[Bug c++/102651] New: typeid(X**) instantiates X

[Bug c++/102651] New: typeid(X**) instantiates X

[pdimov at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

            Bug ID: 102651
           Summary: typeid(X**) instantiates X
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pdimov at gmail dot com
  Target Milestone: ---

Using f.ex. `typeid(std:pair<void, void>**)` tries to instantiate
`std::pair<int, int>` and fails: https://godbolt.org/z/GhbYe3P8j

(One asterisk should be enough, but doesn't work either.)

The example without pair is

```
#include <typeinfo>

template <typename T>
struct S{
    T x;
};

void foo()
{
    typeid( S<void>** );
}
```

https://godbolt.org/z/nG3Kr3Te7

Interestingly, if `S` is incomplete, it works:

```
#include <typeinfo>

template <typename T>
struct S;

void foo()
{
    typeid( S<void>** );
}
```

https://godbolt.org/z/nK8b5n1qn

[Bug c++/102651] [9/10/11/12 Regression] typeid(X**) instantiates X

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |rejects-valid
            Summary|typeid(X**) instantiates X  |[9/10/11/12 Regression]
                   |                            |typeid(X**) instantiates X
   Target Milestone|---                         |9.5

[Bug c++/102651] [9/10/11/12 Regression] typeid(X**) instantiates X

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-10-08
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.  I thought I had saw another bug like this bug I can't seem to find
it.

[Bug c++/102651] [9/10/11/12 Regression] typeid(X**) instantiates X caused by r0-109856

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug c++/102651] [9/10/11/12 Regression] typeid(X**) instantiates X caused by r0-109856

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

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

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

--- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> ---
Created attachment 52817
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=52817&action=edit
fix

Here's a fix, but I'm going to hold it for stage 1, probably backport for 12.2
etc.

[Bug c++/102651] [9/10/11/12 Regression] typeid(X**) instantiates X caused by r0-109856

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

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

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

[Bug c++/102651] [9/10/11/12/13 Regression] typeid(X**) instantiates X caused by r0-109856

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

--- Comment #3 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:97b30a399ef561f6f37a2c08c830fdf3141bb504

commit r13-24-g97b30a399ef561f6f37a2c08c830fdf3141bb504
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Apr 15 00:11:00 2022 -0400

    c++: typeid and instantiation [PR102651]

    PR49387 was a problem with initially asking for a typeid for a class
    template specialization before it was complete, and later actually filling
    in the descriptor when the class was complete, and thus disagreeing on the
    form of the descriptor.  I fixed that by forcing the class to be complete,
    but this testcase shows why that approach is problematic.  So instead let's
    adjust the type of the descriptor later if needed.

            PR c++/102651
            PR c++/49387

    gcc/cp/ChangeLog:

            * rtti.cc (get_tinfo_decl_direct): Don't complete_type.
            (emit_tinfo_decl): Update tdesc type if needed.

    gcc/testsuite/ChangeLog:

            * g++.dg/rtti/typeid-complete1.C: New test.

[Bug c++/102651] [9/10/11/12 Regression] typeid(X**) instantiates X caused by r0-109856

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

--- Comment #4 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Jason Merrill
<jason@gcc.gnu.org>:

https://gcc.gnu.org/g:5237059e04d105fe5441fa7434699eea9a34bf1b

commit r12-8378-g5237059e04d105fe5441fa7434699eea9a34bf1b
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Apr 15 00:11:00 2022 -0400

    c++: typeid and instantiation [PR102651]

    PR49387 was a problem with initially asking for a typeid for a class
    template specialization before it was complete, and later actually filling
    in the descriptor when the class was complete, and thus disagreeing on the
    form of the descriptor.  I fixed that by forcing the class to be complete,
    but this testcase shows why that approach is problematic.  So instead let's
    adjust the type of the descriptor later if needed.

            PR c++/102651
            PR c++/49387

    gcc/cp/ChangeLog:

            * rtti.cc (get_tinfo_decl_direct): Don't complete_type.
            (emit_tinfo_decl): Update tdesc type if needed.

    gcc/testsuite/ChangeLog:

            * g++.dg/rtti/typeid-complete1.C: New test.

[Bug c++/102651] [10/11 Regression] typeid(X**) instantiates X caused by r0-109856

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|9.5                         |10.4

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 9 branch is being closed

[Bug c++/102651] [10/11 Regression] typeid(X**) instantiates X caused by r0-109856

[jakub at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.4                        |10.5

--- Comment #6 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
GCC 10.4 is being released, retargeting bugs to GCC 10.5.

[Bug c++/102651] [11 Regression] typeid(X**) instantiates X caused by r0-109856

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=102651

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|10.5                        |11.5

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> ---
GCC 10 branch is being closed.