Include source node inferences in string literal completions

Author: rbuckton

src/compiler/checker.ts

@@ -1657,8 +1657,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         getFullyQualifiedName,
         getResolvedSignature: (node, candidatesOutArray, argumentCount) =>
             getResolvedSignatureWorker(node, candidatesOutArray, argumentCount, CheckMode.Normal),
-        getResolvedSignatureForStringLiteralCompletions: (call, editingArgument, candidatesOutArray) =>
-            runWithInferenceBlockedFromSourceNode(editingArgument, () => getResolvedSignatureWorker(call, candidatesOutArray, /*argumentCount*/ undefined, CheckMode.IsForStringLiteralArgumentCompletions)),
+        getCandidateSignaturesForStringLiteralCompletions,
         getResolvedSignatureForSignatureHelp: (node, candidatesOutArray, argumentCount) =>
             runWithoutResolvedSignatureCaching(node, () => getResolvedSignatureWorker(node, candidatesOutArray, argumentCount, CheckMode.IsForSignatureHelp)),
         getExpandedParameters,
@@ -1839,17 +1838,41 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
         typeHasCallOrConstructSignatures,
     };
 
+    function getCandidateSignaturesForStringLiteralCompletions(call: CallLikeExpression, editingArgument: Node) {
+        const candidatesSet = new Set<Signature>();
+        const candidates: Signature[] = [];
+
+        // first, get candidates when inference is blocked from the source node.
+        runWithInferenceBlockedFromSourceNode(editingArgument, () => getResolvedSignatureWorker(call, candidates, /*argumentCount*/ undefined, CheckMode.IsForStringLiteralArgumentCompletions));
+        for (const candidate of candidates) {
+            candidatesSet.add(candidate);
+        }
+
+        // reset candidates for second pass
+        candidates.length = 0;
+
+        // next, get candidates where the source node is considered for inference.
+        runWithoutResolvedSignatureCaching(editingArgument, () => getResolvedSignatureWorker(call, candidates, /*argumentCount*/ undefined, CheckMode.IsForStringLiteralArgumentCompletions));
+        for (const candidate of candidates) {
+            candidatesSet.add(candidate);
+        }
+
+        return arrayFrom(candidatesSet);
+    }
+
     function runWithoutResolvedSignatureCaching<T>(node: Node | undefined, fn: () => T): T {
         const containingCall = findAncestor(node, isCallLikeExpression);
-        const containingCallResolvedSignature = containingCall && getNodeLinks(containingCall).resolvedSignature;
         if (containingCall) {
-            getNodeLinks(containingCall).resolvedSignature = undefined;
+            const links = getNodeLinks(containingCall);
+            const containingCallResolvedSignature = links.resolvedSignature;
+            links.resolvedSignature = undefined;
+            const result = fn();
+            links.resolvedSignature = containingCallResolvedSignature;
+            return result;
         }
-        const result = fn();
-        if (containingCall) {
-            getNodeLinks(containingCall).resolvedSignature = containingCallResolvedSignature;
+        else {
+            return fn();
         }
-        return result;
     }
 
     function runWithInferenceBlockedFromSourceNode<T>(node: Node | undefined, fn: () => T): T {

src/compiler/types.ts

@@ -5074,7 +5074,7 @@ export interface TypeChecker {
      */
     getResolvedSignature(node: CallLikeExpression, candidatesOutArray?: Signature[], argumentCount?: number): Signature | undefined;
     /** @internal */ getResolvedSignatureForSignatureHelp(node: CallLikeExpression, candidatesOutArray?: Signature[], argumentCount?: number): Signature | undefined;
-    /** @internal */ getResolvedSignatureForStringLiteralCompletions(call: CallLikeExpression, editingArgument: Node, candidatesOutArray: Signature[]): Signature | undefined;
+    /** @internal */ getCandidateSignaturesForStringLiteralCompletions(call: CallLikeExpression, editingArgument: Node): Signature[];
     /** @internal */ getExpandedParameters(sig: Signature): readonly (readonly Symbol[])[];
     /** @internal */ hasEffectiveRestParameter(sig: Signature): boolean;
     /** @internal */ containsArgumentsReference(declaration: SignatureDeclaration): boolean;

src/services/stringCompletions.ts

@@ -114,7 +114,6 @@ import {
     ScriptElementKind,
     ScriptElementKindModifier,
     ScriptTarget,
-    Signature,
     signatureHasRestParameter,
     SignatureHelp,
     singleElementArray,
@@ -481,9 +480,8 @@ function getAlreadyUsedTypesInStringLiteralUnion(union: UnionTypeNode, current:
 function getStringLiteralCompletionsFromSignature(call: CallLikeExpression, arg: StringLiteralLike, argumentInfo: SignatureHelp.ArgumentInfoForCompletions, checker: TypeChecker): StringLiteralCompletionsFromTypes | undefined {
     let isNewIdentifier = false;
     const uniques = new Map<string, true>();
-    const candidates: Signature[] = [];
     const editingArgument = isJsxOpeningLikeElement(call) ? Debug.checkDefined(findAncestor(arg.parent, isJsxAttribute)) : arg;
-    checker.getResolvedSignatureForStringLiteralCompletions(call, editingArgument, candidates);
+    const candidates = checker.getCandidateSignaturesForStringLiteralCompletions(call, editingArgument);
     const types = flatMap(candidates, candidate => {
         if (!signatureHasRestParameter(candidate) && argumentInfo.argumentCount > candidate.parameters.length) return;
         let type = candidate.getTypeParameterAtPosition(argumentInfo.argumentIndex);

tests/cases/fourslash/stringLiteralCompletionsForGenericConditionalTypesUsingTemplateLiteralTypes.ts

@@ -0,0 +1,15 @@
+/// <reference path="fourslash.ts" />
+
+// NOTE: Test pulled from https://github.com/microsoft/TypeScript/pull/52997
+
+// @Filename: /a.tsx
+//// type PathOf<T, K extends string, P extends string = ""> =
+////   K extends `${infer U}.${infer V}`
+////     ? U extends keyof T ? PathOf<T[U], V, `${P}${U}.`> : `${P}${keyof T & (string | number)}`
+////     : K extends keyof T ? `${P}${K}` : `${P}${keyof T & (string | number)}`;
+////
+//// declare function consumer<K extends string>(path: PathOf<{a: string, b: {c: string}}, K>) : number;
+////
+//// consumer('b./*ts*/')
+
+verify.completions({ marker: ["ts"], exact: ["a", "b", "b.c"] });