feat(transformer/optional-chaining): change parent scope for expression when it wrapped with an arrow function

Author: Dunqing

crates/oxc_transformer/src/es2020/optional_chaining.rs

@@ -51,6 +51,7 @@ use std::mem;
 
 use oxc_allocator::CloneIn;
 use oxc_ast::{ast::*, NONE};
+use oxc_semantic::ScopeFlags;
 use oxc_span::SPAN;
 use oxc_traverse::{Ancestor, BoundIdentifier, MaybeBoundIdentifier, Traverse, TraverseCtx};
 
@@ -244,14 +245,20 @@ impl<'a> OptionalChaining<'a, '_> {
 
     /// Wrap the expression with an arrow function
     ///
-    /// `expr` ->  `() => { return expr; }`
-    fn wrap_arrow_function(expr: &mut Expression<'a>, ctx: &mut TraverseCtx<'a>) -> Expression<'a> {
+    /// `expr` ->  `(() => { return expr; })()`
+    fn wrap_arrow_function_iife(
+        expr: &mut Expression<'a>,
+        ctx: &mut TraverseCtx<'a>,
+    ) -> Expression<'a> {
+        // Create a child scope for the outside arrow function and change the parent scope for the expression
+        let scope_id = ctx.create_child_scope_of_current(ScopeFlags::Arrow | ScopeFlags::Function);
+        ctx.change_parent_scope_for_expression(scope_id, expr);
+
         let kind = FormalParameterKind::ArrowFormalParameters;
         let params = ctx.ast.formal_parameters(SPAN, kind, ctx.ast.vec(), NONE);
         let statements =
             ctx.ast.vec1(ctx.ast.statement_return(SPAN, Some(ctx.ast.move_expression(expr))));
         let body = ctx.ast.function_body(SPAN, ctx.ast.vec(), statements);
-        let scope_id = ctx.current_scope_id();
         let arrow = ctx.ast.alloc_arrow_function_expression_with_scope_id(
             SPAN, false, false, NONE, params, NONE, body, scope_id,
         );
@@ -306,7 +313,7 @@ impl<'a> OptionalChaining<'a, '_> {
             // To insert the temp binding in the correct scope, we wrap the expression with
             // an arrow function. During the chain expression transformation, the temp binding
             // will be inserted into the arrow function's body.
-            Self::wrap_arrow_function(expr, ctx)
+            Self::wrap_arrow_function_iife(expr, ctx)
         } else {
             self.transform_chain_expression_impl(false, expr, ctx)
         }
@@ -320,7 +327,7 @@ impl<'a> OptionalChaining<'a, '_> {
     ) {
         *expr = if self.is_inside_function_parameter {
             // Same as the above `transform_chain_expression` explanation
-            Self::wrap_arrow_function(expr, ctx)
+            Self::wrap_arrow_function_iife(expr, ctx)
         } else {
             // Unfortunately no way to get compiler to see that this branch is provably unreachable.
             // We don't want to inline this function, to keep `enter_expression` as small as possible.
@@ -659,7 +666,6 @@ impl<'a> OptionalChaining<'a, '_> {
         let assignment_expression =
             Self::create_assignment_expression(temp_binding.create_write_target(ctx), expr, ctx);
 
-        let reference = temp_binding.create_read_expression(ctx);
         // `left || (binding = expr) === null`
         let left = Self::create_logical_expression(
             left,
@@ -670,6 +676,7 @@ impl<'a> OptionalChaining<'a, '_> {
         if self.ctx.assumptions.no_document_all {
             left
         } else {
+            let reference = temp_binding.create_read_expression(ctx);
             // `left || (binding = expr) === null || binding === void 0`
             Self::create_logical_expression(left, Self::wrap_void0_check(reference, ctx), ctx)
         }

tasks/coverage/snapshots/semantic_typescript.snap

@@ -2,7 +2,7 @@ commit: d85767ab
 
 semantic_typescript Summary:
 AST Parsed     : 6503/6503 (100.00%)
-Positive Passed: 2923/6503 (44.95%)
+Positive Passed: 2925/6503 (44.98%)
 tasks/coverage/typescript/tests/cases/compiler/2dArrays.ts
 semantic error: Symbol reference IDs mismatch for "Cell":
 after transform: SymbolId(0): [ReferenceId(1)]
@@ -36429,34 +36429,6 @@ Unresolved references mismatch:
 after transform: []
 rebuilt        : ["o1", "o2", "o3", "o4", "o5", "o6"]
 
-tasks/coverage/typescript/tests/cases/conformance/expressions/optionalChaining/optionalChainingInParameterBindingPattern.ts
-semantic error: Scope children mismatch:
-after transform: ScopeId(0): [ScopeId(1), ScopeId(2)]
-rebuilt        : ScopeId(0): [ScopeId(1), ScopeId(2)]
-Bindings mismatch:
-after transform: ScopeId(2): ["_a", "c"]
-rebuilt        : ScopeId(3): ["_a"]
-Scope parent mismatch:
-after transform: ScopeId(2): Some(ScopeId(0))
-rebuilt        : ScopeId(3): Some(ScopeId(2))
-Symbol scope ID mismatch for "c":
-after transform: SymbolId(1): ScopeId(2)
-rebuilt        : SymbolId(1): ScopeId(2)
-
-tasks/coverage/typescript/tests/cases/conformance/expressions/optionalChaining/optionalChainingInParameterInitializer.ts
-semantic error: Scope children mismatch:
-after transform: ScopeId(0): [ScopeId(1), ScopeId(2)]
-rebuilt        : ScopeId(0): [ScopeId(1), ScopeId(2)]
-Bindings mismatch:
-after transform: ScopeId(2): ["_a", "b"]
-rebuilt        : ScopeId(3): ["_a"]
-Scope parent mismatch:
-after transform: ScopeId(2): Some(ScopeId(0))
-rebuilt        : ScopeId(3): Some(ScopeId(2))
-Symbol scope ID mismatch for "b":
-after transform: SymbolId(1): ScopeId(2)
-rebuilt        : SymbolId(1): ScopeId(2)
-
 tasks/coverage/typescript/tests/cases/conformance/expressions/optionalChaining/optionalChainingInference.ts
 semantic error: Bindings mismatch:
 after transform: ScopeId(0): ["b1", "b2", "b3", "b4", "b5", "b6", "b7", "b8", "fnu", "ofnu", "osu", "su", "v1", "v2", "v3", "v4", "v5", "v6", "v7", "v8"]