[Bug c++/95672] New: ICE in cxx_incomplete_type_diagnostic, at cp/typeck2.c:584

[Bug c++/95672] New: ICE in cxx_incomplete_type_diagnostic, at cp/typeck2.c:584

[haoxintu at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95672

            Bug ID: 95672
           Summary: ICE in cxx_incomplete_type_diagnostic, at
                    cp/typeck2.c:584
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: haoxintu at gmail dot com
  Target Milestone: ---

$cat bug.cc
struct g_class : decltype  (auto) ... {  } ;

$g++ bug.cc
bug.cc:1:35: internal compiler error: in cxx_incomplete_type_diagnostic, at
cp/typeck2.c:584
    1 | struct g_class : decltype  (auto) ... {  } ;
      |                                   ^~~
0x5cef74 cxx_incomplete_type_diagnostic(unsigned int, tree_node const*,
tree_node const*, diagnostic_t)
        ../../gcc/cp/typeck2.c:584
0x77b9af cxx_incomplete_type_diagnostic(tree_node const*, tree_node const*,
diagnostic_t)
        ../../gcc/cp/cp-tree.h:7705
0x77b9af complete_type_or_maybe_complain(tree_node*, tree_node*, int)
        ../../gcc/cp/typeck.c:156
0x77b9af complete_type_or_else(tree_node*, tree_node*)
        ../../gcc/cp/typeck.c:166
0x685881 xref_basetypes(tree_node*, tree_node*)
        ../../gcc/cp/decl.c:15099
0x6edfe9 cp_parser_class_head
        ../../gcc/cp/parser.c:24717
0x6edfe9 cp_parser_class_specifier_1
        ../../gcc/cp/parser.c:23874
0x6ee273 cp_parser_class_specifier
        ../../gcc/cp/parser.c:24248
0x6ee273 cp_parser_type_specifier
        ../../gcc/cp/parser.c:17762
0x6ef092 cp_parser_decl_specifier_seq
        ../../gcc/cp/parser.c:14410
0x6efbb1 cp_parser_simple_declaration
        ../../gcc/cp/parser.c:13664
0x7159c6 cp_parser_declaration
        ../../gcc/cp/parser.c:13484
0x7160b4 cp_parser_translation_unit
        ../../gcc/cp/parser.c:4761
0x7160b4 c_parse_file()
        ../../gcc/cp/parser.c:44034
0x7de74b c_common_parse_file()
        ../../gcc/c-family/c-opts.c:1190
Please submit a full bug report,
with preprocessed source if appropriate.
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.

$g++ --version
g++ (GCC) 11.0.0 20200605 (experimental)
Copyright (C) 2020 Free Software Foundation, Inc.
This is free software; see the source for copying conditions.  There is NO
warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.

[Bug c++/95672] ICE in cxx_incomplete_type_diagnostic, at cp/typeck2.c:584

[haoxintu at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95672

--- Comment #1 from Haoxin Tu <haoxintu at gmail dot com> ---
Noted that from GCC 6.1 to the trunk versions have this ICE, too.

[Bug c++/95672] ICE in cxx_incomplete_type_diagnostic, at cp/typeck2.c:584

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95672

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2020-06-15
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |WAITING
                 CC|                            |marxin at gcc dot gnu.org

--- Comment #2 from Martin Liška <marxin at gcc dot gnu.org> ---
Is it an invalid code right?

[Bug c++/95672] ICE in cxx_incomplete_type_diagnostic, at cp/typeck2.c:584

[haoxintu at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95672

--- Comment #3 from Haoxin Tu <haoxintu at gmail dot com> ---
(In reply to Martin Liška from comment #2)
> Is it an invalid code right?

Yes. I think it's not a valid code and other compilers do not accept it, too.

[Bug c++/95672] ICE in cxx_incomplete_type_diagnostic, at cp/typeck2.c:584

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95672

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |NEW
           Keywords|                            |ice-on-invalid-code

[Bug c++/95672] ICE in cxx_incomplete_type_diagnostic, at cp/typeck2.c:584

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95672

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #4 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
type_pack_expansion isn't handled in the switch in
cxx_incomplete_type_diagnostic so we ICE.

[Bug c++/95672] ICE in cxx_incomplete_type_diagnostic, at cp/typeck2.c:584

[xerofoify at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95672

Nicholas Krause <xerofoify at gmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |xerofoify at gmail dot com

--- Comment #5 from Nicholas Krause <xerofoify at gmail dot com> ---
Created attachment 48736
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48736&action=edit
Proposed Fix

This is a proposed fix for the bug. Not sure if we need to emit multiple
messages for different possible template expansion failures.

[Bug c++/95672] ICE in cxx_incomplete_type_diagnostic, at cp/typeck2.c:584

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95672

--- Comment #6 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:11a751ff77fba92de77b099ec5e1896d3a99d482

commit r11-1641-g11a751ff77fba92de77b099ec5e1896d3a99d482
Author: Nicholas Krause <xerofoify@gmail.com>
Date:   Tue Jun 23 15:47:37 2020 -0400

    c++: Handle bad pack expansion in base list. [PR96752]

    This fixes PR95672 by adding the missing TYPE_PACK_EXPANSION case in
    cxx_incomplete_type_diagnostic in order to avoid ICEs on diagnosing
    incomplete template pack expansion cases.

    Tested on powerpc64le-unknown-linux-gnu.

    gcc/cp/ChangeLog:

            PR c++/95672
            * typeck2.c (cxx_incomplete_type_diagnostic): Add missing
            TYPE_EXPANSION_PACK check for diagnosing incomplete types in
            cxx_incomplete_type_diagnostic.

    gcc/testsuite/ChangeLog:

            PR c++/95672
            * g++.dg/template/pr95672.C: New test.

    Signed-off-by: Nicholas Krause <xerofoify@gmail.com>

[Bug c++/95672] ICE in cxx_incomplete_type_diagnostic, at cp/typeck2.c:584

[jason at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95672

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |jason at gcc dot gnu.org
             Status|NEW                         |RESOLVED
   Target Milestone|---                         |11.0
         Resolution|---                         |FIXED

--- Comment #7 from Jason Merrill <jason at gcc dot gnu.org> ---
Fixed for GCC 11.