require module cache should do case-insensitive lookups on case-insensitive file systems

[mnaoumov]

• Version: v12.12.0 (also tried v10.16.3)
• Platform: Windows x64
• Subsystem: module

Windows is using case-insensitive file systems. So essentially myModule.js and MYMODULE.JS are the same files.

Node.JS require is using caching so if you are trying to resolve a module the second time you are getting the same instance of it.

But this cache is case-sensitive so we are getting

require('myModule') === require('myModule');
require('myModule') !== require('MYMODULE');

You may say, that it is by design but I found an important usecase that you should consider.

There are situations when __dirname and process.cwd() are the same but with different cases. So child dependencies would be loaded independently without caching and that can introduce very weird and difficult to identify issues.

I've prepared a demo gist to show the problem

For more details, see my blogpost

[devsnek]

Duplicate of #14019

[mnaoumov]

@devsnek excuse me, but it is not exactly a duplicate. That issue doesn't have a word about caching. Node successfully resolves both modules but treats them as different

[mnaoumov]

@devsnek excuse me, with more accurate searching I found a note in the documentation https://nodejs.org/api/modules.html#modules_module_caching_caveats