[babel 8] Require throw expression to be wrapped in parentheses

packages/babel-parser/src/parse-error/standard-errors.ts

@@ -247,6 +247,8 @@ export default {
  SuperNotAllowed:
  "`super()` is only valid inside a class constructor of a subclass. Maybe a typo in the method name ('constructor') or not extending another class?",
  SuperPrivateField: "Private fields can't be accessed on super.",
+ ThrowExpressionRequireParentheses:
+ "`throw ...` expressions must be wrapped in parentheses.",
  TrailingDecorator: "Decorators must be attached to a class element.",
  TupleExpressionBarIncorrectEndSyntaxType:
  "Tuple expressions ending with '|]' are only allowed when the 'syntaxType' option of the 'recordAndTuple' plugin is set to 'bar'.",

packages/babel-parser/src/parser/expression.ts

@@ -613,17 +613,44 @@ export default abstract class ExpressionParser extends LValParser {
  node.operator = this.state.value;
  node.prefix = true;
 
- if (this.match(tt._throw)) {
+ const isThrow = this.match(tt._throw);
+ let throwMissingParenthesesReported = false;
+ if (isThrow) {
  this.expectPlugin("throwExpressions");
+ if (
+ // TODO: Uncomment for the next minor
+ // this.getPluginOption("throwExpressions", "requireParentheses") ||
+ process.env.BABEL_8_BREAKING &&
+ this.input.charCodeAt(this.state.lastTokStart) !==
+ charCodes.leftParenthesis
+ ) {
+ this.raise(Errors.ThrowExpressionRequireParentheses, {
+ at: node,
+ });
+ throwMissingParenthesesReported = true;
+ }
  }
- const isDelete = this.match(tt._delete);
+
+ const isDelete = !isThrow && this.match(tt._delete);
  this.next();
 
  node.argument = this.parseMaybeUnary(null, true);
 
  this.checkExpressionErrors(refExpressionErrors, true);
 
- if (this.state.strict && isDelete) {
+ if (isThrow) {
+ if (
+ !throwMissingParenthesesReported &&
+ // TODO: Uncomment for the next minor
+ // this.getPluginOption("throwExpressions", "requireParentheses") ||
+ process.env.BABEL_8_BREAKING &&
+ !this.match(tt.parenR)
+ ) {
+ this.raise(Errors.ThrowExpressionRequireParentheses, {
+ at: node,
+ });
+ }
+ } else if (isDelete && this.state.strict) {
  const arg = node.argument;
 
  if (arg.type === "Identifier") {

packages/babel-parser/src/plugin-utils.ts

@@ -243,6 +243,18 @@ export function validatePlugins(plugins: PluginList) {
  " only supported value is '2023-07'.",
  );
  }
+
+ // TODO: Uncomment in the next minor
+ // if (hasPlugin(plugins, "throwExpressions")) {
+ // const requireParentheses = getPluginOption(
+ // plugins,
+ // "throwExpressions",
+ // "requireParentheses",
+ // );
+ // if (requireParentheses != null && typeof requireParentheses !== "boolean") {
+ // throw new Error("'requireParentheses' must be a boolean.");
+ // }
+ // }
 }
 
 // These plugins are defined using a mixin which extends the parser class.

packages/babel-parser/src/typings.d.ts

@@ -38,8 +38,9 @@ export type Plugin =
  | "privateIn" // Enabled by default
  | "regexpUnicodeSets" // Enabled by default
  | "sourcePhaseImports"
- | "throwExpressions"
  | "topLevelAwait"
+ // TODO: Remove in the next minor
+ | "throwExpressions"
  | "v8intrinsic"
  | ParserPluginWithOptions[0];
 
@@ -52,6 +53,8 @@ export type ParserPluginWithOptions =
  | ["optionalChainingAssign", { version: "2023-07" }]
  | ["pipelineOperator", PipelineOperatorPluginOptions]
  | ["recordAndTuple", RecordAndTuplePluginOptions]
+ // TODO: Uncomment for the next minor
+ //| ["throwExpressions", { requireParentheses?: boolean }]
  | ["flow", FlowPluginOptions]
  | ["typescript", TypeScriptPluginOptions];
 

packages/babel-parser/test/fixtures/experimental/throw-expression/comma-babel-7/input.js

