Fixed a string completions regression when requested directly in argument position (#55552)

Author: Andarist

src/compiler/checker.ts

@@ -1917,6 +1917,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
     var anyType = createIntrinsicType(TypeFlags.Any, "any");
     var autoType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.NonInferrableType);
     var wildcardType = createIntrinsicType(TypeFlags.Any, "any");
+    var blockedStringType = createIntrinsicType(TypeFlags.Any, "any");
     var errorType = createIntrinsicType(TypeFlags.Any, "error");
     var unresolvedType = createIntrinsicType(TypeFlags.Any, "unresolved");
     var nonInferrableAnyType = createIntrinsicType(TypeFlags.Any, "any", ObjectFlags.ContainsWideningType);
@@ -25719,7 +25720,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             const constraint = getConstraintOfTypeParameter(inference.typeParameter);
             if (constraint) {
                 const instantiatedConstraint = instantiateType(constraint, context.nonFixingMapper);
-                if (!inferredType || inferredType === wildcardType || !context.compareTypes(inferredType, getTypeWithThisArgument(instantiatedConstraint, inferredType))) {
+                if (!inferredType || inferredType === blockedStringType || !context.compareTypes(inferredType, getTypeWithThisArgument(instantiatedConstraint, inferredType))) {
                     // If the fallback type satisfies the constraint, we pick it. Otherwise, we pick the constraint.
                     inference.inferredType = fallbackType && context.compareTypes(fallbackType, getTypeWithThisArgument(instantiatedConstraint, fallbackType)) ? fallbackType : instantiatedConstraint;
                 }
@@ -38535,7 +38536,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
             case SyntaxKind.NoSubstitutionTemplateLiteral:
             case SyntaxKind.StringLiteral:
                 return hasSkipDirectInferenceFlag(node) ?
-                    wildcardType :
+                    blockedStringType :
                     getFreshTypeOfLiteralType(getStringLiteralType((node as StringLiteralLike).text));
             case SyntaxKind.NumericLiteral: {
                 checkGrammarNumericLiteral(node as NumericLiteral);

tests/cases/fourslash/stringLiteralCompletionsInArgUsingInferenceResultFromPreviousArg.ts

@@ -0,0 +1,35 @@
+/// <reference path="fourslash.ts" />
+
+// @strict: true
+
+//// // https://github.com/microsoft/TypeScript/issues/55545
+//// enum myEnum {
+////   valA = "valA",
+////   valB = "valB",
+//// }
+////
+//// interface myEnumParamMapping {
+////   ["valA"]: "1" | "2";
+////   ["valB"]: "3" | "4";
+//// }
+////
+//// function myFunction<K extends keyof typeof myEnum>(
+////   a: K,
+////   b: myEnumParamMapping[K],
+//// ) {}
+////
+//// myFunction("valA", "/*ts1*/");
+//// myFunction("valA", `/*ts2*/`);
+////
+//// function myFunction2<K extends keyof typeof myEnum>(
+////   a: K,
+////   { b }: { b: myEnumParamMapping[K] },
+//// ) {}
+////
+//// myFunction2("valA", { b: "/*ts3*/" });
+//// myFunction2("valA", { b: `/*ts4*/` });
+
+verify.completions({
+    marker: ["ts1", "ts2", "ts3", "ts4"],
+    exact: ["1", "2"]
+});