Decay return type of r | x when r is result<T&>. Refs #128.

pdimov · pdimov · commit 1b74658f57ca · 2025-12-01T02:11:53.000+02:00
diff --git a/include/boost/system/result.hpp b/include/boost/system/result.hpp
@@ -919,9 +919,10 @@ template<class T, class E> struct is_result< result<T, E> >: std::true_type {};
 // result | value
 
 template<class T, class E, class U,
-    class En = typename std::enable_if<detail::is_value_convertible_to<U, T>::value>::type
+    class En = typename std::enable_if<std::is_convertible<U, typename std::decay<T>::type>::value>::type
 >
-T operator|( result<T, E> const& r, U&& u )
+typename std::decay<T>::type
+operator|( result<T, E> const& r, U&& u )
 {
     if( r )
     {
@@ -934,9 +935,10 @@ T operator|( result<T, E> const& r, U&& u )
 }
 
 template<class T, class E, class U,
-    class En = typename std::enable_if<detail::is_value_convertible_to<U, T>::value>::type
+    class En = typename std::enable_if<std::is_convertible<U, typename std::decay<T>::type>::value>::type
 >
-T operator|( result<T, E>&& r, U&& u )
+typename std::decay<T>::type
+operator|( result<T, E>&& r, U&& u )
 {
     if( r )
     {
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
@@ -165,8 +165,6 @@ boost_test(TYPE run SOURCES result_value_construct6.cpp)
 boost_test(TYPE run SOURCES result_value_construct7.cpp)
 boost_test(TYPE run SOURCES result_error_construct5.cpp)
 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)
 boost_test(TYPE run SOURCES result_and_fn1v.cpp)
diff --git a/test/Jamfile.v2 b/test/Jamfile.v2
@@ -198,8 +198,6 @@ run result_value_construct6.cpp ;
 run result_value_construct7.cpp ;
 run result_error_construct5.cpp ;
 run result_or_value.cpp ;
-compile-fail result_or_value_fail.cpp ;
-compile-fail result_or_value_fail2.cpp ;
 run result_or_fn0v.cpp ;
 run result_or_fn0r.cpp ;
 run result_and_fn1v.cpp ;
diff --git a/test/result_or_fn0r.cpp b/test/result_or_fn0r.cpp
@@ -191,120 +191,102 @@ int main()
 
     {
         int x1 = 1;
-        int x3 = 3;
 
         result<int&> r( x1 );
 
-        int& x = r | fri | x3;
+        auto r2 = r | fri;
 
-        BOOST_TEST_EQ( &x, &x1 );
+        BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );
     }
 
     {
         int x1 = 1;
-        int x3 = 3;
 
         result<int&> const r( x1 );
 
-        int& x = r | fri | x3;
+        auto r2 = r | fri;
 
-        BOOST_TEST_EQ( &x, &x1 );
+        BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );
     }
 
     {
         int x1 = 1;
-        int x3 = 3;
 
-        int& x = result<int&>( x1 ) | fri | x3;
+        auto r2 = result<int&>( x1 ) | fri;
 
-        BOOST_TEST_EQ( &x, &x1 );
+        BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );
     }
 
     {
         int x1 = 1;
-        int x3 = 3;
 
         result<int&> r( x1 );
 
-        int& x = r | fri2 | x3;
+        auto r2 = r | fri2;
 
-        BOOST_TEST_EQ( &x, &x1 );
+        BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );
     }
 
     {
         int x1 = 1;
-        int x3 = 3;
 
         result<int&> const r( x1 );
 
-        int& x = r | fri2 | x3;
+        auto r2 = r | fri2;
 
-        BOOST_TEST_EQ( &x, &x1 );
+        BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );
     }
 
     {
         int x1 = 1;
-        int x3 = 3;
 
-        int& x = result<int&>( x1 ) | fri2 | x3;
+        auto r2 = result<int&>( x1 ) | fri2;
 
-        BOOST_TEST_EQ( &x, &x1 );
+        BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );
     }
 
     {
-        int x3 = 3;
-
         result<int&, E> r( in_place_error );
 
-        int& x = r | fri | x3;
+        auto r2 = r | fri;
 
-        BOOST_TEST_EQ( &x, &*fri() );
+        BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &*fri() );
     }
 
     {
-        int x3 = 3;
-
         result<int&, E> const r( in_place_error );
 
-        int& x = r | fri | x3;
+        auto r2 = r | fri;
 
