QCborValue: fix the move-assignment operatorv5.15.0-beta4

The double-swap technique I used was flawed and broke on
self-assignment. What I had meant to use was the move-and-swap
technique. Thanks to Peppe for pointing it out.

This also fixes a compiler bug in the Green Hills compiler. It was
finding the wrong "swap" function in qSwap:

    using std::swap;
    swap(value1, value2);

It's supposed to find swap(QCborValue &, QCborValue &) due to argument-
dependent lookup. It's instead finding std::swap<QCborValue>, which
recurses.

Fixes: QTBUG-83390
Change-Id: Ibdc95e9af7bd456a94ecfffd1603e1bee90cd107
Reviewed-by: Giuseppe D'Angelo <giuseppe.dangelo@kdab.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/tests/auto/corelib/serialization/qcborvalue/tst_qcborvalue.cpp b/tests/auto/corelib/serialization/qcborvalue/tst_qcborvalue.cpp
index 05cf199abe..64321c11fa 100644
--- a/tests/auto/corelib/serialization/qcborvalue/tst_qcborvalue.cpp
+++ b/tests/auto/corelib/serialization/qcborvalue/tst_qcborvalue.cpp
@@ -385,9 +385,21 @@ void tst_QCborValue::copyCompare()
 {
     QFETCH(QCborValue, v);
     QCborValue other = v;
+
+    // self-moving
+    v = std::move(v);
+    QCOMPARE(v, other); // make sure it's still valid
+
+    // moving
+    v = std::move(other);
+    other = std::move(v);
+
+    // normal copying
+    other = v;
     other = v;
     v = other;
 
+
     QCOMPARE(v.compare(other), 0);
     QCOMPARE(v, other);
     QVERIFY(!(v != other));