microsoft / microsoft/TypeScript

Use the width of a type to add newlines in type assignment error messages

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Beschreibung

Today we ship a one-type-fits-all style for printing type is not assignable to type messages. We'd like to improve this in a pretty simple manner: by occasionally adding newlines. For example with this arbitrary comparison:

let a = { b: { c: { e: { f: 123 } } } };
let b = { b: { c: { e: { f: "123" } } } };
a = b;

Looks like this today:

src/vendor/ata/index.ts(12,1): error TS2322: Type '{ b: { c: { e: { f: string; }; }; }; }' is not assignable to type '{ b: { c: { e: { f: number; }; }; }; }'.
The types of 'b.c.e.f' are incompatible between these types.
    Type 'string' is not assignable to type 'number'.

I propose that because both of the printed types are longer than 20-30 chars, then we switch to:

src/vendor/ata/index.ts(12,1): error TS2322: Type: 
{ b: { c: { e: { f: string; }; }; }; }

is not assignable to type:
{ b: { c: { e: { f: number; }; }; }; }

The types of 'b.c.e.f' are incompatible between these types.
    Type 'string' is not assignable to type 'number'.
Key details
  • Strip the quotes around the type
  • Add colons and newlines if the type is over a certain size. Let's call it 30 characters for now, and make it easy to change and we can experiment at the final stages of review.
Some Examples
No changes
let a = 123
let b = "abc"
a = b
  • Before: src/index.ts(21,1): error TS2322: Type 'string' is not assignable to type 'number'.
  • After: src/index.ts(21,1): error TS2322: Type 'string' is not assignable to type 'number'.

No change! (Though a part of me does really want to drop the quotes for primitives)

window = {}
Type '{}' is not assignable to type 'Window & typeof globalThis'.
  Type '{}' is missing the following properties from type 'Window': clientInformation, closed, customElements, devicePixelRatio, and 189 more. (2322)

No change! {} and Window & typeof globalThis are too small.

Changing one
window = addEventListener
src/index.ts(1,1): error TS2322: Type '{ <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | ... 1 more ... | undefined): void; }' is not assignable to type 'Window & typeof globalThis'.
   Type '{ <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | ... 1 more ... | undefined): void; }' is missing the following properties from type 'Window': HTMLDocument, closed, customElements, devicePixelRatio, and 187 more.
src/vendor/ata/index.ts(12,1): error TS2322: Type: 
{ <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | ... 1 more ... | undefined): void; }

is not assignable to type:
Window & typeof globalThis

  Type '{ <K extends keyof WindowEventMap>(type: K, listener: (this: Window, ev: WindowEventMap[K]) => any, options?: boolean | AddEventListenerOptions | undefined): void; (type: string, listener: EventListenerOrEventListenerObject, options?: boolean | ... 1 more ... | undefined): void; }' is missing the following properties from type 'Window': HTMLDocument, closed, customElements, devicePixelRatio, and 187 more.
Changing both
Animation = AnalyserNode
index.ts(12,1) Type '{ new (context: BaseAudioContext, options?: AnalyserOptions | undefined): AnalyserNode; prototype: AnalyserNode; }' is not assignable to type '{ new (effect?: AnimationEffect | null | undefined, timeline?: AnimationTimeline | null | undefined): Animation; prototype: Animation; }'.
  Types of property 'prototype' are incompatible.
    Type 'AnalyserNode' is missing the following properties from type 'Animation': currentTime, effect, finished, id, and 18 more.
index.ts(12,1) Type:
{ new (context: BaseAudioContext, options?: AnalyserOptions | undefined): AnalyserNode; prototype: AnalyserNode; }

is not assignable to type:
{ new (effect?: AnimationEffect | null | undefined, timeline?: AnimationTimeline | null | undefined): Animation; prototype: Animation; }

  Types of property 'prototype' are incompatible.
    Type 'AnalyserNode' is missing the following properties from type 'Animation': currentTime, effect, finished, id, and 18 more.

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  4. Öffne einen Pull Request, der die Issue-Nummer nennt.

Rechercherichtung

Das Issue enthält Beispiele für Diagnosen bei Typzuweisungen und schlägt einen konfigurierbaren Schwellenwert von 30 Zeichen vor, nennt aber keine Dateien oder Tests. Beginne damit, den Einstiegspunkt des Compilers zu finden, der TS2322-Meldungen formatiert. Als erledigt gilt die Aufgabe, wenn lange Typtexte mit den angeforderten Doppelpunkten und Zeilenumbrüchen aufgeteilt werden, während die kurzen Beispiele unverändert bleiben.

Vom Indexierungsmodell aus dem Issue-Text verfasst.

Bewertung

Tech-Stack
typescript
Bereich
compilers
Issue-Typ
Feature
Schwierigkeit
4/5
Geschätzter Aufwand
3-5 Tage
Aktivitätsstatus
Veraltet
Klarheit
Größtenteils klar
Anfängerfreundlichkeit
38/100

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