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Fix for Awaited<T> inference (#49748)

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This commit is contained in:
Ron Buckton
2022-07-01 15:00:54 -07:00
committed by GitHub
parent ad4ded80e1
commit c6ff5f3b52
6 changed files with 145 additions and 26 deletions
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62
src/compiler/checker.ts
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@@ -36601,6 +36601,37 @@ m2: ${(this.mapper2 as unknown as DebugTypeMapper).__debugToString().split("\n")
type;
}
function isAwaitedTypeNeeded(type: Type) {
// If this is already an `Awaited<T>`, we shouldn't wrap it. This helps to avoid `Awaited<Awaited<T>>` in higher-order.
if (isTypeAny(type) || isAwaitedTypeInstantiation(type)) {
return false;
}
// We only need `Awaited<T>` if `T` contains possibly non-primitive types.
if (isGenericObjectType(type)) {
const baseConstraint = getBaseConstraintOfType(type);
// We only need `Awaited<T>` if `T` has no base constraint, or the base constraint of `T` is `any`, `unknown`, `{}`, `object`,
// or is promise-like.
if (!baseConstraint || (baseConstraint.flags & TypeFlags.AnyOrUnknown) || isEmptyObjectType(baseConstraint) || isThenableType(baseConstraint)) {
return true;
}
}
return false;
}
function tryCreateAwaitedType(type: Type): Type | undefined {
// Nothing to do if `Awaited<T>` doesn't exist
const awaitedSymbol = getGlobalAwaitedSymbol(/*reportErrors*/ true);
if (awaitedSymbol) {
// Unwrap unions that may contain `Awaited<T>`, otherwise its possible to manufacture an `Awaited<Awaited<T> | U>` where
// an `Awaited<T | U>` would suffice.
return getTypeAliasInstantiation(awaitedSymbol, [unwrapAwaitedType(type)]);
}
return undefined;
}
function createAwaitedTypeIfNeeded(type: Type): Type {
// We wrap type `T` in `Awaited<T>` based on the following conditions:
// - `T` is not already an `Awaited<U>`, and
@@ -36610,28 +36641,10 @@ m2: ${(this.mapper2 as unknown as DebugTypeMapper).__debugToString().split("\n")
// - The base constraint of `T` is `any`, `unknown`, `object`, or `{}`, or
// - The base constraint of `T` is an object type with a callable `then` method.
if (isTypeAny(type)) {
return type;
}
// If this is already an `Awaited<T>`, just return it. This helps to avoid `Awaited<Awaited<T>>` in higher-order.
if (isAwaitedTypeInstantiation(type)) {
return type;
}
// Only instantiate `Awaited<T>` if `T` contains possibly non-primitive types.
if (isGenericObjectType(type)) {
const baseConstraint = getBaseConstraintOfType(type);
// Only instantiate `Awaited<T>` if `T` has no base constraint, or the base constraint of `T` is `any`, `unknown`, `{}`, `object`,
// or is promise-like.
if (!baseConstraint || (baseConstraint.flags & TypeFlags.AnyOrUnknown) || isEmptyObjectType(baseConstraint) || isThenableType(baseConstraint)) {
// Nothing to do if `Awaited<T>` doesn't exist
const awaitedSymbol = getGlobalAwaitedSymbol(/*reportErrors*/ true);
if (awaitedSymbol) {
// Unwrap unions that may contain `Awaited<T>`, otherwise its possible to manufacture an `Awaited<Awaited<T> | U>` where
// an `Awaited<T | U>` would suffice.
return getTypeAliasInstantiation(awaitedSymbol, [unwrapAwaitedType(type)]);
}
if (isAwaitedTypeNeeded(type)) {
const awaitedType = tryCreateAwaitedType(type);
if (awaitedType) {
return awaitedType;
}
}
@@ -36693,6 +36706,11 @@ m2: ${(this.mapper2 as unknown as DebugTypeMapper).__debugToString().split("\n")
return typeAsAwaitable.awaitedTypeOfType = mapped;
}
// If `type` is generic and should be wrapped in `Awaited<T>`, return it.
if (isAwaitedTypeNeeded(type)) {
return typeAsAwaitable.awaitedTypeOfType = type;
}
const thisTypeForErrorOut: { value: Type | undefined } = { value: undefined };
const promisedType = getPromisedTypeOfPromise(type, /*errorNode*/ undefined, thisTypeForErrorOut);
if (promisedType) {