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, 21 insertions, 0 deletions

diff --git a/tools/slang-reflection-test/main.cpp b/tools/slang-reflection-test/main.cpp
index 7e5f268f3..872d2ff3a 100644
--- a/tools/slang-reflection-test/main.cpp
+++ b/tools/slang-reflection-test/main.cpp
@@ -372,6 +372,27 @@ static void emitReflectionTypeInfoJSON(
                 }
                 write(writer, "\"");
             }
+
+            // TODO: We should really print the result type for all resource
+            // types, but current test output depends on the old behavior, so
+            // we only add result type output for structured buffers at first.
+            //
+            switch (shape & SLANG_RESOURCE_BASE_SHAPE_MASK)
+            {
+            default:
+                break;
+
+            case SLANG_STRUCTURED_BUFFER:
+                if( auto resultType = type->getResourceResultType() )
+                {
+                    write(writer, ",\n");
+                    write(writer, "\"resultType\": ");
+                    emitReflectionTypeJSON(
+                        writer,
+                        resultType);
+                }
+                break;
+            }
         }
         break;