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, 5 insertions, 1 deletions

diff --git a/tests/reflection/thread-group-size.hlsl.expected b/tests/reflection/thread-group-size.hlsl.expected
index cd5d09e35..46b0eb87e 100644
--- a/tests/reflection/thread-group-size.hlsl.expected
+++ b/tests/reflection/thread-group-size.hlsl.expected
@@ -10,7 +10,11 @@ standard output = {
             "type": {
                 "kind": "resource",
                 "baseShape": "structuredBuffer",
-                "access": "readWrite"
+                "access": "readWrite",
+                "resultType": {
+                    "kind": "scalar",
+                    "scalarType": "float32"
+                }
             }
         }
     ],