Cherry-pick #46645 to release-4.5

src/compiler/checker.ts

@@ -14153,6 +14153,7 @@ namespace ts {
             // We ignore 'never' types in unions
             if (!(flags & TypeFlags.Never)) {
                 includes |= flags & TypeFlags.IncludesMask;
+                if (flags & TypeFlags.Instantiable) includes |= TypeFlags.IncludesInstantiable;
                 if (type === wildcardType) includes |= TypeFlags.IncludesWildcard;
                 if (!strictNullChecks && flags & TypeFlags.Nullable) {
                     if (!(getObjectFlags(type) & ObjectFlags.ContainsWideningType)) includes |= TypeFlags.IncludesNonWideningType;

src/compiler/types.ts

@@ -5187,8 +5187,6 @@ namespace ts {
         // 'Narrowable' types are types where narrowing actually narrows.
         // This *should* be every type other than null, undefined, void, and never
         Narrowable = Any | Unknown | StructuredOrInstantiable | StringLike | NumberLike | BigIntLike | BooleanLike | ESSymbol | UniqueESSymbol | NonPrimitive,
-        /* @internal */
-        NotPrimitiveUnion = Any | Unknown | Enum | Void | Never | Object | Intersection | Instantiable,
         // The following flags are aggregated during union and intersection type construction
         /* @internal */
         IncludesMask = Any | Unknown | Primitive | Never | Object | Union | Intersection | NonPrimitive | TemplateLiteral,
@@ -5201,6 +5199,10 @@ namespace ts {
         IncludesWildcard = IndexedAccess,
         /* @internal */
         IncludesEmptyObject = Conditional,
+        /* @internal */
+        IncludesInstantiable = Substitution,
+        /* @internal */
+        NotPrimitiveUnion = Any | Unknown | Enum | Void | Never | Object | Intersection | IncludesInstantiable,
     }
 
     export type DestructuringPattern = BindingPattern | ObjectLiteralExpression | ArrayLiteralExpression;

tests/baselines/reference/primitiveUnionDetection.js

@@ -0,0 +1,24 @@
+//// [primitiveUnionDetection.ts]
+// Repro from #46624
+
+type Kind = "one" | "two" | "three";
+
+declare function getInterfaceFromString<T extends Kind>(options?: { type?: T } & { type?: Kind }): T;
+
+const result = getInterfaceFromString({ type: 'two' });
+
+
+//// [primitiveUnionDetection.js]
+"use strict";
+// Repro from #46624
+var result = getInterfaceFromString({ type: 'two' });
+
+
+//// [primitiveUnionDetection.d.ts]
+declare type Kind = "one" | "two" | "three";
+declare function getInterfaceFromString<T extends Kind>(options?: {
+    type?: T;
+} & {
+    type?: Kind;
+}): T;
+declare const result: "two";

tests/baselines/reference/primitiveUnionDetection.symbols

@@ -0,0 +1,22 @@
+=== tests/cases/compiler/primitiveUnionDetection.ts ===
+// Repro from #46624
+
+type Kind = "one" | "two" | "three";
+>Kind : Symbol(Kind, Decl(primitiveUnionDetection.ts, 0, 0))
+
+declare function getInterfaceFromString<T extends Kind>(options?: { type?: T } & { type?: Kind }): T;
+>getInterfaceFromString : Symbol(getInterfaceFromString, Decl(primitiveUnionDetection.ts, 2, 36))
+>T : Symbol(T, Decl(primitiveUnionDetection.ts, 4, 40))
+>Kind : Symbol(Kind, Decl(primitiveUnionDetection.ts, 0, 0))
+>options : Symbol(options, Decl(primitiveUnionDetection.ts, 4, 56))
+>type : Symbol(type, Decl(primitiveUnionDetection.ts, 4, 67))
+>T : Symbol(T, Decl(primitiveUnionDetection.ts, 4, 40))
+>type : Symbol(type, Decl(primitiveUnionDetection.ts, 4, 82))
+>Kind : Symbol(Kind, Decl(primitiveUnionDetection.ts, 0, 0))
+>T : Symbol(T, Decl(primitiveUnionDetection.ts, 4, 40))
+
+const result = getInterfaceFromString({ type: 'two' });
+>result : Symbol(result, Decl(primitiveUnionDetection.ts, 6, 5))
+>getInterfaceFromString : Symbol(getInterfaceFromString, Decl(primitiveUnionDetection.ts, 2, 36))
+>type : Symbol(type, Decl(primitiveUnionDetection.ts, 6, 39))
+

tests/baselines/reference/primitiveUnionDetection.types

@@ -0,0 +1,20 @@
+=== tests/cases/compiler/primitiveUnionDetection.ts ===
+// Repro from #46624
+
+type Kind = "one" | "two" | "three";
+>Kind : Kind
+
+declare function getInterfaceFromString<T extends Kind>(options?: { type?: T } & { type?: Kind }): T;
+>getInterfaceFromString : <T extends Kind>(options?: ({ type?: T | undefined; } & { type?: Kind | undefined; }) | undefined) => T
+>options : ({ type?: T | undefined; } & { type?: Kind | undefined; }) | undefined
+>type : T | undefined
+>type : Kind | undefined
+
+const result = getInterfaceFromString({ type: 'two' });
+>result : "two"
+>getInterfaceFromString({ type: 'two' }) : "two"
+>getInterfaceFromString : <T extends Kind>(options?: ({ type?: T | undefined; } & { type?: Kind | undefined; }) | undefined) => T
+>{ type: 'two' } : { type: "two"; }
+>type : "two"
+>'two' : "two"
+

tests/cases/compiler/primitiveUnionDetection.ts

@@ -0,0 +1,10 @@
+// @strict: true
+// @declaration: true
+
+// Repro from #46624
+
+type Kind = "one" | "two" | "three";
+
+declare function getInterfaceFromString<T extends Kind>(options?: { type?: T } & { type?: Kind }): T;
+
+const result = getInterfaceFromString({ type: 'two' });