Don't defer index types for non-generic substitution types

src/compiler/checker.ts

@@ -18903,6 +18903,7 @@ export function createTypeChecker(host: TypeCheckerHost): TypeChecker {
     function getIndexType(type: Type, indexFlags = IndexFlags.None): Type {
         type = getReducedType(type);
         return isNoInferType(type) ? getNoInferType(getIndexType((type as SubstitutionType).baseType, indexFlags)) :
+            type.flags & TypeFlags.Substitution && !isGenericType((type as SubstitutionType).baseType) && !isGenericType((type as SubstitutionType).constraint) ? getUnionType([getIndexType((type as SubstitutionType).baseType, indexFlags), getIndexType((type as SubstitutionType).constraint, indexFlags)]) :
             shouldDeferIndexType(type, indexFlags) ? getIndexTypeForGenericType(type as InstantiableType | UnionOrIntersectionType, indexFlags) :
             type.flags & TypeFlags.Union ? getIntersectionType(map((type as UnionType).types, t => getIndexType(t, indexFlags))) :
             type.flags & TypeFlags.Intersection ? getUnionType(map((type as IntersectionType).types, t => getIndexType(t, indexFlags))) :

tests/baselines/reference/substitutionTypeNonGenericIndexType1.symbols

@@ -0,0 +1,35 @@
+//// [tests/cases/compiler/substitutionTypeNonGenericIndexType1.ts] ////
+
+=== substitutionTypeNonGenericIndexType1.ts ===
+// https://github.com/microsoft/TypeScript/issues/61728
+
+type BasicConditional<T> = keyof T extends any
+>BasicConditional : Symbol(BasicConditional, Decl(substitutionTypeNonGenericIndexType1.ts, 0, 0))
+>T : Symbol(T, Decl(substitutionTypeNonGenericIndexType1.ts, 2, 22))
+>T : Symbol(T, Decl(substitutionTypeNonGenericIndexType1.ts, 2, 22))
+
+  ? true
+  : false;
+
+type Config = { rejectClose: true };
+>Config : Symbol(Config, Decl(substitutionTypeNonGenericIndexType1.ts, 4, 10))
+>rejectClose : Symbol(rejectClose, Decl(substitutionTypeNonGenericIndexType1.ts, 6, 15))
+
+type Test =
+>Test : Symbol(Test, Decl(substitutionTypeNonGenericIndexType1.ts, 6, 36))
+
+  Config extends {}
+>Config : Symbol(Config, Decl(substitutionTypeNonGenericIndexType1.ts, 4, 10))
+
+    ? {
+        rejectClose: BasicConditional<Config>;
+>rejectClose : Symbol(rejectClose, Decl(substitutionTypeNonGenericIndexType1.ts, 9, 7))
+>BasicConditional : Symbol(BasicConditional, Decl(substitutionTypeNonGenericIndexType1.ts, 0, 0))
+>Config : Symbol(Config, Decl(substitutionTypeNonGenericIndexType1.ts, 4, 10))
+      }
+    : never;
+
+type RejectClose = Test["rejectClose"];
+>RejectClose : Symbol(RejectClose, Decl(substitutionTypeNonGenericIndexType1.ts, 12, 12))
+>Test : Symbol(Test, Decl(substitutionTypeNonGenericIndexType1.ts, 6, 36))
+

tests/baselines/reference/substitutionTypeNonGenericIndexType1.types

@@ -0,0 +1,41 @@
+//// [tests/cases/compiler/substitutionTypeNonGenericIndexType1.ts] ////
+
+=== substitutionTypeNonGenericIndexType1.ts ===
+// https://github.com/microsoft/TypeScript/issues/61728
+
+type BasicConditional<T> = keyof T extends any
+>BasicConditional : BasicConditional<T>
+>                 : ^^^^^^^^^^^^^^^^^^^
+
+  ? true
+>true : true
+>     : ^^^^
+
+  : false;
+>false : false
+>      : ^^^^^
+
+type Config = { rejectClose: true };
+>Config : Config
+>       : ^^^^^^
+>rejectClose : true
+>            : ^^^^
+>true : true
+>     : ^^^^
+
+type Test =
+>Test : { rejectClose: BasicConditional<Config>; }
+>     : ^^^^^^^^^^^^^^^                        ^^^
+
+  Config extends {}
+    ? {
+        rejectClose: BasicConditional<Config>;
+>rejectClose : true
+>            : ^^^^
+      }
+    : never;
+
+type RejectClose = Test["rejectClose"];
+>RejectClose : true
+>            : ^^^^
+

