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From: "delleyves at gmx dot ch" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/99550] New: ICE (segfault) on arm with -std=c++2a
Date: Thu, 11 Mar 2021 13:09:50 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99550

            Bug ID: 99550
           Summary: ICE (segfault) on arm with -std=3Dc++2a
           Product: gcc
           Version: 10.2.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: delleyves at gmx dot ch
  Target Milestone: ---

The following code segfaults on "arm-gcc 10.2.1 (none)" (as found on
godbolt.org) when compiled with `-std=3Dc++2a`, but not without that flag.

So does the official ARM GCC release gcc-arm-none-eabi-10-2020-q4-major on
Ubuntu.

On my OSX however, it doesn't segfault. Neither does the x86-64 gcc 10.2 on
godbolt.

```
#include <type_traits>

template <typename value_type_>
struct JoinedRange {
  using value_type =3D value_type_;
  template <bool is_const>
  struct Iterator {
    template <typename T>
    using maybe_const_t =3D std::conditional_t<is_const, const T, T>;

    template <bool>
    friend class Iterator;

   public:
    using value_type =3D JoinedRange::value_type;
    using reference =3D maybe_const_t<value_type>;
    using pointer =3D maybe_const_t<value_type>*;
  };
  using iterator =3D Iterator<false>;
  using const_iterator =3D Iterator<true>;
};

template class JoinedRange<int>;
```=