[Bug c++/97103] New: ICE on nested requires expression template template instantiation

[Bug c++/97103] New: ICE on nested requires expression template template instantiation

[mateusz.pusz at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97103

            Bug ID: 97103
           Summary: ICE on nested requires expression template template
                    instantiation
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mateusz.pusz at gmail dot com
  Target Milestone: ---

```
template<typename R, typename Rep = double>
class quantity {};

template<template<typename, typename> typename Q>
inline constexpr bool valid_template_arguments = requires {
  requires requires { typename Q<int, int>; };
};
static_assert(valid_template_arguments<quantity>);
```

Might be related to https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66564.

[Bug c++/97103] ICE on nested requires expression template template instantiation

[mateusz.pusz at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97103

--- Comment #1 from Mateusz Pusz <mateusz.pusz at gmail dot com> ---
<source>: In instantiation of 'constexpr const bool
valid_template_arguments<template<class R, class Rep> class quantity>':

<source>:8:15:   required from here

<source>:6:32: internal compiler error: in tsubst, at cp/pt.c:15447

    6 |   requires requires { typename Q<int, int>; };                      //
two representation types

      |                       ~~~~~~~~~^~~~~~~~~~~~

0x1b755e9 internal_error(char const*, ...)

        ???:0

0x686d2b fancy_abort(char const*, int, char const*)

        ???:0

0x896a1b tsubst(tree_node*, tree_node*, int, tree_node*)

        ???:0

0x709a42 tsubst_requires_expr(tree_node*, tree_node*, int, tree_node*)

        ???:0

0x709725 tsubst_requires_expr(tree_node*, tree_node*, int, tree_node*)

        ???:0

0x89ac2f instantiate_decl(tree_node*, bool, bool)

        ???:0

0x79044e maybe_instantiate_decl(tree_node*)

        ???:0

0x7935e8 mark_used(tree_node*, int)

        ???:0

0x90bab7 finish_id_expression(tree_node*, tree_node*, tree_node*, cp_id_kind*,
bool, bool, bool*, bool, bool, bool, bool, char const**, unsigned int)

        ???:0

0x862cec c_parse_file()

        ???:0

0x9d3702 c_common_parse_file()

        ???:0

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.

Compiler returned: 1

[Bug c++/97103] ICE on nested requires expression template template instantiation

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97103

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
   Last reconfirmed|                            |2020-09-18
                 CC|                            |ppalka at gcc dot gnu.org
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |ASSIGNED

--- Comment #2 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Confirmed.

[Bug c++/97103] [10/11 Regression] ICE on nested requires expression template template instantiation

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97103

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |10.3
      Known to fail|                            |10.1.0, 10.2.0, 11.0
      Known to work|                            |9.3.0
            Summary|ICE on nested requires      |[10/11 Regression] ICE on
                   |expression template         |nested requires expression
                   |template instantiation      |template template
                   |                            |instantiation

--- Comment #3 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Started with r10-8077.

[Bug c++/97103] [10/11 Regression] ICE on nested requires expression template template instantiation

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97103

--- Comment #4 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:e5d72c840a226fdbab65912f97d42a1dbdaf6ed2

commit r11-3296-ge5d72c840a226fdbab65912f97d42a1dbdaf6ed2
Author: Patrick Palka <ppalka@redhat.com>
Date:   Sat Sep 19 11:02:46 2020 -0400

    c++: Fix self-mapping in map_arguments [PR96531, PR97103]

    With r10-8077 we stopped passing the argified current_template_parms to
    normalize_constraint_expression from finish_nested_requirement, and
    instead made map_arguments perform a self-mapping of parameters when
    args is NULL.  But we're currently not handling parameter packs and
    BOUND_TEMPLATE_TEMPLATE_PARMs properly during this self-mapping, which
    leads to ICEs later during satisfaction.

    To properly handle self-mapping of a parameter pack, this patch
    extends template_parm_to_arg to handle TEMPLATE_PARM_P nodes, and
    makes map_arguments use it.  (This change revealed that the call to
    template_parm_to_arg in convert_generic_types_to_packs was a no-op
    because the argument 't' is never a TREE_LIST, so this patch
    additionally removes this call.)