@@ -0,0 +1,6 @@
+function test() {
+ (throw 1, 2);
+ (3, throw 4);
+ f(throw 5, 6);
+ f(7, throw 8);
+}

packages/babel-parser/test/fixtures/experimental/throw-expression/comma-babel-7/options.json

@@ -0,0 +1,4 @@
+{
+ "BABEL_8_BREAKING": false,
+ "plugins": ["throwExpressions"]
+}

packages/babel-parser/test/fixtures/experimental/throw-expression/comma-babel-7/output.json

@@ -0,0 +1,186 @@
+{
+ "type": "File",
+ "start":0,"end":85,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":6,"column":1,"index":85}},
+ "program": {
+ "type": "Program",
+ "start":0,"end":85,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":6,"column":1,"index":85}},
+ "sourceType": "script",
+ "interpreter": null,
+ "body": [
+ {
+ "type": "FunctionDeclaration",
+ "start":0,"end":85,"loc":{"start":{"line":1,"column":0,"index":0},"end":{"line":6,"column":1,"index":85}},
+ "id": {
+ "type": "Identifier",
+ "start":9,"end":13,"loc":{"start":{"line":1,"column":9,"index":9},"end":{"line":1,"column":13,"index":13},"identifierName":"test"},
+ "name": "test"
+ },
+ "generator": false,
+ "async": false,
+ "params": [],
+ "body": {
+ "type": "BlockStatement",
+ "start":16,"end":85,"loc":{"start":{"line":1,"column":16,"index":16},"end":{"line":6,"column":1,"index":85}},
+ "body": [
+ {
+ "type": "ExpressionStatement",
+ "start":20,"end":33,"loc":{"start":{"line":2,"column":2,"index":20},"end":{"line":2,"column":15,"index":33}},
+ "expression": {
+ "type": "SequenceExpression",
+ "start":21,"end":31,"loc":{"start":{"line":2,"column":3,"index":21},"end":{"line":2,"column":13,"index":31}},
+ "expressions": [
+ {
+ "type": "UnaryExpression",
+ "start":21,"end":28,"loc":{"start":{"line":2,"column":3,"index":21},"end":{"line":2,"column":10,"index":28}},
+ "operator": "throw",
+ "prefix": true,
+ "argument": {
+ "type": "NumericLiteral",
+ "start":27,"end":28,"loc":{"start":{"line":2,"column":9,"index":27},"end":{"line":2,"column":10,"index":28}},
+ "extra": {
+ "rawValue": 1,
+ "raw": "1"
+ },
+ "value": 1
+ }
+ },
+ {
+ "type": "NumericLiteral",
+ "start":30,"end":31,"loc":{"start":{"line":2,"column":12,"index":30},"end":{"line":2,"column":13,"index":31}},
+ "extra": {
+ "rawValue": 2,
+ "raw": "2"
+ },
+ "value": 2
+ }
+ ],
+ "extra": {
+ "parenthesized": true,
+ "parenStart": 20
+ }
+ }
+ },
+ {
+ "type": "ExpressionStatement",
+ "start":36,"end":49,"loc":{"start":{"line":3,"column":2,"index":36},"end":{"line":3,"column":15,"index":49}},
+ "expression": {
+ "type": "SequenceExpression",
+ "start":37,"end":47,"loc":{"start":{"line":3,"column":3,"index":37},"end":{"line":3,"column":13,"index":47}},
+ "expressions": [
+ {
+ "type": "NumericLiteral",
+ "start":37,"end":38,"loc":{"start":{"line":3,"column":3,"index":37},"end":{"line":3,"column":4,"index":38}},
+ "extra": {
+ "rawValue": 3,
+ "raw": "3"
+ },
+ "value": 3
+ },
+ {
+ "type": "UnaryExpression",
+ "start":40,"end":47,"loc":{"start":{"line":3,"column":6,"index":40},"end":{"line":3,"column":13,"index":47}},
+ "operator": "throw",
+ "prefix": true,
