Fix issue that struct with member is not its Differential type (#7434)

Close #6176.

If the struct has a `no_diff` member, it should not be its Differential
type. We miss this check.

1 files changed, 30 insertions, 0 deletions

diff --git a/tests/autodiff/differential-type-syntheize-diagnostics.slang b/tests/autodiff/differential-type-syntheize-diagnostics.slang
new file mode 100644
index 000000000..f8663a5a1
--- /dev/null
+++ b/tests/autodiff/differential-type-syntheize-diagnostics.slang
@@ -0,0 +1,30 @@
+//DIAGNOSTIC_TEST:SIMPLE(filecheck=CHECK):
+
+struct PartlyDiffable : IDifferentiable
+{
+    no_diff float noDiffMember;
+    float diffMember;
+}
+
+float func(PartlyDiffable.Differential x)
+{
+   // CHECK: ([[# @LINE+1]]): error 30027: 'noDiffMember' is not a member of 'PartlyDiffable.Differential'.
+    return x.noDiffMember;
+}
+
+float func1(PartlyDiffable.Differential x)
+{
+   // CHECK-NOT: ([[# @LINE+1]]): error 30027: 'diffMember.
+    return x.diffMember;
+}
+
+RWStructuredBuffer<float> out;
+
+[shader("compute")]
+void compute()
+{
+    // CHECK:  ([[# @LINE+1]]): error 39999: no overload for 'Differential' applicable to arguments of type (float, float)
+    var diff = PartlyDiffable.Differential(1.0f, 2.0f);
+    out[0] = func(diff);
+    out[1] = func1(diff);
+}