Q[Multi]Hash: fix squeeze()

When calling QHash::reserve(), or when creating the
internal QHashPrivate::Data structure, the value 0
for the size parameter is reserved for performing
the squeeze operation.

However commit 8a984ab772dd194e39094e728b869e65912912a7
broke it, by using the 0 value in QHashPrivate::Data
constructors as a mark that no resizing needs to be done.

This patch reverts the problematic commit (also applying
some later fixes to the code), and adds the missing
tests for Q[Multi]Hash::squeeze().

Pick-to: 6.3 6.2
Change-Id: Id644df7b2beb008e6a37b2c89b709adfbd893e25
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>

1 files changed, 29 insertions, 15 deletions

diff --git a/src/corelib/tools/qhash.h b/src/corelib/tools/qhash.h
index 6a545988d4..07e2f2d355 100644
--- a/src/corelib/tools/qhash.h
+++ b/src/corelib/tools/qhash.h
@@ -565,7 +565,6 @@ struct Data
         }
     };
 
-
     Data(size_t reserve = 0)
     {
         numBuckets = GrowthPolicy::bucketsForCapacity(reserve);
@@ -573,25 +572,16 @@ struct Data
         spans = new Span[nSpans];
         seed = QHashSeed::globalSeed();
     }
-    Data(const Data &other, size_t reserved = 0)
-        : size(other.size),
-          numBuckets(other.numBuckets),
-          seed(other.seed)
-    {
-        if (reserved)
-            numBuckets = GrowthPolicy::bucketsForCapacity(qMax(size, reserved));
-        bool resized = numBuckets != other.numBuckets;
-        size_t nSpans = numBuckets >> SpanConstants::SpanShift;
-        spans = new Span[nSpans];
-        size_t otherNSpans = other.numBuckets >> SpanConstants::SpanShift;
 
-        for (size_t s = 0; s < otherNSpans; ++s) {
+    void reallocationHelper(const Data &other, size_t nSpans, bool resized)
+    {
+        for (size_t s = 0; s < nSpans; ++s) {
             const Span &span = other.spans[s];
             for (size_t index = 0; index < SpanConstants::NEntries; ++index) {
                 if (!span.hasNode(index))
                     continue;
                 const Node &n = span.at(index);
-                auto it = resized ? findBucket(n.key) : Bucket{ spans + s, index };
+                auto it = resized ? findBucket(n.key) : Bucket { spans + s, index };
                 Q_ASSERT(it.isUnused());
                 Node *newNode = it.insert();
                 new (newNode) Node(n);
@@ -599,7 +589,31 @@ struct Data
         }
     }
 
-    static Data *detached(Data *d, size_t size = 0)
+    Data(const Data &other) : size(other.size), numBuckets(other.numBuckets), seed(other.seed)
+    {
+        size_t nSpans = numBuckets >> SpanConstants::SpanShift;
+        spans = new Span[nSpans];
+        reallocationHelper(other, nSpans, false);
+    }
+    Data(const Data &other, size_t reserved) : size(other.size), seed(other.seed)
+    {
+        numBuckets = GrowthPolicy::bucketsForCapacity(qMax(size, reserved));
+        size_t nSpans = numBuckets >> SpanConstants::SpanShift;
+        spans = new Span[nSpans];
+        size_t otherNSpans = other.numBuckets >> SpanConstants::SpanShift;
+        reallocationHelper(other, otherNSpans, true);
+    }
+
+    static Data *detached(Data *d)
+    {
+        if (!d)
+            return new Data;
+        Data *dd = new Data(*d);
+        if (!d->ref.deref())
+            delete d;
+        return dd;
+    }
+    static Data *detached(Data *d, size_t size)
     {
         if (!d)
             return new Data(size);