[Bug c++/114675] New: warning for "reference to not fully constructed object"

[Bug c++/114675] New: warning for "reference to not fully constructed object"

[Simon.Richter at hogyros dot de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114675

            Bug ID: 114675
           Summary: warning for "reference to not fully constructed
                    object"
           Product: gcc
           Version: 13.1.1
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: Simon.Richter at hogyros dot de
  Target Milestone: ---

We have an object that contains several sub-objects that should reference each
other through interface pointers. I'd like to make sure that interface pointers
given to objects constructed later already point to initialized objects.

So, for

struct everything {
    everything() : a(), b(c), c(a) { }

    A a;
    B b;
    C c;
};

I'm passing a reference to the not-yet-constructed C object to B's constructor,
so this is unsafe despite being legal C++. I wonder if it would be possible to
generate a warning here.

[Bug c++/114675] warning for "reference to not fully constructed object"

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114675

--- Comment #1 from Jonathan Wakely <redi at gcc dot gnu.org> ---
A complete testcase that actually compiles:

struct A { };
struct C { C(const A&); };
struct B { B(const C&); };

struct everything {
    everything() : a(), b(c), c(a) { }

    A a;
    B b;
    C c;
};

[Bug c++/114675] warning for "reference to not fully constructed object"

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114675

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2024-04-10
             Status|UNCONFIRMED                 |NEW
     Ever confirmed|0                           |1
           Severity|normal                      |enhancement

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Jonathan Wakely from comment #1)
> A complete testcase that actually compiles:
> 
> struct A { };
> struct C { C(const A&); };
> struct B { B(const C&); };
> 
> struct everything {
>     everything() : a(), b(c), c(a) { }
> 
>     A a;
>     B b;
>     C c;
> };

Confirmed. I thought I had saw another bug which was asking for the same thing
but I can't seem to find it right now.

[Bug c++/114675] warning for "reference to not fully constructed object"

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114675

--- Comment #3 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Yeah I looked for a dup too, as I'm sure this has been reported before.