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Per-property super accessors in async functions.

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TypeScript must hoist accessors for super properties when converting
async method bodies to the `__awaiter` pattern for targets before
ES2016.

Previously, TypeScript would reify all property accesses into element
accesses, i.e. convert the property name into a string parameter and
pass it to `super[...]`. That breaks optimizers like Closure Compiler or
Uglify in advanced mode, when property renaming is enabled, as it mixes
quoted and un-quoted property access (`super['x']` vs just `x` at the
declaration site).

This change creates a variable `_superProps` that contains accessors for
each property accessed on super within the async method. This allows
accessing the properties by name (instead of quoted string), which fixes
the quoted/unquoted confusion. The change keeps the generic accessor for
element access statements to match quoting behaviour.

Fixes #21088.
This commit is contained in:
Martin Probst
2018-08-28 10:35:16 +02:00
parent 9aeb6e2ac4
commit f0826cfeaa
20 changed files with 471 additions and 131 deletions
Download Patch File Download Diff File Expand all files Collapse all files

20
src/compiler/checker.ts
View File

@@ -16180,9 +16180,9 @@ namespace ts {
// // js
// ...
// asyncMethod() {
// const _super = name => super[name];
// const _super_asyncMethod = name => super.asyncMethod;
// return __awaiter(this, arguments, Promise, function *() {
// let x = yield _super("asyncMethod").call(this);
// let x = yield _super_asyncMethod.call(this);
// return x;
// });
// }
@@ -16201,19 +16201,19 @@ namespace ts {
// // js
// ...
// asyncMethod(ar) {
// const _super = (function (geti, seti) {
// const cache = Object.create(null);
// return name => cache[name] || (cache[name] = { get value() { return geti(name); }, set value(v) { seti(name, v); } });
// })(name => super[name], (name, value) => super[name] = value);
// const _super_a = {get value() { return super.a; }, set value(v) { super.a = v; }};
// const _super_b = {get value() { return super.b; }, set value(v) { super.b = v; }};
// return __awaiter(this, arguments, Promise, function *() {
// [_super("a").value, _super("b").value] = yield ar;
// [_super_a.value, _super_b.value] = yield ar;
// });
// }
// ...
//
// This helper creates an object with a "value" property that wraps the `super` property or indexed access for both get and set.
// This is required for destructuring assignments, as a call expression cannot be used as the target of a destructuring assignment
// while a property access can.
// This helper creates an object with a "value" property that wraps the `super` property for both get and set. This is required for
// destructuring assignments, as a call expression cannot be used as the target of a destructuring assignment while a property
// access can.
//
// For element access expressions (`super[x]`), we emit a generic helper that forwards the element access in both situations.
if (container.kind === SyntaxKind.MethodDeclaration && hasModifier(container, ModifierFlags.Async)) {
if (isSuperProperty(node.parent) && isAssignmentTarget(node.parent)) {
getNodeLinks(container).flags |= NodeCheckFlags.AsyncMethodWithSuperBinding;

