[Bug c++/113649] New: ICE: nested template class template argument deduction

[Bug c++/113649] New: ICE: nested template class template argument deduction

[schaumb at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113649

            Bug ID: 113649
           Summary: ICE: nested template class template argument deduction
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: schaumb at gmail dot com
  Target Milestone: ---

The following code does not compile, see here https://godbolt.org/z/vz5KMzhsh:


template<class ...Ts>
struct params {
    template <typename Return>
    struct return_type {
        constexpr return_type(Return (*p1)(Ts...)){}
    };

    template <typename Return>
    return_type(Return (*)(Ts...)) -> 
    return_type<Return>;


    template<return_type Any>
    struct addr {};
};

void x(double);

template struct params<double>::addr<&x>;


It runs to internal compiler error:

<source>:19:40: internal compiler error: in build_function_type, at
tree.cc:7488
   19 | template struct params<double>::addr<&x>;
      |                                        ^
0x2647edc internal_error(char const*, ...)
        ???:0
0xa51cb7 fancy_abort(char const*, int, char const*)
        ???:0
0xc72375 do_auto_deduction(tree_node*, tree_node*, tree_node*, int,
auto_deduction_context, tree_node*, int, tree_node*)
        ???:0
0xc76223 coerce_template_parms(tree_node*, tree_node*, tree_node*, int, bool)
        ???:0
0xc93089 lookup_template_class(tree_node*, tree_node*, tree_node*, tree_node*,
int, int)
        ???:0
0xccf8ff finish_template_type(tree_node*, tree_node*, int)
        ???:0
0xc53d2a c_parse_file()
        ???:0
0xda79a9 c_common_parse_file()
        ???:0
Please submit a full bug report, with preprocessed source (by using
-freport-bug).
Please include the complete backtrace with any bug report.
See <https://gcc.gnu.org/bugs/> for instructions.
Compiler returned: 1

[Bug c++/113649] ICE: nested template class template argument deduction

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113649

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2024-01-29
           Keywords|                            |ice-on-valid-code
     Ever confirmed|0                           |1

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Confirmed.

Related (not ICEing but still incorrectly to reject) testcase:
```
template<int>
struct params {
    template <typename Return>
    struct return_type {
        constexpr return_type(Return (*p1)()){}
    };

    template <typename Return>
    return_type(Return (*)()) -> 
    return_type<Return>;


    template<return_type Any>
    struct addr {};
};

void x();

template struct params<1>::addr<&x>;
```

[Bug c++/113649] ICE: nested template class template argument deduction

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113649

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to fail|                            |12.3.0

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
This was rejected before GCC 12.3.0 with an error message about the deduction
guide not being at the namespace level.

[Bug c++/113649] ICE: nested template class template argument deduction

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113649

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

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

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Seems the ICE started with r13-4876-gbd1fc4a219d8c0:

commit bd1fc4a219d8c0fad0ec41002e895b49e384c1c2
Author: Patrick Palka <ppalka@redhat.com>
Date:   Fri Dec 23 09:18:37 2022 -0500

    c++: template friend with variadic constraints [PR107853]

[Bug c++/113649] ICE: nested template class template argument deduction

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=113649

--- Comment #4 from GCC 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:465b9c51f5c79ce3fbb36f1abc7194b39ad9cae7

commit r14-8886-g465b9c51f5c79ce3fbb36f1abc7194b39ad9cae7
Author: Patrick Palka <ppalka@redhat.com>
Date:   Thu Feb 8 09:10:44 2024 -0500

    c++: NTTP type CTAD w/ tmpl from current inst [PR113649]

    Since template argument coercion happens relative to the most general
    template (for a class template at least), during NTTP type CTAD we might
    need to consider outer arguments particularly if the CTAD template is from
    the current instantiation (and so depends on outer template parameters).

    This patch makes do_class_deduction substitute as many levels of outer
    template arguments into a CTAD template (from the current instantiation)
    as it can take.

            PR c++/113649

    gcc/cp/ChangeLog:

            * pt.cc (do_class_deduction): Add outer_targs parameter.
            Substitute outer arguments into the CTAD template.
            (do_auto_deduction): Pass outer_targs to do_class_deduction.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/nontype-class65.C: New test.

    Reviewed-by: Jason Merrill <jason@redhat.com>