Both options for creating .NET 6 WinForms builds have serious show stoppers

[TangibleDave]

I would prefer to create a single-file self-contained install for a WinForms application using .NET 6. However, the removal of trimming in .NET 6 for WinForms applications means that the size of the install is impractical (>100MB - that's just insane for our utilities). With trimming in .NET 5, the size was large, but acceptable.

The "framework-dependent" option is also not practical due to the critical error message (red 'x', etc.) that comes up if .NET 6 is not already installed. This will always scare off a certain percentage of users.

I would like either:

1. trimming restored for WinForms applications in .NET 6 (it worked fine in .NET 5)
   or:
2. the critical error message for installing .NET 6 reworked to something less scary for less sophisticated users

As it is, there is no way I can publish .NET 6 versions of our utilities.

[RussKie]

There're other options too, e.g. https://github.com/Tyrrrz/DotnetRuntimeBootstrapper.

The trimming is not currently supported for Windows Desktop apps due to an extensive dependence on COM and reflection, which are not trim-safe (dotnet/winforms#4649). And if it worked it would be "accidental" (https://twitter.com/andygocke/status/1455320377387732994).
I raised an issue for the docs to be updated to reflect the current state dotnet/docs#27274.

AFAIK this is being worked on, and if all goes well desktop apps may be trimmable in .NET 7.

Moving to the SDK to consider the error message feedback.

[TangibleDave]

DotnetRuntimeBootstrapper looks promising, but it adds another reliance on a third party tool (with its unknown security risks and unpredictable support).

[sfoslund]

@baronfel do you have any thoughts on the critical error message feedback?

[baronfel]

For posterity, here's a snap of what the missing-runtime error looks like on Windows 11 when you run a framework-dependent winforms app (and presumably any framework-dependent app?):

If you click 'yes' there, you get dropped on this page:

I've been using .NET (Core) since it released, and I don't know what the correct answer is in that case. I'm guessing the 'desktop' runtime here, but end users who get this message box aren't going to know that. I definitely think there's room for improvement here, but I'm not sure who owns each part of that experience.

[TangibleDave]

I can't see how that's acceptable - if I try to install a Java application and don't have Java installed I don't think it's this ugly.

[RussKie]

IIRC (it's been a while) but if a user lacked a specific .NET Framework version (e.g. 3.5) by clicking "Yes" we'd start a download of NETFx 3.5 runtime. Perhaps we could somehow do the same - we do know what OS and bitness an app is being run on (e.g. Window 10, arm64) and what SDK the app is targeting (e.g. a Console or Windows Desktop), and we could deduce a download link from this information.

[baronfel]

Perhaps we could somehow do the same - we do know what OS and bitness an app is being run on (e.g. Window 10, arm64) and what SDK the app is targeting (e.g. a Console or Windows Desktop), and we could deduce a download link from this information.

That would be great to get back to that experience. This is a apphost-level thing (see the error dialog code here), so tagging @richlander for input here.

[kant2002]

AFAIK this is being worked on, and if all goes well desktop apps may be trimmable in .NET 7.

@RussKie who is this lovely person whom I should send infinite hugs? Just want to track progress if possible.

[nicko88]

AFAIK this is being worked on, and if all goes well desktop apps may be trimmable in .NET 7.

Any progress on this with .NET 7 Preview 1 released recently?

I am also still using .NET 5 because it works to trim my WinForms app and is way smaller (like 3x smaller) than compiled with .NET 6.