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From: "blubban at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/110565] New: Incomplete note on why initializing int& with
 int is ill-formed
Date: Wed, 05 Jul 2023 19:36:41 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110565

            Bug ID: 110565
           Summary: Incomplete note on why initializing int& with int is
                    ill-formed
           Product: gcc
           Version: unknown
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: blubban at gmail dot com
  Target Milestone: ---

struct X {
    X(int&);
    X(X&&) =3D delete; // the issue reproduces without this line, but the e=
rror
is clearer with it
};

template<int>
void f() {
    new X(0);
}


Expected output:

<source>: In function 'void f()':
<source>:8:12: error: no matching function for call to 'X::X(int)'
    8 |     new X(0);
      |            ^
<source>:2:5: note: candidate: 'X::X(int&)' (near match)
    2 |     X(int&);
      |     ^
<source>:2:5: note:   conversion of argument 1 would be ill-formed:
<source>:8:11: error: cannot bind non-const lvalue reference of type 'int&'=
 to
an rvalue of type 'int'


Actual output:

<source>: In function 'void f()':
<source>:8:12: error: no matching function for call to 'X::X(int)'
    8 |     new X(0);
      |            ^
<source>:2:5: note: candidate: 'X::X(int&)' (near match)
    2 |     X(int&);
      |     ^
<source>:2:5: note:   conversion of argument 1 would be ill-formed:


The template and new-expression are necessary; the error is proper without
them.

https://godbolt.org/z/c1Er5nsjd=