From a670bafc121c20168624f70a388dbe8556402c7f Mon Sep 17 00:00:00 2001
From: kaizhangNV <149626564+kaizhangNV@users.noreply.github.com>
Date: Wed, 9 Jul 2025 11:25:29 -0500
Subject: no_diff diagnostics improvement (#7655)

close #6286.

This PR is to improve the diagnostics for no_diff usage.

In a differentiable function, any calls to a non-diff function with constant arguments should not require no_diff attribute.
This PR adds this extra check at `checkAutoDiffUsages` where it checks the differentiability on IR.

In a differentiable method, we will force to use `[NoDiffThis]` attribute if there is access to non-differentiable `This` type. Once this access is detected we will report a warning to bring users attention that this access won't generate any derivative, they have to use `[NoDiffThis]` to suppress that warning.
This PR adds this check at type checking stage, because it's the easiest way to find out all the `This` accesses.
---
 tests/autodiff/dynamic-dispatch-bwd-diff.slang | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'tests/autodiff/dynamic-dispatch-bwd-diff.slang')

diff --git a/tests/autodiff/dynamic-dispatch-bwd-diff.slang b/tests/autodiff/dynamic-dispatch-bwd-diff.slang
index 5945c22cd..9941aa7b1 100644
--- a/tests/autodiff/dynamic-dispatch-bwd-diff.slang
+++ b/tests/autodiff/dynamic-dispatch-bwd-diff.slang
@@ -17,6 +17,7 @@ struct A : IInterface
 {
     float a;
     [BackwardDifferentiable]
+    [NoDiffThis]
     float calc(float x) { return a*x*x; }
 };
 
@@ -24,6 +25,7 @@ struct B : IInterface
 {
     float a;
     [BackwardDifferentiable]
+    [NoDiffThis]
     float calc(float x) { return a*x*x*x; }
 };
 
-- 
cgit v1.2.3