Refactor `dmul(This, Differential)` to `dmul<T:Real>(T, Differential)` (#3029)

* Refactor `dmul(This, Differential)` to `dmul<T:Real>(T, Differential)`

 - Add AST synthesis support for generic containers
 - Refactor relevant tests

* Merge dmul synthesis with dadd and dzero, and disambiguate using an enum

* Fix trailing spaces

1 files changed, 2 insertions, 2 deletions

diff --git a/tests/autodiff/getter-setter-multi.slang b/tests/autodiff/getter-setter-multi.slang
index 9055e860a..9f03ac4eb 100644
--- a/tests/autodiff/getter-setter-multi.slang
+++ b/tests/autodiff/getter-setter-multi.slang
@@ -34,9 +34,9 @@ struct A : IDifferentiable
     }
 
     [__unsafeForceInlineEarly]
-    static Differential dmul(This a, Differential b)
+    static Differential dmul<T: __BuiltinRealType>(T a, Differential b)
     {
-        B o = {a.x * b.z};
+        B o = {__realCast<float, T>(a) * b.z};
         return o;
     }
 };