Bugs with enum (import and typing)

[loucyx]

When I import a module that has an enum and then I pass a string variable as index, with the noImplicitAny flag set to true, I get an error of implicit any in the index signature.

Examples:

This works but it has an unwanted behavior detailed in the comment:

enum Foobar {
    "foo",
    "bar"
}

var consoleFoobar = (index: string) => {
    // output is of type any. It should be number if the index is string and string if the index is number
    var output = Foobar[index];
    console.log(output);
}

This trows an error:

// a-module.ts
export enum Foobar {
    "foo",
    "bar"
}

// app.ts
import { Foobar } from "./a-module";

var consoleFoobar = (index: string) => {
    var output = Foobar[index]; // Error: Index signature of object type implicitly has an 'any' type.
    console.log(output);
}

[DanielRosenwasser]

Sounds like a dupe of #1232. You may want to look into --suppressImplicitAnyIndexErrors.

--suppressImplicitAnyIndexErrors   Suppress noImplicitAny errors for indexing objects lacking index signatures.

See:

• The wiki page on compiler options
• @danquirk's explanation/context of the issue

[loucyx]

I don't want to suppress the implicit any errors (they are useful), the thing is that enum is trowing errors and it shuldn't.

Let's say I have an enum like this: enum EnumExample { "value" }. When I write EnumExample[0] I should get a string ("value" in this case) or undefined, and when I write EnumExample["value"] I should get a number (0 in this case) or undefined. The bug is that I get an any if the enum is in the same file, and if I load the enum from a module, It trows an index error (error that doesn't trow if is in the same file).

[danquirk]

@lucasmciruzzi with the latest bits in master I see the same behavior in both scenarios (the single file and multi file case). The type of output is any and no errors are reported.

See #592 for why we give an any here.