3.0.0-rc: type error

[sgratzl]

Expected Behavior

I'm trying to bundle my typings using https://github.com/Swatinem/rollup-plugin-dts. However, it fails with the following error:

chart.js/dist/chunks/index.esm.d.ts(1476,14): error TS4025: Exported variable 'Scale' has or is using private name 'Scale'.

see also https://github.com/sgratzl/chartjs-chart-boxplot/runs/2155166769?check_suite_focus=true

Current Behavior

Possible Solution

make sure that all the used types are properly exported

Steps to Reproduce

see https://github.com/sgratzl/chartjs-chart-boxplot/runs/2155166769?check_suite_focus=true

Context

Environment

• Chart.js version: 3.0.0-rc
• Browser name and version:
• Link to your project: https://github.com/sgratzl/chartjs-chart-boxplot/runs/2155166769?check_suite_focus=true

[kurkle]

I'm not sure what would be the error here. Maybe you need to re-export the Scale interface?

Chart.js/types/index.esm.d.ts

Line 1152 in 81342d6

export interface Scale<O extends CoreScaleOptions = CoreScaleOptions> extends Element<{}, O>, LayoutItem {

[etimberg]

The problem here seems to be how the scale gets exported after the build. We use this pattern of declaration merging to define the constructor for the objects that need it. My guess is that once built, the declaration merging is broken.

Src Types

export interface Scale<O extends CoreScaleOptions = CoreScaleOptions> extends Element<{}, O>, LayoutItem {
  ....
}
export const Scale: {
  prototype: Scale;
  new <O extends CoreScaleOptions = CoreScaleOptions>(cfg: AnyObject): Scale<O>;
};

Built Types

interface Scale<O extends CoreScaleOptions = CoreScaleOptions> extends Element<{}, O>, LayoutItem {
  ...
}
declare const Scale: {
  prototype: Scale;
  new <O extends CoreScaleOptions = CoreScaleOptions>(cfg: AnyObject): Scale<O>;
};

[etimberg]

https://stackoverflow.com/questions/66135714/typescript-type-definitions-how-to-declare-class-constructors indicates that one way to handle this would be to use declare class instead of the interface style, but I'm not sure we can write the Scale definition that way since it implements Element and LayoutItem