Typing error in v3.0.0-rc1 Interface 'PoolConnection' cannot simultaneously extend types 'PoolConnection' and 'Connection'

[abentpole]

Hello, I was giving v3.0.0-rc1 a spin and noticed the following issue:

node_modules/mysql2/index.d.ts:86:18 - error TS2320: Interface 'PoolConnection' cannot simultaneously extend types 'PoolConnection' and 'Connection'.
  Named property 'execute' of types 'PoolConnection' and 'Connection' are not identical.

86 export interface PoolConnection extends mysql.PoolConnection, Connection {
                    ~~~~~~~~~~~~~~

This was noticed with Typescript version 4.5.5, though I also just tested with 4.9.3 and confirmed it occurs there too.
Edit: A note that for this to come up when the library is in use; ensure skipLibCheck isn't true.

[sidorares]

could you post a snippet of typescript code to reproduce the error @abentpole ?

[abentpole]

@sidorares Just a matter of importing the promise version of the library in a Typescript project with "skipLibCheck": false.

So to replicate it:

1. npm init
2. npm i mysql2@3.0.0-rc.1 typescript
3. npx tsc --init
4. Open tsconfig.json, go to the bottom and set "skipLibCheck" to false
5. Make a file, index.ts, with the content import * as mysql from 'mysql2/promise';
6. npx tsc and observe the error

[CComparon]

Same problem happening to me. Both with typescript": "4.7.4" and typescript": "4.9.4".

[HofmannZ]

Same issue with version 3.0.1.

[rohan-rao-qp]

Same issue with typescript version 4.9.4. For now, the only way I found to get it running was by setting skipLibCheck: true in tsconfig.

[khanfx]

So for a concrete example -

When faced with this error:

node_modules/mysql2/index.d.ts:86:18 - error TS2320: Interface 'PoolConnection' cannot simultaneously extend types 'PoolConnection' and 'Connection'.
  Named property 'unprepare' of types 'PoolConnection' and 'Connection' are not identical.

86 export interface PoolConnection extends mysql.PoolConnection, Connection {
                    ~~~~~~~~~~~~~~

The items indicated are:

From mysql2\index.d.ts:

  unprepare(sql: string): mysql.PrepareStatementInfo;

From mysql2\typings\mysql\lib\Connection.d.ts:

    unprepare(sql: string): any;

Experimented a little but unsure how to progress.

This seems to be the item over in Typescript that would make this work as specced, but clearly not being built any time soon:

microsoft/TypeScript#16936

[eschneor]

Get this issue, too, when trying to update from "mysql2": "2.3.3" to "mysql2": "3.1.2", using "typescript": "4.9.5".

Is there an ETA to get this in place? Thanks!

[oilop9000]

Same problem here!

[HofmannZ]

I don't think @sidorares is going to fix this. See #1792.

[sidorares]

I really want to fix, just don't have enough time. If anyone wants to help that would be great

[eschneor]

So, for now the solution is to stick with an old version? (before v3.0.0)

[sidorares]

So, for now the solution is to stick with an old version? (before v3.0.0)

• stay on pre v3
• "skipLibCheck": true,
• have your own local types that fix the errors
• submit a PR to fix on mysql2 side, wait it to be reviewed / merged / released

[wellwelwel]

Once the PoolConnection.d.ts has already declared extending the Connection:

declare class PoolConnection extends Connection {
    connection: Connection;
    release(): void;
}

Then it doesn't need to re extends the Connection in index.d.ts #86 like:

export interface PoolConnection extends mysql.PoolConnection, Connection {
  promise(promiseImpl?: PromiseConstructor): PromisePoolConnection;
}

So, just by removing the Connection from extends in index.d.ts, it will work:

export interface PoolConnection extends mysql.PoolConnection {
  promise(promiseImpl?: PromiseConstructor): PromisePoolConnection;
}

I cloned the 3.2.0 release and tested it in a real use, it works perfectly.

@sidorares, can I submit a PR for a change that is too small?

[sidorares]

@wellwelwel should be in npm as v3.2.1 in a minute

#1951

https://github.com/sidorares/node-mysql2/releases/tag/v3.2.1

[sidorares]

@abentpole give v3.2.1 a try and if the issue is fixed we can close it

[HofmannZ]

Does not seem to fix it:

> tsc -p .

node_modules/.pnpm/mysql2@3.2.1/node_modules/mysql2/index.d.ts:10:18 - error TS2430: Interface 'import("/Users/zinohofmann/Projects/github.com/expatfile/firestore-service/node_modules/.pnpm/mysql2@3.2.1/node_modules/mysql2/index").Connection' incorrectly extends interface 'import("/Users/zinohofmann/Projects/github.com/expatfile/firestore-service/node_modules/.pnpm/mysql2@3.2.1/node_modules/mysql2/typings/mysql/index").Connection'.
  The types returned by 'promise(...)' are incompatible between these types.
    Type 'Connection' is missing the following properties from type 'Promise<Connection>': then, catch, finally, [Symbol.toStringTag]

10 export interface Connection extends mysql.Connection {
                    ~~~~~~~~~~

node_modules/.pnpm/mysql2@3.2.1/node_modules/mysql2/index.d.ts:86:18 - error TS2430: Interface 'import("/Users/zinohofmann/Projects/github.com/expatfile/firestore-service/node_modules/.pnpm/mysql2@3.2.1/node_modules/mysql2/index").PoolConnection' incorrectly extends interface 'import("/Users/zinohofmann/Projects/github.com/expatfile/firestore-service/node_modules/.pnpm/mysql2@3.2.1/node_modules/mysql2/typings/mysql/index").PoolConnection'.
  The types returned by 'promise(...)' are incompatible between these types.
    Type 'PoolConnection' is missing the following properties from type 'Promise<Connection>': then, catch, finally, [Symbol.toStringTag]

86 export interface PoolConnection extends mysql.PoolConnection {
                    ~~~~~~~~~~~~~~

node_modules/.pnpm/mysql2@3.2.1/node_modules/mysql2/index.d.ts:90:18 - error TS2430: Interface 'Pool' incorrectly extends interface 'Connection'.
  The types returned by 'promise(...)' are incompatible between these types.
    Type 'Pool' is missing the following properties from type 'Promise<Connection>': then, catch, finally, [Symbol.toStringTag]

90 export interface Pool extends mysql.Connection {
                    ~~~~


Found 3 errors in the same file, starting at: node_modules/.pnpm/mysql2@3.2.1/node_modules/mysql2/index.d.ts:10

 ELIFECYCLE  Command failed with exit code 1.

[wellwelwel]

@HofmannZ

This error is not a part of this issue. I suggest you to look at the issue #1936.
The PR #1949 is who is causing this error and was merged together in 3.2.1 release 😕
Anyway, I submited a PR to fix it too in #1955.

[abentpole]

Sorry @sidorares, I missed your first ping. Gave this a test and can confirm it doesn't happen in v3.3.1.

Thanks!