[WIP] Fix PIL optimizer

pilopt/src/lib.rs

@@ -152,10 +152,23 @@ fn collect_required_symbols<'a, T: FieldElement>(
             .values()
             .map(|p| SymbolReference::from(&p.polynomial.name)),
     );
+
+    let poly_ref_to_id = pil_file
+        .definitions
+        .values()
+        .filter_map(|(symbol, _)| matches!(symbol.kind, SymbolKind::Poly(_)).then_some(symbol))
+        .flat_map(|symbol| symbol.array_elements())
+        .collect::<BTreeMap<_, _>>();
+
     for fun in &pil_file.prover_functions {
         for e in fun.all_children() {
             if let Expression::Reference(_, Reference::Poly(poly_ref)) = e {
-                required_names.insert(SymbolReference::from(poly_ref));
+                let symbol_ref = match poly_ref_to_id.get(&poly_ref.name) {
+                    Some(poly_id) => poly_id_to_definition_name[poly_id].into(),
+                    None => SymbolReference::from(poly_ref),
+                };
+
+                required_names.insert(symbol_ref);
             }
         }
     }

pilopt/tests/optimizer.rs

@@ -283,9 +283,7 @@ fn enum_ref_by_trait() {
 }
 
 #[test]
-#[should_panic = "Symbol not found: N::x[0]"]
 fn handle_array_references_in_prover_functions() {
-    // Reproduces https://github.com/powdr-labs/powdr/issues/2051
     let input = r#"namespace N(8);
     col witness x[1];
 
@@ -300,5 +298,16 @@ fn handle_array_references_in_prover_functions() {
         }
     };
     "#;
-    optimize(analyze_string::<GoldilocksField>(input).unwrap()).to_string();
+    let expectation = r#"namespace N(8);
+    col witness x[1];
+    N::x[0]' = N::x[0] + 1;
+    {
+        let intermediate = N::x[0] + 1_expr;
+        query |i| {
+            let _: expr = intermediate;
+        }
+    };
+"#;
+    let optimized = optimize(analyze_string::<GoldilocksField>(input).unwrap()).to_string();
+    assert_eq!(optimized, expectation);
 }