contained value.
 Ensures:  :: `index() == I`.
 Returns:  :: A reference to the new contained value.
 Throws:   ::
@@ -511,8 +511,8 @@ template<size_t I, class V, class... A>
 +
 Requires: :: `I < sizeof...(T)`.
 Effects:  ::
-  Destroys the currently contained value, then initializes a new contained
-  value as if using the expression `Ti(il, std::forward<A>(a)...)`.
+  Initializes a new contained value as if using the expression
+  `Ti(il, std::forward<A>(a)...)`, then destroys the currently contained value.
 Ensures:  :: `index() == I`.
 Returns:  :: A reference to the new contained value.
 Throws:   ::

include/boost/variant2/variant.hpp

@@ -81,6 +81,8 @@ struct monostate
 {
 };
 
+#if !BOOST_WORKAROUND(BOOST_MSVC, < 1940)
+
 constexpr bool operator<(monostate, monostate) noexcept { return false; }
 constexpr bool operator>(monostate, monostate) noexcept { return false; }
 constexpr bool operator<=(monostate, monostate) noexcept { return true; }
@@ -88,6 +90,17 @@ constexpr bool operator>=(monostate, monostate) noexcept { return true; }
 constexpr bool operator==(monostate, monostate) noexcept { return true; }
 constexpr bool operator!=(monostate, monostate) noexcept { return false; }
 
+#else
+
+constexpr bool operator<(monostate const&, monostate const&) noexcept { return false; }
+constexpr bool operator>(monostate const&, monostate const&) noexcept { return false; }
+constexpr bool operator<=(monostate const&, monostate const&) noexcept { return true; }
+constexpr bool operator>=(monostate const&, monostate const&) noexcept { return true; }
+constexpr bool operator==(monostate const&, monostate const&) noexcept { return true; }
+constexpr bool operator!=(monostate const&, monostate const&) noexcept { return false; }
+
+#endif
+
 // variant forward declaration
 
 template<class... T> class variant;
@@ -1568,7 +1581,7 @@ public:
 
     template<class U,
         class Ud = typename std::decay<U>::type,
-        class E1 = typename std::enable_if< !std::is_same<Ud, variant>::value && !detail::is_in_place_index<Ud>::value && !detail::is_in_place_type<Ud>::value >::type,
+        class E1 = typename std::enable_if< !std::is_same<Ud, variant>::value && !std::is_base_of<variant, Ud>::value && !detail::is_in_place_index<Ud>::value && !detail::is_in_place_type<Ud>::value >::type,
         class V = detail::resolve_overload_type<U&&, T...>,
         class E2 = typename std::enable_if<std::is_constructible<V, U&&>::value>::type
         >

test/Jamfile

@@ -119,3 +119,5 @@ run variant_visit_r.cpp : : :
     <toolset>gcc,<target-os>windows:<variant>release
     <toolset>gcc,<target-os>cygwin:<variant>release
     ;
+
+compile variant_derived_construct.cpp ;

test/variant_derived_construct.cpp

@@ -0,0 +1,33 @@
+// Copyright 2021 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/variant2/variant.hpp>
+
+using namespace boost::variant2;
+
+template<class... T> class X: variant<T...>
+{
+    using base = variant<T...>;
+    using base::base;
+};
+
+struct Y
+{
+    Y( Y const& rhs ) = default;
+
+    template<class T> Y( T const& t )
+    {
+        t.bar();
+    }
+};
+
+int main()
+{
+    using W = X<int, double, Y>;
+
+    W a( 1 );
+    W b( a );
+
+    (void)b;
+}

test/variant_eq_ne.cpp

@@ -88,5 +88,12 @@ int main()
         BOOST_TEST_NOT( v1 != v2 );
     }
 
+    {
+        variant<monostate> v1, v2;
+
+        BOOST_TEST( v1 == v2 );
+        BOOST_TEST_NOT( v1 != v2 );
+    }
+
     return boost::report_errors();
 }

test/variant_eq_ne_cx.cpp

@@ -93,6 +93,13 @@ int main()
         STATIC_ASSERT( !(v1 == v2) );
         STATIC_ASSERT( !(v1 != v2) );
     }
+
+    {
+        constexpr variant<monostate> v1, v2;
+
+        STATIC_ASSERT( v1 == v2 );
+        STATIC_ASSERT( !(v1 != v2) );
+    }
 }
 
 #endif

test/variant_in_place_index_construct_cx.cpp

@@ -105,7 +105,7 @@ int main()
         STATIC_ASSERT( v.index() == 4 );
     }
 
-#if BOOST_WORKAROUND(BOOST_GCC, >= 100000 && BOOST_GCC < 100200)
+#if BOOST_WORKAROUND(BOOST_GCC, >= 100000 && BOOST_GCC < 110000)
 
     // no idea why this fails on g++ 10
 

test/variant_in_place_type_construct_cx.cpp

@@ -102,7 +102,7 @@ int main()
         STATIC_ASSERT( holds_alternative<X>(v) );
     }
 
-#if BOOST_WORKAROUND(BOOST_GCC, >= 100000 && BOOST_GCC < 100200)
+#if BOOST_WORKAROUND(BOOST_GCC, >= 100000 && BOOST_GCC < 110000)
 
     // no idea why this fails on g++ 10
 

test/variant_lt_gt.cpp

@@ -81,5 +81,14 @@ int main()
         BOOST_TEST_NOT( v1 >= v2 );
     }
 
+    {
+        variant<monostate> v1, v2;
+
+        BOOST_TEST_NOT( v1 < v2 );
+        BOOST_TEST_NOT( v1 > v2 );
+        BOOST_TEST( v1 <= v2 );
+        BOOST_TEST( v1 >= v2 );
+    }
+
     return boost::report_errors();
 }

test/variant_lt_gt_cx.cpp

@@ -86,6 +86,15 @@ int main()
         STATIC_ASSERT( !(v1 <= v2) );
         STATIC_ASSERT( !(v1 >= v2) );
     }
+
+    {
+        constexpr variant<monostate> v1, v2;
+
+        STATIC_ASSERT( !(v1 < v2) );
+        STATIC_ASSERT( !(v1 > v2) );
+        STATIC_ASSERT( v1 <= v2 );
+        STATIC_ASSERT( v1 >= v2 );
+    }
 }
 
 #endif