[Bug libstdc++/104559] New: vector<bool> v; v.insert(v.begin()); compiles, but it shouldn't

[Bug libstdc++/104559] New: vector<bool> v; v.insert(v.begin()); compiles, but it shouldn't

[arthur.j.odwyer at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104559

            Bug ID: 104559
           Summary: vector<bool> v; v.insert(v.begin()); compiles, but it
                    shouldn't
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: libstdc++
          Assignee: unassigned at gcc dot gnu.org
          Reporter: arthur.j.odwyer at gmail dot com
  Target Milestone: ---

// https://godbolt.org/z/3efs3aY67
#include <vector>
int main() {
    std::vector<bool> v;
    v.insert(v.begin());  // libstdc++ accepts!
}

Somehow libstdc++ believes that `vector<bool>::insert(_Bit_const_reference)`
should work. (I bet it inserts "false" at the given position, but I haven't
checked.)

[Bug libstdc++/104559] vector<bool> v; v.insert(v.begin()); compiles, but it shouldn't

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104559

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
>From include/bits/stl_bvector.h"

      iterator
#if __cplusplus >= 201103L
      insert(const_iterator __position, const bool& __x = bool())
#else
      insert(iterator __position, const bool& __x = bool())
#endif

Looks like it has been there since std::vector<bool> was added back in
1999/2000 or so.

[Bug libstdc++/104559] vector<bool> v; v.insert(v.begin()); compiles, but it shouldn't

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104559

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2022-02-16
           Keywords|                            |accepts-invalid

--- Comment #2 from Jonathan Wakely <redi at gcc dot gnu.org> ---
(In reply to Arthur O'Dwyer from comment #0)
> Somehow libstdc++ believes that `vector<bool>::insert(_Bit_const_reference)`
> should work. 

?

That's not what your example does.

I'll try to do some archaeology for the default argument tomorrow and see why
we have it.

[Bug libstdc++/104559] vector<bool> v; v.insert(v.begin()); compiles, but it shouldn't

[de34 at live dot cn]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104559

Jiang An <de34 at live dot cn> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |de34 at live dot cn

--- Comment #3 from Jiang An <de34 at live dot cn> ---
The default argument has been present in a very early (perhaps the first)
version of libstdc++. 
https://github.com/gcc-mirror/gcc/blob/6599da043e22e96ac830fb50a61c1b6d95d1b142/libstdc%2B%2B/stl/bvector.h#L472

AFIAK this default argument has never been a part of the C++ standard, but was
in in some prehistoric working drafts. Seems removed by WG21-N1051.
http://www.open-std.org/JTC1/SC22/WG21/docs/wp/html/cd2/lib-containers.html#lib.vector.bool
http://www.open-std.org/JTC1/SC22/WG21/docs/papers/1997/N1051.asc

[Bug libstdc++/104559] vector<bool> v; v.insert(v.begin()); compiles, but it shouldn't

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104559

--- Comment #4 from Jonathan Wakely <redi at gcc dot gnu.org> ---
Yep, that's why we have it, thanks. But it should have been excised years ago.

I'll deprecate it, and kill it some time after GCC 12.

[Bug libstdc++/104559] vector<bool> v; v.insert(v.begin()); compiles, but it shouldn't

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104559

--- Comment #5 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The master branch has been updated by Jonathan Wakely <redi@gcc.gnu.org>:

https://gcc.gnu.org/g:12a88e6e208fa45a449775bfb9353c777a6081aa

commit r12-7289-g12a88e6e208fa45a449775bfb9353c777a6081aa
Author: Jonathan Wakely <jwakely@redhat.com>
Date:   Thu Feb 17 17:37:42 2022 +0000

    libstdc++: Deprecate non-standard std::vector<bool>::insert(pos) [PR104559]

    The SGI STL and pre-1998 drafts of the C++ standard had a default
    argument for vector<bool>::insert(iterator, const bool&) which was
    remove by N1051. The default argument is still present in libstdc++ for
    some reason. There are no tests verifying it as an extension, so I don't
    think it has been kept intentionally.

    This removes the default argument but adds an overload without the
    second parameter, and adds the deprecated attribute to it. This allows
    any code using it to keep working (for now) but with a warning.

    libstdc++-v3/ChangeLog:

            PR libstdc++/104559
            * doc/xml/manual/evolution.xml: Document deprecation.
            * doc/html/manual/api.html: Regenerate.
            * include/bits/stl_bvector.h (insert(const_iterator, const bool&)):
            Remove default argument.
            (insert(const_iterator)): New overload with deprecated attribute.
            * testsuite/23_containers/vector/bool/modifiers/insert/104559.cc:
            New test.

[Bug libstdc++/104559] vector<bool> v; v.insert(v.begin()); compiles, but it shouldn't

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104559

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|---                         |FIXED

--- Comment #6 from Jonathan Wakely <redi at gcc dot gnu.org> ---
.

[Bug libstdc++/104559] vector<bool> v; v.insert(v.begin()); compiles, but it shouldn't

[redi at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104559

Jonathan Wakely <redi at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |12.0