Make interface types non c-style in Slang2026. (#7260)

* Make interface types non c-style.

* Make Optional<T> work with autodiff and existential types.

* Fix.

* patch behind slang 2026.

* Fix warnings.

* cleanup.

* Fix tests.

* Fix.

* Fix com interface lowering.

* Add comment to test.

* regenerate command line reference

* Add test for passing `none` to autodiff function.

* Fix recording of `getDynamicObjectRTTIBytes`.

* Fix nested Optional types.

---------

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

1 files changed, 59 insertions, 0 deletions

diff --git a/tests/autodiff/optional.slang b/tests/autodiff/optional.slang
new file mode 100644
index 000000000..a86440413
--- /dev/null
+++ b/tests/autodiff/optional.slang
@@ -0,0 +1,59 @@
+//TEST(compute):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-slang -compute -output-using-type
+//TEST(compute,vulkan):COMPARE_COMPUTE_EX(filecheck-buffer=CHECK):-vk -slang -compute -output-using-type
+
+[Differentiable]
+Optional<float> sumSquare(Optional<float> a, Optional<float> b)
+{
+    if (let x = a)
+    {
+        if (let y = b)
+        {
+            return x * x + y * y;
+        }
+        else
+        {
+            return x * x;
+        }
+    }
+    else if (let y = b)
+    {
+        return y * y;
+    }
+    return none;
+}
+
+//TEST_INPUT:ubuffer(data=[0 0 0], stride=4):out,name=outputBuffer
+RWStructuredBuffer<float> outputBuffer;
+
+[numthreads(1,1,1)]
+void computeMain()
+{
+    var dpa = diffPair<Optional<float>>(3.0f, none);
+    var dpb = diffPair<Optional<float>>(4.0f, none);
+
+    bwd_diff(sumSquare)(dpa, dpb, 1.0f);
+
+    outputBuffer[0] = -1;
+
+    // CHECK: 14.0
+    if (dpa.d.hasValue && dpb.d.hasValue)
+        outputBuffer[0] = dpa.d.value + dpb.d.value;
+
+    // CHECK: 1.0
+    dpa = diffPair<Optional<float>>(3.0f, none);
+    dpb = diffPair<Optional<float>>(4.0f, none);
+    bwd_diff(sumSquare)(dpa, dpb, none);
+    if (dpa.d.value == 0.0 && dpb.d.value == 0.0)
+    {
+        outputBuffer[1] = 1.0f;
+    }
+
+     // CHECK: 100.0
+     dpa = diffPair<Optional<float>>(none, none);
+     dpb = diffPair<Optional<float>>(4.0f, none);
+     bwd_diff(sumSquare)(dpa, dpb, 1.0);
+     if (dpa.d == none)
+     {
+         outputBuffer[2] = 100.0f;
+     }
+}
\ No newline at end of file