Reject overwrites by the same index in QPromise::addResult()

One can call addResult(value, index) twice and consequently set the
value twice by the same index. This seems rather strange and probably
should not be allowed. This commit rejects setting results when there's
already a valid result by that index. Consequently, this fixes memory
leaks caused by N-times-called addResult(..., index)

Fixes: QTBUG-86828
Change-Id: I77494f2cb73ce727ffad721cfcdcaa420899eb25
Reviewed-by: Sona Kurazyan <sona.kurazyan@qt.io>

1 files changed, 13 insertions, 6 deletions

diff --git a/tests/auto/corelib/thread/qpromise/tst_qpromise.cpp b/tests/auto/corelib/thread/qpromise/tst_qpromise.cpp
index 2b8853ccd7..62e3711d42 100644
--- a/tests/auto/corelib/thread/qpromise/tst_qpromise.cpp
+++ b/tests/auto/corelib/thread/qpromise/tst_qpromise.cpp
@@ -169,12 +169,12 @@ void tst_QPromise::addResult()
     auto f = promise.future();
 
     // add as lvalue
+    int resultAt0 = 456;
     {
-        int result = 456;
-        promise.addResult(result);
+        promise.addResult(resultAt0);
         QCOMPARE(f.resultCount(), 1);
-        QCOMPARE(f.result(), result);
-        QCOMPARE(f.resultAt(0), result);
+        QCOMPARE(f.result(), resultAt0);
+        QCOMPARE(f.resultAt(0), resultAt0);
     }
     // add as rvalue
     {
@@ -190,13 +190,20 @@ void tst_QPromise::addResult()
         QCOMPARE(f.resultCount(), 3);
         QCOMPARE(f.resultAt(2), result);
     }
-    // add at position and overwrite
+    // add as lvalue at position and overwrite
     {
         int result = -1;
         const auto originalCount = f.resultCount();
         promise.addResult(result, 0);
         QCOMPARE(f.resultCount(), originalCount);
-        QCOMPARE(f.resultAt(0), result);
+        QCOMPARE(f.resultAt(0), resultAt0); // overwrite does not work
+    }
+    // add as rvalue at position and overwrite
+    {
+        const auto originalCount = f.resultCount();
+        promise.addResult(-1, 0);
+        QCOMPARE(f.resultCount(), originalCount);
+        QCOMPARE(f.resultAt(0), resultAt0); // overwrite does not work
     }
 }