-        BOOST_TEST_EQ( &x, &*fri() );
+        BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &*fri() );
     }
 
     {
-        int x3 = 3;
-
-        int& x = result<int&, E>( in_place_error ) | fri | x3;
+        auto r2 = result<int&, E>( in_place_error ) | fri;
 
-        BOOST_TEST_EQ( &x, &*fri() );
+        BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &*fri() );
     }
 
     {
-        int x3 = 3;
-
         result<int&, E> r( in_place_error );
 
-        int& x = r | fri2 | x3;
+        auto r2 = r | fri2;
 
-        BOOST_TEST_EQ( &x, &x3 );
+        BOOST_TEST( r2.has_error() );
     }
 
     {
-        int x3 = 3;
-
         result<int&, E> const r( in_place_error );
 
-        int& x = r | fri2 | x3;
+        auto r2 = r | fri2;
 
-        BOOST_TEST_EQ( &x, &x3 );
+        BOOST_TEST( r2.has_error() );
     }
 
     {
-        int x3 = 3;
+        auto r2 = result<int&, E>( in_place_error ) | fri2;
 
-        int& x = result<int&, E>( in_place_error ) | fri2 | x3;
-
-        BOOST_TEST_EQ( &x, &x3 );
+        BOOST_TEST( r2.has_error() );
     }
 
     {
diff --git a/test/result_or_value.cpp b/test/result_or_value.cpp
@@ -4,6 +4,8 @@
 
 #include <boost/system/result.hpp>
 #include <boost/core/lightweight_test.hpp>
+#include <boost/core/lightweight_test_trait.hpp>
+#include <type_traits>
 
 using namespace boost::system;
 
@@ -110,9 +112,22 @@ int main()
 
         result<int&> r( x1 );
 
-        int& x = r | x2;
+        {
+            auto&& x3 = r | x2;
 
-        BOOST_TEST_EQ( &x, &x1 );
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype(x3)> ));
+
+            BOOST_TEST_EQ( x3, x1 );
+            BOOST_TEST_NE( &x3, &x1 );
+        }
+
+        {
+            auto&& x4 = r | 3;
+
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype( x4 )> ));
+
+            BOOST_TEST_EQ( x4, x1 );
+        }
     }
 
     {
@@ -121,46 +136,111 @@ int main()
 
         result<int&> const r( x1 );
 
-        int& x = r | x2;
+        {
+            auto&& x3 = r | x2;
+
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype(x3)> ));
+
+            BOOST_TEST_EQ( x3, x1 );
+            BOOST_TEST_NE( &x3, &x1 );
+        }
 
-        BOOST_TEST_EQ( &x, &x1 );
+        {
+            auto&& x4 = r | 3;
+
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype( x4 )> ));
+
+            BOOST_TEST_EQ( x4, x1 );
+        }
     }
 
     {
         int x1 = 1;
         int x2 = 2;
 
-        int& x = result<int&>( x1 ) | x2;
+        {
+            auto&& x3 = result<int&>( x1 ) | x2;
+
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype(x3)> ));
+
+            BOOST_TEST_EQ( x3, x1 );
+            BOOST_TEST_NE( &x3, &x1 );
+        }
+
+        {
+            auto&& x4 = result<int&>( x1 ) | 3;
+
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype( x4 )> ));
 
-        BOOST_TEST_EQ( &x, &x1 );
+            BOOST_TEST_EQ( x4, x1 );
+        }
     }
 
     {
         int x2 = 2;
 
         result<int&, E> r( in_place_error );
 
-        int& x = r | x2;
+        {
+            auto&& x3 = r | x2;
 
-        BOOST_TEST_EQ( &x, &x2 );
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype(x3)> ));
+
+            BOOST_TEST_EQ( x3, x2 );
+            BOOST_TEST_NE( &x3, &x2 );
+        }
+
+        {
+            auto&& x4 = r | 3;
+
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype( x4 )> ));
+
+            BOOST_TEST_EQ( x4, 3 );
+        }
     }
 
     {
         int x2 = 2;
 
         result<int&, E> const r( in_place_error );
 
-        int& x = r | x2;
+        {
+            auto&& x3 = r | x2;
+
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype(x3)> ));
+
+            BOOST_TEST_EQ( x3, x2 );
+            BOOST_TEST_NE( &x3, &x2 );
+        }
 
