Fixed an issue with string mappings over generic intersections not being deferred in conditional types (#55856)

tests/cases/conformance/types/literal/stringMappingDeferralInConditionalTypes.ts

@@ -0,0 +1,21 @@
+// @strict: true
+// @noEmit: true
+
+// https://github.com/microsoft/TypeScript/issues/55847
+
+type A<S> = Lowercase<S & string> extends "foo" ? 1 : 0;
+let x1: A<"foo"> = 1; // ok
+
+type B<S> = Lowercase<S & string> extends `f${string}` ? 1 : 0;
+let x2: B<"foo"> = 1; // ok
+
+type C<S> = Capitalize<Lowercase<S & string>> extends "Foo" ? 1 : 0;
+let x3: C<"foo"> = 1; // ok
+
+type D<S extends string> = Capitalize<Lowercase<S>> extends "Foo" ? 1 : 0;
+let x4: D<"foo"> = 1; // ok
+
+type E<S> = Lowercase<`f${S & string}` & `${S & string}f`>;
+type F = E<""> extends "f" ? 1 : 0; // 1
+type G<S> = E<S> extends "f" ? 1 : 0; 
+let x5: G<""> = 1; // ok