[Bug c++/101098] New: [11/12 Regression] ICE in instantiate_body, at cp/pt.c:25858

[Bug c++/101098] New: [11/12 Regression] ICE in instantiate_body, at cp/pt.c:25858

[gscfq@t-online.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101098

            Bug ID: 101098
           Summary: [11/12 Regression] ICE in instantiate_body, at
                    cp/pt.c:25858
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gscfq@t-online.de
  Target Milestone: ---

Changed between 20200621 and 20200628, r9 accepts it.
With option -fconcepts and file g++.dg/cpp2a/concepts-explicit-spec1.C
or the following variant :


$ cat z1.cc
template<typename T> concept C = __is_class(T);
struct Y { int n; } y;
template<C T> void g(T) { }
int called;
template<> void g(Y) { called = 3; }
int main() { g(y); }


$ g++-9 -c z1.cc -fconcepts
$
$ g++-12-20210613 -c z1.cc -fconcepts
z1.cc: In instantiation of 'void g(T) [with T = Y]':
z1.cc:6:15:   required from here
z1.cc:3:27: internal compiler error: Segmentation fault
    3 | template<C T> void g(T) { }
      |                           ^
0xd4d42f crash_signal
        ../../gcc/toplev.c:327
0x822254 instantiate_body
        ../../gcc/cp/pt.c:25858
0x823223 instantiate_decl(tree_node*, bool, bool)
        ../../gcc/cp/pt.c:26141
0x83d9eb instantiate_pending_templates(int)
        ../../gcc/cp/pt.c:26220
0x752232 c_parse_final_cleanups()
        ../../gcc/cp/decl2.c:4966

[Bug c++/101098] [11/12 Regression] ICE in instantiate_body, at cp/pt.c:25858

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101098

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |11.2

[Bug c++/101098] [11/12 Regression] ICE in instantiate_body, at cp/pt.c:25858 since r10-3735-gcb57504a55015891

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101098

Martin Liška <marxin at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org
   Last reconfirmed|                            |2021-06-17
            Summary|[11/12 Regression] ICE in   |[11/12 Regression] ICE in
                   |instantiate_body, at        |instantiate_body, at
                   |cp/pt.c:25858               |cp/pt.c:25858 since
                   |                            |r10-3735-gcb57504a55015891
     Ever confirmed|0                           |1

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Confirmed, started with r10-3735-gcb57504a55015891.

[Bug c++/101098] [11/12 Regression] ICE in instantiate_body, at cp/pt.c:25858 since r10-3735-gcb57504a55015891

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101098

--- Comment #2 from Jason Merrill <jason at gcc dot gnu.org> ---
The ICE does not happen with -std=c++20.

[Bug c++/101098] [11/12 Regression] ICE with explicit specialization of constrained function template

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101098

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

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

[Bug c++/101098] [11/12 Regression] ICE with explicit specialization of constrained function template

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101098

--- 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:ddd25bd1a7c8f456bc914e34b77d43f39a1062d4

commit r12-2230-gddd25bd1a7c8f456bc914e34b77d43f39a1062d4
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Jul 9 13:50:01 2021 -0400

    c++: concepts TS and explicit specialization [PR101098]

    duplicate_decls was not recognizing the explicit specialization as matching
    the implicit specialization of g<Y> because
    function_requirements_equivalent_p was seeing the C constraint on the
    implicit one and not on the explicit.

            PR c++/101098

    gcc/cp/ChangeLog:

            * decl.c (function_requirements_equivalent_p): Only compare
            trailing requirements on a specialization.

    gcc/testsuite/ChangeLog:

            * g++.dg/concepts/explicit-spec1.C: New test.

[Bug c++/101098] [11/12 Regression] ICE with explicit specialization of constrained function template

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101098

--- Comment #4 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:8b273a8566e7806e9498c78b16c30c9d81d6e81b

commit r11-8716-g8b273a8566e7806e9498c78b16c30c9d81d6e81b
Author: Jason Merrill <jason@redhat.com>
Date:   Fri Jul 9 13:50:01 2021 -0400

    c++: concepts TS and explicit specialization [PR101098]

    duplicate_decls was not recognizing the explicit specialization as matching
    the implicit specialization of g<Y> because
    function_requirements_equivalent_p was seeing the C constraint on the
    implicit one and not on the explicit.

            PR c++/101098

    gcc/cp/ChangeLog:

            * decl.c (function_requirements_equivalent_p): Only compare
            trailing requirements on a specialization.

    gcc/testsuite/ChangeLog:

            * g++.dg/concepts/explicit-spec1.C: New test.

[Bug c++/101098] [11/12 Regression] ICE with explicit specialization of constrained function template

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101098

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

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

--- Comment #5 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 11.2/12.

[Bug c++/101098] [11/12 Regression] ICE with explicit specialization of constrained function template

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101098

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |StevenSun2021 at hotmail dot com

--- Comment #6 from Patrick Palka <ppalka at gcc dot gnu.org> ---
*** Bug 99686 has been marked as a duplicate of this bug. ***