QGeoTileSpec: properly implement qHash()HEADdev

The qHash() overload was missing the seed argument and returned only
32-bits, even on 64-bit platforms, since it was never ported from Qt 5
to Qt 6 style.

Fix by rewriting the overload to idiomatic form, to wit:

- make it a hidden friend
  - since it was out-of-line, I opted to add a hash() member function
    so we don't need to overload
- mark as noexcept
- add the seed argument and port to size_t
- implement using qHashMulti instead of rolling your own combiner
- move the implementation beside operator== to enable easy
  side-by-side comparison for consistency

Pick-to: 6.11 6.8
Task-number: QTBUG-145851
Change-Id: I90d1f00ced0d3d24d52d3667de5ad664af14e07c
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>

3 files changed, 19 insertions, 10 deletions

diff --git a/src/location/maps/qgeotilespec.cpp b/src/location/maps/qgeotilespec.cpp
index 8249101a..ad68a7d4 100644
--- a/src/location/maps/qgeotilespec.cpp
+++ b/src/location/maps/qgeotilespec.cpp
@@ -99,15 +99,9 @@ bool QGeoTileSpec::isLess(const QGeoTileSpec &rhs) const noexcept
     return (*(d.constData()) < *(rhs.d.constData()));
 }
 
-unsigned int qHash(const QGeoTileSpec &spec)
-{
-    unsigned int result = (qHash(spec.plugin()) * 13) % 31;
-    result += ((spec.mapId() * 17) % 31) << 5;
-    result += ((spec.zoom() * 19) % 31) << 10;
-    result += ((spec.x() * 23) % 31) << 15;
-    result += ((spec.y() * 29) % 31) << 20;
-    result += (spec.version() % 3) << 25;
-    return result;
+size_t QGeoTileSpec::hash(size_t seed) const noexcept
+{
+    return d->hash(seed);
 }
 
 QDebug operator<< (QDebug dbg, const QGeoTileSpec &spec)
diff --git a/src/location/maps/qgeotilespec_p.h b/src/location/maps/qgeotilespec_p.h
index 91b5d76c..27365f1c 100644
--- a/src/location/maps/qgeotilespec_p.h
+++ b/src/location/maps/qgeotilespec_p.h
@@ -72,9 +72,11 @@ private:
 
     bool isEqual(const QGeoTileSpec &rhs) const noexcept;
     bool isLess(const QGeoTileSpec &rhs) const noexcept;
+    size_t hash(size_t seed) const noexcept;
+    friend size_t qHash(const QGeoTileSpec &key, size_t seed = 0) noexcept
+    { return key.hash(seed); }
 };
 
-Q_LOCATION_EXPORT unsigned int qHash(const QGeoTileSpec &spec);
 
 Q_LOCATION_EXPORT QDebug operator<<(QDebug, const QGeoTileSpec &);
 
diff --git a/src/location/maps/qgeotilespec_p_p.h b/src/location/maps/qgeotilespec_p_p.h
index 0f1c2314..cf07b1f7 100644
--- a/src/location/maps/qgeotilespec_p_p.h
+++ b/src/location/maps/qgeotilespec_p_p.h
@@ -15,6 +15,7 @@
 // We mean it.
 //
 
+#include <QtCore/qhashfunctions.h>
 #include <QString>
 #include <QSharedData>
 
@@ -29,6 +30,18 @@ public:
           x_(x), y_(y), version_(version)
     {}
 
+
+    size_t hash(size_t seed) const
+    {
+        return qHashMulti(seed,
+                          mapId_,
+                          zoom_,
+                          x_,
+                          y_,
+                          version_,
+                          plugin_);
+    }
+
     inline bool operator==(const QGeoTileSpecPrivate &rhs) const
     {
         return mapId_ == rhs.mapId_