fix(ssa refactor): Ignore array out of bounds errors when enable_side_effects is false

crates/noirc_evaluator/src/ssa_refactor/acir_gen/acir_ir/acir_variable.rs

@@ -122,6 +122,14 @@ impl AcirContext {
         self.add_data(var_data)
     }
 
+    /// True if the given AcirVar refers to a constant zero value
+    pub(crate) fn is_constant_zero(&self, var: &AcirVar) -> bool {
+        match self.vars[var] {
+            AcirVarData::Const(field) => field.is_zero(),
+            _ => false,
+        }
+    }
+
     /// Adds a new Variable to context whose value will
     /// be constrained to be the negation of `var`.
     ///

crates/noirc_evaluator/src/ssa_refactor/acir_gen/mod.rs

@@ -284,6 +284,20 @@ impl Context {
             .try_to_u64()
             .expect("Expected array index to fit into a u64") as usize;
 
+        if index >= array.len() {
+            // Ignore the error if side effects are disabled.
+            if let Some(var) = self.current_side_effects_enabled_var {
+                if self.acir_context.is_constant_zero(&var) {
+                    let result_type = dfg.type_of_value(dfg.instruction_results(instruction)[0]);
+                    let value = self.create_default_value(result_type);
+                    self.define_result(dfg, instruction, value);
+                    return;
+                }
+            }
+            // TODO: Can we save a source Location for this error?
+            panic!("Index {} is out of bounds for array of length {}", index, array.len());
+        }
+
         let value = match store_value {
             Some(store_value) => {
                 let store_value = self.convert_value(store_value, dfg);
@@ -680,6 +694,11 @@ impl Context {
             }
         }
     }
+
+    /// Creates a default, meaningless value meant only to be a valid value of the given type.
+    fn create_default_value(&mut self, result_type: Type) -> AcirValue {
+        self.convert_ssa_block_param(&result_type)
+    }
 }
 
 #[cfg(test)]