Add diagnostic for calling non-bwd-diff func from bwd-diff func. (#2602)

1 files changed, 28 insertions, 0 deletions

diff --git a/tests/diagnostics/autodiff-data-flow-2.slang b/tests/diagnostics/autodiff-data-flow-2.slang
new file mode 100644
index 000000000..aa923c5d6
--- /dev/null
+++ b/tests/diagnostics/autodiff-data-flow-2.slang
@@ -0,0 +1,28 @@
+//DIAGNOSTIC_TEST:SIMPLE:
+
+float nonDiff(float x)
+{
+    return x;
+}
+
+[ForwardDifferentiable]
+float f(float x)
+{
+    return x * x;
+}
+
+[BackwardDifferentiable]
+float g(float x)
+{
+    float val = f(x + 1); // Error: f must also be backward-differentiable
+    return val;
+}
+
+[BackwardDifferentiable]
+float h(float x)
+{
+    float val = 0;
+    // no diagnostic by clarifying intention.
+    val = no_diff(f(x + 1));
+    return val;
+}