153
src/compiler/transformers/es2017.ts
View File

@@ -32,6 +32,15 @@ namespace ts {
let enclosingFunctionParameterNames: UnderscoreEscapedMap<true>;
/**
* Keeps track of property names accessed on super (`super.x`) within async functions.
*/
let capturedSuperProperties: UnderscoreEscapedMap<true>;
/** Whether the async function contains an element access on super (`super[x]`). */
let hasSuperElementAccess: boolean;
/** A set of node IDs for generated super accessors (variable statements). */
const substitutedSuperAccessors: boolean[] = [];
// Save the previous transformation hooks.
const previousOnEmitNode = context.onEmitNode;
const previousOnSubstituteNode = context.onSubstituteNode;
@@ -53,10 +62,6 @@ namespace ts {
}
function visitor(node: Node): VisitResult<Node> {
if ((node.transformFlags & TransformFlags.ContainsES2017) === 0) {
return node;
}
switch (node.kind) {
case SyntaxKind.AsyncKeyword:
// ES2017 async modifier should be elided for targets < ES2017
@@ -77,6 +82,18 @@ namespace ts {
case SyntaxKind.ArrowFunction:
return visitArrowFunction(<ArrowFunction>node);
case SyntaxKind.PropertyAccessExpression:
if (capturedSuperProperties && isPropertyAccessExpression(node) && node.expression.kind === SyntaxKind.SuperKeyword) {
capturedSuperProperties.set(node.name.escapedText, true);
}
return visitEachChild(node, visitor, context);
case SyntaxKind.ElementAccessExpression:
if (capturedSuperProperties && (<ElementAccessExpression>node).expression.kind === SyntaxKind.SuperKeyword) {
hasSuperElementAccess = true;
}
return visitEachChild(node, visitor, context);
default:
return visitEachChild(node, visitor, context);
}
@@ -398,6 +415,11 @@ namespace ts {
recordDeclarationName(parameter, enclosingFunctionParameterNames);
}
const savedCapturedSuperProperties = capturedSuperProperties;
const savedHasSuperElementAccess = hasSuperElementAccess;
capturedSuperProperties = createUnderscoreEscapedMap<true>();
hasSuperElementAccess = false;
let result: ConciseBody;
if (!isArrowFunction) {
const statements: Statement[] = [];
@@ -415,18 +437,26 @@ namespace ts {
addStatementsAfterPrologue(statements, endLexicalEnvironment());
// Minor optimization, emit `_super` helper to capture `super` access in an arrow.
// This step isn't needed if we eventually transform this to ES5.
const emitSuperHelpers = languageVersion >= ScriptTarget.ES2015 && resolver.getNodeCheckFlags(node) & (NodeCheckFlags.AsyncMethodWithSuperBinding | NodeCheckFlags.AsyncMethodWithSuper);
if (emitSuperHelpers) {
enableSubstitutionForAsyncMethodsWithSuper();
const variableStatement = createSuperAccessVariableStatement(resolver, node, capturedSuperProperties);
substitutedSuperAccessors[getNodeId(variableStatement)] = true;
addStatementsAfterPrologue(statements, [variableStatement]);
}
const block = createBlock(statements, /*multiLine*/ true);
setTextRange(block, node.body);
// Minor optimization, emit `_super` helper to capture `super` access in an arrow.
// This step isn't needed if we eventually transform this to ES5.
if (languageVersion >= ScriptTarget.ES2015) {
if (emitSuperHelpers && hasSuperElementAccess) {
// Emit helpers for super element access expressions (`super[x]`).
if (resolver.getNodeCheckFlags(node) & NodeCheckFlags.AsyncMethodWithSuperBinding) {
enableSubstitutionForAsyncMethodsWithSuper();
addEmitHelper(block, advancedAsyncSuperHelper);
}
else if (resolver.getNodeCheckFlags(node) & NodeCheckFlags.AsyncMethodWithSuper) {
enableSubstitutionForAsyncMethodsWithSuper();
addEmitHelper(block, asyncSuperHelper);
}
}
@@ -452,6 +482,8 @@ namespace ts {
}
enclosingFunctionParameterNames = savedEnclosingFunctionParameterNames;
capturedSuperProperties = savedCapturedSuperProperties;
hasSuperElementAccess = savedHasSuperElementAccess;
return result;
}
@@ -493,6 +525,8 @@ namespace ts {
context.enableEmitNotification(SyntaxKind.GetAccessor);
context.enableEmitNotification(SyntaxKind.SetAccessor);
