Fix swc-project#1788

kdy1 · Jun 11, 2021 · ba163fc · ba163fc
1 parent a2f277a
commit ba163fc
Showing 1 changed file with 85 additions and 3 deletions.
diff --git a/ecmascript/transforms/compat/src/es2020/operators.rs b/ecmascript/transforms/compat/src/es2020/operators.rs
@@ -2,7 +2,8 @@ use swc_common::DUMMY_SP;
 use swc_ecma_ast::*;
 use swc_ecma_transforms_base::{ext::MapWithMut, perf::Check};
 use swc_ecma_transforms_macros::fast_path;
-use swc_ecma_utils::prepend;
+use swc_ecma_utils::ExprFactory;
+use swc_ecma_utils::{alias_if_required, prepend};
 use swc_ecma_visit::{
     as_folder, noop_visit_mut_type, noop_visit_type, Fold, Node, Visit, VisitMut, VisitMutWith,
 };
@@ -20,8 +21,89 @@ struct Operators {
 impl VisitMut for Operators {
     noop_visit_mut_type!();
 
-    fn visit_mut_expr(&mut self, n: &mut Expr) {
-        n.visit_mut_children_with(self);
+    fn visit_mut_expr(&mut self, e: &mut Expr) {
+        e.visit_mut_children_with(self);
+
+        match e {
+            Expr::Assign(AssignExpr {
+                span,
+                op: op!("||="),
+                left: PatOrExpr::Expr(left),
+                right,
+            }) if left.is_ident() || left.is_member() => {
+                let (alias, aliased) = alias_if_required(
+                    match &**left {
+                        Expr::Member(MemberExpr {
+                            obj: ExprOrSuper::Expr(obj),
+                            ..
+                        }) => &obj,
+                        _ => left,
+                    },
+                    "_ref",
+                );
+                let aliased = aliased
+                    && match &**left {
+                        Expr::Member(MemberExpr {
+                            obj: ExprOrSuper::Super(..),
+                            ..
+                        }) => false,
+                        _ => true,
+                    };
+
+                if aliased {
+                    self.vars.push(VarDeclarator {
+                        span: DUMMY_SP,
+                        name: Pat::Ident(alias.clone().into()),
+                        init: None,
+                        definite: false,
+                    });
+                }
+
+                let result_left = if aliased {
+                    let left: MemberExpr = left.clone().member().unwrap();
+
+                    Box::new(Expr::Member(MemberExpr {
+                        span: left.span,
+                        obj: AssignExpr {
+                            span: DUMMY_SP,
+                            op: op!("="),
+                            left: PatOrExpr::Pat(Box::new(Pat::Ident(alias.clone().into()))),
+                            right: left.obj.expr().unwrap(),
+                        }
+                        .as_obj(),
+                        prop: left.prop,
+                        computed: left.computed,
+                    }))
+                } else {
+                    Box::new(Expr::Ident(left.clone().ident().unwrap()))
+                };
+
+                let right = Box::new(Expr::Assign(AssignExpr {
+                    span: DUMMY_SP,
+                    op: op!("="),
+                    left: if aliased {
+                        let left = left.take().member().unwrap();
+                        PatOrExpr::Expr(Box::new(Expr::Member(MemberExpr {
+                            span: DUMMY_SP,
+                            obj: alias.clone().as_obj(),
+                            prop: left.prop,
+                            computed: left.computed,
+                        })))
+                    } else {
+                        PatOrExpr::Pat(Box::new(Pat::Ident(left.take().ident().unwrap().into())))
+                    },
+                    right: right.take(),
+                }));
+
+                *e = Expr::Bin(BinExpr {
+                    span: *span,
+                    op: op!("||"),
+                    left: result_left,
+                    right,
+                });
+            }
+            _ => {}
+        }
     }
 
     fn visit_mut_module(&mut self, n: &mut Module) {