PR 57779 New debug check

[Jonathan Wakely]

On 10 July 2013 21:31, François Dumont wrote:
> Hi
>
>     This is a proposal to add a new debug like proposed in PR 57779.
>
>     I fully implemented it that is to say that I also detect when trying to
> self insert pointers to the std::vector rather than iterators.

Excellent.

>     I had to introduce a __is_lvalue_reference, should I add it to
> bits/cpp_type_traits.h or is there another way to access it without the
> C++11 mode ?

No, sadly std::is_lvalue_reference cannot be used in C++03 mode.

I think cpp_type_traits.h is the best place for it.

+      // Only containers having all elements in continuous memory can have its
+      // elements passed through pointers.

Should be:

      // Only containers with all elements in contiguous memory can have their
      // elements passed through pointers.

In particular, it should be s/continuous/contiguous/

+      if (&(*(__it._M_get_sequence()->_M_base().end()))

Isn't this a dereference of a non-dereferenceable iterator?

+      // Simply can't say so consider it is fine.

s/consider/assume/

+  /* Checks that an iterator do not belong to the same sequence that the one of
+   * a reference iterator.

I would say:

  /* Checks that iterators do not refer to the same sequence.


+  /* This overload detect when passing pointers to the contained
elements rather
+     than using iterators.

Should be "detects"


+  /* For node based container, having not random access iterators,
+   * implementation supports usage of not foreign iterator.

I'm not sure what this means!  I think it should be

+  /* For node-based containers that don't have random access iterators,
+   * this implementation supports usage of non-foreign iterators.

Is that statement true?  This program says no:

#include <set>
int main()
{
    std::multiset<int> s{ 1, 11, 21, 31, 41 };
    s.insert(s.begin(), s.end());
}

Even if it's true, would it be possible to detect that case when
_GLIBCXX_DEBUG_PEDANTIC is defined?  That is supposed to disable GNU
extensions.


>     * include/debug/formatter.h (_Debug_msg_id): Add
>     __msg_insert_itself_range entry.

Could that be called something a bit clearer?
Maybe __msg_insert_range_from_self?