typescript transform confused about types and values with the same name

Bug Report

Current Behavior

babel is confused about a duplicate declaration when a type is imported and a value with the same name is declared locally. See code below.

Input Code

The following code results in a “Duplicate declaration” error, but is accepted by TypeScript (the compiler). It’s because the SomeThing import is a type (for example export interface SomeThing{}), whereas the local const declaration is a value, so the two are not actually in any conflict.

import { SomeThing } from './module';
const SomeThing = 1;

Expected behavior/code

The babel typescript transform should accept the same code as the typescript compiler.

Babel Configuration (.babelrc, package.json, cli command)

module.exports = {
  presets: [
    "next/babel",
    "@zeit/next-typescript/babel"
  ],
  plugins: [
    ["react-intl", { messagesDir: "./locale/en/messages/" }],
    ["emotion", { inline: true, autoLabel: true }],
    ["transform-define", require("./env.js")]
  ]
};

Environment

• Babel version(s): @babel/plugin-syntax-typescript@7.0.0-beta.47

[dollysingh3192]

Facing similar issue and posted on Stack Overflow as well with minimal reproduction on Github repo:

https://stackoverflow.com/questions/64323473/typeerror-duplicate-declaration-module-build-failed-error-in-typescript-projec

Any plans on this issue to be fix in near future?

[loganfsmyth]

@andy-ms Any thoughts on this? To me it seems like a place where we’d accept that Babel behaves differently from TS because TS overrode the standard spec behavior.