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From: "piotrwn1 at gmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/100667] New: std::tuple<A&&> cannot be constructed from A&&, if A not defined (only forward declared) Date: Wed, 19 May 2021 08:00:54 +0000 [thread overview] Message-ID: <bug-100667-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100667 Bug ID: 100667 Summary: std::tuple<A&&> cannot be constructed from A&&, if A not defined (only forward declared) Product: gcc Version: 11.1.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: piotrwn1 at gmail dot com Target Milestone: --- The following code stops working when switching from gcc10 to gcc11 (gcc11.1 and trunk too) (both c++17 and c++20): #include <utility> #include <tuple> class A; std::tuple<A&&> foo(A&& a) { return std::tuple<A&&>(std::move(a)); } It looks that std library code start requiring this to pass: std::is_nothrow_constructible<A&&, A>... Actually - I got this error when using gmock library (MOCK_METHOD), then I extracted the problem to get SSCCE. Error logs (https://godbolt.org/z/TqMar3Tn6): In file included from /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/bits/move.h:57, from /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/bits/stl_pair.h:59, from /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/utility:70, from <source>:1: /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/type_traits: In instantiation of 'struct std::is_nothrow_constructible<A&&, A>': /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/type_traits:133:12: required from 'struct std::__and_<std::is_nothrow_constructible<A&&, A> >' /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:649:66: required from 'static constexpr bool std::tuple<_Elements>::__nothrow_constructible() [with _UElements = {A}; _Elements = {A&&}]' /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:733:49: required from 'constexpr std::tuple<_Elements>::tuple(_UElements&& ...) [with _UElements = {A}; bool _Valid = true; typename std::enable_if<std::tuple<_Elements>::_TCC<_Valid>::__is_implicitly_constructible<_UElements ...>(), bool>::type <anonymous> = true; _Elements = {A&&}]' <source>:7:40: required from here /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/type_traits:971:25: error: invalid use of incomplete type 'class A' 971 | = __bool_constant<__is_nothrow_constructible(_Tp, _Args...)>; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <source>:4:7: note: forward declaration of 'class A' 4 | class A; | ^ In file included from <source>:2: /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple: In instantiation of 'static constexpr bool std::tuple<_Elements>::__nothrow_constructible() [with _UElements = {A}; _Elements = {A&&}]': /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:733:49: required from 'constexpr std::tuple<_Elements>::tuple(_UElements&& ...) [with _UElements = {A}; bool _Valid = true; typename std::enable_if<std::tuple<_Elements>::_TCC<_Valid>::__is_implicitly_constructible<_UElements ...>(), bool>::type <anonymous> = true; _Elements = {A&&}]' <source>:7:40: required from here /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:649:73: error: 'value' is not a member of 'std::__and_<std::is_nothrow_constructible<A&&, A> >' 649 | __and_<is_nothrow_constructible<_Elements, _UElements>...>::value; | ^~~~~ /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple: In instantiation of 'constexpr std::tuple<_Elements>::tuple(_UElements&& ...) [with _UElements = {A}; bool _Valid = true; typename std::enable_if<std::tuple<_Elements>::_TCC<_Valid>::__is_implicitly_constructible<_UElements ...>(), bool>::type <anonymous> = true; _Elements = {A&&}]': <source>:7:40: required from here /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:733:49: in 'constexpr' expansion of 'std::tuple<A&&>::__nothrow_constructible<A>()' /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:732:9: error: 'constexpr' call flows off the end of the function 732 | tuple(_UElements&&... __elements) | ^~~~~ ASM generation compiler returned: 1 In file included from /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/bits/move.h:57, from /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/bits/stl_pair.h:59, from /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/utility:70, from <source>:1: /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/type_traits: In instantiation of 'struct std::is_nothrow_constructible<A&&, A>': /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/type_traits:133:12: required from 'struct std::__and_<std::is_nothrow_constructible<A&&, A> >' /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:649:66: required from 'static constexpr bool std::tuple<_Elements>::__nothrow_constructible() [with _UElements = {A}; _Elements = {A&&}]' /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:733:49: required from 'constexpr std::tuple<_Elements>::tuple(_UElements&& ...) [with _UElements = {A}; bool _Valid = true; typename std::enable_if<std::tuple<_Elements>::_TCC<_Valid>::__is_implicitly_constructible<_UElements ...>(), bool>::type <anonymous> = true; _Elements = {A&&}]' <source>:7:40: required from here /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/type_traits:971:25: error: invalid use of incomplete type 'class A' 971 | = __bool_constant<__is_nothrow_constructible(_Tp, _Args...)>; | ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ <source>:4:7: note: forward declaration of 'class A' 4 | class A; | ^ In file included from <source>:2: /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple: In instantiation of 'static constexpr bool std::tuple<_Elements>::__nothrow_constructible() [with _UElements = {A}; _Elements = {A&&}]': /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:733:49: required from 'constexpr std::tuple<_Elements>::tuple(_UElements&& ...) [with _UElements = {A}; bool _Valid = true; typename std::enable_if<std::tuple<_Elements>::_TCC<_Valid>::__is_implicitly_constructible<_UElements ...>(), bool>::type <anonymous> = true; _Elements = {A&&}]' <source>:7:40: required from here /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:649:73: error: 'value' is not a member of 'std::__and_<std::is_nothrow_constructible<A&&, A> >' 649 | __and_<is_nothrow_constructible<_Elements, _UElements>...>::value; | ^~~~~ /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple: In instantiation of 'constexpr std::tuple<_Elements>::tuple(_UElements&& ...) [with _UElements = {A}; bool _Valid = true; typename std::enable_if<std::tuple<_Elements>::_TCC<_Valid>::__is_implicitly_constructible<_UElements ...>(), bool>::type <anonymous> = true; _Elements = {A&&}]': <source>:7:40: required from here /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:733:49: in 'constexpr' expansion of 'std::tuple<A&&>::__nothrow_constructible<A>()' /opt/compiler-explorer/gcc-11.1.0/include/c++/11.1.0/tuple:732:9: error: 'constexpr' call flows off the end of the function 732 | tuple(_UElements&&... __elements) | ^~~~~ Execution build compiler returned: 1
next reply other threads:[~2021-05-19 8:00 UTC|newest] Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top 2021-05-19 8:00 piotrwn1 at gmail dot com [this message] 2021-05-19 9:09 ` [Bug libstdc++/100667] [11/12 Regression] " redi at gcc dot gnu.org 2021-06-18 7:56 ` ostash at ostash dot kiev.ua 2021-07-28 7:07 ` rguenth at gcc dot gnu.org 2022-04-21 7:49 ` rguenth at gcc dot gnu.org 2023-05-29 10:05 ` [Bug libstdc++/100667] [11/12/13/14 " jakub at gcc dot gnu.org 2023-05-29 11:16 ` piotrwn1 at gmail dot com 2024-03-27 12:59 ` redi at gcc dot gnu.org 2024-03-27 13:36 ` redi at gcc dot gnu.org 2024-03-27 14:02 ` redi at gcc dot gnu.org 2024-03-27 14:03 ` redi at gcc dot gnu.org 2024-03-27 14:14 ` redi at gcc dot gnu.org 2024-03-27 17:44 ` redi at gcc dot gnu.org 2024-03-28 18:26 ` cvs-commit at gcc dot gnu.org 2024-03-28 22:33 ` [Bug libstdc++/100667] [11/12/13 " redi at gcc dot gnu.org 2024-05-01 20:31 ` cvs-commit at gcc dot gnu.org
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