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Type 'any[]' is not assignable to type '[any, any]' when constructing a Map from array of entries #22870
Description
During my work at webpack/webpack#6862 I noticed this error.
TypeScript Version: 2.7.8-rc
Search Terms:
Code
https://github.com/webpack/webpack/blob/master/lib/util/objectToMap.js
function objectToMap(obj) {
return new Map(Object.keys(obj).map(key => [key, obj[key]]));
};Expected behavior:
No error
Actual behavior:
lib/util/objectToMap.js:9:17 - error TS2345: Argument of type 'any[][]' is not assignable to parameter of type 'Iterable<[any, any]>'.
Types of property '[Symbol.iterator]' are incompatible.
Type '() => IterableIterator<any[]>' is not assignable to type '() => Iterator<[any, any]>'.
Type 'IterableIterator<any[]>' is not assignable to type 'Iterator<[any, any]>'.
Types of property 'next' are incompatible.
Type '{ (value?: any): IteratorResult<any[]>; (value?: any): IteratorResult<any[]>; }' is not assignable to type '{ (value?: any): IteratorResult<[any, any]>; (value?: any): IteratorResult<[any, any]>; }'.
Type 'IteratorResult<any[]>' is not assignable to type 'IteratorResult<[any, any]>'.
Type 'any[]' is not assignable to type '[any, any]'.
Property '0' is missing in type 'any[]'.
9 return new Map(Object.keys(obj).map(key => [key, obj[key]]));
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Activity
DanielRosenwasser commentedon Mar 26, 2018
I think this looks like a duplicate of #11152.
MartinJohns commentedon Mar 26, 2018
The tuple is inferred to be an array. As a temporary workaround you can just specify the exact type when calling
map:That will make it explicit that you want a tuple.
mhegazy commentedon Mar 26, 2018
in a .js file you can cast using
/** @type ... */:typescript-bot commentedon Apr 10, 2018
Automatically closing this issue for housekeeping purposes. The issue labels indicate that it is unactionable at the moment or has already been addressed.