Re: [PATCH][_GLIBCXX_DEBUG] Remove useless checks

[François Dumont via Gcc-patches]

On 23/01/23 10:22, Jonathan Wakely wrote:

On Mon, 23 Jan 2023 at 06:02, François Dumont via Libstdc++
<libstd...@gcc.gnu.org> wrote:

      libstdc++: [_GLIBCXX_DEBUG] Remove useless constructor checks

      Creating a safe iterator from a normal iterator is done within the
library where we
      already know that it is done correctly. The rare situation where a
user would use safe
      iterators for his own purpose is non-Standard code so outside
_GLIBCXX_DEBUG scope. For
      those reasons the __msg_init_singular is useless and can be removed.

      Additionally in the copy constructor used for post-increment and
post-decrement operators
      the __msg_init_copy_singular check can also be ommitted because of
the preliminary
      __msg_bad_inc and __msg_bad_dec checks.

      libstdc++-v3/ChangeLog:

              * include/debug/safe_iterator.h
(_Safe_iterator<>::_Unsafe_call): New.

I don't like the name "unsafe call". Why is it unsafe? As you say
above, we don't need to check because we know that it's only called in
a context where it's safe. Can we call it _Unchecked instead of
_Unsafe_call? That seems like a more accurate description of the
behaviour.

              (_Safe_iterator(const _Safe_iterator&, _Unsafe_call): New.
              (_Safe_iterator::operator++(int)): Use latter.
              (_Safe_iterator::operator--(int)): Likewise.
              (_Safe_iterator(_Iterator, const _Safe_sequence_base*)):
Remove !_M_insular()
              check.
              * include/debug/safe_local_iterator.h
(_Safe_local_iterator<>::_Unsafe_call):
              New.
              (_Safe_local_iterator(const _Safe_local_iterator&,
_Unsafe_call): New.
              (_Safe_local_iterator::operator++(int)): Use latter.
              * src/c++11/debug.cc (_S_debug_messages): Add as comment
the _Debug_msg_id
              entry associated to the array entry.

These comments are a great idea, thanks.

If you agree with the _Unchecked name, OK to commit with that change.

It's unsafe because it's unchecked so _Unchecked is fine for me too :-)

Committed with the requested change.

Thanks