[Bug c++/99899] New: ICE: in do_auto_deduction, at cp/pt.c:29630

[Bug c++/99899] New: ICE: in do_auto_deduction, at cp/pt.c:29630

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99899

            Bug ID: 99899
           Summary: ICE: in do_auto_deduction, at cp/pt.c:29630
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

This is a small variant of fixed PR 99815, PR 99869.

https://godbolt.org/z/zrnPqdenx

template <typename...> concept C = true;

struct S { int a, b; };

template <typename... Ts>
auto bar(Ts...) { C<Ts...> auto [a, b] = S{}; }


<source>: In function 'auto bar(Ts ...)':
<source>:6:44: internal compiler error: in do_auto_deduction, at cp/pt.c:29630
    6 | auto bar(Ts...) { C<Ts...> auto [a, b] = S{}; }
      |                                            ^
0x1cfd119 internal_error(char const*, ...)
        ???:0
0x6baa1b fancy_abort(char const*, int, char const*)
        ???:0
0x90a8c4 do_auto_deduction(tree_node*, tree_node*, tree_node*, int,
auto_deduction_context, tree_node*, int)
        ???:0
0x7b1e34 cp_finish_decl(tree_node*, tree_node*, bool, tree_node*, int)
        ???:0
0x8e140d c_parse_file()
        ???:0
0xa606f2 c_common_parse_file()
        ???:0
Please submit a full bug report,
with preprocessed source if appropriate.

[Bug c++/99899] [11 Regression] ICE: in do_auto_deduction, at cp/pt.c:29630

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99899

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |ppalka at gcc dot gnu.org
     Ever confirmed|0                           |1
            Summary|ICE: in do_auto_deduction,  |[11 Regression] ICE: in
                   |at cp/pt.c:29630            |do_auto_deduction, at
                   |                            |cp/pt.c:29630
           Priority|P3                          |P1
             Status|UNCONFIRMED                 |ASSIGNED
           Keywords|                            |ice-on-valid-code
   Target Milestone|---                         |11.0
           Assignee|unassigned at gcc dot gnu.org      |ppalka at gcc dot gnu.org
   Last reconfirmed|                            |2021-04-05

--- Comment #1 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Confirmed, started with r11-7540.

[Bug c++/99899] [11 Regression] ICE: in do_auto_deduction, at cp/pt.c:29630

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99899

--- Comment #2 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:66de517b1c1dd22df7914f8e9a083cd5a73adbe2

commit r11-7997-g66de517b1c1dd22df7914f8e9a083cd5a73adbe2
Author: Patrick Palka <ppalka@redhat.com>
Date:   Mon Apr 5 23:35:56 2021 -0400

    c++: placeholder type constraint in structured binding [PR99899]

    In this PR, we're crashing because the constraint handling inside
    do_auto_deduction doesn't expect to see an adc_decomp_type context.
    This patch fixes this by treating adc_decomp_type like adc_variable_type
    or adc_return_type during placeholder type constraint checking.

    Meanwhile, I noticed we weren't checking constraints at all when binding
    an array via a structured binding, since do_auto_deduction would exit
    early and bypass the constraint check.  This patch fixes this by
    replacing the early exit with an appropriate setup of the 'targs'
    vector.

    gcc/cp/ChangeLog:

            PR c++/99899
            * pt.c (do_auto_deduction): Don't exit early when deducing the
            array type of a structured binding.  Also handle adc_decomp_type
            during constraint checking.

    gcc/testsuite/ChangeLog:

            PR c++/99899
            * g++.dg/cpp2a/concepts-placeholder7.C: New test.
            * g++.dg/cpp2a/concepts-placeholder8.C: New test.

[Bug c++/99899] [11 Regression] ICE: in do_auto_deduction, at cp/pt.c:29630

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99899

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

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

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed.