[Bug c++/101043] New: ICE in check_noexcept_r for lambda conditional noexcept via requires expression

[Bug c++/101043] New: ICE in check_noexcept_r for lambda conditional noexcept via requires expression

[jbassett271 at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101043

            Bug ID: 101043
           Summary: ICE in check_noexcept_r for lambda conditional
                    noexcept via requires expression
           Product: gcc
           Version: 10.3.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jbassett271 at gmail dot com
  Target Milestone: ---

GCC has an internal compiler error for requires expressions inside the noexcept
clause of a lambda inside a templated function:

https://godbolt.org/z/oWhq9sf8M


template <typename T>
struct set {
  bool contains(T const&) const { return true; }
};

template <typename T>
void intersect(set<T> const& lhs, set<T> const& rhs) {
  auto f = [&]<typename T1>(T1&& _1) noexcept(requires {
    { rhs.contains(_1) } noexcept;
  }) {
      return rhs.contains(_1);
  };
}

int main() {
  set<int> lhs;
  set<int> rhs;
  intersect(lhs, rhs);
}


Error message:

<source>: In instantiation of 'void intersect(const set<T>&, const set<T>&)
[with T = int]':
<source>:18:21:   required from here
<source>:9:7: internal compiler error: in check_noexcept_r, at cp/except.c:1123
    9 |     { rhs.contains(_1) } noexcept;
      |     ~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
Please submit a full bug report,
with preprocessed source if appropriate.
See <https://gcc.gnu.org/bugs/> for instructions.


The commandline arguments, according to the Compiler Explorer link (cleaned a
little):

-g -o output.s -masm=intel -S -fdiagnostics-color=always -std=c++20 example.cpp

Clang compiles this fine.

I was able to replicate this bug in GCC versions 10.1, 10.2, 10.3, and 11.1.

[Bug c++/101043] ICE in check_noexcept_r for lambda conditional noexcept via requires expression

[marxin at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101043

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2021-06-14
                 CC|                            |jason at gcc dot gnu.org,
                   |                            |marxin at gcc dot gnu.org

--- Comment #1 from Martin Liška <marxin at gcc dot gnu.org> ---
Started with r10-3735-gcb57504a55015891. It was rejected before the revision.

[Bug c++/101043] ICE in check_noexcept_r for lambda conditional noexcept via requires expression

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101043

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2021-06-14 00:00:00         |2021-10-1

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The ICE moved in GCC 11+:
<source>: In instantiation of 'void intersect(const set<T>&, const set<T>&)
[with T = int]':
<source>:19:12:   required from here
<source>:9:12: internal compiler error: in strip_typedefs_expr, at
cp/tree.c:1864

[Bug c++/101043] ICE in check_noexcept_r for lambda conditional noexcept via requires expression

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101043

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=98333

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Andrew Pinski from comment #2)
> The ICE moved in GCC 11+:
> <source>: In instantiation of 'void intersect(const set<T>&, const set<T>&)
> [with T = int]':
> <source>:19:12:   required from here
> <source>:9:12: internal compiler error: in strip_typedefs_expr, at
> cp/tree.c:1864

Maybe the patch for PR 98333 changed where the ICE is ...

[Bug c++/101043] ICE in check_noexcept_r for lambda conditional noexcept via requires expression

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101043

--- 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:40a7707a7ea3568cee2cd80cd7e83b7eda678410

commit r14-5504-g40a7707a7ea3568cee2cd80cd7e83b7eda678410
Author: Patrick Palka <ppalka@redhat.com>
Date:   Wed Nov 15 12:17:55 2023 -0500

    c++: partially inst requires-expr in noexcept-spec [PR101043]

    Here we're ICEing from strip_typedefs for the partially instantiated
    requires-expression when walking its REQUIRES_EXPR_EXTRA_ARGS which
    in this case is a TREE_LIST with non-empty TREE_PURPOSE (to hold the
    captured local specialization 't' as per build_extra_args) which
    strip_typedefs doesn't expect.

    We can probably skip walking REQUIRES_EXPR_EXTRA_ARGS at all since it
    shouldn't contain any typedefs in the first place, but it seems safer
    and more generally useful to just teach strip_typedefs to handle non-empty
    TREE_PURPOSE the obvious way.  (The code asserts TREE_PURPOSE was empty
    even since since its inception i.e. r189298.)

            PR c++/101043

    gcc/cp/ChangeLog:

            * tree.cc (strip_typedefs_expr) <case TREE_LIST>: Handle
            non-empty TREE_PURPOSE.

    gcc/testsuite/ChangeLog:

            * g++.dg/cpp2a/concepts-requires37.C: New test.

[Bug c++/101043] ICE in check_noexcept_r for lambda conditional noexcept via requires expression

[ppalka at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101043

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
         Resolution|---                         |FIXED
             Status|NEW                         |RESOLVED
                 CC|                            |ppalka at gcc dot gnu.org
   Target Milestone|---                         |14.0

--- Comment #5 from Patrick Palka <ppalka at gcc dot gnu.org> ---
Fixed for GCC 14.