[Bug c++/105655] New: [12/13 Regression] ICE on invalid deduction

[Bug c++/105655] New: [12/13 Regression] ICE on invalid deduction

[egor.pugin at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105655

            Bug ID: 105655
           Summary: [12/13 Regression] ICE on invalid deduction
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: egor.pugin at gmail dot com
  Target Milestone: ---

Works on 11.3, does not work on 12 and trunk.
https://godbolt.org/z/YrEbn3K6f

template <class T>
struct A
{
    template <class L, class R>
    struct B
    {
        B(const L & left, const R & right)
        {}
    };

    template <class L, class R>
    B(const L &, const R &) -> B<L, R>;
};

template <class L, class R>
using C = A<int>::B<L, R>;

int main()
{
    C x{0, 0};
}

[Bug c++/105655] [12/13 Regression] ICE on invalid deduction

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105655

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-05-19

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Started with r10-5020-g1a291106384cabc7.

[Bug c++/105655] [12/13 Regression] ICE on invalid deduction

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105655

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-valid-code
           Priority|P3                          |P2
            Version|unknown                     |12.1.0
   Target Milestone|---                         |12.2

[Bug c++/105655] [12/13 Regression] ICE on invalid deduction

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105655

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++/105655] [12/13 Regression] ICE on invalid deduction

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105655

--- Comment #2 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:34970d08c6297e12f3f9117b6ac19fb2de522e24

commit r13-769-g34970d08c6297e12f3f9117b6ac19fb2de522e24
Author: Jason Merrill <jason@redhat.com>
Date:   Wed May 25 12:38:58 2022 -0400

    c++: CTAD with alias and nested template [PR105655]

    Here, alias_ctad_tweaks expect tsubst_decl of a FUNCTION_DECL to return a
    FUNCTION_DECL.  A reasonable expectation, but in this case we were
replacing
    the template args of the class-scope deduction guide with equivalent args,
    so looking in the hash table we found the partial instantiation stored when
    instantiating A<int>, which is a TEMPLATE_DECL.  It's fine for that to be
    what is stored, but tsubst_function_decl should never return it.

            PR c++/105655

    gcc/cp/ChangeLog:

            * pt.cc (build_template_decl): Add assert.
            (tsubst_function_decl): Don't return a template.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/class-deduction-alias13.C: New test.

[Bug c++/105655] [12 Regression] ICE on invalid deduction

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105655

--- Comment #3 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:d81be519fd6547654f1eda6976e95524db7d39b7

commit r12-8442-gd81be519fd6547654f1eda6976e95524db7d39b7
Author: Jason Merrill <jason@redhat.com>
Date:   Wed May 25 12:38:58 2022 -0400

    c++: CTAD with alias and nested template [PR105655]

    Here, alias_ctad_tweaks expect tsubst_decl of a FUNCTION_DECL to return a
    FUNCTION_DECL.  A reasonable expectation, but in this case we were
replacing
    the template args of the class-scope deduction guide with equivalent args,
    so looking in the hash table we found the partial instantiation stored when
    instantiating A<int>, which is a TEMPLATE_DECL.  It's fine for that to be
    what is stored, but tsubst_function_decl should never return it.

            PR c++/105655

    gcc/cp/ChangeLog:

            * pt.cc (build_template_decl): Add assert.
            (tsubst_function_decl): Don't return a template.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/class-deduction-alias13.C: New test.

[Bug c++/105655] [12 Regression] ICE on invalid deduction

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105655

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

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

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for 12.2/13.