Sequelize v6.x.x model definition by extending Model class with TypeScript v5.x.x issue

Issue Creation Checklist

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Bug Description

Sequelize v6 model definition by extending Model class using TypeScript v5.x.x results in tsc compilation errors:

1. Method 'set' in class 'X' is not assignable to the same method in base 'Model'
2. Method 'setAttributes' in class 'X' is not assignable to the same method in base 'Model'

where class X is model being defined using inheritance.

Same tsc compilation errors occur when using the sequelize-typescript v2.x.x and TypeScript v5.x.x..

Warnings are raised when using Sequelize v7.x.x and TypeScript v5.x.x.

Reproducible Example

Here is the link to the SSCCE for this issue: https://github.com/oglisa-dev/sequelize-typescript-v5-issue-sscce

What do you expect to happen?

Arbitrary model X should be defined by extending Model class without any tsc compilation errors when using Sequelize v6.x.x and TypeScript v5.x.x.

Arbitrary model X should be defined by extending Model class using sequelize-typescript without any tsc compilation errors when using sequelize-typescript v2.x.x and TypeScript v5.x.x.

Arbitrary model X should be defined by extending Model class without any warnings when using Sequelize v7.x.x and TypeScript v5.x.x.

What is actually happening?

// using sequelize v6
import { DataTypes, Model, Sequelize } from "sequelize";

// ts errors:
// Method 'set' in class 'User' is not assignable to the same method in base 'Model'
// Method 'setAttributes' in class 'User' is not assignable to the same method in base 'Model'
export class User extends Model {
  declare firstname: string;
  declare lastname: string;
}

// using sequelize-typescript v2
import { Table, Column, Model } from 'sequelize-typescript';

// ts errors
// Method 'set' in class 'Person' is not assignable to the same method in base 'Model'
// Method 'setAttributes' in class 'Person' is not assignable to the same method in base 'Model'
@Table
export class Person extends Model {
  @Column
  firstname: string;

  @Column
  lastname: Date;
}

// using sequelize v7
import {CreationOptional, DataTypes, InferAttributes, InferCreationAttributes, Model} from '@sequelize/core';
import { Attribute, PrimaryKey, AutoIncrement, NotNull } from '@sequelize/core/decorators-legacy';

// warnings (not errors)
// Method 'set' in class 'User' is not assignable to the same method in base 'Model'
// Method 'setAttributes' in class 'User' is not assignable to the same method in base 'Model'
export class User extends Model<InferAttributes<User>, InferCreationAttributes<User>> {
  @Attribute(DataTypes.INTEGER)
  @PrimaryKey
  @AutoIncrement
  declare id: CreationOptional<number>;

  @Attribute(DataTypes.STRING)
  @NotNull
  declare firstName: string;

  @Attribute(DataTypes.STRING)
  declare lastName: string | null;
}

Environment

• Sequelize version: v6.33.0
• Node.js version: v20.7.0
• TypeScript version: v5.2.2

Would you be willing to resolve this issue by submitting a Pull Request?

• Yes, I have the time and I know how to start.
• Yes, I have the time but I will need guidance.
• No, I don't have the time, but my company or I are supporting Sequelize through donations on OpenCollective.
• No, I don't have the time, and I understand that I will need to wait until someone from the community or maintainers is interested in resolving my issue.

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Start with the linked SSCCE repository and reproduce the TypeScript 5 compilation errors for the Sequelize v6 model examples. Then inspect the Model class definitions involved in set and setAttributes, comparing the v6, sequelize-typescript v2, and Sequelize v7 cases. Done means the examples compile without errors or warnings under the stated versions.