context.enableEmitNotification(SyntaxKind.Constructor);
// We need to be notified when entering the generated accessor arrow functions.
context.enableEmitNotification(SyntaxKind.VariableStatement);
}
}
@@ -516,6 +550,14 @@ namespace ts {
return;
}
}
// Disable substitution in the generated super accessor itself.
else if (enabledSubstitutions && substitutedSuperAccessors[getNodeId(node)]) {
const savedEnclosingSuperContainerFlags = enclosingSuperContainerFlags;
enclosingSuperContainerFlags = 0 as NodeCheckFlags;
previousOnEmitNode(hint, node, emitCallback);
enclosingSuperContainerFlags = savedEnclosingSuperContainerFlags;
return;
}
previousOnEmitNode(hint, node, emitCallback);
}
@@ -548,8 +590,10 @@ namespace ts {
function substitutePropertyAccessExpression(node: PropertyAccessExpression) {
if (node.expression.kind === SyntaxKind.SuperKeyword) {
return createSuperAccessInAsyncMethod(
createLiteral(idText(node.name)),
return setTextRange(
createPropertyAccess(
createFileLevelUniqueName("_superProps"),
node.name),
node
);
}
@@ -558,7 +602,7 @@ namespace ts {
function substituteElementAccessExpression(node: ElementAccessExpression) {
if (node.expression.kind === SyntaxKind.SuperKeyword) {
return createSuperAccessInAsyncMethod(
return createSuperElementAccessInAsyncMethod(
node.argumentExpression,
node
);
@@ -593,7 +637,7 @@ namespace ts {
|| kind === SyntaxKind.SetAccessor;
}
function createSuperAccessInAsyncMethod(argumentExpression: Expression, location: TextRange): LeftHandSideExpression {
function createSuperElementAccessInAsyncMethod(argumentExpression: Expression, location: TextRange): LeftHandSideExpression {
if (enclosingSuperContainerFlags & NodeCheckFlags.AsyncMethodWithSuperBinding) {
return setTextRange(
createPropertyAccess(
@@ -620,6 +664,89 @@ namespace ts {
}
}
/** Creates a variable named `_superProps` with accessor properties for the given property names. */
export function createSuperAccessVariableStatement(resolver: EmitResolver, node: FunctionLikeDeclaration, names: UnderscoreEscapedMap<true>) {
// Create a variable declaration with a getter/setter (if binding) definition for each name:
// const _superProps = Object.create(null, { x: { get: () => super.x, set: (v) => super.x = v }, ... });
const hasBinding = (resolver.getNodeCheckFlags(node) & NodeCheckFlags.AsyncMethodWithSuperBinding) !== 0;
const accessors: PropertyAssignment[] = [];
names.forEach((_, key) => {
const name = unescapeLeadingUnderscores(key);
const getterAndSetter: PropertyAssignment[] = [];
getterAndSetter.push(createPropertyAssignment(
"get",
createArrowFunction(
/* modifiers */ undefined,
/* typeParameters */ undefined,
/* parameters */ [],
/* type */ undefined,
/* equalsGreaterThanToken */ undefined,
createPropertyAccess(
createSuper(),
name
)
)
));
if (hasBinding) {
getterAndSetter.push(
createPropertyAssignment(
"set",
createArrowFunction(
/* modifiers */ undefined,
/* typeParameters */ undefined,
/* parameters */ [
createParameter(
/* decorators */ undefined,
/* modifiers */ undefined,
/* dotDotDotToken */ undefined,
"v",
/* questionToken */ undefined,
/* type */ undefined,
/* initializer */ undefined
)
],
/* type */ undefined,
/* equalsGreaterThanToken */ undefined,
createAssignment(
createPropertyAccess(
createSuper(),
name),
createIdentifier("v")
)
)
)
);
}
accessors.push(
createPropertyAssignment(
name,
createObjectLiteral(getterAndSetter),
)
);
});
return createVariableStatement(
/* modifiers */ undefined,
createVariableDeclarationList(
[
createVariableDeclaration(
createFileLevelUniqueName("_superProps"),
/* type */ undefined,
createCall(
createPropertyAccess(
createIdentifier("Object"),
"create"
),
/* typeArguments */ undefined,
[
createNull(),
createObjectLiteral(accessors, /* multiline */ true)
]
)
)
],
NodeFlags.Const));
}
const awaiterHelper: EmitHelper = {
name: "typescript:awaiter",
scoped: false,

