System.Environment.GetFolderPath (Environment.SpecialFolder.ApplicationData) Is the wrong path on MacOS

[Clancey]

Description

When you call the following code, it is correct on Windows and Linux, but MacOS you get the linux path
var path = System.Environment.GetFolderPath (Environment.SpecialFolder.ApplicationData)
paths actual value = ~/.config
It should be ~/Library/Application Support

Configuration

MacOS

[Dotnet-GitSync-Bot]

I couldn't figure out the best area label to add to this issue. If you have write-permissions please help me learn by adding exactly one area label.

[lewing]

The code is here

runtime/src/libraries/System.Private.CoreLib/src/System/Environment.GetFolderPathCore.Unix.cs

Line 100 in b570558

case SpecialFolder.ApplicationData:

and there are OSX specific overrides for other folders.

[danmoseley]

Thanks @Clancey . Does ~./config have any plausible meaning on Mac, ie what is the chance a change would break apps?

I assume LocalApplicationData needs a change also?

[Clancey]

A change shouldn't break existing apps. It would just treat it as a fresh install since the user folder location would change.

[Clancey]

There are 2 folders on MacOS, /Library/Application Support/ and ~/Library/Application Support. Global vs User. Not sure which should map where.

[migueldeicaza]

.config is an XDG-istm, which is a Linux-only thing. MacOS predates XDG.

[SingleAccretion]

@Clancey If you want to do this in a backwards-compatible manner (aka the only feasible way), you would need to propose some new API and obsolete/hide the old one. For example, there could be a new overload of Environment.GetFolderPath() with a new enum argument (CrossPlatSpecialFolder) and a new behavior that would be "correct". This would be necessary because adding new members to SpecialFolder is also a breaking change (arguably even more breaking than the change of the macOS folder). This of course runs into problems of API duplication vs API obsoletion and all the headaches that causes, so I could see this actually being less desirable than the current behavior given how widely used the API in question is.