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, 35 insertions, 0 deletions

diff --git a/tests/language-feature/nested-optional.slang b/tests/language-feature/nested-optional.slang
new file mode 100644
index 000000000..8fdeac33b
--- /dev/null
+++ b/tests/language-feature/nested-optional.slang
@@ -0,0 +1,35 @@
+//TEST:INTERPRET(filecheck=CHECK):
+
+Optional<Optional<int>> getNone() { return none; }
+
+void main()
+{
+    Optional<Optional<Optional<int>>> val = Optional<Optional<int>>(5);
+    Optional<Optional<Optional<int>>> defaultVal1 = none;
+    Optional<Optional<Optional<int>>> defaultVal2 = getNone();
+
+    // CHECK: 8
+    printf("%d\n", sizeof(val));
+
+    // CHECK: success
+    if (defaultVal1.hasValue == defaultVal2.hasValue)
+    {
+        printf("success\n");
+    }
+    else
+    {
+        printf("failure\n");
+    }
+
+    // CHECK: value: 5
+    if (let x = val)
+    {
+        if (let y = x)
+        {
+            if (let z = y)
+            {
+                printf("value: %d\n", z);
+            }
+        }
+    }
+}
\ No newline at end of file