[Bug c++/94492] New: no way to silence -Wdeprecated-copy for aggregates

[Bug c++/94492] New: no way to silence -Wdeprecated-copy for aggregates

[nok.raven at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94492

            Bug ID: 94492
           Summary: no way to silence -Wdeprecated-copy for aggregates
           Product: gcc
           Version: 10.0
            Status: UNCONFIRMED
          Keywords: diagnostic
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: nok.raven at gmail dot com
  Target Milestone: ---

There is no way to silence the warning without making a type non-aggregate.
A simplified case from Boost.Proto:

#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wdeprecated-copy"
struct expr
{
    int a, b;
    expr& operator=(const expr&) { return *this; }
};
#pragma GCC diagnostic pop

#include <type_traits>
static_assert(std::is_aggregate_v<expr>);

expr foo(expr e)
{
    return e;
}

<source>: In function 'expr foo(expr)':
<source>:15:12: error: implicitly-declared 'constexpr expr::expr(const expr&)'
is deprecated [-Werror=deprecated-copy]
   15 |     return e;
      |            ^
<source>:6:11: note: because 'expr' has user-provided 'expr&
expr::operator=(const expr&)'
    6 |     expr& operator=(const expr&) { return *this; }
      |           ^~~~~~~~

[Bug c++/94492] no way to silence -Wdeprecated-copy for aggregates

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94492

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2020-04-06
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

[Bug c++/94492] no way to silence -Wdeprecated-copy for aggregates

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94492

Jason Merrill <jason at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |jason at gcc dot gnu.org
             Status|NEW                         |ASSIGNED
                 CC|                            |jason at gcc dot gnu.org

[Bug c++/94492] no way to silence -Wdeprecated-copy for aggregates

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94492

--- Comment #1 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jason Merrill <jason@gcc.gnu.org>:

https://gcc.gnu.org/g:620cd7861e1266991c9c2a82e1e2d5f4d723ec88

commit r12-1144-g620cd7861e1266991c9c2a82e1e2d5f4d723ec88
Author: Jason Merrill <jason@redhat.com>
Date:   Tue Apr 27 17:13:39 2021 -0400

    c++: -Wdeprecated-copy and #pragma diagnostic [PR94492]

    -Wdeprecated-copy was depending only on the state of the warning at the
    point where we call the function, making it hard to use #pragma diagnostic
    to suppress the warning for a particular implicitly declared function.

    But checking whether the warning is enabled at the location of the implicit
    declaration turned out to be a bit complicated; option_enabled only tests
    whether it was enabled at the start of compilation, the actual test only
    existed in the middle of diagnostic_report_diagnostic.  So this patch
    factors it out and adds a new warning_enabled function to diagnostic.h.

    gcc/ChangeLog:

            PR c++/94492
            * diagnostic.h (warning_enabled_at): Declare.
            * diagnostic.c (diagnostic_enabled): Factor out from...
            (diagnostic_report_diagnostic): ...here.
            (warning_enabled_at): New.

    gcc/cp/ChangeLog:

            PR c++/94492
            * decl2.c (cp_warn_deprecated_use): Check warning_enabled_at.

    gcc/testsuite/ChangeLog:

            PR c++/94492
            * g++.dg/cpp0x/depr-copy4.C: New test.

[Bug c++/94492] no way to silence -Wdeprecated-copy for aggregates

[nok.raven at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94492

--- Comment #2 from Nikita Kniazev <nok.raven at gmail dot com> ---
Could this be backported? The issue affects every release with
-Wdeprecated-copy, which are GCC 9+.

[Bug c++/94492] no way to silence -Wdeprecated-copy for aggregates

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=94492

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED
   Target Milestone|---                         |12.0

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed.