Pavel Emelyanov 27e96be6ad B+tree: Clean const_iterator->iterator conversion ...

The tree code have const and non-const overloads for searching methods
like find(), lower_bound(), etc. Not to implement them twice, it's coded
like

   const_iterator find() const {
       ... // the implementation itself
   }

   iterator find() {
       return iterator(const_cast<const *>(this)->find());
   }

i.e. -- const overload is called, and returned by it const_iterator is
converted into a non-const iterator. For that the latter has dedicated
constructor with two inaccuracies: it's not marked as explicit and it
accepts const rvalue reference.

This patch fixes both.

Althogh this disables implicit const -> non-const conversion of
iterators, the constructor in question is public, which still opens a
way for conversion (without const_cast<>). This constructor is better
be marked private, but there's double_decker class that uses bptree
and exploits the same hacks in its finding methods, so it needs this
constructor to be callable. Alas.

Signed-off-by: Pavel Emelyanov <xemul@scylladb.com>

Closes scylladb/scylladb#23069

2025-02-26 23:17:27 +02:00

13 KiB

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