From 9dfaa6363938a7ed9f1ec2c151dc5edc2a2d0177 Mon Sep 17 00:00:00 2001
From: Jacco van den Berg <jaccoberg2281@gmail.com>
Date: Thu, 4 Aug 2022 01:06:15 +0200
Subject: [PATCH] Move parameter of TType in ChartMeta to first option (#10550)

* move paramter of TType in ChartMeta to first option

* add missing ChartMeta change

* Add note in migration guide
---
 docs/migration/v4-migration.md                 |  3 +++
 types/index.esm.d.ts                           | 14 ++++++--------
 types/tests/controllers/doughnut_meta_total.ts |  2 +-
 3 files changed, 10 insertions(+), 9 deletions(-)

diff --git a/docs/migration/v4-migration.md b/docs/migration/v4-migration.md
index 71810e91f..252488ca8 100644
--- a/docs/migration/v4-migration.md
+++ b/docs/migration/v4-migration.md
@@ -11,3 +11,6 @@ A number of changes were made to the configuration options passed to the `Chart`
 #### Specific changes
 
 * The radialLinear grid indexable and scriptable options don't decrease the index of the specified grid line anymore.
+
+#### Type changes
+* The order of the `ChartMeta` parameters have been changed from `<Element, DatasetElement, Type>` to `<Type, Element, DatasetElement>`
diff --git a/types/index.esm.d.ts b/types/index.esm.d.ts
index 4284e2d10..cf2dcb1c0 100644
--- a/types/index.esm.d.ts
+++ b/types/index.esm.d.ts
@@ -458,11 +458,9 @@ interface ChartMetaCommon<TElement extends Element = Element, TDatasetElement ex
 }
 
 export type ChartMeta<
+  TType extends ChartType = ChartType,
   TElement extends Element = Element,
   TDatasetElement extends Element = Element,
-  // TODO - V4, move this to the first parameter.
-  // When this was introduced, doing so was a breaking change
-  TType extends ChartType = ChartType,
 > = DeepPartial<
 { [key in ChartType]: ChartTypeRegistry[key]['metaExtensions'] }[TType]
 > & ChartMetaCommon<TElement, TDatasetElement>;
@@ -580,7 +578,7 @@ export class DatasetController<
 
   readonly chart: Chart;
   readonly index: number;
-  readonly _cachedMeta: ChartMeta<TElement, TDatasetElement, TType>;
+  readonly _cachedMeta: ChartMeta<TType, TElement, TDatasetElement>;
   enableOptionSharing: boolean;
   // If true, the controller supports the decimation
   // plugin. Defaults to `false` for all controllers
@@ -597,7 +595,7 @@ export class DatasetController<
   draw(): void;
   reset(): void;
   getDataset(): ChartDataset;
-  getMeta(): ChartMeta<TElement, TDatasetElement, TType>;
+  getMeta(): ChartMeta<TType, TElement, TDatasetElement>;
   getScaleForId(scaleID: string): Scale | undefined;
   configure(): void;
   initialize(): void;
@@ -633,9 +631,9 @@ export class DatasetController<
   setHoverStyle(element: TElement, datasetIndex: number, index: number): void;
 
   parse(start: number, count: number): void;
-  protected parsePrimitiveData(meta: ChartMeta<TElement, TDatasetElement, TType>, data: AnyObject[], start: number, count: number): AnyObject[];
-  protected parseArrayData(meta: ChartMeta<TElement, TDatasetElement, TType>, data: AnyObject[], start: number, count: number): AnyObject[];
-  protected parseObjectData(meta: ChartMeta<TElement, TDatasetElement, TType>, data: AnyObject[], start: number, count: number): AnyObject[];
+  protected parsePrimitiveData(meta: ChartMeta<TType, TElement, TDatasetElement>, data: AnyObject[], start: number, count: number): AnyObject[];
+  protected parseArrayData(meta: ChartMeta<TType, TElement, TDatasetElement>, data: AnyObject[], start: number, count: number): AnyObject[];
+  protected parseObjectData(meta: ChartMeta<TType, TElement, TDatasetElement>, data: AnyObject[], start: number, count: number): AnyObject[];
   protected getParsed(index: number): TParsedData;
   protected applyStack(scale: Scale, parsed: unknown[]): number;
   protected updateRangeFromParsed(
diff --git a/types/tests/controllers/doughnut_meta_total.ts b/types/tests/controllers/doughnut_meta_total.ts
index 5a57295ce..da94fa0d8 100644
--- a/types/tests/controllers/doughnut_meta_total.ts
+++ b/types/tests/controllers/doughnut_meta_total.ts
@@ -12,5 +12,5 @@ const chart = new Chart('id', {
 
 // A cast is required because the exact type of ChartMeta will vary with
 // mixed charts
-const meta = <ChartMeta<Element, Element, 'doughnut'>>chart.getDatasetMeta(0);
+const meta = <ChartMeta<'doughnut', Element, Element>>chart.getDatasetMeta(0);
 const total = meta.total;
-- 
2.47.3