97
src/compiler/transformers/esnext.ts
View File

@@ -26,6 +26,13 @@ namespace ts {
let enclosingFunctionFlags: FunctionFlags;
let enclosingSuperContainerFlags: NodeCheckFlags = 0;
/** Keeps track of property names accessed on super (`super.x`) within async functions. */
let capturedSuperProperties: UnderscoreEscapedMap<true>;
/** Whether the async function contains an element access on super (`super[x]`). */
let hasSuperElementAccess: boolean;
/** A set of node IDs for generated super accessors. */
const substitutedSuperAccessors: boolean[] = [];
return chainBundle(transformSourceFile);
function transformSourceFile(node: SourceFile) {
@@ -54,10 +61,6 @@ namespace ts {
}
function visitorWorker(node: Node, noDestructuringValue: boolean): VisitResult<Node> {
if ((node.transformFlags & TransformFlags.ContainsESNext) === 0) {
return node;
}
switch (node.kind) {
case SyntaxKind.AwaitExpression:
return visitAwaitExpression(node as AwaitExpression);
@@ -101,6 +104,16 @@ namespace ts {
return visitParenthesizedExpression(node as ParenthesizedExpression, noDestructuringValue);
case SyntaxKind.CatchClause:
return visitCatchClause(node as CatchClause);
case SyntaxKind.PropertyAccessExpression:
if (capturedSuperProperties && isPropertyAccessExpression(node) && node.expression.kind === SyntaxKind.SuperKeyword) {
capturedSuperProperties.set(node.name.escapedText, true);
}
return visitEachChild(node, visitor, context);
case SyntaxKind.ElementAccessExpression:
if (capturedSuperProperties && (<ElementAccessExpression>node).expression.kind === SyntaxKind.SuperKeyword) {
hasSuperElementAccess = true;
}
return visitEachChild(node, visitor, context);
default:
return visitEachChild(node, visitor, context);
}
@@ -655,41 +668,57 @@ namespace ts {
const statementOffset = addPrologue(statements, node.body!.statements, /*ensureUseStrict*/ false, visitor);
appendObjectRestAssignmentsIfNeeded(statements, node);
statements.push(
createReturn(
createAsyncGeneratorHelper(
context,
createFunctionExpression(
/*modifiers*/ undefined,
createToken(SyntaxKind.AsteriskToken),
node.name && getGeneratedNameForNode(node.name),
/*typeParameters*/ undefined,
/*parameters*/ [],
/*type*/ undefined,
updateBlock(
node.body!,
visitLexicalEnvironment(node.body!.statements, visitor, context, statementOffset)
)
const savedCapturedSuperProperties = capturedSuperProperties;
const savedHasSuperElementAccess = hasSuperElementAccess;
capturedSuperProperties = createUnderscoreEscapedMap<true>();
hasSuperElementAccess = false;
const returnStatement = createReturn(
createAsyncGeneratorHelper(
context,
createFunctionExpression(
/*modifiers*/ undefined,
createToken(SyntaxKind.AsteriskToken),
node.name && getGeneratedNameForNode(node.name),
/*typeParameters*/ undefined,
/*parameters*/ [],
/*type*/ undefined,
updateBlock(
node.body!,
visitLexicalEnvironment(node.body!.statements, visitor, context, statementOffset)
)
)
)
);
// Minor optimization, emit `_super` helper to capture `super` access in an arrow.
// This step isn't needed if we eventually transform this to ES5.
const emitSuperHelpers = languageVersion >= ScriptTarget.ES2015 && resolver.getNodeCheckFlags(node) & (NodeCheckFlags.AsyncMethodWithSuperBinding | NodeCheckFlags.AsyncMethodWithSuper);
if (emitSuperHelpers) {
enableSubstitutionForAsyncMethodsWithSuper();
const variableStatement = createSuperAccessVariableStatement(resolver, node, capturedSuperProperties);
substitutedSuperAccessors[getNodeId(variableStatement)] = true;
addStatementsAfterPrologue(statements, [variableStatement]);
}
statements.push(returnStatement);
addStatementsAfterPrologue(statements, endLexicalEnvironment());
const block = updateBlock(node.body!, statements);
// Minor optimization, emit `_super` helper to capture `super` access in an arrow.
// This step isn't needed if we eventually transform this to ES5.
if (languageVersion >= ScriptTarget.ES2015) {
if (emitSuperHelpers && hasSuperElementAccess) {
if (resolver.getNodeCheckFlags(node) & NodeCheckFlags.AsyncMethodWithSuperBinding) {
enableSubstitutionForAsyncMethodsWithSuper();
addEmitHelper(block, advancedAsyncSuperHelper);
}
else if (resolver.getNodeCheckFlags(node) & NodeCheckFlags.AsyncMethodWithSuper) {
enableSubstitutionForAsyncMethodsWithSuper();
addEmitHelper(block, asyncSuperHelper);
}
}
capturedSuperProperties = savedCapturedSuperProperties;
hasSuperElementAccess = savedHasSuperElementAccess;
return block;
}
@@ -758,6 +787,8 @@ namespace ts {
context.enableEmitNotification(SyntaxKind.GetAccessor);
context.enableEmitNotification(SyntaxKind.SetAccessor);
context.enableEmitNotification(SyntaxKind.Constructor);
// We need to be notified when entering the generated accessor arrow functions.
context.enableEmitNotification(SyntaxKind.VariableStatement);
}
}
@@ -781,6 +812,14 @@ namespace ts {
return;
}
}
// Disable substitution in the generated super accessor itself.
else if (enabledSubstitutions && substitutedSuperAccessors[getNodeId(node)]) {
const savedEnclosingSuperContainerFlags = enclosingSuperContainerFlags;
enclosingSuperContainerFlags = 0 as NodeCheckFlags;
previousOnEmitNode(hint, node, emitCallback);
enclosingSuperContainerFlags = savedEnclosingSuperContainerFlags;
return;
}
previousOnEmitNode(hint, node, emitCallback);
}
@@ -813,8 +852,10 @@ namespace ts {
function substitutePropertyAccessExpression(node: PropertyAccessExpression) {
if (node.expression.kind === SyntaxKind.SuperKeyword) {
return createSuperAccessInAsyncMethod(
createLiteral(idText(node.name)),
return setTextRange(
createPropertyAccess(
createFileLevelUniqueName("_superProps"),
node.name),
node
);
}
@@ -823,7 +864,7 @@ namespace ts {
function substituteElementAccessExpression(node: ElementAccessExpression) {
if (node.expression.kind === SyntaxKind.SuperKeyword) {
return createSuperAccessInAsyncMethod(
return createSuperElementAccessInAsyncMethod(
node.argumentExpression,
node
);
@@ -858,7 +899,7 @@ namespace ts {
|| kind === SyntaxKind.SetAccessor;
}
function createSuperAccessInAsyncMethod(argumentExpression: Expression, location: TextRange): LeftHandSideExpression {
function createSuperElementAccessInAsyncMethod(argumentExpression: Expression, location: TextRange): LeftHandSideExpression {
if (enclosingSuperContainerFlags & NodeCheckFlags.AsyncMethodWithSuperBinding) {
return setTextRange(
createPropertyAccess(