[Bug c++/59950] New: Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary

[Bug c++/59950] New: Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary

[richard-gccbugzilla at metafoo dot co.uk]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

            Bug ID: 59950
           Summary: Bogus diagnostic "taking address of temporary" taking
                    address of trivial no-op assignment to temporary
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: richard-gccbugzilla at metafoo dot co.uk

GCC rejects this valid code:

 struct Foo {};
 int f(Foo *p);
 int n = f(&(Foo() = Foo()));

... saying ...

<stdin>:3:27: error: taking address of temporary [-fpermissive]

The incorrect diagnostic only appears if 'Foo' is empty and its assignment
operator is defaulted. (Maybe the assignment is getting folded away before the
check is performed?)

Google ref b/12744615

[Bug c++/59950] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary

[richard-gccbugzilla at metafoo dot co.uk]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

--- Comment #1 from Richard Smith <richard-gccbugzilla at metafoo dot co.uk> ---
Additional clarification was requested: "Foo() = Foo()" means
"Foo().operator=(Foo())". The 'operator=' has return type 'Foo&', thus that
expression is not a temporary.

[Bug c++/59950] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary

[paolo.carlini at oracle dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-03-19
     Ever confirmed|0                           |1

[Bug c++/59950] [9/10/11/12 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Martin Sebor from comment #2)
> The current top of 6.0 trunk still issues the bogus diagnostic.  Confirming
> also with prior versions.

Note this example is different as it worked in 4.6.4 but the first example
failed in 4.6.4.

[Bug c++/59950] [9/10/11/12 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Martin Sebor from comment #2)
> The current top of 6.0 trunk still issues the bogus diagnostic.  Confirming
> also with prior versions.

Actually this example is invalid code as DR 1312 (which was recorded as PR
79832, see that bug for it was fixed in GCC 9+).

[Bug c++/59950] [9/10/11/12 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |9.5

[Bug c++/59950] [9/10/11/12 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

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

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

[Bug c++/59950] [9/10/11/12 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

--- Comment #5 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:fe5cee6f62a0b229d9d51616b7490331d39b5ddd

commit r12-6862-gfe5cee6f62a0b229d9d51616b7490331d39b5ddd
Author: Jason Merrill <jason@redhat.com>
Date:   Mon Jan 24 00:01:40 2022 -0500

    c++: assignment to temporary [PR59950]

    Given build_this of a TARGET_EXPR, cp_build_fold_indirect_ref returns the
    TARGET_EXPR.  But that's the wrong value category for the result of the
    defaulted class assignment operator, which returns an lvalue, so we need to
    actually build the INDIRECT_REF.

            PR c++/59950

    gcc/cp/ChangeLog:

            * call.cc (build_over_call): Use cp_build_indirect_ref.

    gcc/testsuite/ChangeLog:

            * g++.dg/init/assign2.C: New test.

[Bug c++/59950] [9/10/11 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[9/10/11/12 Regression]     |[9/10/11 Regression] Bogus
                   |Bogus diagnostic "taking    |diagnostic "taking address
                   |address of temporary"       |of temporary" taking
                   |taking address of trivial   |address of trivial no-op
                   |no-op assignment to         |assignment to temporary
                   |temporary with empty class  |with empty class

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for GCC 12 so far.

[Bug c++/59950] [9/10/11 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

Patrick Palka <ppalka at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |aschepler at gmail dot com

--- Comment #7 from Patrick Palka <ppalka at gcc dot gnu.org> ---
*** Bug 54319 has been marked as a duplicate of this bug. ***

[Bug c++/59950] [9/10/11 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

--- Comment #8 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-11 branch has been updated by Jason Merrill
<jason@gcc.gnu.org>:

https://gcc.gnu.org/g:cb123480984d49c6a6e81b026633fc8ffff7883e

commit r11-9681-gcb123480984d49c6a6e81b026633fc8ffff7883e
Author: Jason Merrill <jason@redhat.com>
Date:   Mon Jan 24 00:01:40 2022 -0500

    c++: assignment to temporary [PR59950]

    Given build_this of a TARGET_EXPR, cp_build_fold_indirect_ref returns the
    TARGET_EXPR.  But that's the wrong value category for the result of the
    defaulted class assignment operator, which returns an lvalue, so we need to
    actually build the INDIRECT_REF.

            PR c++/59950

    gcc/cp/ChangeLog:

            * call.c (build_over_call): Use cp_build_indirect_ref.

    gcc/testsuite/ChangeLog:

            * g++.dg/init/assign2.C: New test.

[Bug c++/59950] [9/10 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[9/10/11 Regression] Bogus  |[9/10 Regression] Bogus
                   |diagnostic "taking address  |diagnostic "taking address
                   |of temporary" taking        |of temporary" taking
                   |address of trivial no-op    |address of trivial no-op
                   |assignment to temporary     |assignment to temporary
                   |with empty class            |with empty class

--- Comment #9 from Jason Merrill <jason at gcc dot gnu.org> ---
And 11.3

[Bug c++/59950] [9/10 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

--- Comment #10 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Jason Merrill
<jason@gcc.gnu.org>:

https://gcc.gnu.org/g:080e737a851d57697d0aac55749296c5c454c421

commit r10-10723-g080e737a851d57697d0aac55749296c5c454c421
Author: Jason Merrill <jason@redhat.com>
Date:   Mon Jan 24 00:01:40 2022 -0500

    c++: assignment to temporary [PR59950]

    Given build_this of a TARGET_EXPR, cp_build_fold_indirect_ref returns the
    TARGET_EXPR.  But that's the wrong value category for the result of the
    defaulted class assignment operator, which returns an lvalue, so we need to
    actually build the INDIRECT_REF.

            PR c++/59950

    gcc/cp/ChangeLog:

            * call.c (build_over_call): Use cp_build_indirect_ref.

    gcc/testsuite/ChangeLog:

            * g++.dg/init/assign2.C: New test.

[Bug c++/59950] [9 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

--- Comment #11 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-9 branch has been updated by Jason Merrill
<jason@gcc.gnu.org>:

https://gcc.gnu.org/g:3daf541e8fe2dd0807a3dd49a9b8c065d7d46731

commit r9-10170-g3daf541e8fe2dd0807a3dd49a9b8c065d7d46731
Author: Jason Merrill <jason@redhat.com>
Date:   Mon Jan 24 00:01:40 2022 -0500

    c++: assignment to temporary [PR59950]

    Given build_this of a TARGET_EXPR, cp_build_fold_indirect_ref returns the
    TARGET_EXPR.  But that's the wrong value category for the result of the
    defaulted class assignment operator, which returns an lvalue, so we need to
    actually build the INDIRECT_REF.

            PR c++/59950

    gcc/cp/ChangeLog:

            * call.c (build_over_call): Use cp_build_indirect_ref.

    gcc/testsuite/ChangeLog:

            * g++.dg/init/assign2.C: New test.

[Bug c++/59950] [9 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

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

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

--- Comment #12 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 9.5/10.4/11.3/12.

[Bug c++/59950] [9 Regression] Bogus diagnostic "taking address of temporary" taking address of trivial no-op assignment to temporary with empty class

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=59950

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jlame646 at gmail dot com

--- Comment #13 from Jonathan Wakely <redi at gcc dot gnu.org> ---
*** Bug 106489 has been marked as a duplicate of this bug. ***