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From: "sbence92 at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/100800] New: ternary operator doesn't accept T with
 conversion operator and nullptr
Date: Thu, 27 May 2021 11:45:00 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100800

            Bug ID: 100800
           Summary: ternary operator doesn't accept T with conversion
                    operator and nullptr
           Product: gcc
           Version: 11.1.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: sbence92 at gmail dot com
  Target Milestone: ---
              Host: x86_64-w64-mingw32, x86_64-linux-gnu
            Target: x86_64-w64-mingw32, x86_64-linux-gnu
             Build: x86_64-w64-mingw32, x86_64-linux-gnu

The following code fails to compile with the following message:
error: operands to '?:' have different types 'S2' and 'std::nullptr_t'

Even though S2 is convertible to S* and nullptr is convertible to S* so they
have a common type to convert to. Also the standard mentions that pointer
conversion rules are applied to bring the second and third operand to a com=
mon
type, so this code seems to be valid.
FYI clang and icc accepts this, msvc and gcc doesn't.


struct S{};

struct S2 {
  operator S*();
};

S* f() { return true ? S2{} : nullptr; }=