Support Single-file executable in Windows 7

[NN---]

Windows 7 doesn't have WinRT API set, making it delay loaded allows running single file executable in Windows 7.
dotnet/sdk#23177

.NET code already performs late binding in utils.cpp and in mscoree CMakeLists.txt .
But not for singlefilehost.exe

The final change should be backported since .NET 6 is the latest LTS version.

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Issue Details

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Windows 7 doesn't have WinRT API set, making it delay loaded allows running single file executable in Windows 7.
dotnet/sdk#23177

.NET code already performs late binding in utils.cpp and in mscoree CMakeLists.txt .
But not for singlefilehost.exe

Author:	NN---
Assignees:	-
Labels:	area-Single-File, community-contribution
Milestone:	-

[NN---]

@jkoritzinsky Is there anything preventing this PR to be merged ? Is it possible to backport it to .NET 6 ?

[vitek-karas]

@VSadov could you please review this as well?

My main concern is if this is enough. The single-file superhost statically links several other native libs from the runtime, do any of those have a similar problem?

[NN---]

Comparing .NET 5 and .NET 6 single file output, the API set WinRT is the only difference as far as I have seen.
Of course in order to build a single file with Windows 7 runtime identifier I had to remove the RID check in the .NET SDK.

I couldn't figure why the same code doesn't make a statically loaded API set in previous versions.
The code calling RoInitialize in threads.cpp hasn't been changed for years.

[VSadov]

The change looks good. I just need to try the end-to-end scenario with an app running on actual Windows7.

[VSadov]

I have verified that with this fix singlefile apps run on Windows7 SP1

I've tried:

• default console app
• default wpf app
• default wpf app with IncludeNativeLibrariesForSelfExtract

[VSadov]

BTW. The OS image that I used is fairly minimal, but it looks like it has UCRT (i.e. ucrtbse.dll is present). It was likely installed with some of the updates.

Since UCRT is not a part of OS, it might need to be documented as a requirement on Win7. It is still better than not running at all.

[VSadov]

@NN--- : Thanks!!!

[NN---]

Great news!
Can you backport it to .NET 6?
Should I open PR for it?

There is also a small issue with .NET SDK as I mentioned.
The targets file preventing build for Windows 7 RID.
I proposed replacing error with warning, probably better to not show anything and declare single file for Windows 7 as supported.
What do you think ?

[VSadov]

Can you backport it to .NET 6?
Should I open PR for it?

There is a bit more process for servicing changes to LTS branch. That is intentional to ensure it is stable.
I will follow up with backporting once we see no issues in main.

We will get to the error/warning too.
Thanks for making this change!

[NN---]

I opened relevant PRs for SDK and 6.0 branch. Without SDK fix, the publishing still fails.
It would be wonderful to have single-file support back in .NET 6 LTS.
My assumption is that not only me who needs this useful feature.

[NN---]

BTW. The OS image that I used is fairly minimal, but it looks like it has UCRT (i.e. ucrtbse.dll is present). It was likely installed with some of the updates.

.NET already requires Windows 7 SP1.