fix

benchmark/babel-parser/real-case-ts/bench.mjs

@@ -1,7 +1,9 @@
-import baseline from "@babel-baseline/parser";
-import current from "@babel/parser";
+import { copyFileSync, readFileSync, rmSync } from "fs";
+// eslint-disable-next-line import/no-extraneous-dependencies
+import { commonJS } from "$repo-utils";
 import { Benchmark } from "../../util.mjs";
-import { readFileSync } from "fs";
+
+const { require } = commonJS(import.meta.url);
 
 const benchmark = new Benchmark();
 
@@ -27,10 +29,25 @@ function benchCases(name, implementation, options) {
  });
  }
 }
+copyFileSync(
+ require.resolve("@babel-baseline/parser"),
+ "./parser-baseline.cjs"
+);
+copyFileSync(
+ "../../../packages/babel-parser/lib/index.js",
+ "./parser-current.cjs"
+);
+
+const baseline = require("./parser-baseline.cjs");
+const current = require("./parser-current.cjs");
 
 benchCases("current", current.parse);
 benchCases("baseline", baseline.parse);
 benchCases("current", current.parse);
 benchCases("baseline", baseline.parse);
 
+benchmark.suite.on("complete", () => {
+ rmSync("./parser-current.cjs");
+ rmSync("./parser-baseline.cjs");
+});
 benchmark.run();

packages/babel-parser/src/plugins/typescript/index.ts

@@ -3694,6 +3694,9 @@ export default (superClass: ClassWithMixin<typeof Parser, IJSXParserMixin>) =>
  binding: BindingFlag,
  ) {
  switch (type) {
+ // Allow "typecasts" to appear on the left of assignment expressions,
+ // because it may be in an arrow function.
+ // e.g. `const f = (foo: number = 0) => foo;`
  case "TSTypeCastExpression":
  return true;
  case "TSParameterProperty":
@@ -3707,6 +3710,8 @@ export default (superClass: ClassWithMixin<typeof Parser, IJSXParserMixin>) =>
  (binding !== BindingFlag.TYPE_NONE ||
  !isUnparenthesizedInAssign) && ["expression", true]
  );
+ default:
+ return super.isValidLVal(type, isUnparenthesizedInAssign, binding);
  }
  }
 

packages/babel-parser/test/fixtures/typescript/assign/invalid/input.ts

@@ -0,0 +1 @@
+(a = b) += 1;

packages/babel-parser/test/fixtures/typescript/assign/invalid/output.json

@@ -0,0 +1,53 @@
+{
+ "type": "File",
+ "start":0,"end":13,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":13,"index":13}},
+ "errors": [
+ "SyntaxError: Invalid left-hand side in assignment expression. (1:1)"
+ ],
+ "program": {
+ "type": "Program",
+ "start":0,"end":13,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":13,"index":13}},
+ "sourceType": "module",
+ "interpreter": null,
+ "body": [
+ {
+ "type": "ExpressionStatement",
+ "start":0,"end":13,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":13,"index":13}},
+ "expression": {
+ "type": "AssignmentExpression",
+ "start":0,"end":12,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":1,"column":12,"index":12}},
+ "operator": "+=",
+ "left": {
+ "type": "AssignmentExpression",
+ "start":1,"end":6,"loc":{"start":{"line":1,"column":1,"index":1},"end":{"line":1,"column":6,"index":6}},
+ "operator": "=",
+ "left": {
+ "type": "Identifier",
+ "start":1,"end":2,"loc":{"start":{"line":1,"column":1,"index":1},"end":{"line":1,"column":2,"index":2},"identifierName":"a"},
+ "name": "a"
+ },
+ "right": {
+ "type": "Identifier",
+ "start":5,"end":6,"loc":{"start":{"line":1,"column":5,"index":5},"end":{"line":1,"column":6,"index":6},"identifierName":"b"},
+ "name": "b"
+ },
+ "extra": {
+ "parenthesized": true,
+ "parenStart": 0
+ }
+ },
+ "right": {
+ "type": "NumericLiteral",
+ "start":11,"end":12,"loc":{"start":{"line":1,"column":11,"index":11},"end":{"line":1,"column":12,"index":12}},
+ "extra": {
+ "rawValue": 1,
+ "raw": "1"
+ },
+ "value": 1
+ }
+ }
+ }
+ ],
+ "directives": []
+ }
+}