[Bug c++/108104] New: ICE in unify, at cp/pt.c:24333 with template partial specialization

[Bug c++/108104] New: ICE in unify, at cp/pt.c:24333 with template partial specialization

[gawain.bolton at free dot fr]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108104

            Bug ID: 108104
           Summary: ICE in unify, at cp/pt.c:24333 with template partial
                    specialization
           Product: gcc
           Version: 12.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gawain.bolton at free dot fr
  Target Milestone: ---

Created attachment 54091
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54091&action=edit
ICE with template partial specialization - No issue if WITH_STATE is 0 i.e. if
the State parameter is absent

Please see attached file which causes an internal compiler error.

Note that there is no issue if the "State" template argument is removed as can
be shown if you set WITH_STATE to 0.

No issue found with clang >= v13.0

ICE found with all versions of GCC I tried (from GCC v4.9.4 to GCC v12.2)

[Bug c++/108104] ICE in unify, at cp/pt.c:24333 with template partial specialization and pointer to memeber function and nullptr

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108104

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-valid-code
            Summary|ICE in unify, at            |ICE in unify, at
                   |cp/pt.c:24333 with template |cp/pt.c:24333 with template
                   |partial specialization      |partial specialization and
                   |                            |pointer to memeber function
                   |                            |and nullptr

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Reduced testcase:
```
struct ss {
    void h();
};
template <int, void (ss::*m)()> struct Fred {};
template <int state> struct Fred<state, nullptr> {};
Fred<1, &ss::h> f1;
```

[Bug c++/108104] ICE in unify, at cp/pt.c:24333 with template partial specialization and pointer to memeber function and nullptr

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108104

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
      Known to fail|                            |5.1.0
   Last reconfirmed|                            |2022-12-14

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Before GCC 5, we produced:
<source>:5:48: internal compiler error: unexpected expression '(void
(ss::*)())(nullptr)' of kind cast_expr
 template <int state> struct Fred<state, nullptr> {};
                                                ^

[Bug c++/108104] ICE in unify, at cp/pt.c:24333 with template partial specialization and pointer to memeber function and nullptr

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108104

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
It is definitely a pointer to member function issue.
I tried with just a pointer to a function and it worked and even a pointer to a
member field works too:
```
struct ss {
    int t;
};
template <int, int ss::*m> struct Fred {};
template <int state> struct Fred<state, nullptr> {};
Fred<1, &ss::t> f1;
```

[Bug c++/108104] ICE in unify, at cp/pt.c:24333 with template partial specialization and pointer to memeber function and nullptr

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108104

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

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

[Bug c++/108104] ICE in unify, at cp/pt.c:24333 with template partial specialization and pointer to memeber function and nullptr

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108104

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

https://gcc.gnu.org/g:38304846d18d6bb14b0fd6c627c5c6d43a814d01

commit r13-4728-g38304846d18d6bb14b0fd6c627c5c6d43a814d01
Author: Patrick Palka <ppalka@redhat.com>
Date:   Thu Dec 15 15:38:47 2022 -0500

    c++: partial ordering with memfn ptr cst [PR108104]

    Here we're triggering an overzealous assert in unify during partial
    ordering since the member function pointer constants are represented as
    ordinary CONSTRUCTORs (with TYPE_PTRMEMFUNC_P TREE_TYPE) but the assert
    expects COMPOUND_LITERAL_P constructors.

            PR c++/108104

    gcc/cp/ChangeLog:

            * pt.cc (unify) <default>: Relax assert to accept any
            CONSTRUCTOR parm, not just COMPOUND_LITERAL_P one.

    gcc/testsuite/ChangeLog:

            * g++.dg/template/ptrmem33.C: New test.

[Bug c++/108104] ICE in unify, at cp/pt.c:24333 with template partial specialization and pointer to memeber function and nullptr

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108104

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |12.3

--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed on trunk so far

[Bug c++/108104] ICE in unify, at cp/pt.c:24333 with template partial specialization and pointer to memeber function and nullptr

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108104

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-12 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:6e09ca0cba625b8bb2ef50f9df726eb455ebb813

commit r12-8997-g6e09ca0cba625b8bb2ef50f9df726eb455ebb813
Author: Patrick Palka <ppalka@redhat.com>
Date:   Thu Dec 15 15:38:47 2022 -0500

    c++: partial ordering with memfn ptr cst [PR108104]

    Here we're triggering an overzealous assert in unify during partial
    ordering since the member function pointer constants are represented as
    ordinary CONSTRUCTORs (with TYPE_PTRMEMFUNC_P TREE_TYPE) but the assert
    expects COMPOUND_LITERAL_P constructors.

            PR c++/108104

    gcc/cp/ChangeLog:

            * pt.cc (unify) <default>: Relax assert to accept any
            CONSTRUCTOR parm, not just COMPOUND_LITERAL_P one.

    gcc/testsuite/ChangeLog:

            * g++.dg/template/ptrmem33.C: New test.

    (cherry picked from commit 38304846d18d6bb14b0fd6c627c5c6d43a814d01)

[Bug c++/108104] ICE in unify, at cp/pt.c:24333 with template partial specialization and pointer to memeber function and nullptr

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108104

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

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

--- Comment #7 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 12.3/13, thanks for the bug report.