QMultiHash has access to two sizes: one of them is shared with QHash,
stored in QHashPrivate::Data::size, which counts keys; the other, which
is what our public size() function returns, is stored in
QMultiHash::m_size and counts plain (key,value) entries. We forgot to
update it in the non-const operator[] that created a node.
I've reviewed the rest of the code and can't find any more places where
the item count may be changed and m_size isn't updated.
[ChangeLog][QtCore][QMultiHash] Fixed a bug that caused an element that
was created by operator[] to not be counted, resulting in a hash map
with an incorrect element count and which could cause an assertion
failure depending on how the hash was later mutated.
Fixes: QTBUG-112534
Pick-to: 6.2 6.4 6.5
Change-Id: Idd5e1bb52be047d7b4fffffd17527ec274e1d99e
Reviewed-by: Lars Knoll <lars@knoll.priv.no>