Don't report results when the results list is empty

When inserting items into the result store, a ResultItem is created,
which stores a pointer to the results list and their size. If the size
of the ResultItem is set to 0, it means that a single result is stored.
In case of trying to report results via an empty list, the size is 0, so
result store treats it as a single result.

Added checks before storing the results to make sure that the result
list isn't empty. Note that empty lists are allowed in some cases for
the filter mode, because ResultStoreBase::addResults() knows how to
handle those cases correctly.

Task-number: QTBUG-80957
Change-Id: I399af4c3eef6adf82fea5df031fe9a9075006b1f
Reviewed-by: Mårten Nordheim <marten.nordheim@qt.io>
(cherry picked from commit 08de1fb28153d8170b592796a84032897afa4206)

2 files changed, 36 insertions, 0 deletions

diff --git a/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp b/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
index 0bdadedfac..c09301ee75 100644
--- a/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
+++ b/tests/auto/corelib/thread/qfuture/tst_qfuture.cpp
@@ -627,6 +627,26 @@ void tst_QFuture::futureInterface()
         VoidResult a;
         a.run().waitForFinished();
     }
+
+    {
+        QFutureInterface<int> fi;
+        fi.reportStarted();
+        fi.reportResults(QVector<int> {});
+        fi.reportFinished();
+
+        QVERIFY(fi.results().empty());
+    }
+
+    {
+        QFutureInterface<int> fi;
+        fi.reportStarted();
+        QVector<int> values = { 1, 2, 3 };
+        fi.reportResults(values);
+        fi.reportResults(QVector<int> {});
+        fi.reportFinished();
+
+        QCOMPARE(fi.results(), values.toList());
+    }
 }
 
 template <typename T>
diff --git a/tests/auto/corelib/thread/qresultstore/tst_qresultstore.cpp b/tests/auto/corelib/thread/qresultstore/tst_qresultstore.cpp
index fba617e34d..a1742b3182 100644
--- a/tests/auto/corelib/thread/qresultstore/tst_qresultstore.cpp
+++ b/tests/auto/corelib/thread/qresultstore/tst_qresultstore.cpp
@@ -175,6 +175,14 @@ void tst_QtConcurrentResultStore::addResults()
 
     ++it;
     QCOMPARE(it, store.end());
+
+    QVector<int> empty;
+    const auto countBefore = store.count();
+    QCOMPARE(store.addResults(countBefore, &empty), -1);
+    QCOMPARE(store.count(), countBefore);
+
+    QCOMPARE(store.addResults(countBefore, &vec1), countBefore);
+    QCOMPARE(store.count(), countBefore + vec1.size());
 }
 
 void tst_QtConcurrentResultStore::resultIndex()
@@ -338,6 +346,14 @@ void tst_QtConcurrentResultStore::filterMode()
     QCOMPARE(store.contains(6), true);
     QCOMPARE(store.contains(7), true);
     QCOMPARE(store.contains(8), false);
+
+    QVector<int> empty;
+    const auto countBefore = store.count();
+    QCOMPARE(store.addResults(countBefore, &empty), -1);
+    QCOMPARE(store.count(), countBefore);
+
+    QCOMPARE(store.addResult(countBefore, &int2), countBefore);
+    QCOMPARE(store.count(), countBefore + 1);
 }
 
 void tst_QtConcurrentResultStore::addCanceledResult()