Allow missing baseUrl for TS 4.1+

[jakebailey]

TypeScript 4.1+ support paths without baseUrl. See:

• https://devblogs.microsoft.com/typescript/announcing-typescript-4-1-beta/
• Allow 'paths' without 'baseUrl' microsoft/TypeScript#40101

Effectively, the paths become relative to the tsconfig.json file.

I'm testing a project with the new beta and baseUrl removed to get better auto-completion, but it appears this library (which is used by tsconfig-paths-webpack-plugin) requires baseUrl to be specified. I've even tried in the plugin to override baseUrl with . (which is pretty much what TS does), but since the plugin loads the config using this library and this library throws an error, the plugin doesn't get to the point where it could override the config.

Perhaps if the config has no baseUrl, it could be treated as a baseUrl of '.'? Or, change the result to allow undefined locations (and update the plugin)?

2022 EDIT: since it's been a long time and this hasn't been fixed, I had written my own little function to do everything needed for path mapping: https://github.com/microsoft/pyright/blob/169c6089b9914870c43622743c75844657cd9d70/build/lib/webpack.js#L90

[jakebailey]

TS 4.1 has been released, with the implicit baseUrl. I've worked around it for now by using a second duplicate config file with baseUrl set.

[aleclarson]

If anyone stumbles on this and wants to help, please provide a minimal reproduction of tsconfig-paths failing when baseUrl is undefined. Thanks!

[marvinroger]

Hi @aleclarson, thanks for taking a look at this issue.

There you go: https://github.com/marvinroger/tsconfig-paths-baseurl-reproduction

[aleclarson]

@marvinroger #208