repl: reject --watch without script

src/node.cc

@@ -993,6 +993,13 @@ static ExitCode InitializeNodeWithArgsInternal(
     exit_code =
         ProcessGlobalArgsInternal(argv, exec_argv, errors, kDisallowedInEnvvar);
     if (exit_code != ExitCode::kNoFailure) return exit_code;
+
+    auto env_opts = per_process::cli_options->per_isolate->per_env;
+    if (env_opts->watch_mode && !env_opts->test_runner &&
+        env_opts->watch_mode_paths.empty() && argv->size() < 2) {
+      errors->push_back("--watch requires specifying a file");
+      return ExitCode::kInvalidCommandLineArgument;
+    }
   }
 
   // Set the process.title immediately after processing argv if --title is set.

src/node_options.cc

@@ -266,8 +266,6 @@ void EnvironmentOptions::CheckOptions(std::vector<std::string>* errors,
     } else if (test_runner_force_exit) {
       errors->push_back("either --watch or --test-force-exit "
                         "can be used, not both");
-    } else if (!test_runner && watch_mode_paths.empty() && argv->size() < 1) {
-      errors->push_back("--watch requires specifying a file");
     }
 
 #ifndef ALLOW_ATTACHING_DEBUGGER_IN_WATCH_MODE

test/sequential/test-watch-mode-watch-flags.mjs

@@ -51,6 +51,15 @@ async function runNode({
 tmpdir.refresh();
 
 describe('watch mode - watch flags', { concurrency: !process.env.TEST_PARALLEL, timeout: 60_000 }, () => {
+  it('should require a file to watch', async () => {
+    const { code, signal, stderr, stdout } = await common.spawnPromisified(execPath, ['--watch']);
+
+    assert.strictEqual(code, 9);
+    assert.strictEqual(signal, null);
+    assert.match(stderr, /--watch requires specifying a file/);
+    assert.strictEqual(stdout, '');
+  });
+
   it('when multiple `--watch` flags are provided should run as if only one was', async () => {
     const projectDir = tmpdir.resolve('project-multi-flag');
     mkdirSync(projectDir);