Bug: [no-misused-promises] Possible false positive in 5.27.0 #5121

doberkofler · 2022-05-31T14:23:35Z

Before You File a Bug Report Please Confirm You Have Done The Following...

I have tried restarting my IDE and the issue persists.
I have updated to the latest version of the packages.
I have searched for related issues and found none that matched my issue.
I have read the FAQ and my problem is not listed.

Playground Link

https://typescript-eslint.io/play/#ts=4.7.2&sourceType=module&code=C4TwDgpgBAJghsOAVc0C8UDeBXAzhAJwEsYAuKAO2wFsAjQgXwG4AoFgM2woGNgiB7CrARwA4hGAA1OABsSCCAAowcAnAD85AEoRu-AjAA8uYMQoBzADRQuAawr8A7hQB8UAD6VsMmQEpyAAoE-NRE+IZ2Ds5umCxQUAQS2ARCQSFhEAB0ibj8MgBuSipqvqwMbBAAHmD6wFBwuCA8UJw8fIJQ+DKKeIQk5FR0hP5QaaHh8IgokB5ePjFxUHoUJsKIUBhwjnBEdZNiEtJyk0o4+MQwDL71uKPB4xCG+9PQnlTzrPFE7FCK+1AAQjQGHefiwi3iiWAySEsXi8KgmSR+0sEKgzEW5UWUJhcxkZRYQA&eslintrc=N4KAkARApgHgLlAdgEwM4QFwAIDa5IAOANgK4DmAlohgAJwCeBUqAxgE4UFwC0zRVcAPR8B3NlBYB7ALbSkyKMggAafBGLkqtBk1YcuvVP0RCAhkSIQQWLAF1VNiGxJFmmLKBuO6jZu048IiaCiJLc0hSoJKiK3ARsMpFu2HheXtBsCWwq1mkeuXlYECwAFhIA1qgAapIUyABKUHAkbIjuAGbmMQVeAL49ttb9vUA&tsconfig=N4KABGBEDGD2C2AHAlgGwKYCcDyiAuysAdgM6QBcYoEEkJemy0eAcgK6qoDCAFutAGsylBm3TgwAXxCSgA

Repro Code

export async function sel(key: pkType): Promise<showProfileType | null> {
	const data = await dataGetValidate('!LAS_MOD_User_JSON.getEmpl', {emplid: key.emplid}) as Promise<showProfileType | null>;
	if (data !== null) {
		return {
			...data, // eslint-disable-line @typescript-eslint/no-misused-promises
			removeimg: false,
			removesign: false,
		};
	}

	return null;
}

ESLint Config

{
  "parser": "/Users/doberkofler/MyDev/ljs_app/trunk/periscope/node_modules/@typescript-eslint/parser/dist/index.js",
  "parserOptions": {
    "project": [
      "./tsconfig.json",
      "./test/selenium/tsconfig.json"
    ]
  },
  "plugins": [
    "@typescript-eslint"
  ],
  "rules": {
    "@typescript-eslint/no-misused-promises": "error"
  }
}

tsconfig

{
  "compilerOptions": {
    "allowJs": true,
    "checkJs": false,
    "skipLibCheck": true,
    "noEmit": true,
    "downlevelIteration": true,
    "sourceMap": true,
    "strict": true,
    "noImplicitAny": true,
    "strictNullChecks": true,
    "noImplicitThis": false,
    "noUnusedLocals": true,
    "noUnusedParameters": false,
    "noImplicitReturns": true,
    "noFallthroughCasesInSwitch": true,
    "noUncheckedIndexedAccess": false,
    "useUnknownInCatchVariables": true,
    "exactOptionalPropertyTypes": false,
    "esModuleInterop": true,
    "declaration": false,
    "importHelpers": true,
    "moduleResolution": "node",
    "target": "es2017",
    "module": "esnext",
    "jsx": "react",
    "baseUrl": "../",
    "outDir": "../temp",
    "removeComments": true,
    "lib": [
      "dom"
    ],
    "paths": {
      "@alias_root/*": [
        "./*"
      ]
    }
  },
  "compileOnSave": false,
  "include": [
    "src/**/*",
    "test/unittest/**/*"
  ],
  "exclude": [
    "node_modules"
  ]
}

Expected Result

I would not expect the warning (this still worked in version 5.26.0)

Actual Result

The warning Expected a non-Promise value to be spreaded in an object @typescript-eslint/no-misused-promises in shown since the upgrade to version 5.27.0

Additional Info

Unfortunately, I was not able to reproduce the error in the playground

Versions

package	version
`@typescript-eslint/eslint-plugin`	`5.27.0`
`@typescript-eslint/parser`	`5.27.0`
`TypeScript`	`4.7.2`
`ESLint`	`8.16.0`
`node`	`18.1.0`

The text was updated successfully, but these errors were encountered:

armano2 · 2022-05-31T15:02:20Z

this is working correctly -> it should warn you about this,

currently you are casting awaited value to Promise

const data = await dataGetValidate({userid}) as Promise<dataType | null>;

this code is interpreted as

const data = (await dataGetValidate({userid})) as Promise<dataType | null>;

Solution:

