feat: add expression statements and assign expressions

src/middle/builder.rs

@@ -272,6 +272,9 @@ impl FuncBuilder {
                     });
                 }
             }
+            TypedStmtKind::Expression { expr } => {
+                self.lower_expr(expr);
+            }
         }
     }
 
@@ -309,6 +312,21 @@ impl FuncBuilder {
 
                 Operand::Copy(temp)
             }
+            TypedExprKind::Assign { lval, rval } => {
+                let rval_op = self.lower_expr(rval);
+
+                let local_id = match &lval.kind {
+                    TypedExprKind::Identifier { name } => self.lookup(name),
+                    _ => panic!("invalid lval in MIR lowering"),
+                };
+
+                self.emit_stmt(Statement {
+                    kind: StatementKind::Assign(local_id, Rvalue::Use(rval_op.clone())),
+                    span: expr.span,
+                });
+
+                rval_op
+            }
         }
     }
 }