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Disallow await inside async arrow params (#10469)

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* Disallow await inside async arrow params

* Use -1 as default for awaitPos/yieldPos
This commit is contained in:
Nicolò Ribaudo
2019-10-02 07:37:40 +02:00
committed by GitHub
parent fa5057f9fb
commit a219b6de7a
11 changed files with 526 additions and 41 deletions
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83
packages/babel-parser/src/parser/expression.js
View File

@@ -490,11 +490,7 @@ export default class ExpressionParser extends LValParser {
// Parse unary operators, both prefix and postfix.
parseMaybeUnary(refShorthandDefaultPos: ?Pos): N.Expression {
if (
this.isContextual("await") &&
(this.scope.inAsync ||
(!this.scope.inFunction && this.options.allowAwaitOutsideFunction))
) {
if (this.isContextual("await") && this.isAwaitAllowed()) {
return this.parseAwait();
} else if (this.state.type.prefix) {
const node = this.startNode();
@@ -676,8 +672,8 @@ export default class ExpressionParser extends LValParser {
const oldYieldPos = this.state.yieldPos;
const oldAwaitPos = this.state.awaitPos;
this.state.maybeInArrowParameters = true;
this.state.yieldPos = 0;
this.state.awaitPos = 0;
this.state.yieldPos = -1;
this.state.awaitPos = -1;
this.next();
@@ -716,8 +712,34 @@ export default class ExpressionParser extends LValParser {
// We keep the old value if it isn't null, for cases like
// (x = async(yield)) => {}
this.state.yieldPos = oldYieldPos || this.state.yieldPos;
this.state.awaitPos = oldAwaitPos || this.state.awaitPos;
//
// Hi developer of the future :) If you are implementing generator
// arrow functions, please read the note below about "await" and
// verify if the same logic is needed for yield.
if (oldYieldPos !== -1) this.state.yieldPos = oldYieldPos;
// Await is trickier than yield. When parsing a possible arrow function
// (e.g. something starting with `async(`) we don't know if its possible
// parameters will actually be inside an async arrow function or if it is
// a normal call expression.
// If it ended up being a call expression, if we are in a context where
// await expression are disallowed (and thus "await" is an identifier)
// we must be careful not to leak this.state.awaitPos to an even outer
// context, where "await" could not be an identifier.
// For example, this code is valid because "await" isn't directly inside
// an async function:
//
// async function a() {
// function b(param = async (await)) {
// }
// }
//
if (
(!this.isAwaitAllowed() && !oldMaybeInArrowParameters) ||
oldAwaitPos !== -1
) {
this.state.awaitPos = oldAwaitPos;
}
}
this.state.maybeInArrowParameters = oldMaybeInArrowParameters;
@@ -1231,8 +1253,8 @@ export default class ExpressionParser extends LValParser {
const oldAwaitPos = this.state.awaitPos;
const oldInFSharpPipelineDirectBody = this.state.inFSharpPipelineDirectBody;
this.state.maybeInArrowParameters = true;
this.state.yieldPos = 0;
this.state.awaitPos = 0;
this.state.yieldPos = -1;
this.state.awaitPos = -1;
this.state.inFSharpPipelineDirectBody = false;
const innerStartPos = this.state.start;
@@ -1310,8 +1332,8 @@ export default class ExpressionParser extends LValParser {
// We keep the old value if it isn't null, for cases like
// (x = (yield)) => {}
this.state.yieldPos = oldYieldPos || this.state.yieldPos;
this.state.awaitPos = oldAwaitPos || this.state.awaitPos;
if (oldYieldPos !== -1) this.state.yieldPos = oldYieldPos;
if (oldAwaitPos !== -1) this.state.awaitPos = oldAwaitPos;
if (!exprList.length) {
this.unexpected(this.state.lastTokStart);
@@ -1804,8 +1826,8 @@ export default class ExpressionParser extends LValParser {
): T {
const oldYieldPos = this.state.yieldPos;
const oldAwaitPos = this.state.awaitPos;
this.state.yieldPos = 0;
this.state.awaitPos = 0;
this.state.yieldPos = -1;
this.state.awaitPos = -1;
this.initFunction(node, isAsync);
node.generator = !!isGenerator;
@@ -1842,8 +1864,8 @@ export default class ExpressionParser extends LValParser {
const oldYieldPos = this.state.yieldPos;
const oldAwaitPos = this.state.awaitPos;
this.state.maybeInArrowParameters = false;
this.state.yieldPos = 0;
this.state.awaitPos = 0;
this.state.yieldPos = -1;
this.state.awaitPos = -1;
if (params) this.setArrowFunctionParameters(node, params);
this.parseFunctionBody(node, true);
@@ -2117,11 +2139,18 @@ export default class ExpressionParser extends LValParser {
);
}
if (this.scope.inAsync && word === "await") {
this.raise(
startLoc,
"Can not use 'await' as identifier inside an async function",
);
if (word === "await") {
if (this.scope.inAsync) {
this.raise(
startLoc,
"Can not use 'await' as identifier inside an async function",
);
} else if (
this.state.awaitPos === -1 &&
(this.state.maybeInArrowParameters || this.isAwaitAllowed())
) {
this.state.awaitPos = this.state.start;
}
}
if (this.state.inClassProperty && word === "arguments") {
@@ -2151,10 +2180,16 @@ export default class ExpressionParser extends LValParser {
}
}
isAwaitAllowed(): boolean {
if (this.scope.inFunction) return this.scope.inAsync;
if (this.options.allowAwaitOutsideFunction) return true;
return false;
}
// Parses await expression inside async function.
parseAwait(): N.AwaitExpression {
if (!this.state.awaitPos) {
if (this.state.awaitPos === -1) {
this.state.awaitPos = this.state.start;
}
const node = this.startNode();
@@ -2183,7 +2218,7 @@ export default class ExpressionParser extends LValParser {
// Parses yield expression inside generator.
parseYield(noIn?: ?boolean): N.YieldExpression {
if (!this.state.yieldPos) {
if (this.state.yieldPos === -1) {
this.state.yieldPos = this.state.start;
}
const node = this.startNode();

