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Merge pull request #9204 from Microsoft/promiseAndAsyncUpdates

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Update Promise and PromiseLike, fix async functions issues with never.
This commit is contained in:
Ron Buckton
2016-06-21 18:09:28 -07:00
committed by GitHub
parent 851a75ef5e 90e344e457
commit 12bfb7e987
17 changed files with 1024 additions and 100 deletions
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src/compiler/checker.ts
+35 -37
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@@ -2794,6 +2794,10 @@ namespace ts {
return type && (type.flags & TypeFlags.Any) !== 0;
}
function isTypeNever(type: Type) {
return type && (type.flags & TypeFlags.Never) !== 0;
}
// Return the type of a binding element parent. We check SymbolLinks first to see if a type has been
// assigned by contextual typing.
function getTypeForBindingElementParent(node: VariableLikeDeclaration) {
@@ -11779,6 +11783,16 @@ namespace ts {
return emptyObjectType;
}
function createPromiseReturnType(func: FunctionLikeDeclaration, promisedType: Type) {
const promiseType = createPromiseType(promisedType);
if (promiseType === emptyObjectType) {
error(func, Diagnostics.An_async_function_or_method_must_have_a_valid_awaitable_return_type);
return unknownType;
}
return promiseType;
}
function getReturnTypeFromBody(func: FunctionLikeDeclaration, contextualMapper?: TypeMapper): Type {
const contextualSignature = getContextualSignatureForFunctionLikeDeclaration(func);
if (!func.body) {
@@ -11814,19 +11828,12 @@ namespace ts {
else {
types = checkAndAggregateReturnExpressionTypes(func, contextualMapper);
if (!types) {
return neverType;
// For an async function, the return type will not be never, but rather a Promise for never.
return isAsync ? createPromiseReturnType(func, neverType) : neverType;
}
if (types.length === 0) {
if (isAsync) {
// For an async function, the return type will not be void, but rather a Promise for void.
const promiseType = createPromiseType(voidType);
if (promiseType === emptyObjectType) {
error(func, Diagnostics.An_async_function_or_method_must_have_a_valid_awaitable_return_type);
return unknownType;
}
return promiseType;
}
return voidType;
// For an async function, the return type will not be void, but rather a Promise for void.
return isAsync ? createPromiseReturnType(func, voidType) : voidType;
}
}
// When yield/return statements are contextually typed we allow the return type to be a union type.
@@ -11840,7 +11847,7 @@ namespace ts {
else {
error(func, Diagnostics.No_best_common_type_exists_among_return_expressions);
// Defer to unioning the return types so we get a) downstream errors earlier and b) better Salsa experience
return getUnionType(types);
return isAsync ? createPromiseReturnType(func, getUnionType(types)) : getUnionType(types);
}
}
@@ -11853,21 +11860,10 @@ namespace ts {
}
const widenedType = getWidenedType(type);
if (isAsync) {
// From within an async function you can return either a non-promise value or a promise. Any
// Promise/A+ compatible implementation will always assimilate any foreign promise, so the
// return type of the body is awaited type of the body, wrapped in a native Promise<T> type.
const promiseType = createPromiseType(widenedType);
if (promiseType === emptyObjectType) {
error(func, Diagnostics.An_async_function_or_method_must_have_a_valid_awaitable_return_type);
return unknownType;
}
return promiseType;
}
else {
return widenedType;
}
// From within an async function you can return either a non-promise value or a promise. Any
// Promise/A+ compatible implementation will always assimilate any foreign promise, so the
// return type of the body is awaited type of the body, wrapped in a native Promise<T> type.
return isAsync ? createPromiseReturnType(func, widenedType) : widenedType;
}
function checkAndAggregateYieldOperandTypes(func: FunctionLikeDeclaration, contextualMapper: TypeMapper): Type[] {
@@ -13896,7 +13892,7 @@ namespace ts {
function checkNonThenableType(type: Type, location?: Node, message?: DiagnosticMessage) {
type = getWidenedType(type);
if (!isTypeAny(type) && isTypeAssignableTo(type, getGlobalThenableType())) {
if (!isTypeAny(type) && !isTypeNever(type) && isTypeAssignableTo(type, getGlobalThenableType())) {
if (location) {
if (!message) {
message = Diagnostics.Operand_for_await_does_not_have_a_valid_callable_then_member;
@@ -13927,12 +13923,15 @@ namespace ts {
// }
//
if (promise.flags & TypeFlags.Any) {
if (isTypeAny(promise)) {
return undefined;
}
if ((promise.flags & TypeFlags.Reference) && (<GenericType>promise).target === tryGetGlobalPromiseType()) {
return (<GenericType>promise).typeArguments[0];
if (promise.flags & TypeFlags.Reference) {
if ((<GenericType>promise).target === tryGetGlobalPromiseType()
|| (<GenericType>promise).target === getGlobalPromiseLikeType()) {
return (<GenericType>promise).typeArguments[0];
}
}
const globalPromiseLikeType = getInstantiatedGlobalPromiseLikeType();
@@ -13941,17 +13940,17 @@ namespace ts {
}
const thenFunction = getTypeOfPropertyOfType(promise, "then");
if (thenFunction && (thenFunction.flags & TypeFlags.Any)) {
if (!thenFunction || isTypeAny(thenFunction)) {
return undefined;
}
const thenSignatures = thenFunction ? getSignaturesOfType(thenFunction, SignatureKind.Call) : emptyArray;
const thenSignatures = getSignaturesOfType(thenFunction, SignatureKind.Call);
if (thenSignatures.length === 0) {
return undefined;
}
const onfulfilledParameterType = getTypeWithFacts(getUnionType(map(thenSignatures, getTypeOfFirstParameterOfSignature)), TypeFacts.NEUndefined);
if (onfulfilledParameterType.flags & TypeFlags.Any) {
if (isTypeAny(onfulfilledParameterType)) {
return undefined;
}
@@ -13960,12 +13959,11 @@ namespace ts {
return undefined;
}
const valueParameterType = getUnionType(map(onfulfilledParameterSignatures, getTypeOfFirstParameterOfSignature));
return valueParameterType;
return getUnionType(map(onfulfilledParameterSignatures, getTypeOfFirstParameterOfSignature));
}
function getTypeOfFirstParameterOfSignature(signature: Signature) {
return getTypeAtPosition(signature, 0);
return signature.parameters.length > 0 ? getTypeAtPosition(signature, 0) : neverType;
}
/**