[tzs]

Generally, the way app stores work is that the developer uploads a copy of the app to the app store, and then the app store makes and distributes copies of that for people that request the app.

Note that since it is the app store making those copies for end users, the app store needs permission of the copyright owner to do so. There will be something in the agreement between the app developer and the app store that says that the developer grants such permission when the developer submits the app.

For app code whose copyright is actually owned by the developer, that's all that is necessary. The developer is able to grant all the necessary permissions to the app store.

If the app contains code that the developer does not own, then the app store also needs permission from the owner of that code in order to make and distribute copies of the app.

Consider a developer who includes someone else's GPL code in their app. To be able to make and distribute copies of it, the app store is going to have to obey GPL.

Most app stores require downloaders to agree to a license agreement with the app store, which typically includes things like prohibiting reverse engineering and prohibiting reselling or making and distributing copies.

GPL, however, prohibits such restrictions. If you impose such restrictions, GPL does not give you copyright permission to make and distribute copies. This makes the app store license and GPL incompatible, and so the software cannot be distributed on the store.

[amluto]

IMO this is pure laziness on the part of the app store. Any store could just say “this app is licensed to you under the GPL — download source here.”

Even ignoring licensing, I think app stores could add considerable value by offering reproducible builds. Let developers upload source, verify the has (git tree hash or plain sha256sum), and rebuild in a sandbox server-side. Reject the submission unless the binary’s hash matches the developer’s.

Now stick a badge on it: “verified open-source build”. And give it a small bonus in ranking relative to other apps.

[toohotatopic]

Adding that license information doesn't help the end user to run modified code. You need an apple developer license to run changes that you have made. Thus, the code is not free.

On the other hand, apple offering to compile and run any modification that users made will never happen. Then, people could start with one program and run whatever they want. The app store would collapse.

[amluto]

That doesn’t contradict my point. Apple could achieve two goals here:

1. Allowing GPL code in a lightweight and compliant manner at a essentially no cost to Apple.

2. Adding a class of free (or paid) open-source apps that are more trustworthy. If Apple could effectively replace a decent fraction of the free shitware apps on the App Store with better free, open-source apps, the value to end-users and hence the value of the platform would increase.

There is no requirement in the GPL that recipients of source code be able to run modified versions of the code on the target device.

[saagarjha]

> Most app stores require downloaders to agree to a license agreement with the app store, which typically includes things like prohibiting reverse engineering and prohibiting reselling or making and distributing copies.

Apple’s (https://www.apple.com/legal/internet-services/itunes/dev/std...) actually has a very interesting clause that seems like you can discard their EULA and substitute your own (with some minimal restrictions pertaining to making sure that you don’t bring Apple into it and comply with warranty laws and such):

> Your license to each App is subject to your prior acceptance of either this Licensed Application End User License Agreement (“Standard EULA”), or a custom end user license agreement between you and the Application Provider (“Custom EULA”), if one is provided.

So can you just substitute one that grants your users the GPL freedoms?