+ "argument": {
+ "type": "NumericLiteral",
+ "start":46,"end":47,"loc":{"start":{"line":3,"column":12,"index":46},"end":{"line":3,"column":13,"index":47}},
+ "extra": {
+ "rawValue": 4,
+ "raw": "4"
+ },
+ "value": 4
+ }
+ }
+ ],
+ "extra": {
+ "parenthesized": true,
+ "parenStart": 36
+ }
+ }
+ },
+ {
+ "type": "ExpressionStatement",
+ "start":52,"end":66,"loc":{"start":{"line":4,"column":2,"index":52},"end":{"line":4,"column":16,"index":66}},
+ "expression": {
+ "type": "CallExpression",
+ "start":52,"end":65,"loc":{"start":{"line":4,"column":2,"index":52},"end":{"line":4,"column":15,"index":65}},
+ "callee": {
+ "type": "Identifier",
+ "start":52,"end":53,"loc":{"start":{"line":4,"column":2,"index":52},"end":{"line":4,"column":3,"index":53},"identifierName":"f"},
+ "name": "f"
+ },
+ "arguments": [
+ {
+ "type": "UnaryExpression",
+ "start":54,"end":61,"loc":{"start":{"line":4,"column":4,"index":54},"end":{"line":4,"column":11,"index":61}},
+ "operator": "throw",
+ "prefix": true,
+ "argument": {
+ "type": "NumericLiteral",
+ "start":60,"end":61,"loc":{"start":{"line":4,"column":10,"index":60},"end":{"line":4,"column":11,"index":61}},
+ "extra": {
+ "rawValue": 5,
+ "raw": "5"
+ },
+ "value": 5
+ }
+ },
+ {
+ "type": "NumericLiteral",
+ "start":63,"end":64,"loc":{"start":{"line":4,"column":13,"index":63},"end":{"line":4,"column":14,"index":64}},
+ "extra": {
+ "rawValue": 6,
+ "raw": "6"
+ },
+ "value": 6
+ }
+ ]
+ }
+ },
+ {
+ "type": "ExpressionStatement",
+ "start":69,"end":83,"loc":{"start":{"line":5,"column":2,"index":69},"end":{"line":5,"column":16,"index":83}},
+ "expression": {
+ "type": "CallExpression",
+ "start":69,"end":82,"loc":{"start":{"line":5,"column":2,"index":69},"end":{"line":5,"column":15,"index":82}},
+ "callee": {
+ "type": "Identifier",
+ "start":69,"end":70,"loc":{"start":{"line":5,"column":2,"index":69},"end":{"line":5,"column":3,"index":70},"identifierName":"f"},
+ "name": "f"
+ },
+ "arguments": [
+ {
+ "type": "NumericLiteral",
+ "start":71,"end":72,"loc":{"start":{"line":5,"column":4,"index":71},"end":{"line":5,"column":5,"index":72}},
+ "extra": {
+ "rawValue": 7,
+ "raw": "7"
+ },
+ "value": 7
+ },
+ {
+ "type": "UnaryExpression",
+ "start":74,"end":81,"loc":{"start":{"line":5,"column":7,"index":74},"end":{"line":5,"column":14,"index":81}},
+ "operator": "throw",
+ "prefix": true,
+ "argument": {
+ "type": "NumericLiteral",
+ "start":80,"end":81,"loc":{"start":{"line":5,"column":13,"index":80},"end":{"line":5,"column":14,"index":81}},
+ "extra": {
+ "rawValue": 8,
+ "raw": "8"
+ },
+ "value": 8
+ }
+ }
+ ]
+ }
+ }
+ ],
+ "directives": []
+ }
+ }
+ ],
+ "directives": []
+ }
+}

packages/babel-parser/test/fixtures/experimental/throw-expression/comma/input.js

@@ -1,3 +1,6 @@
 function test() {
  (throw 1, 2);
+ (3, throw 4);
+ f(throw 5, 6);
+ f(7, throw 8);
 }

packages/babel-parser/test/fixtures/experimental/throw-expression/comma/options.json

@@ -1,3 +1,4 @@
 {
+ "BABEL_8_BREAKING": true,
  "plugins": ["throwExpressions"]
 }