QHash: non-readonly iteration access destroys iterator

Example:

    QHash<QString, QString> hash;
    for (const QString & key: QStringList{ "a","b","c","d","e","f","g","h" })
    {
        hash.insert(key, "value of " + key);
    }

    for (auto it = hash.keyBegin(); it != hash.keyEnd(); ++it)
    {
        qWarning() << *it << " --> " << hash[*it];
    }

generates the following output (and is aborted if address sanitizer is active):

"g"  -->  ""
"a"  -->  "value of a"
"c"  -->  "value of c"
"e"  -->  "value of e"
"d"  -->  "value of d"
"h"  -->  "value of h"
"f"  -->  "value of f"
"b"  -->  "value of b"

Problem:

• non-const operator[] calls d->findOrInsert(key)
• findOrInsert() increases hash size, even if key exists
• the realloc destroys the iterator

Expected:

Only resize hash if the key is not found and must be inserted.