diff options
| author | Lars Knoll <lars.knoll@qt.io> | 2020-10-26 09:18:00 +0100 |
|---|---|---|
| committer | Lars Knoll <lars.knoll@qt.io> | 2020-11-03 16:28:14 +0100 |
| commit | a9c52dbdf47a6a070b84c8d34ae3c0c29a8ac1e8 (patch) | |
| tree | 7ff3b7ea17d1d2a6b860bd6eab60525ff05e25f5 | |
| parent | ba1266baec820ab82b4dccb45f7c248052e8962e (diff) | |
Fix qHash(QMultiHash)
The old code was trying to convert a multi hash to a QHash. While
that worked in Qt 5 it won't compile in Qt 6 anymore.
QHashCombineCommutative also can't be used with a std::pair.
ADL won't find the correct instance with a namespaced build,
as qHash(std::pair) is defined after QHashCommutative. Fix
the code to compile and work correctly.
Change-Id: Ice2bc3ab4244e310cbbb5e0f31fc11eb14f5faf3
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
| -rw-r--r-- | src/corelib/tools/qhash.h | 21 | ||||
| -rw-r--r-- | tests/auto/corelib/tools/qhash/tst_qhash.cpp | 10 |
2 files changed, 24 insertions, 7 deletions
diff --git a/src/corelib/tools/qhash.h b/src/corelib/tools/qhash.h index cee58a0f2f9..67b3e026df8 100644 --- a/src/corelib/tools/qhash.h +++ b/src/corelib/tools/qhash.h @@ -1848,21 +1848,28 @@ template <class Key, class T> size_t qHash(const QHash<Key, T> &key, size_t seed = 0) noexcept(noexcept(qHash(std::declval<Key&>())) && noexcept(qHash(std::declval<T&>()))) { - QtPrivate::QHashCombineCommutative hash; + size_t hash = 0; for (auto it = key.begin(), end = key.end(); it != end; ++it) { - const Key &k = it.key(); - const T &v = it.value(); - seed = hash(seed, std::pair<const Key&, const T&>(k, v)); + QtPrivate::QHashCombine combine; + size_t h = combine(seed, it.key()); + // use + to keep the result independent of the ordering of the keys + hash += combine(h, it.value()); } - return seed; + return hash; } template <class Key, class T> inline size_t qHash(const QMultiHash<Key, T> &key, size_t seed = 0) noexcept(noexcept(qHash(std::declval<Key&>())) && noexcept(qHash(std::declval<T&>()))) { - const QHash<Key, T> &key2 = key; - return qHash(key2, seed); + size_t hash = 0; + for (auto it = key.begin(), end = key.end(); it != end; ++it) { + QtPrivate::QHashCombine combine; + size_t h = combine(seed, it.key()); + // use + to keep the result independent of the ordering of the keys + hash += combine(h, it.value()); + } + return hash; } QT_END_NAMESPACE diff --git a/tests/auto/corelib/tools/qhash/tst_qhash.cpp b/tests/auto/corelib/tools/qhash/tst_qhash.cpp index d5a8db7553f..d63ed7043ec 100644 --- a/tests/auto/corelib/tools/qhash/tst_qhash.cpp +++ b/tests/auto/corelib/tools/qhash/tst_qhash.cpp @@ -73,6 +73,7 @@ private slots: void emplace(); void badHashFunction(); + void hashOfHash(); }; struct IdentityTracker { @@ -1754,5 +1755,14 @@ void tst_QHash::badHashFunction() } +void tst_QHash::hashOfHash() +{ + QHash<int, int> hash; + (void)qHash(hash); + + QMultiHash<int, int> multiHash; + (void)qHash(multiHash); +} + QTEST_APPLESS_MAIN(tst_QHash) #include "tst_qhash.moc" |