1 files changed, 44 insertions, 0 deletions
diff --git a/tests/diagnostics/autodiff-primal-substitute.slang b/tests/diagnostics/autodiff-primal-substitute.slang
new file mode 100644
index 000000000..178698719
--- /dev/null
+++ b/tests/diagnostics/autodiff-primal-substitute.slang
@@ -0,0 +1,44 @@
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK): -target spirv -entry computeMain -stage compute
+
+//TEST_INPUT:ubuffer(data=[0 0 0 0], stride=4):out,name=outputBufferPrimal
+RWStructuredBuffer<float> outputBufferPrimal;
+
+//TEST_INPUT:ubuffer(data=[1 2 3 4], stride=4):name=gradBuffer
+RWStructuredBuffer<float> gradBuffer;
+
+struct BufferWithGrad
+{
+    RWStructuredBuffer<float> primal;
+    RWStructuredBuffer<float> grad;
+
+    [Differentiable]
+    void add(float value) { primal[0] = primal[0] + detach(value); }
+
+    // check for diagnostic:
+    // CHECK-DAG: ([[# @LINE+1]]): error 31158
+    [PrimalSubstituteOf(add)]
+    void add_subst(float value)
+    {
+    }
+
+    [BackwardDerivativeOf(add)]
+    void add_bwd(inout DifferentialPair<float> d)
+    {
+        d = diffPair(d.p, grad[0]);
+    }
+}
+
+[Differentiable]
+void diffCall(BufferWithGrad result)
+{
+    result.add(1.0f);
+}
+
+[shader("compute")]
+[numthreads(1, 1, 1)]
+void computeMain(uint3 dispatchThreadID: SV_DispatchThreadID)
+{
+    BufferWithGrad bg = {outputBufferPrimal, gradBuffer};
+    diffCall(bg); 
+    bwd_diff(diffCall)(bg);
+}