[Bug c++/110523] New: [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[Bug c++/110523] New: [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

            Bug ID: 110523
           Summary: [14 Regression] ICE in redeclare_class_template, at
                    cp/pt.cc:6391 on json-3.11.2
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: slyfox at gcc dot gnu.org
  Target Milestone: ---

Noticed ICE on r14-2233-gfca6d9c12f5bf0 when was building json-3.11.2 package.

Extracted reproducer:

// $ cat bug.cpp
template <typename, typename> struct adl_serializer;

template <template <typename, typename> class = adl_serializer>
class basic_json;

template <typename> struct json_pointer {
  template <template <typename, typename> class> friend class basic_json;
};
template <template <typename, typename> class> struct basic_json {
  using json_pointer = json_pointer<int>;
};
basic_json<>::json_pointer __trans_tmp_1_DOCTEST_ANON_FUNC_2() {
  json_pointer<basic_json<>> ptr_j;
}

$ g++ -c bug.cpp
bug.cpp:10:9: warning: declaration of 'using basic_json<
<template-parameter-1-1> >::json_pointer = struct json_pointer<int>' changes
meaning of 'json_pointer' [-Wchanges-meaning]
   10 |   using json_pointer = json_pointer<int>;
      |         ^~~~~~~~~~~~
bug.cpp:10:24: note: used here to mean 'struct json_pointer<int>'
   10 |   using json_pointer = json_pointer<int>;
      |                        ^~~~~~~~~~~~~~~~~
bug.cpp:6:28: note: declared here
    6 | template <typename> struct json_pointer {
      |                            ^~~~~~~~~~~~
bug.cpp: In instantiation of 'struct json_pointer<basic_json<> >':
bug.cpp:13:30:   required from here
bug.cpp:7:63: internal compiler error: in redeclare_class_template, at
cp/pt.cc:6391
    7 |   template <template <typename, typename> class> friend class
basic_json;
      |                                                              
^~~~~~~~~~
0x708b6c redeclare_class_template(tree_node*, tree_node*, tree_node*)
        ../../source/gcc/cp/pt.cc:6391
0x8fe749 tsubst_friend_class
        ../../source/gcc/cp/pt.cc:11590
0x8fe749 instantiate_class_template(tree_node*)
        ../../source/gcc/cp/pt.cc:12446
0x9398ed complete_type(tree_node*)
        ../../source/gcc/cp/typeck.cc:138
0x7c49e2 start_decl_1(tree_node*, bool)
        ../../source/gcc/cp/decl.cc:5980
0x7de3e9 start_decl_1(tree_node*, bool)
        ../../source/gcc/cp/decl.cc:5946
0x7de3e9 start_decl(cp_declarator const*, cp_decl_specifier_seq*, int,
tree_node*, tree_node*, tree_node**)
        ../../source/gcc/cp/decl.cc:5946
0x8b70b7 cp_parser_init_declarator
        ../../source/gcc/cp/parser.cc:22951
0x88f971 cp_parser_simple_declaration
        ../../source/gcc/cp/parser.cc:15435
0x891520 cp_parser_declaration_statement
        ../../source/gcc/cp/parser.cc:14516
0x891c39 cp_parser_statement
        ../../source/gcc/cp/parser.cc:12574
0x892d6d cp_parser_statement_seq_opt
        ../../source/gcc/cp/parser.cc:13000
0x892e0f cp_parser_compound_statement
        ../../source/gcc/cp/parser.cc:12952
0x8b5881 cp_parser_function_body
        ../../source/gcc/cp/parser.cc:25372
0x8b5881 cp_parser_ctor_initializer_opt_and_function_body
        ../../source/gcc/cp/parser.cc:25423
0x8b6a4e cp_parser_function_definition_after_declarator
        ../../source/gcc/cp/parser.cc:32058
0x8b7dcc cp_parser_function_definition_from_specifiers_and_declarator
        ../../source/gcc/cp/parser.cc:31975
0x8b7dcc cp_parser_init_declarator
        ../../source/gcc/cp/parser.cc:22831
0x88f971 cp_parser_simple_declaration
        ../../source/gcc/cp/parser.cc:15435
0x8c1ddb cp_parser_declaration
        ../../source/gcc/cp/parser.cc:15121

$ g++ -v
Using built-in specs.
COLLECT_GCC=/<<NIX>>/gcc-14.0.0/bin/g++
COLLECT_LTO_WRAPPER=/<<NIX>>/gcc-14.0.0/libexec/gcc/x86_64-unknown-linux-gnu/14.0.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with:
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 99999999 (experimental) (GCC)

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

--- Comment #1 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
Created attachment 55452
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55452&action=edit
bug.cpp.orig.xz

In case I reduced the file incorrectly attaching bug.cpp.orig.xz which should
build with both gcc-13 and gcc-14.