7
packages/babel-parser/src/parser/statement.js
View File

@@ -1050,12 +1050,14 @@ export default class StatementParser extends ExpressionParser {
node.id = this.parseFunctionId(requireId);
}
const oldMaybeInArrowParameters = this.state.maybeInArrowParameters;
const oldInClassProperty = this.state.inClassProperty;
const oldYieldPos = this.state.yieldPos;
const oldAwaitPos = this.state.awaitPos;
this.state.maybeInArrowParameters = false;
this.state.inClassProperty = false;
this.state.yieldPos = 0;
this.state.awaitPos = 0;
this.state.yieldPos = -1;
this.state.awaitPos = -1;
this.scope.enter(functionFlags(node.async, node.generator));
if (!isStatement) {
@@ -1084,6 +1086,7 @@ export default class StatementParser extends ExpressionParser {
this.checkFunctionStatementId(node);
}
this.state.maybeInArrowParameters = oldMaybeInArrowParameters;
this.state.inClassProperty = oldInClassProperty;
this.state.yieldPos = oldYieldPos;
this.state.awaitPos = oldAwaitPos;

6
packages/babel-parser/src/parser/util.js
View File

@@ -159,15 +159,15 @@ export default class UtilParser extends Tokenizer {
checkYieldAwaitInDefaultParams() {
if (
this.state.yieldPos &&
(!this.state.awaitPos || this.state.yieldPos < this.state.awaitPos)
this.state.yieldPos !== -1 &&
(this.state.awaitPos === -1 || this.state.yieldPos < this.state.awaitPos)
) {
this.raise(
this.state.yieldPos,
"Yield cannot be used as name inside a generator function",
);
}
if (this.state.awaitPos) {
if (this.state.awaitPos !== -1) {
this.raise(
this.state.awaitPos,
"Await cannot be used as name inside an async function",

4
packages/babel-parser/src/tokenizer/state.js
View File

@@ -97,8 +97,8 @@ export default class State {
decoratorStack: Array<Array<N.Decorator>> = [[]];
// Positions to delayed-check that yield/await does not exist in default parameters.
yieldPos: number = 0;
awaitPos: number = 0;
yieldPos: number = -1;
awaitPos: number = -1;
// Token store.
tokens: Array<Token | N.Comment> = [];