rhi: Be more graceful when one destroys a resource after the QRhi

One is a bad application or library in this case, but nonetheless
we should handle this more gracefully then just crashing due to
the QRhi already having been destroyed. Mainly because in Qt 5 one
could get away with the same: releasing OpenGL objects underneath,
for example, a QSGPlainTexture with no (or wrong) GL context did
not generate any user visible fatal errors. So we should not crash
in Qt 6 either with these code bases.

In debug builds or when QT_RHI_LEAK_CHECK is set, one will get the
unreleased resources warning printed in Qt 6, which is a step
forward compared to Qt 5. So there is still some indication that
something is badly designed, even if the application survives.

Task-number: QTBUG-95394
Pick-to: 6.2
Change-Id: I944f4f425ff126e7363a82aff926b280ccf1dfc3
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Andy Nichols <andy.nichols@qt.io>

1 files changed, 49 insertions, 0 deletions

diff --git a/tests/auto/gui/rhi/qrhi/tst_qrhi.cpp b/tests/auto/gui/rhi/qrhi/tst_qrhi.cpp
index 8b6f55b3b6..be825c8ac2 100644
--- a/tests/auto/gui/rhi/qrhi/tst_qrhi.cpp
+++ b/tests/auto/gui/rhi/qrhi/tst_qrhi.cpp
@@ -137,6 +137,8 @@ private slots:
     void renderbufferImportOpenGL();
     void threeDimTexture_data();
     void threeDimTexture();
+    void leakedResourceDestroy_data();
+    void leakedResourceDestroy();
 
 private:
     void setWindowType(QWindow *window, QRhi::Implementation impl);
@@ -3985,5 +3987,52 @@ void tst_QRhi::threeDimTexture()
     }
 }
 
+void tst_QRhi::leakedResourceDestroy_data()
+{
+    rhiTestData();
+}
+
+void tst_QRhi::leakedResourceDestroy()
+{
+    QFETCH(QRhi::Implementation, impl);
+    QFETCH(QRhiInitParams *, initParams);
+
+    QScopedPointer<QRhi> rhi(QRhi::create(impl, initParams));
+    if (!rhi)
+        QSKIP("QRhi could not be created, skipping");
+
+    // Incorrectly destroy the QRhi before the resources created from it.  Attempting to
+    // destroy the resources afterwards is pointless, the native resources are leaked.
+    // Nonetheless, it should not crash, which is what we are testing here.
+    //
+    // We do not however have control over other, native and 3rd party components: a
+    // validation or debug layer, or a memory allocator may warn, assert, or abort when
+    // not releasing all native resources correctly.
+#ifndef QT_NO_DEBUG
+    // don't want asserts from vkmemalloc, skip the test in debug builds
+    if (impl == QRhi::Vulkan)
+        QSKIP("Skipping leaked resource destroy test due to Vulkan and debug build");
+#endif
+
+    QScopedPointer<QRhiBuffer> buffer(rhi->newBuffer(QRhiBuffer::Immutable, QRhiBuffer::VertexBuffer, 256));
+    QVERIFY(buffer->create());
+
+    QScopedPointer<QRhiTexture> texture(rhi->newTexture(QRhiTexture::RGBA8, QSize(512, 512), 1, QRhiTexture::RenderTarget));
+    QVERIFY(texture->create());
+
+    QScopedPointer<QRhiTextureRenderTarget> rt(rhi->newTextureRenderTarget({ texture.data() }));
+    QScopedPointer<QRhiRenderPassDescriptor> rpDesc(rt->newCompatibleRenderPassDescriptor());
+    QVERIFY(rpDesc);
+    rt->setRenderPassDescriptor(rpDesc.data());
+    QVERIFY(rt->create());
+
+    if (impl == QRhi::Vulkan)
+        qDebug("Vulkan validation layer warnings may be printed below - this is expected");
+
+    rhi.reset();
+
+    // let the scoped ptr do its job with the resources
+}
+
 #include <tst_qrhi.moc>
 QTEST_MAIN(tst_QRhi)