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |14.0
           Keywords|                            |ice-on-valid-code

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Re-reducing it so it is warning free as the original was warning free.

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2023-07-02
     Ever confirmed|0                           |1

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Better reduced testcase:
```
template <typename> class v {};
template <template <typename> class a = v>
class basic_json {};
template <typename t>
struct json_pointer {
  template <template <typename> class a>
    friend class basic_json;
  using type = t;
};
json_pointer<int>::type t;
json_pointer<basic_json<>>::type t1;
```

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

David Binderman <dcb314 at hotmail dot com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |dcb314 at hotmail dot com

--- Comment #4 from David Binderman <dcb314 at hotmail dot com> ---
I see something similar when building dlib:

/home/dcb38/rpmbuild/BUILD/dlib-65bce59a1512cf222dec01d3e0f29b612dd181f5/dlib/../dlib/dnn/core.h:799:22:
internal compiler error: in redeclare_class_template, at cp/pt.cc:6391

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

--- Comment #5 from David Binderman <dcb314 at hotmail dot com> ---
The compiler seems to break as follows:

/home/dcb38/gcc/results.20230701/bin/gcc
/home/dcb38/gcc/results.20230703.asan.ubsan/bin/gcc
/home/dcb38/rpmbuild/BUILD/dlib-65bce59a1512cf222dec01d3e0f29b612dd181f5/dlib/../dlib/dnn/core.h:799:22:
internal compiler error: in redeclare_class_template, at cp/pt.cc:6391

$ /home/dcb38/gcc/results.20230701/bin/gcc -v 2>&1 | grep exp
gcc version 14.0.0 20230630 (experimental) (c3c0ba5436170e01) 
$ /home/dcb38/gcc/results.20230703.asan.ubsan/bin/gcc -v 2>&1 | grep exp
gcc version 14.0.0 20230703 (experimental) (9a856f67ee2f13ea) 

$ git log c3c0ba5436170e01..9a856f67ee2f13ea | grep -c "^commit"
45
$

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

--- Comment #6 from David Binderman <dcb314 at hotmail dot com> ---
The only C++ related commit in that range is:

commit db38b285ba61c5b888adc0d117177bfd774c1153
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Jun 30 15:05:22 2023 -0400

    c++: fix up caching of level lowered ttps

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

--- Comment #7 from David Binderman <dcb314 at hotmail dot com> ---
I have tried to start a git bisect and the current range is 
g:f3d87219dd502d5c .. g:9757e4440bd8755d.

This is 15 commits.

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[dcb314 at hotmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

--- Comment #8 from David Binderman <dcb314 at hotmail dot com> ---
(In reply to David Binderman from comment #7)
> I have tried to start a git bisect and the current range is 
> g:f3d87219dd502d5c .. g:9757e4440bd8755d.
> 
> This is 15 commits.

I messed this one up and started again. As expected,
Patrick's commit seems to be the one:

$ git bisect bad db38b285ba61c5b8
db38b285ba61c5b888adc0d117177bfd774c1153 is the first bad commit
commit db38b285ba61c5b888adc0d117177bfd774c1153
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Jun 30 15:05:22 2023 -0400

    c++: fix up caching of level lowered ttps

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

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

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

--- Comment #9 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Simplified:

template<template<class, class> class>
class basic_json;

template<class> struct json_pointer {
  template<template<class, class> class> friend class basic_json;
};

template struct json_pointer<int>;
template struct json_pointer<char>;
template struct json_pointer<long>;

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

--- Comment #10 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:2c60368ab5706a870a1a3be190acc4d673672c30

commit r14-2421-g2c60368ab5706a870a1a3be190acc4d673672c30
Author: Patrick Palka <ppalka@redhat.com>
Date:   Mon Jul 10 10:59:40 2023 -0400

    c++: redeclare_class_template and ttps [PR110523]

    Now that we cache level-lowered ttps we can end up processing the same
    ttp multiple times via (multiple calls to) redeclare_class_template, so
    we can't assume a ttp's DECL_CONTEXT is initially empty.

            PR c++/110523

    gcc/cp/ChangeLog:

            * pt.cc (redeclare_class_template): Relax the ttp DECL_CONTEXT
            assert, and downgrade it to a checking assert.

    gcc/testsuite/ChangeLog:

            * g++.dg/template/ttp37.C: New test.

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

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

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

--- Comment #11 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed.

[Bug c++/110523] [14 Regression] ICE in redeclare_class_template, at cp/pt.cc:6391 on json-3.11.2

[slyfox at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=110523

--- Comment #12 from Sergei Trofimovich <slyfox at gcc dot gnu.org> ---
I confirm ICE gone away for json-3.11.2. json-3.11.2 still odes not compile
same as in https://gcc.gnu.org/PR110580