chunkFileNames needs to be case sensitive

[shirotech]

• Rollup Version: 1.21.4
• Operating System (or Browser): Mac
• Node Version: v10.16.3

How Do We Reproduce?

config
chunkFileNames: '[name].js',

Expected Behavior

It is expected to generate name which is case sensitive.

Actual Behavior

It is generating Date.js and date.js the same as date.js and it confuses the bundle.

[lukastaegert]

Not sure I understand you correctly. At the moment the names ARE case sensitive in that Date and date are different. You are meaning to say we should make it case-insensitive, i.e. if Date.js and date.js end up next to each other, we deconflict one of them?

[shirotech]

No, I meant that for example Date.js and date.js gets combined to date.js for some reason, so currently, it is insensitive. We need it to make it sensitive for all cases. I'm not exactly sure what causes this case-insensitivity, but when I remove the option chunkFileNames it works fine.

[lukastaegert]

As you are on a Mac, I would assume you are on a case-insensitive file system as this is the default. That means that when there is a file on the disk named date.js and you store a file named Date.js, then that will replace the existing file. My guess is that it is not Rollup that is replacing the file but your operating system. The reason is that Rollup is, as far as I know, case-sensitive, which means that it thinks date.js and Date.js are different file names and there is no reason to change one of the names before writing to disk (you could check by inspecting the bundle passed to the generateBundle hook if it has separate entries for the two files). The only people for whom this would be the correct choice, though, would be Linux users and some Mac users that specifically chose a case-sensitive file system, so case-insensitive deduplication by default would definitely be the prudent choice.

[yesmeck]

@lukastaegert Consider we have two virtual modules named \0date.js and \0Date.js, rollup treats these two modules are different, then writing them to _virtual/_date.js and _virtual/_Date.js, and on a case-insensitive OS，the later _virtual/_Date.js will override _virtual/_date.js.

I'm trying to fix this issue #3317, but don't know why CI are failed, could you have a look.