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From: "mpolacek at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/114697] New: [DR 233] references in user defined
 conversions
Date: Thu, 11 Apr 2024 18:33:22 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114697

            Bug ID: 114697
           Summary: [DR 233] references in user defined conversions
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mpolacek at gcc dot gnu.org
  Target Milestone: ---

This should compile:

```
  struct Z {};

  struct A {
    operator Z&();          // #1
    operator const Z&();
  };

  struct B {
    operator Z();           // #2
    operator const Z&&();
  };

  const Z& r1 =3D A();          // OK, uses #1
  const Z&& r2 =3D B();         // OK, uses #2
```

but we reject it with:

cwg233.C:13:15: error: conversion from =E2=80=98A=E2=80=99 to =E2=80=98cons=
t Z&=E2=80=99 is ambiguous
   13 | const Z& r1 =3D A();          // OK, uses #1
      |               ^~~
cwg233.C:4:3: note: candidate: =E2=80=98A::operator Z&()=E2=80=99
    4 |   operator Z&();          // #1
      |   ^~~~~~~~
cwg233.C:5:3: note: candidate: =E2=80=98A::operator const Z&()=E2=80=99
    5 |   operator const Z&();
      |   ^~~~~~~~=