rhi: Improve srb layout serialization helpers

Be idiomatic and return the output iterator one past the last element.
Otherwise passing in a plain pointer (as exercised by the autotest now)
fails to function because we write over the same 4 elements again and
again for each binding.

Pick-to: 6.2
Change-Id: If74463fa5140ffa2b1d5be97b71868848ad46614
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 9 insertions, 0 deletions

diff --git a/tests/auto/gui/rhi/qrhi/tst_qrhi.cpp b/tests/auto/gui/rhi/qrhi/tst_qrhi.cpp
index 603acc03de..8398dac3eb 100644
--- a/tests/auto/gui/rhi/qrhi/tst_qrhi.cpp
+++ b/tests/auto/gui/rhi/qrhi/tst_qrhi.cpp
@@ -3273,6 +3273,7 @@ void tst_QRhi::srbLayoutCompatibility()
         QVERIFY(srb2->isLayoutCompatible(srb1.data()));
 
         QCOMPARE(srb1->serializedLayoutDescription(), srb2->serializedLayoutDescription());
+        QVERIFY(srb1->serializedLayoutDescription().count() == 0);
     }
 
     // different count (not compatible)
@@ -3290,6 +3291,8 @@ void tst_QRhi::srbLayoutCompatibility()
         QVERIFY(!srb2->isLayoutCompatible(srb1.data()));
 
         QVERIFY(srb1->serializedLayoutDescription() != srb2->serializedLayoutDescription());
+        QVERIFY(srb1->serializedLayoutDescription().count() == 0);
+        QVERIFY(srb2->serializedLayoutDescription().count() == 1 * QRhiShaderResourceBinding::LAYOUT_DESC_ENTRIES_PER_BINDING);
     }
 
     // full match (compatible)
@@ -3314,6 +3317,7 @@ void tst_QRhi::srbLayoutCompatibility()
         QVERIFY(!srb1->serializedLayoutDescription().isEmpty());
         QVERIFY(!srb2->serializedLayoutDescription().isEmpty());
         QCOMPARE(srb1->serializedLayoutDescription(), srb2->serializedLayoutDescription());
+        QVERIFY(srb1->serializedLayoutDescription().count() == 2 * QRhiShaderResourceBinding::LAYOUT_DESC_ENTRIES_PER_BINDING);
 
         // see what we would get if a binding list got serialized "manually", without pulling it out from the srb after building
         // (the results should be identical)
@@ -3323,6 +3327,11 @@ void tst_QRhi::srbLayoutCompatibility()
         QVector<quint32> layoutDesc2;
         QRhiShaderResourceBinding::serializeLayoutDescription(srb2->cbeginBindings(), srb2->cendBindings(), std::back_inserter(layoutDesc2));
         QCOMPARE(layoutDesc2, srb2->serializedLayoutDescription());
+
+        // exercise with an "output iterator" different from back_inserter
+        quint32 layoutDesc3[2 * QRhiShaderResourceBinding::LAYOUT_DESC_ENTRIES_PER_BINDING];
+        QRhiShaderResourceBinding::serializeLayoutDescription(srb1->cbeginBindings(), srb1->cendBindings(), layoutDesc3);
+        QVERIFY(!memcmp(layoutDesc3, layoutDesc1.constData(), sizeof(quint32) * 2 * QRhiShaderResourceBinding::LAYOUT_DESC_ENTRIES_PER_BINDING));
     }
 
     // different visibility (not compatible)