[Bug c++/99507] New: Can't return static address from immediate function

[Bug c++/99507] New: Can't return static address from immediate function

[johelegp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99507

            Bug ID: 99507
           Summary: Can't return static address from immediate function
           Product: gcc
           Version: 11.0
               URL: https://godbolt.org/z/vnPToT
            Status: UNCONFIRMED
          Keywords: rejects-valid
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: johelegp at gmail dot com
                CC: johelegp at gmail dot com
  Target Milestone: ---

See https://godbolt.org/z/vnPToT.
```C++
constexpr int i{0};
consteval const int& iref() { return i; }
[[maybe_unused]] constexpr const int* a{&iref()};
```

[Bug c++/99507] Can't return static address from immediate function

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99507

Jakub Jelinek <jakub at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2021-03-10
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |jakub at gcc dot gnu.org

--- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Created attachment 50351
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=50351&action=edit
gcc11-pr99507.patch

Untested fix.

[Bug c++/99507] Can't return static address from immediate function

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99507

--- Comment #2 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jakub Jelinek <jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:425afe1f0c907e6469cef1672160c9c95177e71a

commit r11-7645-g425afe1f0c907e6469cef1672160c9c95177e71a
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Mar 12 10:11:24 2021 +0100

    c++: Fix up calls to immediate functions returning reference [PR99507]

    build_cxx_call calls convert_from_reference at the end, so if an immediate
    function returns a reference, we were constant evaluating not just that
    call, but that call wrapped in an INDIRECT_REF.  That unfortunately means
    it can constant evaluate to something non-addressable, so if code later
    needs to take its address it will fail.

    The following patch fixes that by undoing the convert_from_reference
    wrapping for the cxx_constant_value evaluation and readdding it ad the end.

    2021-03-12  Jakub Jelinek  <jakub@redhat.com>

            PR c++/99507
            * call.c (build_over_call): For immediate evaluation of functions
            that return references, undo convert_from_reference effects before
            calling cxx_constant_value and call convert_from_reference
            afterwards.

            * g++.dg/cpp2a/consteval19.C: New test.

[Bug c++/99507] Can't return static address from immediate function

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99507

--- Comment #3 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
Fixed on the trunk so far.  Should be backported to 10 later.

[Bug c++/99507] Can't return static address from immediate function

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99507

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jakub Jelinek
<jakub@gcc.gnu.org>:

https://gcc.gnu.org/g:3ef0d71f64408b527169a740ea7dc5f4d169b0b6

commit r10-9484-g3ef0d71f64408b527169a740ea7dc5f4d169b0b6
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Mar 12 10:11:24 2021 +0100

    c++: Fix up calls to immediate functions returning reference [PR99507]

    build_cxx_call calls convert_from_reference at the end, so if an immediate
    function returns a reference, we were constant evaluating not just that
    call, but that call wrapped in an INDIRECT_REF.  That unfortunately means
    it can constant evaluate to something non-addressable, so if code later
    needs to take its address it will fail.

    The following patch fixes that by undoing the convert_from_reference
    wrapping for the cxx_constant_value evaluation and readdding it ad the end.

    2021-03-12  Jakub Jelinek  <jakub@redhat.com>

            PR c++/99507
            * call.c (build_over_call): For immediate evaluation of functions
            that return references, undo convert_from_reference effects before
            calling cxx_constant_value and call convert_from_reference
            afterwards.

            * g++.dg/cpp2a/consteval19.C: New test.

    (cherry picked from commit 425afe1f0c907e6469cef1672160c9c95177e71a)

[Bug c++/99507] Can't return static address from immediate function

[johelegp at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99507

Johel Ernesto Guerrero Peña <johelegp at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |RESOLVED
      Known to work|                            |10.3.0, 11.1.0
         Resolution|---                         |FIXED
      Known to fail|                            |10.2.0

--- Comment #5 from Johel Ernesto Guerrero Peña <johelegp at gmail dot com> ---
Thank you.

[Bug c++/99507] Can't return static address from immediate function

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99507

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |10.3