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Support higher order inferences for constructor functions
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@ahejlsberg
ahejlsberg committed Apr 25, 2019
1 parent b010010 commit 4384c90
Showing 1 changed file with 25 additions and 9 deletions.
34 changes: 25 additions & 9 deletions src/compiler/checker.ts
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Expand Up @@ -8563,7 +8563,9 @@ namespace ts {
function getSignatureInstantiation(signature: Signature, typeArguments: Type[] | undefined, isJavascript: boolean, inferredTypeParameters?: ReadonlyArray<TypeParameter>): Signature {
const instantiatedSignature = getSignatureInstantiationWithoutFillingInTypeArguments(signature, fillMissingTypeArguments(typeArguments, signature.typeParameters, getMinTypeArgumentCount(signature.typeParameters), isJavascript));
if (inferredTypeParameters) {
const returnSignature = getSingleCallSignature(getReturnTypeOfSignature(instantiatedSignature));
const returnType = getReturnTypeOfSignature(instantiatedSignature);
const returnSignature = getSingleSignature(returnType, SignatureKind.Call, /*allowMembers*/ false) ||
getSingleSignature(returnType, SignatureKind.Construct, /*allowMembers*/ false);
if (returnSignature) {
const newReturnSignature = cloneSignature(returnSignature);
newReturnSignature.typeParameters = inferredTypeParameters;
Expand Down Expand Up @@ -8639,7 +8641,8 @@ namespace ts {
// object type literal or interface (using the new keyword). Each way of declaring a constructor
// will result in a different declaration kind.
if (!signature.isolatedSignatureType) {
const isConstructor = signature.declaration!.kind === SyntaxKind.Constructor || signature.declaration!.kind === SyntaxKind.ConstructSignature; // TODO: GH#18217
const kind = signature.declaration ? signature.declaration.kind : SyntaxKind.Unknown;
const isConstructor = kind === SyntaxKind.Constructor || kind === SyntaxKind.ConstructSignature || kind === SyntaxKind.ConstructorType;
const type = createObjectType(ObjectFlags.Anonymous);
type.members = emptySymbols;
type.properties = emptyArray;
Expand Down Expand Up @@ -20421,11 +20424,19 @@ namespace ts {

// If type has a single call signature and no other members, return that signature. Otherwise, return undefined.
function getSingleCallSignature(type: Type): Signature | undefined {
return getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ false);
}

function getSingleSignature(type: Type, kind: SignatureKind, allowMembers: boolean): Signature | undefined {
if (type.flags & TypeFlags.Object) {
const resolved = resolveStructuredTypeMembers(<ObjectType>type);
if (resolved.callSignatures.length === 1 && resolved.constructSignatures.length === 0 &&
resolved.properties.length === 0 && !resolved.stringIndexInfo && !resolved.numberIndexInfo) {
return resolved.callSignatures[0];
if (allowMembers || resolved.properties.length === 0 && !resolved.stringIndexInfo && !resolved.numberIndexInfo) {
if (kind === SignatureKind.Call && resolved.callSignatures.length === 1 && resolved.constructSignatures.length === 0) {
return resolved.callSignatures[0];
}
if (kind === SignatureKind.Construct && resolved.constructSignatures.length === 1 && resolved.callSignatures.length === 0) {
return resolved.constructSignatures[0];
}
}
}
return undefined;
Expand Down Expand Up @@ -23760,15 +23771,17 @@ namespace ts {

function instantiateTypeWithSingleGenericCallSignature(node: Expression | MethodDeclaration | QualifiedName, type: Type, checkMode?: CheckMode) {
if (checkMode && checkMode & (CheckMode.Inferential | CheckMode.SkipGenericFunctions)) {
const signature = getSingleCallSignature(type);
const callSignature = getSingleSignature(type, SignatureKind.Call, /*allowMembers*/ true);
const constructSignature = getSingleSignature(type, SignatureKind.Construct, /*allowMembers*/ true);
const signature = callSignature || constructSignature;
if (signature && signature.typeParameters) {
if (checkMode & CheckMode.SkipGenericFunctions) {
skippedGenericFunction(node, checkMode);
return anyFunctionType;
}
const contextualType = getApparentTypeOfContextualType(<Expression>node);
if (contextualType) {
const contextualSignature = getSingleCallSignature(getNonNullableType(contextualType));
if (contextualType && !isMixinConstructorType(contextualType)) {
const contextualSignature = getSingleSignature(getNonNullableType(contextualType), callSignature ? SignatureKind.Call : SignatureKind.Construct, /*allowMembers*/ false);
if (contextualSignature && !contextualSignature.typeParameters) {
const context = getInferenceContext(node)!;
// We have an expression that is an argument of a generic function for which we are performing
Expand All @@ -23777,7 +23790,10 @@ namespace ts {
// if the outer function returns a function type with a single non-generic call signature and
// if some of the outer function type parameters have no inferences so far. If so, we can
// potentially add inferred type parameters to the outer function return type.
const returnSignature = context.signature && getSingleCallSignature(getReturnTypeOfSignature(context.signature));
const returnType = context.signature && getReturnTypeOfSignature(context.signature);
const returnSignature = returnType && (
getSingleSignature(returnType, SignatureKind.Call, /*allowMembers*/ false) ||
getSingleSignature(returnType, SignatureKind.Construct, /*allowMembers*/ false));
if (returnSignature && !returnSignature.typeParameters && !every(context.inferences, hasInferenceCandidates)) {
// Instantiate the signature with its own type parameters as type arguments, possibly
// renaming the type parameters to ensure they have unique names.
Expand Down

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