-  const data = await dataGetValidate({userid}) as Promise<dataType | null>;
+  const data = await (dataGetValidate({userid}) as Promise<dataType | null>);

i copied your tsconfig to be able to reproduce this see repro

bradzacher · 2022-05-31T15:37:58Z

@armano is correct!
await has a lower precedence than as - meaning instead of

await (thing as Promise)

you have

(await thing) as promise

The rule is working correctly and has caught a bug in your code!

doberkofler · 2022-05-31T16:13:00Z

this is working correctly -> it should warn you about this,

currently you are casting awaited value to Promise
const data = await dataGetValidate({userid}) as Promise<dataType | null>;
this code is interpreted as
const data = (await dataGetValidate({userid})) as Promise<dataType | null>;
Solution:
-  const data = await dataGetValidate({userid}) as Promise<dataType | null>;
+  const data = await (dataGetValidate({userid}) as Promise<dataType | null>);
i copied your tsconfig to be able to reproduce this see repro

@armano2 Thank you for you feedback. I understand and was actually thinking the same but when using const data = (await dataGetValidate({userid})) as Promise<dataType | null>; the rule '@typescript-eslint/no-misused-promises': ['error', {checksVoidReturn: false}] complains about Unnecessary parentheses around expression.

doberkofler · 2022-05-31T16:18:05Z

i copied your tsconfig to be able to reproduce this see repro

@armano2 Would be be so kind and tell me what I did miss in the Playground? I tried for quite some time and somehow was not able to reproduce the problem.

armano2 · 2022-05-31T16:18:54Z

you forgot to input your tsconfig, and to be precise "target": "es2017"

recently we did some changes how you have to input configs, to give users easier way to reproduce issues

doberkofler · 2022-05-31T16:21:16Z

you forgot to input your tsconfig, and to be precise "target": "es2017"

@armano2 Thank you. I must somehow have removed the target and then missed to put it back.

bradzacher · 2022-05-31T16:27:43Z

@doberkofler for sure! next time if you could filter out the non-ts-eslint rules that'd go a long way.
I was super surprised when I couldn't open this issue at all this morning because it crashed the GH app AND chrome on my phone!
I'll file a bug with GH for that!

I understand and was actually thinking the same but when using const data = (await dataGetValidate({userid})) as Promise<dataType | null>; the rule '@typescript-eslint/no-misused-promises': ['error', {checksVoidReturn: false}] complains about Unnecessary parentheses around expression.

Your code should be

await (thing as Promise)

not

(await thing) as Promise

The former code you are "casting" it to a promise and then awaiting it (i.e. your result will be of type T from Promise<T>).
The latter code you are awaiting it and then "casting it to a promise (i.e. your result will be of type Promise<T>), which is incorrect.

Here's a playground to better show the correct parenthisation

doberkofler · 2022-05-31T16:38:02Z

@bradzacher I understand but when using the proper parentheses (sorry but I just copied the wrong code before) I get Unnecessary parentheses around expression. 8:22 - 8:23.

Example

bradzacher · 2022-05-31T16:39:49Z

That's a bug in the @typescript-eslint/no-extra-parens lint rule!

doberkofler · 2022-05-31T16:44:25Z

Thank you! Now I fully understand and sorry for not digging deeper before opening the SR. It seems I somehow just wanted it to be related to the improved no-misused-promises rule instead of actually checking the precedence rules ;-)

doberkofler · 2022-05-31T16:46:21Z

Should I open a new SR or ... ?

bradzacher · 2022-05-31T17:14:01Z

I just filed one on your behalf! #5124

doberkofler added bug Something isn't working package: eslint-plugin Issues related to @typescript-eslint/eslint-plugin triage Waiting for team members to take a look labels May 31, 2022

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bradzacher closed this as completed May 31, 2022

bradzacher added working as intended Issues that are closed as they are working as intended fix: user error issue was fixed by correcting the configuration / correcting the code and removed bug Something isn't working triage Waiting for team members to take a look labels May 31, 2022

JoshuaKGoldberg mentioned this issue May 31, 2022

Repo: Update issue templates to explicitly ask for minimal config reproductions #5122

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bradzacher mentioned this issue May 31, 2022

Bug: [no-extra-parens] incorrect precedence for await vs assertion #5124

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4 tasks

armano2 mentioned this issue May 31, 2022

chore(website): [playground] support enum values and remove compilerOptions filter #5125

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Bug: [no-misused-promises] Possible false positive in 5.27.0 #5121

Bug: [no-misused-promises] Possible false positive in 5.27.0 #5121

doberkofler commented May 31, 2022 •

edited by bradzacher

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armano2 commented May 31, 2022 •

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doberkofler commented May 31, 2022

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bradzacher commented May 31, 2022

doberkofler commented May 31, 2022

doberkofler commented May 31, 2022

bradzacher commented May 31, 2022

Bug: [no-misused-promises] Possible false positive in 5.27.0 #5121

Bug: [no-misused-promises] Possible false positive in 5.27.0 #5121

Comments

doberkofler commented May 31, 2022 • edited by bradzacher Loading

Before You File a Bug Report Please Confirm You Have Done The Following...

Playground Link

Repro Code

ESLint Config

tsconfig

Expected Result

Actual Result

Additional Info

Versions

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