Fix uses of dynamic_cast on types in reflection API (#731)

The `Type` infrastructure uses a class hierarchy, but blindly `dynamic_cast`ing to a desired case doesn't always give the expected result, because a `Type` could represent a `typedef` (a `NamedExpressionType`) that itself resolves to, e.g, a vector type (a `VectorExpressionType`). In that case a `dynamic_cast<VectorExpressionType*>(someType)` would fail, even though the type logically represents a vector. The `Type::As<T>()` method is designed to handle this case, by "looking through" simple `typedef`s to get at the real definition of a type.

The fix in this case is to use `Type::As<T>()` at various points in the reflection code (`reflection.cpp`) instead of `dynamic_cast`.

This problem surfaced with a `StructuredBuffer<float2>` not reflecting correctly, because the element type (`float2`) is actually a `typedef` (for `vector<float,2>`), so I've included a test case that stresses that case. Getting the right output in the test required tweaking the `slang-reflection-test` tool to produce additional output for resource types (currently narrowed down to only affect structured buffers to avoid large diffs in expected test outputs).

1 files changed, 19 insertions, 0 deletions

diff --git a/tests/reflection/structured-buffer.slang b/tests/reflection/structured-buffer.slang
new file mode 100644
index 000000000..491d61486
--- /dev/null
+++ b/tests/reflection/structured-buffer.slang
@@ -0,0 +1,19 @@
+//TEST:REFLECTION:-profile ps_4_0 -target hlsl
+
+// Confirm that we reflect the contents of structure-buffer types correctly.
+
+struct S
+{
+	float2 a;
+	float  b;
+	uint   c;
+};
+
+StructuredBuffer<uint> x;
+StructuredBuffer<float2> y;
+StructuredBuffer<S> z;
+
+float4 main() : SV_Target
+{
+    return x[0] + y[0].xyxy + z[0].a.xyxy;
+}
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