microsoft / microsoft/TypeScript
Constants + Generic causing TS4023 ("but cannot be named")
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@weswigham is already working on this.
Since Apr 13, 2020.
Needs Investigation
Rescheduled
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Description
TypeScript Version: 3.8, but also the 3.9 beta
Search Terms: ts4023 cannot be named constant
Code
Create a tsconfig with declaration: true. Then, in main.ts:
import {StructType} from './lib';
declare function foo<T>(): T;
export const exportedFooFunc = foo<StructType>();
In lib.ts:
export const SOME_CONSTANT = 'fieldKey';
export type MakeStruct<S> = S;
export type StructType = MakeStruct<{
readonly [SOME_CONSTANT]: any;
}>;
Old instructions (don't repro anymore)
Create a tsconfig with declaration: true. Then, in main.ts:
import {
ReturnType1,
ReturnType2,
} from './lib';
export const impl1 = (): ReturnType1 => ({
});
export const impl2 = (): ReturnType2 => ({
});
In lib.ts:
export const SOME_CONSTANT = 'myConstant';
export type WrapType<S> = S;
export type ReturnType1 = WrapType<{
[SOME_CONSTANT]?: {};
}>;
export type ReturnType2 = {
[SOME_CONSTANT]?: {};
};
Expected behavior:
The file should be properly compiled.
Actual behavior:
TypeScript reports a diagnostic:
Exported variable 'exportedFooFunc' has or is using name 'SOME_CONSTANT' from external module "/.../lib" but cannot be named.
Playground Link: n/a
Related Issues: n/a
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