[Bug c++/100198] New: ICE: unexpected expression 'E' of kind template_parm_index

[Bug c++/100198] New: ICE: unexpected expression 'E' of kind template_parm_index

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100198

            Bug ID: 100198
           Summary: ICE: unexpected expression 'E' of kind
                    template_parm_index
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

12 Regression extremely related to fixed PR 100109.

template <int... E>
void f() {
  ([] { enum e { e = E }; }(), ...);
}

template void f<0>();

<source>:3:14: internal compiler error: unexpected expression 'E' of kind
template_parm_index
    3 |   ([] { enum e { e = E }; }(), ...);
      |              ^
0x1d02fc9 internal_error(char const*, ...)
        ???:0
0x7a6f3d build_enumerator(tree_node*, tree_node*, tree_node*, tree_node*,
unsigned int)
        ???:0
0x92c558 lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
        ???:0
0x91843d tsubst(tree_node*, tree_node*, int, tree_node*)
        ???:0
0x9184e7 tsubst(tree_node*, tree_node*, int, tree_node*)
        ???:0
0x94ba12 tsubst_lambda_expr(tree_node*, tree_node*, int, tree_node*)
        ???:0
0x932f5f tsubst_pack_expansion(tree_node*, tree_node*, int, tree_node*)
        ???:0
0x91e31f instantiate_decl(tree_node*, bool, bool)
        ???:0
0x96024b instantiate_pending_templates(int)
        ???:0
0x7cd029 c_parse_final_cleanups()
        ???:0
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.

[Bug c++/100198] ICE: unexpected expression 'E' of kind template_parm_index

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100198

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |ice-on-invalid-code

--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
would be nice if you'd hinted on whether you think your testcases are valid C++
or not.  guessing invalid here

[Bug c++/100198] ICE: unexpected expression 'E' of kind template_parm_index

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100198

--- Comment #2 from 康桓瑋 <hewillk at gmail dot com> ---
(In reply to Richard Biener from comment #1)
> would be nice if you'd hinted on whether you think your testcases are valid
> C++ or not.  guessing invalid here

Oops, I should do that, this is a valid code.

https://godbolt.org/z/Kx67MP85f

[Bug c++/100198] [12 Regression] ICE: unexpected expression 'E' of kind template_parm_index

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100198

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-04-22
   Target Milestone|---                         |12.0
            Summary|ICE: unexpected expression  |[12 Regression] ICE:
                   |'E' of kind                 |unexpected expression 'E'
                   |template_parm_index         |of kind template_parm_index
                 CC|                            |mpolacek at gcc dot gnu.org
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed.

[Bug c++/100198] [12 Regression] ICE with enum in lambda in pack expansion

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100198

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
           Keywords|                            |needs-bisection

[Bug c++/100198] [12 Regression] ICE with enum in lambda in pack expansion

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100198

--- Comment #4 from Jason Merrill <jason at gcc dot gnu.org> ---
Nested classes/enums like this are broken in pack expansions if they depend on
parameter packs.  The patch for PR100109 changed this from rejects-valid to
ice-on-valid, but it isn't something newly broken.  I suppose I could change it
back to rejects-valid by reverting the PR100109 patch, but that's just trading
one ICE for another.

This functionality isn't going to be implemented for GCC 12.

[Bug c++/100198] [12 Regression] ICE with enum in lambda in pack expansion

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100198

--- Comment #5 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:4d2efec9f229c2e2e7cb6c3f06beb4c3e9d244a1

commit r12-6909-g4d2efec9f229c2e2e7cb6c3f06beb4c3e9d244a1
Author: Jason Merrill <jason@redhat.com>
Date:   Thu Jan 27 17:46:43 2022 -0500

    c++: pack in enumerator in lambda [PR100198]

    The GCC 8 lambda overhaul fixed most uses of lambdas in pack expansions,
but
    local enums and classes within such lambdas that depend on parameter packs
    are still broken.  For now, give a sorry instead of an ICE or incorrect
    error.

            PR c++/100198
            PR c++/100030
            PR c++/100282

    gcc/cp/ChangeLog:

            * parser.cc (cp_parser_enumerator_definition): Sorry on parameter
            pack in lambda.
            (cp_parser_class_head): And in class attributes.
            * pt.cc (check_for_bare_parameter_packs): Sorry instead of error
            in lambda.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp0x/lambda/lambda-variadic13.C: Accept the sorry
            as well as the correct error.
            * g++.dg/cpp0x/lambda/lambda-variadic14.C: Likewise.
            * g++.dg/cpp0x/lambda/lambda-variadic14a.C: New test.
            * g++.dg/cpp0x/lambda/lambda-variadic15.C: New test.
            * g++.dg/cpp0x/lambda/lambda-variadic16.C: New test.

[Bug c++/100198] enum in lambda in pack expansion

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100198

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[12 Regression] ICE with    |enum in lambda in pack
                   |enum in lambda in pack      |expansion
                   |expansion                   |
           Keywords|ice-on-valid-code,          |rejects-valid
                   |needs-bisection             |

--- Comment #6 from Jason Merrill <jason at gcc dot gnu.org> ---
ICE regression fixed, leaving the PR open for the rejects-valid bug that is not
a regression.

[Bug c++/100198] enum in lambda in pack expansion

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100198

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|12.0                        |---