-        BOOST_TEST_EQ( &x, &x2 );
+        {
+            auto&& x4 = r | 3;
+
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype( x4 )> ));
+
+            BOOST_TEST_EQ( x4, 3 );
+        }
     }
 
     {
         int x2 = 2;
 
-        int& x = result<int&, E>( in_place_error ) | x2;
+        {
+            auto&& x3 = result<int&, E>( in_place_error ) | x2;
+
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype(x3)> ));
+
+            BOOST_TEST_EQ( x3, x2 );
+            BOOST_TEST_NE( &x3, &x2 );
+        }
+
+        {
+            auto&& x4 = result<int&, E>( in_place_error ) | 3;
+
+            BOOST_TEST_TRAIT_FALSE(( std::is_lvalue_reference<decltype( x4 )> ));
 
-        BOOST_TEST_EQ( &x, &x2 );
+            BOOST_TEST_EQ( x4, 3 );
+        }
     }
 
     return boost::report_errors();
diff --git a/test/result_or_value_fail.cpp b/test/result_or_value_fail.cpp
diff --git a/test/result_or_value_fail2.cpp b/test/result_or_value_fail2.cpp

Original file line number	Diff line number	Diff line change
`@@ -919,9 +919,10 @@ template<class T, class E> struct is_result< result<T, E> >: std::true_type {};`
`919`	`919`	`// result \| value`
`920`	`920`
`921`	`921`	`template<class T, class E, class U,`
`922`		`- class En = typename std::enable_if<detail::is_value_convertible_to<U, T>::value>::type`
	`922`	`+ class En = typename std::enable_if<std::is_convertible<U, typename std::decay<T>::type>::value>::type`
`923`	`923`	`>`
`924`		`-T operator\|( result<T, E> const& r, U&& u )`
	`924`	`+typename std::decay<T>::type`
	`925`	`+operator\|( result<T, E> const& r, U&& u )`
`925`	`926`	`{`
`926`	`927`	`if( r )`
`927`	`928`	`{`
`@@ -934,9 +935,10 @@ T operator\|( result<T, E> const& r, U&& u )`
`934`	`935`	`}`
`935`	`936`
`936`	`937`	`template<class T, class E, class U,`
`937`		`- class En = typename std::enable_if<detail::is_value_convertible_to<U, T>::value>::type`
	`938`	`+ class En = typename std::enable_if<std::is_convertible<U, typename std::decay<T>::type>::value>::type`
`938`	`939`	`>`
`939`		`-T operator\|( result<T, E>&& r, U&& u )`
	`940`	`+typename std::decay<T>::type`
	`941`	`+operator\|( result<T, E>&& r, U&& u )`
`940`	`942`	`{`
`941`	`943`	`if( r )`
`942`	`944`	`{`
Original file line number	Diff line number	Diff line change
`@@ -191,120 +191,102 @@ int main()`
`191`	`191`
`192`	`192`	`{`
`193`	`193`	`int x1 = 1;`
`194`		`- int x3 = 3;`
`195`	`194`
`196`	`195`	`result<int&> r( x1 );`
`197`	`196`
`198`		`- int& x = r \| fri \| x3;`
	`197`	`+ auto r2 = r \| fri;`
`199`	`198`
`200`		`- BOOST_TEST_EQ( &x, &x1 );`
	`199`	`+ BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );`
`201`	`200`	`}`
`202`	`201`
`203`	`202`	`{`
`204`	`203`	`int x1 = 1;`
`205`		`- int x3 = 3;`
`206`	`204`
`207`	`205`	`result<int&> const r( x1 );`
`208`	`206`
`209`		`- int& x = r \| fri \| x3;`
	`207`	`+ auto r2 = r \| fri;`
`210`	`208`
`211`		`- BOOST_TEST_EQ( &x, &x1 );`
	`209`	`+ BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );`
`212`	`210`	`}`
`213`	`211`
`214`	`212`	`{`
`215`	`213`	`int x1 = 1;`
`216`		`- int x3 = 3;`
`217`	`214`
`218`		`- int& x = result<int&>( x1 ) \| fri \| x3;`
	`215`	`+ auto r2 = result<int&>( x1 ) \| fri;`
`219`	`216`
`220`		`- BOOST_TEST_EQ( &x, &x1 );`
	`217`	`+ BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );`
`221`	`218`	`}`
`222`	`219`
`223`	`220`	`{`
`224`	`221`	`int x1 = 1;`
`225`		`- int x3 = 3;`
`226`	`222`
`227`	`223`	`result<int&> r( x1 );`
`228`	`224`
`229`		`- int& x = r \| fri2 \| x3;`
	`225`	`+ auto r2 = r \| fri2;`
`230`	`226`
`231`		`- BOOST_TEST_EQ( &x, &x1 );`
	`227`	`+ BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );`
`232`	`228`	`}`
`233`	`229`
`234`	`230`	`{`
`235`	`231`	`int x1 = 1;`
`236`		`- int x3 = 3;`
`237`	`232`
`238`	`233`	`result<int&> const r( x1 );`
`239`	`234`
`240`		`- int& x = r \| fri2 \| x3;`
	`235`	`+ auto r2 = r \| fri2;`
`241`	`236`
`242`		`- BOOST_TEST_EQ( &x, &x1 );`
	`237`	`+ BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );`
`243`	`238`	`}`
`244`	`239`
`245`	`240`	`{`
`246`	`241`	`int x1 = 1;`
`247`		`- int x3 = 3;`
`248`	`242`
`249`		`- int& x = result<int&>( x1 ) \| fri2 \| x3;`
	`243`	`+ auto r2 = result<int&>( x1 ) \| fri2;`
`250`	`244`
`251`		`- BOOST_TEST_EQ( &x, &x1 );`
	`245`	`+ BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &*r2, &x1 );`
`252`	`246`	`}`
`253`	`247`
`254`	`248`	`{`
`255`		`- int x3 = 3;`
`256`		`-`
`257`	`249`	`result<int&, E> r( in_place_error );`
`258`	`250`
`259`		`- int& x = r \| fri \| x3;`
	`251`	`+ auto r2 = r \| fri;`
`260`	`252`
`261`		`- BOOST_TEST_EQ( &x, &*fri() );`
	`253`	`+ BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &r2, &fri() );`
`262`	`254`	`}`
`263`	`255`
`264`	`256`	`{`
`265`		`- int x3 = 3;`
`266`		`-`
`267`	`257`	`result<int&, E> const r( in_place_error );`
`268`	`258`
`269`		`- int& x = r \| fri \| x3;`
	`259`	`+ auto r2 = r \| fri;`
`270`	`260`
`271`		`- BOOST_TEST_EQ( &x, &*fri() );`
	`261`	`+ BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &r2, &fri() );`
`272`	`262`	`}`
`273`	`263`
`274`	`264`	`{`
`275`		`- int x3 = 3;`
`276`		`-`
`277`		`- int& x = result<int&, E>( in_place_error ) \| fri \| x3;`
	`265`	`+ auto r2 = result<int&, E>( in_place_error ) \| fri;`
`278`	`266`
`279`		`- BOOST_TEST_EQ( &x, &*fri() );`
	`267`	`+ BOOST_TEST( r2.has_value() ) && BOOST_TEST_EQ( &r2, &fri() );`
`280`	`268`	`}`
`281`	`269`
`282`	`270`	`{`
`283`		`- int x3 = 3;`
`284`		`-`
`285`	`271`	`result<int&, E> r( in_place_error );`
`286`	`272`
`287`		`- int& x = r \| fri2 \| x3;`
	`273`	`+ auto r2 = r \| fri2;`
`288`	`274`
`289`		`- BOOST_TEST_EQ( &x, &x3 );`
	`275`	`+ BOOST_TEST( r2.has_error() );`
`290`	`276`	`}`
`291`	`277`
`292`	`278`	`{`
`293`		`- int x3 = 3;`
`294`		`-`
`295`	`279`	`result<int&, E> const r( in_place_error );`
`296`	`280`
`297`		`- int& x = r \| fri2 \| x3;`
	`281`	`+ auto r2 = r \| fri2;`
`298`	`282`
`299`		`- BOOST_TEST_EQ( &x, &x3 );`
	`283`	`+ BOOST_TEST( r2.has_error() );`
`300`	`284`	`}`
`301`	`285`
`302`	`286`	`{`
`303`		`- int x3 = 3;`
	`287`	`+ auto r2 = result<int&, E>( in_place_error ) \| fri2;`
`304`	`288`
`305`		`- int& x = result<int&, E>( in_place_error ) \| fri2 \| x3;`
`306`		`-`
`307`		`- BOOST_TEST_EQ( &x, &x3 );`
	`289`	`+ BOOST_TEST( r2.has_error() );`
`308`	`290`	`}`
`309`	`291`
`310`	`292`	`{`