Detect working directory for flat config. (#1815)

Author: dbaeumer

playgrounds/flat-config-fail/f1/app.js

@@ -0,0 +1,12 @@
+function bar() {
+	if (foo) {
+		foo++;
+	}
+}
+
+function foo(x) {
+	console.log(x);
+	bar();
+	var x = 10;
+	console.log(undef);
+}

playgrounds/flat-config-fail/f1/eslint.config.js

@@ -0,0 +1,51 @@
+const globals = require('globals');
+const typescriptParser =  require('@typescript-eslint/parser');
+const typescriptPlugin = require('@typescript-eslint/eslint-plugin');
+
+module.exports = [
+	"eslint:recommended",
+	{
+		files: ["**/*.js"],
+		languageOptions: {
+			sourceType: "module",
+			globals: {
+				...globals.browser,
+				...globals.node,
+				...globals.es6,
+				...globals.commonjs
+			}
+		},
+	},
+	{
+		files: ["sub/*.js"],
+		rules: {
+			"no-undef": "warn",
+			"no-console": "warn"
+		}
+	},
+	{
+		files: ["*.ts", "**/*.ts"],
+		plugins: {
+			"@typescript-eslint": typescriptPlugin
+		},
+		languageOptions: {
+			sourceType: "module",
+			parser: typescriptParser,
+			parserOptions: {
+				project: "./tsconfig.json",
+				ecmaVersion: 2020
+			}
+		},
+		rules: {
+			"semi": "off",
+			"@typescript-eslint/semi": "error",
+			"no-extra-semi": "warn",
+			"curly": "warn",
+			"quotes": ["error", "single", { "allowTemplateLiterals": true } ],
+			"eqeqeq": "error",
+			"indent": "off",
+			"@typescript-eslint/indent": ["warn", "tab", { "SwitchCase": 1 } ],
+			"@typescript-eslint/no-floating-promises": "error"
+		}
+	}
+]