Fail slang-test when VVL printed errors (#8280)

fixes https://github.com/shader-slang/slang/issues/8271

This PR does the following,
- Fail slang-test when there are VVL error messages.
- VVL error for `gfx-unit-test-tool/` were not captured properly by the
debug callback.
- Set an environment variable,
`VK_INSTANCE_LAYERS=VK_LAYER_KHRONOS_validation`, for CI and
VisualStudio project setup.
- Ignores VVL error about NullHandle is used for the acceleration
structure; a fix is at ToT of VVL and not available from release build
yet.
- Fix VVL error complaining about the varying inputs are not provided
for the tests, `gfx-unit-test-tool/linkTimeTypeLayout.internal` and
`gfx-unit-test-tool/linkTimeTypeLayoutNested.internal`.

---------

Co-authored-by: slangbot <ellieh+slangbot@nvidia.com>
Co-authored-by: slangbot <186143334+slangbot@users.noreply.github.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/tools/gfx/vulkan/vk-shader-object.cpp b/tools/gfx/vulkan/vk-shader-object.cpp
index eaee69edb..58cb23f22 100644
--- a/tools/gfx/vulkan/vk-shader-object.cpp
+++ b/tools/gfx/vulkan/vk-shader-object.cpp
@@ -504,7 +504,6 @@ void ShaderObjectImpl::writeAccelerationStructureDescriptor(
             static_cast<AccelerationStructureImpl*>(resourceViews[i].Ptr());
         VkWriteDescriptorSetAccelerationStructureKHR writeAS = {};
         writeAS.sType = VK_STRUCTURE_TYPE_WRITE_DESCRIPTOR_SET_ACCELERATION_STRUCTURE_KHR;
-        VkAccelerationStructureKHR nullHandle = VK_NULL_HANDLE;
         if (accelerationStructure)
         {
             writeAS.accelerationStructureCount = 1;
@@ -512,6 +511,12 @@ void ShaderObjectImpl::writeAccelerationStructureDescriptor(
         }
         else
         {
+            // The Vulkan spec states: If the nullDescriptor feature is not enabled, each element of
+            // pAccelerationStructures must not be VK_NULL_HANDLE
+            SLANG_ASSERT(
+                context.device->m_api.m_extendedFeatures.robustness2Features.nullDescriptor);
+
+            static const VkAccelerationStructureKHR nullHandle = VK_NULL_HANDLE;
             writeAS.accelerationStructureCount = 1;
             writeAS.pAccelerationStructures = &nullHandle;
         }