tests/baselines/reference/substitutionTypeNonGenericIndexType2.symbols

@@ -0,0 +1,30 @@
+//// [tests/cases/compiler/substitutionTypeNonGenericIndexType2.ts] ////
+
+=== substitutionTypeNonGenericIndexType2.ts ===
+type BasicConditional<T> = keyof T extends infer R ? R : never;
+>BasicConditional : Symbol(BasicConditional, Decl(substitutionTypeNonGenericIndexType2.ts, 0, 0))
+>T : Symbol(T, Decl(substitutionTypeNonGenericIndexType2.ts, 0, 22))
+>T : Symbol(T, Decl(substitutionTypeNonGenericIndexType2.ts, 0, 22))
+>R : Symbol(R, Decl(substitutionTypeNonGenericIndexType2.ts, 0, 48))
+>R : Symbol(R, Decl(substitutionTypeNonGenericIndexType2.ts, 0, 48))
+
+type Config = { rejectClose: true };
+>Config : Symbol(Config, Decl(substitutionTypeNonGenericIndexType2.ts, 0, 63))
+>rejectClose : Symbol(rejectClose, Decl(substitutionTypeNonGenericIndexType2.ts, 2, 15))
+
+type Test = Config extends {}
+>Test : Symbol(Test, Decl(substitutionTypeNonGenericIndexType2.ts, 2, 36))
+>Config : Symbol(Config, Decl(substitutionTypeNonGenericIndexType2.ts, 0, 63))
+
+  ? {
+      rejectClose: BasicConditional<Config>;
+>rejectClose : Symbol(rejectClose, Decl(substitutionTypeNonGenericIndexType2.ts, 5, 5))
+>BasicConditional : Symbol(BasicConditional, Decl(substitutionTypeNonGenericIndexType2.ts, 0, 0))
+>Config : Symbol(Config, Decl(substitutionTypeNonGenericIndexType2.ts, 0, 63))
+    }
+  : never;
+
+const test: Test["rejectClose"] = "rejectClose";
+>test : Symbol(test, Decl(substitutionTypeNonGenericIndexType2.ts, 10, 5))
+>Test : Symbol(Test, Decl(substitutionTypeNonGenericIndexType2.ts, 2, 36))
+

tests/baselines/reference/substitutionTypeNonGenericIndexType2.types

@@ -0,0 +1,32 @@
+//// [tests/cases/compiler/substitutionTypeNonGenericIndexType2.ts] ////
+
+=== substitutionTypeNonGenericIndexType2.ts ===
+type BasicConditional<T> = keyof T extends infer R ? R : never;
+>BasicConditional : BasicConditional<T>
+>                 : ^^^^^^^^^^^^^^^^^^^
+
+type Config = { rejectClose: true };
+>Config : Config
+>       : ^^^^^^
+>rejectClose : true
+>            : ^^^^
+>true : true
+>     : ^^^^
+
+type Test = Config extends {}
+>Test : { rejectClose: BasicConditional<Config>; }
+>     : ^^^^^^^^^^^^^^^                        ^^^
+
+  ? {
+      rejectClose: BasicConditional<Config>;
+>rejectClose : "rejectClose"
+>            : ^^^^^^^^^^^^^
+    }
+  : never;
+
+const test: Test["rejectClose"] = "rejectClose";
+>test : "rejectClose"
+>     : ^^^^^^^^^^^^^
+>"rejectClose" : "rejectClose"
+>              : ^^^^^^^^^^^^^
+

tests/cases/compiler/substitutionTypeNonGenericIndexType1.ts

@@ -0,0 +1,18 @@
+// @strict: true
+// @noEmit: true
+
+// https://github.com/microsoft/TypeScript/issues/61728
+
+type BasicConditional<T> = keyof T extends any
+  ? true
+  : false;
+
+type Config = { rejectClose: true };
+type Test =
+  Config extends {}
+    ? {
+        rejectClose: BasicConditional<Config>;
+      }
+    : never;
+
+type RejectClose = Test["rejectClose"];

tests/cases/compiler/substitutionTypeNonGenericIndexType2.ts

@@ -0,0 +1,14 @@
+// @strict: true
+// @noEmit: true
+
+type BasicConditional<T> = keyof T extends infer R ? R : never;
+
+type Config = { rejectClose: true };
+
+type Test = Config extends {}
+  ? {
+      rejectClose: BasicConditional<Config>;
+    }
+  : never;
+
+const test: Test["rejectClose"] = "rejectClose";