fix(es/parser): Revert #4067 (#4540)

crates/swc_ecma_parser/src/lib.rs

@@ -350,8 +350,6 @@ pub struct Context {
 
     in_function: bool,
 
-    in_arrow_function: bool,
-    is_direct_child_of_braceless_arrow_function: bool,
     /// This indicates current scope or the scope out of arrow function is
     /// function declaration or function expression or not.
     inside_non_arrow_function_scope: bool,

crates/swc_ecma_parser/src/parser/class_and_fn.rs

@@ -1284,7 +1284,6 @@ impl<'a, I: Tokens> Parser<I> {
         let ctx = Context {
             in_async: is_async,
             in_generator: is_generator,
-            in_arrow_function: is_arrow_function,
             inside_non_arrow_function_scope: if is_arrow_function {
                 self.ctx().inside_non_arrow_function_scope
             } else {
@@ -1523,13 +1522,7 @@ fn has_use_strict(block: &BlockStmt) -> Option<Span> {
 impl<I: Tokens> FnBodyParser<BlockStmtOrExpr> for Parser<I> {
     fn parse_fn_body_inner(&mut self, is_simple_parameter_list: bool) -> PResult<BlockStmtOrExpr> {
         if is!(self, '{') {
-            let cur_ctx = self.ctx();
-            let ctx = Context {
-                is_direct_child_of_braceless_arrow_function: false,
-                ..cur_ctx
-            };
-            let result = self.with_ctx(ctx).parse_block(false);
-            result.map(|block_stmt| {
+            self.parse_block(false).map(|block_stmt| {
                 if !is_simple_parameter_list {
                     if let Some(span) = has_use_strict(&block_stmt) {
                         self.emit_err(span, SyntaxError::IllegalLanguageModeDirective);
@@ -1538,14 +1531,7 @@ impl<I: Tokens> FnBodyParser<BlockStmtOrExpr> for Parser<I> {
                 BlockStmtOrExpr::BlockStmt(block_stmt)
             })
         } else {
-            let cur_ctx = self.ctx();
-            let ctx = Context {
-                is_direct_child_of_braceless_arrow_function: cur_ctx.in_arrow_function,
-                ..cur_ctx
-            };
-            self.with_ctx(ctx)
-                .parse_assignment_expr()
-                .map(BlockStmtOrExpr::Expr)
+            self.parse_assignment_expr().map(BlockStmtOrExpr::Expr)
         }
     }
 }

crates/swc_ecma_parser/src/parser/expr.rs

@@ -732,11 +732,7 @@ impl<'a, I: Tokens> Parser<I> {
 
         let is_direct_child_of_cond = self.ctx().is_direct_child_of_cond;
         // This is slow path. We handle arrow in conditional expression.
-        if self.syntax().typescript()
-            && self.ctx().in_cond_expr
-            && !self.ctx().is_direct_child_of_braceless_arrow_function
-            && is!(self, ':')
-        {
+        if self.syntax().typescript() && self.ctx().in_cond_expr && is!(self, ':') {
             // TODO: Remove clone
             let items_ref = &paren_items;
             if let Some(expr) = self.try_parse_ts(|p| {