[Bug c++/59526] New: [C++11] Defaulted special member functions don't accept noexcept if a member has a non-trivial noexcept operator in the corresponding special member function

[Bug c++/59526] New: [C++11] Defaulted special member functions don't accept noexcept if a member has a non-trivial noexcept operator in the corresponding special member function

[bootsarehax at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59526

            Bug ID: 59526
           Summary: [C++11] Defaulted special member functions don't
                    accept noexcept if a member has a non-trivial noexcept
                    operator in the corresponding special member function
           Product: gcc
           Version: 4.8.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bootsarehax at gmail dot com

The following code fails for struct X on gcc 4.8.2 with:

bla.cpp:15:3: error: function ‘X::X()’ defaulted on its first declaration with
an exception-specification that differs from the implicit declaration ‘X::X()’
   X() noexcept = default;

bla.cpp:16:6: error: function ‘X& X::operator=(X&&)’ defaulted on its first
declaration with an exception-specification that differs from the implicit
declaration ‘X& X::operator=(X&&)’
   X& operator=(X&&) noexcept = default;

#include <type_traits>

template<bool b>
struct F {
  F() noexcept(b) {}
  F& operator=(F&&) noexcept(b) {return *this;}
};

struct Simple {
  Simple() noexcept {}
  Simple& operator=(Simple&&) noexcept {return *this;}
};

struct X {
  X() noexcept = default;
  X& operator=(X&&) noexcept = default;
  F<true> f;
};
struct X2 {
  X2() /* noexcept */ = default;
  X2& operator=(X2&&) /* noexcept */ = default;
  F<true> f;
};
struct X3 {
  X3() noexcept = default;
  X3& operator=(X3&&) noexcept = default;
  Simple f;
};

static_assert(std::is_nothrow_constructible<X>::value, "");
static_assert(std::is_nothrow_move_assignable<X>::value, "");
static_assert(std::is_nothrow_constructible<X2>::value, "");
static_assert(std::is_nothrow_move_assignable<X2>::value, "");
static_assert(std::is_nothrow_constructible<X3>::value, "");
static_assert(std::is_nothrow_move_assignable<X3>::value, "");

X2 shows that a noexcept function is implicitly generated. X3 shows that it is
necessary for the noexcept operator to depend on a template parameter to
trigger this behavior.
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idV645

Kai Tietz <ktietz at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ktietz at gcc dot gnu.org

--- Comment #2 from Kai Tietz <ktietz at gcc dot gnu.org> ---
Hmm, by this report I can't make much out of it.  To see the failure reported
in config.log for this test might be helpful.  I can't reproduce the issue by
building mingw-w64 based toolchain, so it seems to be something specific to
MinGW.org setup...

AFAICS might be the cause for this issue the lack of installed headers/runtime.
As you were using as prefix /mingw/local/, are you sure crt and headers are
installed in /mingw/local/mingw32/include and /mingw/local/mingw32/lib?

[Bug c++/59526] [C++11] Defaulted special member functions don't accept noexcept if a member has a non-trivial noexcept operator in the corresponding special member function

[redi at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59526

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2014-02-09
     Ever confirmed|0                           |1

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Trunk doesn't give the same errors, but fails two of the assertions:

n.cc:30:1: error: static assertion failed: 
 static_assert(std::is_nothrow_constructible<X>::value, "");
 ^
n.cc:31:1: error: static assertion failed: 
 static_assert(std::is_nothrow_move_assignable<X>::value, "");
 ^

[Bug c++/59526] [C++11] Defaulted special member functions don't accept noexcept if a member has a non-trivial noexcept operator in the corresponding special member function

[daniel.kruegler at googlemail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59526

--- Comment #2 from Daniel Krügler <daniel.kruegler at googlemail dot com> ---
(In reply to Jonathan Wakely from comment #1)
> Trunk doesn't give the same errors, but fails two of the assertions:
> 
> n.cc:30:1: error: static assertion failed: 
>  static_assert(std::is_nothrow_constructible<X>::value, "");

The reason seems to be that the compiler makes this a deleted function, arguing 

"'X::X() noexcept' is implicitly deleted because its exception-specification
does not match the implicit exception-specification 'noexcept
(<uninstantiated>)' X() noexcept = default;"

This looks incorrect to me.
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Subject: [Bug fortran/59395] [4.8 Regression] double free with procedure pointer component
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http://gcc.gnu.org/bugzilla/show_bug.cgi?idY395

--- Comment #5 from janus at gcc dot gnu.org ---
Pretty much a duplicate of PR 58803 after all.

[Bug c++/59526] [C++11] Defaulted special member functions don't accept noexcept if a member has a non-trivial noexcept operator in the corresponding special member function

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59526

Paolo Carlini <paolo.carlini at oracle dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |5.0

--- Comment #3 from Paolo Carlini <paolo.carlini at oracle dot com> ---
This is fixed for 5.0.

[Bug c++/59526] [C++11] Defaulted special member functions don't accept noexcept if a member has a non-trivial noexcept operator in the corresponding special member function

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59526

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Francois Dumont <fdumont@gcc.gnu.org>:

https://gcc.gnu.org/g:92456291849fe88303bbcab366f41dcd4a885ad5

commit r14-3926-g92456291849fe88303bbcab366f41dcd4a885ad5
Author: François Dumont <fdumont@gcc.gnu.org>
Date:   Wed Aug 23 19:15:43 2023 +0200

    libstdc++: [_GLIBCXX_INLINE_VERSION] Fix <format> friend declaration

    GCC do not consider the inline namespace in friend function declarations.
    This is PR c++/59526, we need to explicit this namespace.

    libstdc++-v3/ChangeLog:

            * include/std/format (std::__format::_Arg_store): Explicit version
            namespace on make_format_args friend declaration.

[Bug c++/59526] [C++11] Defaulted special member functions don't accept noexcept if a member has a non-trivial noexcept operator in the corresponding special member function

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59526

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-13 branch has been updated by Jonathan Wakely
<redi@gcc.gnu.org>:

https://gcc.gnu.org/g:0547f663ee09aa5887dcd1bb0ea48eba24a30485

commit r13-7917-g0547f663ee09aa5887dcd1bb0ea48eba24a30485
Author: François Dumont <fdumont@gcc.gnu.org>
Date:   Wed Aug 23 19:15:43 2023 +0200

    libstdc++: [_GLIBCXX_INLINE_VERSION] Fix <format> friend declaration

    GCC do not consider the inline namespace in friend function declarations.
    This is PR c++/59526, we need to explicit this namespace.

    libstdc++-v3/ChangeLog:

            * include/std/format (std::__format::_Arg_store): Explicit version
            namespace on make_format_args friend declaration.

    (cherry picked from commit 92456291849fe88303bbcab366f41dcd4a885ad5)