[Bug c++/98305] New: Incomprehensible -Wmismatched-new-delete warning

[Bug c++/98305] New: Incomprehensible -Wmismatched-new-delete warning

[sbergman at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98305

            Bug ID: 98305
           Summary: Incomprehensible -Wmismatched-new-delete warning
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sbergman at redhat dot com
  Target Milestone: ---

With recent GCC 11 trunk (at git commit
8dede2411195eb2fd672d8d0c758f94732bd6d77):

> $ cat test.cc
> #include <cstddef>
> template<typename> struct Reference {};
> template<typename> struct S2 {
>   static void * operator new(std::size_t);
>   static void operator delete(void *);
>   S2();
> };
> void f() { new S2<Reference<int>>; }

> $ g++ -Wmismatched-new-delete -c test.cc
> test.cc: In function ‘void f()’:
> test.cc:8:16: warning: ‘static void S2< <template-parameter-1-1> >::operator delete(void*) [with <template-parameter-1-1> = Reference<int>]’ called on pointer returned from a mismatched allocation function [-Wmismatched-new-delete]
>     8 | void f() { new S2<Reference<int>>; }
>       |                ^~~~~~~~~~~~~~~~~~
> test.cc:8:16: note: returned from ‘static void* S2< <template-parameter-1-1> >::operator new(std::size_t) [with <template-parameter-1-1> = Reference<int>]’

(And oddly enough, the warning disappears when Reference is renamed to e.g.
S1.)

[Bug c++/98305] Incomprehensible -Wmismatched-new-delete warning

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98305

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
           Keywords|                            |diagnostic
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2020-12-16
   Target Milestone|---                         |11.0
                 CC|                            |msebor at gcc dot gnu.org

--- Comment #1 from Martin Sebor <msebor at gcc dot gnu.org> ---
The warning compares the mangled names of the operators and doesn't interpret
template instantiations quite correctly.

[Bug c++/98305] Incomprehensible -Wmismatched-new-delete warning

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98305

Martin Sebor <msebor at gcc dot gnu.org> changed:

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

[Bug c++/98305] spurious -Wmismatched-new-delete on template instance

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98305

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|Incomprehensible            |spurious
                   |-Wmismatched-new-delete     |-Wmismatched-new-delete on
                   |warning                     |template instance
           Keywords|                            |patch

--- Comment #2 from Martin Sebor <msebor at gcc dot gnu.org> ---
https://gcc.gnu.org/pipermail/gcc-patches/2020-December/562141.html

[Bug c++/98305] spurious -Wmismatched-new-delete on template instance

[sbergman at redhat dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98305

--- Comment #3 from Stephan Bergmann <sbergman at redhat dot com> ---
(In reply to Martin Sebor from comment #2)
> https://gcc.gnu.org/pipermail/gcc-patches/2020-December/562141.html

Thanks; can confirm that fixes my LibreOffice build.

[Bug c++/98305] spurious -Wmismatched-new-delete on template instance

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98305

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

https://gcc.gnu.org/g:fd64f348a6b40621dc2bcc743f5fdfb31ed0894c

commit r11-6507-gfd64f348a6b40621dc2bcc743f5fdfb31ed0894c
Author: Martin Sebor <msebor@redhat.com>
Date:   Wed Jan 6 13:36:18 2021 -0700

    PR c++/98305 spurious -Wmismatched-new-delete on template instance

    gcc/ChangeLog:

            PR c++/98305
            * builtins.c (new_delete_mismatch_p): New overload.
            (new_delete_mismatch_p (tree, tree)): Call it.

    gcc/testsuite/ChangeLog:

            PR c++/98305
            * g++.dg/warn/Wmismatched-new-delete-3.C: New test.

[Bug c++/98305] spurious -Wmismatched-new-delete on template instance

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98305

Martin Sebor <msebor at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
         Resolution|---                         |FIXED

--- Comment #5 from Martin Sebor <msebor at gcc dot gnu.org> ---
Committed in r11-6507.