    As for bound ttps, map_arguments before r10-8077 would map a
    BOUND_TEMPLATE_TEMPLATE_PARM not to itself but to its underlying
    TEMPLATE_TEMPLATE_PARM.  We could restore this behavior in
    map_arguments, but since a bound ttp is not really a template parameter
    it seems better to make keep_template_parm not give us a bound ttp in
    the first place.  So this patch makes keep_template_parm return the
    underlying ttp when it sees a bound ttp.

    gcc/cp/ChangeLog:

            PR c++/96531
            PR c++/97103
            * constraint.cc (map_arguments): Call template_parm_to_arg
            in the self-mapping case.
            (finish_shorthand_constraint): No need to build a TREE_LIST
            before calling template_parm_to_arg.
            * pt.c (template_parm_to_arg): Rewrite to handle TEMPLATE_PARM_P
            nodes as well as DECL_TEMPLATE_PARM_P nodes, and to make the
            overlying TREE_LIST node optional.
            (keep_template_parm): Don't record a BOUND_TEMPLATE_TEMPLATE_PARM,
            instead record its corresponding TEMPLATE_TEMPLATE_PARM.
            (convert_generic_types_to_packs): Don't call
            template_parm_to_arg.

    gcc/testsuite/ChangeLog:

            PR c++/96531
            PR c++/97103
            * g++.dg/cpp2a/concepts-ttp2.C: New test.
            * g++.dg/cpp2a/concepts-variadic1.C: New test.

[Bug c++/97103] [10 Regression] ICE on nested requires expression template template instantiation

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97103

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
      Known to work|                            |11.0
      Known to fail|11.0                        |
           Priority|P3                          |P2
            Summary|[10/11 Regression] ICE on   |[10 Regression] ICE on
                   |nested requires expression  |nested requires expression
                   |template template           |template template
                   |instantiation               |instantiation

--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> ---
Fixed on trunk sofar.

[Bug c++/97103] [10 Regression] ICE on nested requires expression template template instantiation

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97103

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The releases/gcc-10 branch has been updated by Patrick Palka
<ppalka@gcc.gnu.org>:

https://gcc.gnu.org/g:a834e6d59d74ccaefbcbbed5ea7ee25305057853

commit r10-9634-ga834e6d59d74ccaefbcbbed5ea7ee25305057853
Author: Patrick Palka <ppalka@redhat.com>
Date:   Sat Sep 19 11:02:46 2020 -0400

    c++: Fix self-mapping in map_arguments [PR96531, PR97103]

    With r10-8077 we stopped passing the argified current_template_parms to
    normalize_constraint_expression from finish_nested_requirement, and
    instead made map_arguments perform a self-mapping of parameters when
    args is NULL.  But we're currently not handling parameter packs and
    BOUND_TEMPLATE_TEMPLATE_PARMs properly during this self-mapping, which
    leads to ICEs later during satisfaction.

    To properly handle self-mapping of a parameter pack, this patch
    extends template_parm_to_arg to handle TEMPLATE_PARM_P nodes, and
    makes map_arguments use it.  (This change revealed that the call to
    template_parm_to_arg in convert_generic_types_to_packs was a no-op
    because the argument 't' is never a TREE_LIST, so this patch
    additionally removes this call.)

    As for bound ttps, map_arguments before r10-8077 would map a
    BOUND_TEMPLATE_TEMPLATE_PARM not to itself but to its underlying
    TEMPLATE_TEMPLATE_PARM.  We could restore this behavior in
    map_arguments, but since a bound ttp is not really a template parameter
    it seems better to make keep_template_parm not give us a bound ttp in
    the first place.  So this patch makes keep_template_parm return the
    underlying ttp when it sees a bound ttp.

    gcc/cp/ChangeLog:

            PR c++/96531
            PR c++/97103
            * constraint.cc (map_arguments): Call template_parm_to_arg
            in the self-mapping case.
            (finish_shorthand_constraint): No need to build a TREE_LIST
            before calling template_parm_to_arg.
            * pt.c (template_parm_to_arg): Rewrite to handle TEMPLATE_PARM_P
            nodes as well as DECL_TEMPLATE_PARM_P nodes, and to make the
            overlying TREE_LIST node optional.
            (keep_template_parm): Don't record a BOUND_TEMPLATE_TEMPLATE_PARM,
            instead record its corresponding TEMPLATE_TEMPLATE_PARM.
            (convert_generic_types_to_packs): Don't call
            template_parm_to_arg.

    gcc/testsuite/ChangeLog:

            PR c++/96531
            PR c++/97103
            * g++.dg/cpp2a/concepts-ttp2.C: New test.
            * g++.dg/cpp2a/concepts-variadic1.C: New test.

    (cherry picked from commit e5d72c840a226fdbab65912f97d42a1dbdaf6ed2)

[Bug c++/97103] [10 Regression] ICE on nested requires expression template template instantiation

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97103

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

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

--- Comment #7 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed.