fix: remove "util" lib as not supported

Author: uhyo

build/build.ts

@@ -24,13 +24,6 @@ async function main() {
     /(?:^|\/|\\).+\.d\.ts$/.test(libFile)
   );
 
-  // copy special "util" file
-  const utilFile = path.join(betterLibDir, "lib.util.d.ts");
-  await writeFile(
-    path.join(distDir, "lib.util.d.ts"),
-    await readFile(utilFile, "utf8")
-  );
-
   // modify each lib file
   for (const libFile of libFiles) {
     const tsLibFile = path.join(tsLibDir, libFile);

generated/lib.es5.d.ts

@@ -1,5 +1,15 @@
 /// <reference no-default-lib="true" />
-/// <reference lib="util" />
+
+// -----------
+// additional utility types
+type UnionToIntersection<T> = (
+  T extends any ? (arg: T) => void : never
+) extends (arg: infer F) => void
+  ? F
+  : unknown;
+
+type Awaited<T> = T extends PromiseLike<infer U> ? Awaited<U> : T;
+// -----------
 
 /**
  * Evaluates JavaScript code and executes it.

generated/lib.util.d.ts

@@ -1,5 +1,15 @@
 /// <reference no-default-lib="true" />
-/// <reference lib="util" />
+
+// -----------
+// additional utility types
+type UnionToIntersection<T> = (
+  T extends any ? (arg: T) => void : never
+) extends (arg: infer F) => void
+  ? F
+  : unknown;
+
+type Awaited<T> = T extends PromiseLike<infer U> ? Awaited<U> : T;
+// -----------
 
 /**
  * Evaluates JavaScript code and executes it.