The inferred type of 'loader' cannot be named without a reference

[ziimakc]

What version of Remix are you using?

1.6.5

Steps to Reproduce

pnpm@7.5.1
typescript@4.7.3

import { json } from '@remix-run/node';
import { useLoaderData } from '@remix-run/react';

export async function loader() {
  return json({ greeting: 'Hello!' });
}

export default function App() {
  const data = useLoaderData<typeof loader>();
  return <div>{data.greeting}</div>;
}

tsconfig:

{
  "exclude": ["**/node_modules"],
  "compilerOptions": {
    /* Visit https://aka.ms/tsconfig.json to read more about this file */

    /* Projects */
    // "incremental": true,                              /* Enable incremental compilation */
    // "composite": true,                                /* Enable constraints that allow a TypeScript project to be used with project references. */
    // "tsBuildInfoFile": "./",                          /* Specify the folder for .tsbuildinfo incremental compilation files. */
    // "disableSourceOfProjectReferenceRedirect": true,  /* Disable preferring source files instead of declaration files when referencing composite projects */
    // "disableSolutionSearching": true,                 /* Opt a project out of multi-project reference checking when editing. */
    // "disableReferencedProjectLoad": true,             /* Reduce the number of projects loaded automatically by TypeScript. */

    /* Language and Environment */
    "target": "ES2021" /* Set the JavaScript language version for emitted JavaScript and include compatible library declarations. */,
    // "lib": ["ES2022"],                                /* Specify a set of bundled library declaration files that describe the target runtime environment. */
    // "jsx": "preserve",                                /* Specify what JSX code is generated. */
    // "experimentalDecorators": true,                   /* Enable experimental support for TC39 stage 2 draft decorators. */
    // "emitDecoratorMetadata": true,                    /* Emit design-type metadata for decorated declarations in source files. */
    // "jsxFactory": "",                                 /* Specify the JSX factory function used when targeting React JSX emit, e.g. 'React.createElement' or 'h' */
    // "jsxFragmentFactory": "",                         /* Specify the JSX Fragment reference used for fragments when targeting React JSX emit e.g. 'React.Fragment' or 'Fragment'. */
    // "jsxImportSource": "",                            /* Specify module specifier used to import the JSX factory functions when using `jsx: react-jsx*`.` */
    // "reactNamespace": "",                             /* Specify the object invoked for `createElement`. This only applies when targeting `react` JSX emit. */
    // "noLib": true,                                    /* Disable including any library files, including the default lib.d.ts. */
    "useDefineForClassFields": true /* Emit ECMAScript-standard-compliant class fields. */,

    /* Modules */
    "module": "ES2022" /* Specify what module code is generated. For node 14+ - ES6, for browser - ES6 */,
    // "rootDir": "./",                                  /* Specify the root folder within your source files. */
    "moduleResolution": "node" /* Specify how TypeScript looks up a file from a given module specifier. */,
    // "baseUrl": "./",                                  /* Specify the base directory to resolve non-relative module names. */
    // "paths": {},                                      /* Specify a set of entries that re-map imports to additional lookup locations. */
    // "rootDirs": [],                                   /* Allow multiple folders to be treated as one when resolving modules. */
    // "typeRoots": [],                                  /* Specify multiple folders that act like `./node_modules/@types`. */
    // "types": [],                                      /* Specify type package names to be included without being referenced in a source file. */
    // "allowUmdGlobalAccess": true,                     /* Allow accessing UMD globals from modules. */
    "resolveJsonModule": true /* Enable importing .json files */,
    // "noResolve": true,                                /* Disallow `import`s, `require`s or `<reference>`s from expanding the number of files TypeScript should add to a project. */

    /* JavaScript Support */
    "allowJs": true /* Allow JavaScript files to be a part of your program. Use the `checkJS` option to get errors from these files. */,
    "checkJs": true /* Enable error reporting in type-checked JavaScript files. */,
    // "maxNodeModuleJsDepth": 0,                        /* Specify the maximum folder depth used for checking JavaScript files from `node_modules`. Only applicable with `allowJs`. */

