Language server ignores SLINT_ENABLE_EXPERIMENTAL_FEATURES

[Enyium]

I'm on Windows 10 and set the environment variable SLINT_ENABLE_EXPERIMENTAL_FEATURES globally to 1. But even though I terminated and restarted VS Code, the changed keyword still gives me an error (for changed-callbacks). Running $env:SLINT_ENABLE_EXPERIMENTAL_FEATURES in the VS Code PowerShell console confirms that the value is 1. cargo run also works without problems.

It would also be nice, if there'd be a non-global project-only way of ungating the feature; if possible via the file .vscode/settings.json.

[ogoffart]

The language server doesn't ignore the SLINT_ENABLE_EXPERIMENTAL_FEATURES.
What error do you get exactly?

[Enyium]

In a component:

    changed current-item => {
        root.old-item = current-item;
    }

changed has wavy red underlining:

Change callbacks are experimental and not yet implemented in this version of Slint

I have this extension installed: https://marketplace.visualstudio.com/items?itemName=Slint.slint.

[hunger]

Did you log out and back in again? Better yet: Reboot.

In my experience just restarting an application is not enough to get fresh env vars on Windows (and most unixes for that matter).

[Enyium]

In my experience just restarting an application is not enough to get fresh env vars on Windows

In my experience, it is. It's about whether the process is a child process of another process. If it's not, it gets an up-to-date set of env vars from the OS. Only some software seems to be proactive: Directory Opus seems to read the set of env vars from the OS before starting a child process.

Did you log out and back in again? Better yet: Reboot.

In the meantime I rebooted, and the error is still there.

[ogoffart]

the slint-lsp process should be a child process of vscode.
I must admit i haven't tried Windows, but it does work on Linux.
Is there something we should do to re-read the env variables?

That said, we could make it an actual settings or enable it by default in the nightly extension.

[ogoffart]

Were you able to check why the slint-lsp process doesn't see the SLINT_ENABLE_EXPERIMENTAL_FEATURES env variable in your case?

[Enyium]

With System Informer, I detected the process of the VS Code window, then found the only child process of the subtree with slint in the name C:\Users\...\.vscode\extensions\slint.slint-1.7.2\bin\slint-lsp-x86_64-pc-windows-msvc.exe and looked at its env vars (through the process's property dialog in "Environment" tab).

There, I could see the process's env vars under the groups "Process", "User" and "System". Neither me nor ChatGPT know of a way to find out what group an env var belongs to. And since having SLINT_ENABLE_EXPERIMENTAL_FEATURES=1 defined for the system as well as for the user only displays it in the group "System" in the System Informer process property dialog, I think it simply compares the values to the system and user env vars.

Anyways, the slint....exe process does have its SLINT_ENABLE_EXPERIMENTAL_FEATURES env var set to 1, and still generates errors for changed-callbacks.

BTW: These changed-callback errors supersede other error messages since I started to use changed-callbacks in my project, deferring the other errors to build time through cargo run, and making .slint files permanently red.

[hunger]

I am pretty sure we build support for experimental features into the LSP at all times, so I fully expect the 1.7.2 LSP to support this. You could try the nightly extension, that works for me... but as I said, that should not be necessary.

I have no real idea what might be going wrong here right now :-(

[Enyium]

With the nightly extension, it works (I don't get the errors anymore). Does this mean that it's only a matter of time until it also works with the regular extension? My regular extension is at v1.7.2.

Note that I may have to edit the file (like add a space) after opening the project before the error appears.

[hunger]

The changed callback is planned to become stable in 1.8, so the next stable release will just work without the need to enable experimental features at all.