Add operator|( result, nullary-returning-result )

test/CMakeLists.txt

@@ -171,3 +171,4 @@ boost_test(TYPE run SOURCES result_or_value.cpp)
 boost_test(TYPE compile-fail SOURCES result_or_value_fail.cpp)
 boost_test(TYPE compile-fail SOURCES result_or_value_fail2.cpp)
 boost_test(TYPE run SOURCES result_or_fn0v.cpp)
+boost_test(TYPE run SOURCES result_or_fn0r.cpp)

test/Jamfile.v2

@@ -201,3 +201,4 @@ run result_or_value.cpp : : : $(CPP11) ;
 compile-fail result_or_value_fail.cpp : $(CPP11) ;
 compile-fail result_or_value_fail2.cpp : $(CPP11) ;
 run result_or_fn0v.cpp : : : $(CPP11) ;
+run result_or_fn0r.cpp : : : $(CPP11) ;

test/result_or_fn0r.cpp

@@ -0,0 +1,339 @@
+// Copyright 2017, 2021, 2022 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#include <boost/system/result.hpp>
+#include <boost/core/lightweight_test.hpp>
+
+using namespace boost::system;
+
+struct X
+{
+    int v_;
+};
+
+struct Y
+{
+    int v_;
+
+    explicit Y( int v ): v_( v ) {}
+    Y( X x ): v_( x.v_) {}
+
+    Y( Y const& ) = delete;
+    Y& operator=( Y const& ) = delete;
+
+    Y( Y&& r ): v_( r.v_ )
+    {
+        r.v_ = 0;
+    }
+
+    Y& operator=( Y&& ) = delete;
+};
+
+struct E
+{
+};
+
+result<int, E> fi()
+{
+    return 2;
+}
+
+result<int, E> fi2()
+{
+    return E();
+}
+
+result<Y, E> fy()
+{
+    return Y{ 2 };
+}
+
+result<Y, E> fy2()
+{
+    return E();
+}
+
+result<int&, E> fri()
+{
+    static int x = 2;
+    return x;
+}
+
+result<int&, E> fri2()
+{
+    return E();
+}
+
+result<void, E> fv()
+{
+    return {};
+}
+
+result<void, E> fv2()
+{
+    return E();
+}
+
+int main()
+{
+    {
+        result<int> r( 1 );
+
+        int x = r | fi | 3;
+
+        BOOST_TEST_EQ( x, 1 );
+    }
+
+    {
+        result<int> const r( 1 );
+
+        int x = r | fi | 3;
+
+        BOOST_TEST_EQ( x, 1 );
+    }
+
+    {
+        int x = result<int>( 1 ) | fi | 3;
+
+        BOOST_TEST_EQ( x, 1 );
+    }
+
+    {
+        result<int> r( 1 );
+
+        int x = r | fi2 | 3;
+
+        BOOST_TEST_EQ( x, 1 );
+    }
+
+    {
+        result<int> const r( 1 );
+
+        int x = r | fi2 | 3;
+
+        BOOST_TEST_EQ( x, 1 );
+    }
+
+    {
+        int x = result<int>( 1 ) | fi2 | 3;
+
+        BOOST_TEST_EQ( x, 1 );
+    }
+
+    {
+        result<int> r( in_place_error );
+
+        int x = r | fi | 3;
+
+        BOOST_TEST_EQ( x, 2 );
+    }
+
+    {
+        result<int> const r( in_place_error );
+
+        int x = r | fi | 3;
+
+        BOOST_TEST_EQ( x, 2 );
+    }
+
+    {
+        int x = result<int>( in_place_error ) | fi | 3;
+
+        BOOST_TEST_EQ( x, 2 );
+    }
+
+    {
+        result<int> r( in_place_error );
+
+        int x = r | fi2 | 3;
+
+        BOOST_TEST_EQ( x, 3 );
+    }
+
+    {
+        result<int> const r( in_place_error );
+
+        int x = r | fi2 | 3;
+
+        BOOST_TEST_EQ( x, 3 );
+    }
+
+    {
+        int x = result<int>( in_place_error ) | fi2 | 3;