    /* Emit */
    "declaration": true /* Generate .d.ts files from TypeScript and JavaScript files in your project. */,
    "declarationMap": true /* Create sourcemaps for d.ts files. */,
    // "emitDeclarationOnly": true,                      /* Only output d.ts files and not JavaScript files. */
    "sourceMap": true /* Create source map files for emitted JavaScript files. */,
    // "outFile": "./",                                  /* Specify a file that bundles all outputs into one JavaScript file. If `declaration` is true, also designates a file that bundles all .d.ts output. */
    // "outDir": "./",                                   /* Specify an output folder for all emitted files. */
    "removeComments": true /* Disable emitting comments. */,
    // "noEmit": true,                                   /* Disable emitting files from a compilation. */
    "importHelpers": true /* Allow importing helper functions from tslib (needs to be installed) once per project, instead of including them per-file. */,
    "importsNotUsedAsValues": "error" /* Specify emit/checking behavior for imports that are only used for types */,
    "preserveValueImports": true /* When combined with isolatedModules imported types must be marked as type-only */,
    "downlevelIteration": true /* Emit more compliant, but verbose and less performant JavaScript for iteration. */,
    // "sourceRoot": "",                                 /* Specify the root path for debuggers to find the reference source code. */
    // "mapRoot": "",                                    /* Specify the location where debugger should locate map files instead of generated locations. */
    // "inlineSourceMap": true,                          /* Include sourcemap files inside the emitted JavaScript. */
    // "inlineSources": true,                            /* Include source code in the sourcemaps inside the emitted JavaScript. */
    // "emitBOM": true,                                  /* Emit a UTF-8 Byte Order Mark (BOM) in the beginning of output files. */
    "newLine": "LF" /* Set the newline character for emitting files. */,
    // "stripInternal": true,                            /* Disable emitting declarations that have `@internal` in their JSDoc comments. */
    // "noEmitHelpers": true,                            /* Disable generating custom helper functions like `__extends` in compiled output. */
    // "noEmitOnError": true,                            /* Disable emitting files if any type checking errors are reported. */
    // "preserveConstEnums": true,                       /* Disable erasing `const enum` declarations in generated code. */
    // "declarationDir": "./",                           /* Specify the output directory for generated declaration files. */

    /* Interop Constraints */
    "isolatedModules": true /* Ensure that each file can be safely transpiled without relying on other imports. */,
    "allowSyntheticDefaultImports": true /* Allow 'import x from y' when a module doesn't have a default export. */,
    "esModuleInterop": true /* Emit additional JavaScript to ease support for importing CommonJS modules. This enables `allowSyntheticDefaultImports` for type compatibility. */,
    // "preserveSymlinks": true,                         /* Disable resolving symlinks to their realpath. This correlates to the same flag in node. */
    "forceConsistentCasingInFileNames": true /* Ensure that casing is correct in imports. */,

    /* Type Checking */
    "strict": true /* Enable all strict type-checking options. */,
    // "noImplicitAny": true,                            /* Part of strict. Enable error reporting for expressions and declarations with an implied `any` type.. */
    // "strictNullChecks": true,                         /* Part of strict. When type checking, take into account `null` and `undefined`. */
    // "strictFunctionTypes": true,                      /* Part of strict. When assigning functions, check to ensure parameters and the return values are subtype-compatible. */
    // "strictBindCallApply": true,                      /* Part of strict. Check that the arguments for `bind`, `call`, and `apply` methods match the original function. */
    // "strictPropertyInitialization": true,             /* Part of strict. Check for class properties that are declared but not set in the constructor. */
    // "noImplicitThis": true,                           /* Part of strict. Enable error reporting when `this` is given the type `any`. */
    // "useUnknownInCatchVariables": true,               /* Part of strict. Type catch clause variables as 'unknown' instead of 'any'. */
    // "alwaysStrict": true,                             /* Part of strict. Ensure 'use strict' is always emitted. */
    "noUnusedLocals": false /* Enable error reporting when a local variables aren't read. */,
    "noUnusedParameters": false /* Raise an error when a function parameter isn't read */,
    "exactOptionalPropertyTypes": true /* Interpret optional property types as written, rather than adding 'undefined'. */,
    "noImplicitReturns": true /* Enable error reporting for codepaths that do not explicitly return in a function. */,
    "noFallthroughCasesInSwitch": true /* Enable error reporting for fallthrough cases in switch statements. */,
    "noUncheckedIndexedAccess": true /* Include 'undefined' in index signature results */,
    "noImplicitOverride": true /* Ensure overriding members in derived classes are marked with an override modifier. */,
    "noPropertyAccessFromIndexSignature": true /* Enforces using indexed accessors for keys declared using an indexed type */,
    "allowUnusedLabels": false /* Disable error reporting for unused labels. */,
    "allowUnreachableCode": false /* Disable error reporting for unreachable code. */,

