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From: "deco33000 at yandex dot com" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug c++/101780] New: Missing initializers whereas structure has
 default initializers
Date: Wed, 04 Aug 2021 19:53:44 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D101780

            Bug ID: 101780
           Summary: Missing initializers whereas structure has default
                    initializers
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: deco33000 at yandex dot com
  Target Milestone: ---

Hi,

The issue is a false positive warning being issued whereas even if there are
missing initializers, the rest of the struct is default initialized.


// Type your code here, or load an example.
#include <iostream>
#include <vector>
using namespace std;

struct A {
  union {
    int i =3D 82, j;
  };
  int a =3D 98, b =3D 22;
};

int main() {
  A polo =3D {.a =3D 45};

  cout << polo.a << endl;
  cout << polo.i << endl;

  return 0;
}
warning: missing initializer for member 'A::<anonymous>'
[-Wmissing-field-initializers]


Try on godbolt:
https://godbolt.org/z/ohnWPqcE5

Can you confirm it is the intended behavior?
If so, could we make the message clearer, adding: "the following designated
fields X,Y,Z will be default initialized. P,Q,R are left uninitialized."

That way, it is much more useful as a warning, instead of making the dev fe=
ar
of undefined behavior, when there is not.

Thanks,=