main.ts(2,21): error TS2307: Cannot find module 'external' or its corresponding type declarations.


==== external.d.ts (0 errors) ====
    export var x: number
    
==== main.ts (1 errors) ====
    declare module "M" {
        import {x} from "external"
                        ~~~~~~~~~~
!!! error TS2307: Cannot find module 'external' or its corresponding type declarations.
    }