[Bug c++/115425] New: ICE: tree check: expected type_pack_expansion or expr_pack_expansion, have error_mark in tsubst_pack_expansion, at cp/pt.cc:13778

[Bug c++/115425] New: ICE: tree check: expected type_pack_expansion or expr_pack_expansion, have error_mark in tsubst_pack_expansion, at cp/pt.cc:13778

[hewillk at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115425

            Bug ID: 115425
           Summary: ICE: tree check: expected type_pack_expansion or
                    expr_pack_expansion, have error_mark in
                    tsubst_pack_expansion, at cp/pt.cc:13778
           Product: gcc
           Version: 15.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: hewillk at gmail dot com
  Target Milestone: ---

This seems like 15 regressions and may related to the constexpr static local
variable.

https://godbolt.org/z/sf4f3Woqa

#include <tuple>

template<std::size_t... Is>
void foo(std::index_sequence<Is...>);

template<auto>
struct S;

template<class T>
auto test() {
  using Seq = std::make_index_sequence<std::tuple_size_v<T>>;
  constexpr static auto x = foo<Seq>();
  return []<std::size_t... Is>(std::index_sequence<Is...>) {
    (typename S<x[Is]>::type{}, ...);
  }(std::make_index_sequence<0>{});
}

int main() {
  test<std::tuple<>>();
}

[Bug c++/115425] ICE: tree check: expected type_pack_expansion or expr_pack_expansion, have error_mark in tsubst_pack_expansion, at cp/pt.cc:13778

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115425

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
> 15 regressions

It might not be because this is a checking enabled ICE.

[Bug c++/115425] [13/14/15 regression] ICE: tree check: expected type_pack_expansion or expr_pack_expansion, have error_mark in tsubst_pack_expansion, at cp/pt.cc:13778

[sjames at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115425

Sam James <sjames at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|ICE: tree check: expected   |[13/14/15 regression] ICE:
                   |type_pack_expansion or      |tree check: expected
                   |expr_pack_expansion, have   |type_pack_expansion or
                   |error_mark in               |expr_pack_expansion, have
                   |tsubst_pack_expansion, at   |error_mark in
                   |cp/pt.cc:13778              |tsubst_pack_expansion, at
                   |                            |cp/pt.cc:13778

--- Comment #2 from Sam James <sjames at gcc dot gnu.org> ---
The ICE started in 13.

[Bug c++/115425] [13/14/15 regression] ICE: tree check: expected type_pack_expansion or expr_pack_expansion, have error_mark in tsubst_pack_expansion, at cp/pt.cc:13778

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115425

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-06-13
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Target Milestone|---                         |13.4
                 CC|                            |mpolacek at gcc dot gnu.org

--- Comment #3 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Started with r13-272-gdc6c96f0707aba:

commit dc6c96f0707aba6c2c94f41f3ccd0713381e372c
Author: Patrick Palka <ppalka@redhat.com>
Date:   Tue May 10 11:52:21 2022 -0400

    c++: Harden *_PACK_EXPANSION and *_ARGUMENT_PACK macros

I think the fix is just

--- a/gcc/cp/pt.cc
+++ b/gcc/cp/pt.cc
@@ -13748,6 +13748,8 @@ tsubst_pack_expansion (tree t, tree args,
tsubst_flags_t complain,
       else
    result = tsubst (pattern, args, complain, in_decl);
       result = make_pack_expansion (result, complain);
+      if (result == error_mark_node)
+   return error_mark_node;
       PACK_EXPANSION_LOCAL_P (result) = PACK_EXPANSION_LOCAL_P (t);
       PACK_EXPANSION_SIZEOF_P (result) = PACK_EXPANSION_SIZEOF_P (t);
       if (PACK_EXPANSION_AUTO_P (t))

[Bug c++/115425] [13/14/15 regression] ICE: tree check: expected type_pack_expansion or expr_pack_expansion, have error_mark in tsubst_pack_expansion, at cp/pt.cc:13778

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115425

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

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

[Bug c++/115425] [13/14/15 regression] ICE: tree check: expected type_pack_expansion or expr_pack_expansion, have error_mark in tsubst_pack_expansion, at cp/pt.cc:13778

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115425

--- Comment #4 from GCC Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Marek Polacek <mpolacek@gcc.gnu.org>:

https://gcc.gnu.org/g:ed6ffc4e62f716d1b31d599d22594dd969da137f

commit r15-1621-ged6ffc4e62f716d1b31d599d22594dd969da137f
Author: Marek Polacek <polacek@redhat.com>
Date:   Fri Jun 14 17:50:29 2024 -0400

    c++: ICE with generic lambda and pack expansion [PR115425]

    In r13-272 we hardened the *_PACK_EXPANSION and *_ARGUMENT_PACK macros.
    That trips up here because make_pack_expansion returns error_mark_node
    and we access that with PACK_EXPANSION_LOCAL_P.

            PR c++/115425

    gcc/cp/ChangeLog:

            * pt.cc (tsubst_pack_expansion): Return error_mark_node if
            make_pack_expansion doesn't work out.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/lambda-generic12.C: New test.

[Bug c++/115425] [13/14 regression] ICE: tree check: expected type_pack_expansion or expr_pack_expansion, have error_mark in tsubst_pack_expansion, at cp/pt.cc:13778

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115425

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED
            Summary|[13/14/15 regression] ICE:  |[13/14 regression] ICE:
                   |tree check: expected        |tree check: expected
                   |type_pack_expansion or      |type_pack_expansion or
                   |expr_pack_expansion, have   |expr_pack_expansion, have
                   |error_mark in               |error_mark in
                   |tsubst_pack_expansion, at   |tsubst_pack_expansion, at
                   |cp/pt.cc:13778              |cp/pt.cc:13778

--- Comment #5 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Fixed on trunk.