fix: Fix evaluation order of assignments with side-effects in their rhs

compiler/noirc_evaluator/src/ssa/ssa_gen/mod.rs

@@ -519,7 +519,7 @@
     ///   br loop_entry(v0)
     /// loop_entry(i: Field):
     ///   v2 = lt i v1
     ///   brif v2, then: loop_body, else: loop_end
     /// loop_body():
     ///   v3 = ... codegen body ...
     ///   v4 = add 1, i
@@ -664,7 +664,7 @@
     ///
     /// ```text
     ///   v0 = ... codegen cond ...
     ///   brif v0, then: then_block, else: else_block
     /// then_block():
     ///   v1 = ... codegen a ...
     ///   br end_if(v1)
@@ -679,7 +679,7 @@
     ///
     /// ```text
     ///   v0 = ... codegen cond ...
     ///   brif v0, then: then_block, else: end_if
     /// then_block:
     ///   v1 = ... codegen a ...
     ///   br end_if()
@@ -1083,8 +1083,8 @@
     }
 
     fn codegen_assign(&mut self, assign: &ast::Assign) -> Result<Values, RuntimeError> {
-        let lhs = self.extract_current_value(&assign.lvalue)?;
         let rhs = self.codegen_expression(&assign.expression)?;
+        let lhs = self.extract_current_value(&assign.lvalue)?;
 
         self.assign_new_value(lhs, rhs);
         Ok(Self::unit_value())

test_programs/execution_success/assign_evaluation_order/Nargo.toml

@@ -0,0 +1,6 @@
+[package]
+name = "assign_evaluation_order"
+type = "bin"
+authors = [""]
+
+[dependencies]

test_programs/execution_success/assign_evaluation_order/src/main.nr

@@ -0,0 +1,29 @@
+fn main() {
+    let result1 = bug_8262((1, true, false));
+    assert_eq(result1, 2);
+
+    let result2 = bug_8337();
+    assert_eq(result2, [10, 40, 10]);
+}
+
+fn bug_8262(mut a: (i32, bool, bool)) -> i32 {
+    a.1 = if a.1 {
+        a = (2, a.2, a.1);
+        true
+    } else {
+        !a.2
+    };
+    a.0
+}
+
+fn bug_8337() -> [Field; 3] {
+    let mut a = [10, 20, 30];
+    a[1] = {
+        a = {
+            a[2] = a[0];
+            [a[0], 40, a[2]]
+        };
+        a[1]
+    };
+    a
+}