+
+        BOOST_TEST_EQ( x, 3 );
+    }
+
+    {
+        Y y = result<X>( X{1} ) | fy | X{3};
+
+        BOOST_TEST_EQ( y.v_, 1 );
+    }
+
+    {
+        Y y = result<X>( X{1} ) | fy2 | X{3};
+
+        BOOST_TEST_EQ( y.v_, 1 );
+    }
+
+    {
+        Y y = result<X, E>( in_place_error ) | fy | X{3};
+
+        BOOST_TEST_EQ( y.v_, 2 );
+    }
+
+    {
+        Y y = result<X, E>( in_place_error ) | fy2 | Y{3};
+
+        BOOST_TEST_EQ( y.v_, 3 );
+    }
+
+    {
+        int x1 = 1;
+        int x3 = 3;
+
+        result<int&> r( x1 );
+
+        int& x = r | fri | x3;
+
+        BOOST_TEST_EQ( &x, &x1 );
+    }
+
+    {
+        int x1 = 1;
+        int x3 = 3;
+
+        result<int&> const r( x1 );
+
+        int& x = r | fri | x3;
+
+        BOOST_TEST_EQ( &x, &x1 );
+    }
+
+    {
+        int x1 = 1;
+        int x3 = 3;
+
+        int& x = result<int&>( x1 ) | fri | x3;
+
+        BOOST_TEST_EQ( &x, &x1 );
+    }
+
+    {
+        int x1 = 1;
+        int x3 = 3;
+
+        result<int&> r( x1 );
+
+        int& x = r | fri2 | x3;
+
+        BOOST_TEST_EQ( &x, &x1 );
+    }
+
+    {
+        int x1 = 1;
+        int x3 = 3;
+
+        result<int&> const r( x1 );
+
+        int& x = r | fri2 | x3;
+
+        BOOST_TEST_EQ( &x, &x1 );
+    }
+
+    {
+        int x1 = 1;
+        int x3 = 3;
+
+        int& x = result<int&>( x1 ) | fri2 | x3;
+
+        BOOST_TEST_EQ( &x, &x1 );
+    }
+
+    {
+        int x3 = 3;
+
+        result<int&, E> r( in_place_error );
+
+        int& x = r | fri | x3;
+
+        BOOST_TEST_EQ( &x, &*fri() );
+    }
+
+    {
+        int x3 = 3;
+
+        result<int&, E> const r( in_place_error );
+
+        int& x = r | fri | x3;
+
+        BOOST_TEST_EQ( &x, &*fri() );
+    }
+
+    {
+        int x3 = 3;
+
+        int& x = result<int&, E>( in_place_error ) | fri | x3;
+
+        BOOST_TEST_EQ( &x, &*fri() );
+    }
+
+    {
+        int x3 = 3;
+
+        result<int&, E> r( in_place_error );
+
+        int& x = r | fri2 | x3;
+
+        BOOST_TEST_EQ( &x, &x3 );
+    }
+
+    {
+        int x3 = 3;
+
+        result<int&, E> const r( in_place_error );
+
+        int& x = r | fri2 | x3;
+
+        BOOST_TEST_EQ( &x, &x3 );
+    }
+
+    {
+        int x3 = 3;
+
+        int& x = result<int&, E>( in_place_error ) | fri2 | x3;
+
+        BOOST_TEST_EQ( &x, &x3 );
+    }
+
+    {
+        result<void> r;
+        result<void, E> r2 = r | fv;
+
+        BOOST_TEST( r2.has_value() );
+    }
+
+    {
+        result<void> r;
+        result<void, E> r2 = r | fv2;
+
+        BOOST_TEST( r2.has_value() );
+    }
+
+    {
+        result<void> r( in_place_error );
+        result<void, E> r2 = r | fv;
+
+        BOOST_TEST( r2.has_value() );
+    }
+
+    {
+        result<void> r( in_place_error );
+        result<void, E> r2 = r | fv2;
+
+        BOOST_TEST( r2.has_error() );
+    }
+
+    return boost::report_errors();
+}