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isValidMethodAccess: Instantiate signature this type if necessary #21722

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Merged
1 commit merged into from
Mar 6, 2018
Merged

isValidMethodAccess: Instantiate signature this type if necessary #21722

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23 changes: 17 additions & 6 deletions src/compiler/checker.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -6959,7 +6959,10 @@ namespace ts {
}

function createSignatureInstantiation(signature: Signature, typeArguments: Type[]): Signature {
return instantiateSignature(signature, createTypeMapper(signature.typeParameters, typeArguments), /*eraseTypeParameters*/ true);
return instantiateSignature(signature, createSignatureTypeMapper(signature, typeArguments), /*eraseTypeParameters*/ true);
}
function createSignatureTypeMapper(signature: Signature, typeArguments: Type[]): TypeMapper {
return createTypeMapper(signature.typeParameters, typeArguments);
}

function getErasedSignature(signature: Signature): Signature {
Expand Down Expand Up @@ -11408,8 +11411,8 @@ namespace ts {
}
}

function createInferenceContext(typeParameters: TypeParameter[], signature: Signature, flags: InferenceFlags, compareTypes?: TypeComparer, baseInferences?: InferenceInfo[]): InferenceContext {
const inferences = baseInferences ? map(baseInferences, cloneInferenceInfo) : map(typeParameters, createInferenceInfo);
function createInferenceContext(typeParameters: TypeParameter[], signature: Signature | undefined, flags: InferenceFlags, compareTypes?: TypeComparer, baseInferences?: InferenceInfo[]): InferenceContext {
const inferences = baseInferences ? baseInferences.map(cloneInferenceInfo) : typeParameters.map(createInferenceInfo);
const context = mapper as InferenceContext;
context.typeParameters = typeParameters;
context.signature = signature;
Expand Down Expand Up @@ -16399,15 +16402,23 @@ namespace ts {
return isValidPropertyAccessWithType(node, node.expression, property.escapedName, type)
&& (!(property.flags & SymbolFlags.Method) || isValidMethodAccess(property, type));
}
function isValidMethodAccess(method: Symbol, type: Type) {
function isValidMethodAccess(method: Symbol, actualThisType: Type): boolean {
const propType = getTypeOfFuncClassEnumModule(method);
const signatures = getSignaturesOfType(getNonNullableType(propType), SignatureKind.Call);
Debug.assert(signatures.length !== 0);
return signatures.some(sig => {
const thisType = getThisTypeOfSignature(sig);
return !thisType || isTypeAssignableTo(type, thisType);
const signatureThisType = getThisTypeOfSignature(sig);
return !signatureThisType || isTypeAssignableTo(actualThisType, getInstantiatedSignatureThisType(sig, signatureThisType, actualThisType));
});
}
function getInstantiatedSignatureThisType(sig: Signature, signatureThisType: Type, actualThisType: Type): Type {
if (!sig.typeParameters) {
return signatureThisType;
}
const context = createInferenceContext(sig.typeParameters, sig, InferenceFlags.None);
inferTypes(context.inferences, actualThisType, signatureThisType);
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It's a little weird to do limited inference here, but maybe it makes sense because this is called solely for completions? The inference and instantiation will happen later, and lead to an error, in normal compilation.

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Since the call expression doesn't actually exist (we're just considering adding the completion, all that exists so far is obj.), this won't have a corresponding normal compilation.

return instantiateType(signatureThisType, createSignatureTypeMapper(sig, getInferredTypes(context)));
}

function isValidPropertyAccessWithType(
node: PropertyAccessExpression | QualifiedName,
Expand Down
6 changes: 4 additions & 2 deletions tests/cases/fourslash/completionsMethodWithThisParameter.ts
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Expand Up @@ -4,12 +4,14 @@
//// value: T; // Make the type parameter actually matter
//// ms(this: A<string>) {}
//// mo(this: A<{}>) {}
//// mp<P>(this: A<P>) {}
//// mps<P extends string>(this: A<P>) {}
////}
////
////const s = new A<string>();
////const n = new A<number>();
////s./*s*/;
////n./*n*/;

verify.completionsAt("s", ["value", "ms", "mo"]);
verify.completionsAt("n", ["value", "mo"]);
verify.completionsAt("s", ["value", "ms", "mo", "mp", "mps"]);
verify.completionsAt("n", ["value", "mo", "mp"]);