QHash::squeeze() was unconditionally calling reserve(0), which is
always allocating memory (even for 0 size).
This was leading to a confusing situation when calling squeeze() on
a default-constructed container with 0 capacity() actually allocated
memory. This is very misleading, as squeeze() is supposed to free
unneeded memory, not to allocate more.
This patch adds a check for non-zero capacity. As a result, nothing
is done for default-constructed container.
Note that this patch also affects the QSet::squeeze() behavior, because
QSet uses QHash as its underlying data type.
Task-number: QTBUG-91736
Pick-to: 6.2 6.1
Change-Id: Ib1c3c8b7b3de6ddeefea0e70b1ec71803e8fd3b3
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
Reviewed-by: Andreas Buhr <andreas.buhr@qt.io>
b095d26878