Debugger: Add a visualizer for QMultiHash

...and a very primitive test.

Note that the visualization of `QMultiHash::iterator` does not work
(this is a common problem for other containers too).
I am not convinced that making effort to make it work now is worth it.

Fixes: QTCREATORBUG-32313
Change-Id: If68cf17c8aa6d63da752aef07072725131bdbf52
Reviewed-by: hjk <hjk@qt.io>

share/qtcreator/debugger/qttypes.py

@@ -928,6 +928,13 @@ def qform__QHash():
 def qdump__QHash(d, value):
     qdumpHelper_QHash(d, value, value.type[0], value.type[1])
 
+def qdump__QMultiHash(d, value):
+    key_type = value.type[0]
+    value_type = value.type[1]
+    if d.qtVersionAtLeast(0x060000):
+        qdumpHelper_QMultiHash_6(d, value, key_type, value_type)
+    else:
+        qdumpHelper_QHash_5(d, value, key_type, value_type)
 
 def qdump__QVariantHash(d, value):
     qdumpHelper_QHash(d, value, d.createType('@QString'), d.createType('@QVariant'))
@@ -1033,6 +1040,40 @@ def qdumpHelper_QHash_6(d, value, keyType, valueType):
             #    d.putValue('total: %s item size: %s' % (count, entry_size))
 
 
+def qdumpHelper_QMultiHash_6(d, value, key_type, value_type):
+    dptr, size = d.split('pq', value)
+    if dptr == 0:
+        d.putItemCount(0)
+        return
+
+    ref, _pad, _d_size, buckets, _seed, spans = d.split('i@qqqp', dptr)
+
+    d.check(0 <= size and size <= 100 * 1000 * 1000)
+    d.check(-1 <= ref and ref < 100000)
+    d.putItemCount(size)
+
+    if d.isExpanded():
+        type_code = f'{{{key_type.name}}}@p'
+        _pp, entry_size, _fields = d.describeStruct(type_code)
+        with Children(d, size):
+            span_size = 128 + 2 * d.ptrSize() # Including tail padding.
+            nspans = int((buckets + 127) / 128)
+            count = 0
+            for b in range(nspans):
+                span = spans + b * span_size
+                offsets, entries, _allocated, _next_free = d.split('128spbb', span)
+                for i in range(128):
+                    offset = offsets[i]
+                    if offset != 255: # Entry is used
+                        entry = entries + offset * entry_size
+                        key, _pad, chain = d.split(type_code, entry)
+                        next = chain
+                        while next != 0:
+                            val, _pad, next = d.split(f'{{{value_type.name}}}@p', next)
+                            d.putPairItem(count, (key, val), 'key', 'value')
+                            count += 1
+
+
 def qform__QHashNode():
     return [DisplayFormat.CompactMap]
 

tests/auto/debugger/tst_dumpers.cpp

@@ -2538,6 +2538,32 @@ void tst_Dumpers::dumper_data()
                + Check5("it3.key", "33", "int")
                + Check5("it3.value", FloatValue("33"), "float");
 
+    // clang-format off
+    QTest::newRow("QMultiHash")
+            << Data("#include <QMultiHash>",
+
+                    R"(const QMultiHash<int, int> empty;
+                    QMultiHash<int, int> mh;
+                    mh.insert(1, 1);
+                    mh.insert(2, 2);
+                    mh.insert(1, 3);
+                    mh.insert(2, 4);
+                    mh.insert(1, 5);)",
+
+            "&empty, &mh")
+
+               + CoreProfile()
+
+               + Check("empty", "<0 items>", "QMultiHash<int, int>")
+               + Check("mh", "<5 items>", "QMultiHash<int, int>")
+               // due to unordered nature of the container, checking specific item values
+               // is not possible
+               + Check("mh.0.key", ValuePattern("[1,2]"), "int")
+               + Check("mh.0.value", ValuePattern("[1-5]"), "int")
+               + Check("mh.4.key", ValuePattern("[1,2]"), "int")
+               + Check("mh.4.value", ValuePattern("[1-5]"), "int");
+    // clang-format on
+
 
     QTest::newRow("QHostAddress")
             << Data("#include <QHostAddress>\n",