    /* Completeness */
    // "skipDefaultLibCheck": true,                      /* Skip type checking .d.ts files that are included with TypeScript. Use skipLibCheck instead. */
    "skipLibCheck": true /* Skip type checking all .d.ts files. */
  "include": [
    "remix.env.d.ts",
    "server/**/*.ts",
    "src/**/*.ts",
    "src/**/*.tsx"
  ],
  "compilerOptions": {
    "target": "ES2020",
    "module": "ES2020",
    "lib": ["DOM", "DOM.Iterable", "esnext"],
    "jsx": "react-jsx",
    "baseUrl": ".",
    "noEmit": true,
    "forceConsistentCasingInFileNames": true,
    "allowJs": true,
    "strict": true,
    "esModuleInterop": true,
    "isolatedModules": true,
    "moduleResolution": "node",
    "resolveJsonModule": true
  }
}

Expected Behavior

No error should be shown

Actual Behavior

VSCode shows error:

The inferred type of 'loader' cannot be named without a reference to '.pnpm/@remix-run+server-runtime@1.6.5_biqbaboplfbrettd7655fr4n2y/node_modules/@remix-run/server-runtime'. This is likely not portable. A type annotation is necessary.ts(2742)

[dmarkow]

This is because your project has the @typescript-eslint/explicit-function-return-type eslint rule turned on, which doesn't let you have a plain export async function loader() without any type annotation. If you want to infer types without having to add explicit return types to all of your loader functions, I think you'll have to keep that rule turned off, or maybe use the allowedNames option for that rule:

{
  "@typescript-eslint/explicit-function-return-type": [
    "error",
    {
      "allowedNames": ["loader"]
    }
  ]
}

[ziimakc]

@dmarkow thanks for the tip, but I raised issue about typescript error and not eslint, look at the last part on screenshot.

[ziimakc]

Solved by installing @remix-run/server-runtime as dependency, not sure that is how it should work

[dmarkow]

@ziimakc Ahh, sorry -- didn't catch that!

[kiliman]

@ziimakc you shouldn't have to install that package directly.

Remix type inference is working fine for me on a vanilla Remix App Server project. I wonder if it's a PNPM related issue.

[esamattis]

I'm seeing this too with pnpm and installing @remix-run/server-runtime does not fix it for me.

But I think I known why this is happening. The "cannot be named without a reference to" error usually means that a package is exporting a type that is using another type that is not exported.

It seems that JsonFunction and TypedResponse types used by the json() are not exported in the @remix-run/node package.

definitions are in the @remix-run/server-runtime package:

remix/packages/remix-server-runtime/responses.ts

Lines 1 to 30 in db0619d

	export type JsonFunction = <Data extends unknown>(
	data: Data,
	init?: number | ResponseInit
	) => TypedResponse<Data>;
	// must be a type since this is a subtype of response
	// interfaces must conform to the types they extend
	export type TypedResponse<T extends unknown = unknown> = Response & {
	json(): Promise<T>;
	};
	/**
	* This is a shortcut for creating `application/json` responses. Converts `data`
	* to JSON and sets the `Content-Type` header.
	*
	* @see https://remix.run/api/remix#json
	*/
	export const json: JsonFunction = (data, init = {}) => {
	let responseInit = typeof init === "number" ? { status: init } : init;
	let headers = new Headers(responseInit.headers);
	if (!headers.has("Content-Type")) {
	headers.set("Content-Type", "application/json; charset=utf-8");
	}
	return new Response(JSON.stringify(data), {
	...responseInit,
	headers,
	});
	};

But only the json() is exported in the @remix-run/node package:

remix/packages/remix-node/index.ts

Lines 38 to 49 in db0619d

	export {
	createRequestHandler,
	createSession,
	isCookie,
	isSession,
	json,
	MaxPartSizeExceededError,
	redirect,
	unstable_composeUploadHandlers,
	unstable_createMemoryUploadHandler,
	unstable_parseMultipartFormData,
	} from "@remix-run/server-runtime";

which causes the "cannot be named without a reference to" error.

I can actually fix this error by patching the exports to the @remix-run/node package:

remix-type-bug.mp4

Submitted a PR #3797

[ziimakc]

fixed