With <http://cgit.freedesktop.org/libreoffice/core/commit/?id=112bdf84d684590e042725c7173e059b4afa2f83> "Removed dangerous rtl::O[U]String[Buffer]::operator sal_{char,Unicode} const *." the member functions rtl::OStringBuffer::charAt rtl::OStringBuffer::setCharAt rtl::OUStringBuffer::charAt rtl::OUStringBuffer::setCharAt (that followed a misguided inspiration from Java's StringBuffer) are obsolete. They should be marked as SAL_DEPRECATED and their uses be replaced with uses of operator [].
Just finished removing these on master
Migrating Whiteboard tags to Keywords: (EasyHack) [NinjaEdit]