Stuck on an issue?

Lightrun Answers was designed to reduce the constant googling that comes with debugging 3rd party libraries. It collects links to all the places you might be looking at while hunting down a tough bug.

And, if you’re still stuck at the end, we’re happy to hop on a call to see how we can help out.

Error: Type cannot be used to index type after two indexes

See original GitHub issue

TypeScript Version: 2.7.1, 2.8.0-dev.20180208

Search Terms: Type cannot be used to index type

Code

interface IExample {
    foo: {
        bar: {
            baz: number;
        }
    }
}

type F = <
    name extends keyof IExample,
    val extends keyof IExample[name]
>() => IExample[name][val]['baz']; // ← Type '"baz"' cannot be used to index type 'IExample[name][val]'.

Expected behavior: In version 2.7.0-dev.20171115 this code was checking without errors.

Actual behavior: Now in throws error: Type ‘“baz”’ cannot be used to index type ‘IExample[name][val]’.

Playground Link: https://www.typescriptlang.org/play/index.html#src=interface IExample { foo%3A { bar%3A { baz%3A number%3B } } } type F %3D < name extends keyof IExample%2C val extends keyof IExample[name] >() %3D> IExample[name][val][‘baz’]%3B

Issue Analytics

State:
Created 6 years ago
Reactions:19
Comments:12 (4 by maintainers)

Top GitHub Comments

17reactions

wycatscommented, Apr 15, 2018

Actually, it’s really weird! I’m getting type errors, but TS is getting the derived type right anyway!

10reactions

moretolikecommented, Nov 29, 2018

ERROR in node_modules/@amcharts/amcharts4/.internal/charts/types/XYChart.d.ts(258,33): error TS2344: Type ‘this[“_xAxisRendererType”]’ does not satisfy the constraint ‘AxisRenderer’. Type ‘AxisRendererX’ is not assignable to type ‘AxisRenderer’. Types of property ‘events’ are incompatible. Type ‘SpriteEventDispatcher<AMEvent<AxisRendererX, IAxisRendererXEvents>>’ is not assignable to type ‘SpriteEventDispatcher<AMEvent<this[“_xAxisRendererType”], this[“_xAxisRendererType”][“_events”]>>’. Type ‘AMEvent<AxisRendererX, IAxisRendererXEvents>’ is not assignable to type ‘AMEvent<this[“_xAxisRendererType”], this[“_xAxisRendererType”][“_events”]>’. node_modules/@amcharts/amcharts4/.internal/charts/types/XYChart.d.ts(264,33): error TS2344: Type ‘this[“_yAxisRendererType”]’ does not satisfy the constraint ‘AxisRenderer’. Type ‘AxisRendererY’ is not assignable to type ‘AxisRenderer’. Types of property ‘events’ are incompatible. Type ‘SpriteEventDispatcher<AMEvent<AxisRendererY, IAxisRendererYEvents>>’ is not assignable to type ‘SpriteEventDispatcher<AMEvent<this[“_yAxisRendererType”], this[“_yAxisRendererType”][“_events”]>>’. Type ‘AMEvent<AxisRendererY, IAxisRendererYEvents>’ is not assignable to type ‘AMEvent<this[“_yAxisRendererType”], this[“_yAxisRendererType”][“_events”]>’. node_modules/@amcharts/amcharts4/.internal/charts/types/XYChart.d.ts(503,31): error TS2344: Type ‘this[“_xAxisRendererType”]’ does not satisfy the constraint ‘AxisRenderer’. node_modules/@amcharts/amcharts4/.internal/charts/types/XYChart.d.ts(513,31): error TS2344: Type ‘this[“_yAxisRendererType”]’ does not satisfy the constraint ‘AxisRenderer’. node_modules/@amcharts/amcharts4/.internal/core/utils/Object.d.ts(60,117): error TS2536: Type ‘Key’ cannot be used to index type ‘Object’. node_modules/@amcharts/amcharts4/.internal/core/utils/Object.d.ts(67,109): error TS2536: Type ‘Key’ cannot be used to index type ‘Object’. node_modules/@amcharts/amcharts4/.internal/core/utils/Object.d.ts(76,116): error TS2536: Type ‘Key’ cannot be used to index type ‘Object’. node_modules/@amcharts/amcharts4/.internal/core/utils/Type.d.ts(25,32): error TS2304: Cannot find name ‘Extract’.

Please… Help Me…