Design-time builds should not lock tasks coming from packages

From @jasonwilliams200OK on March 8, 2016 9:11

Steps to Reproduce:

1. Open a project in VS2015 which has dependency on Microsoft.Bcl.Build.Tasks.dll.
2. Build the project and keep the project opened.
3. While the project is still opened in VS after the build, open cmd and cd into the solution directory and run rmdir /s/q packages (or PowerShell’s rm -r -fo packages).
   • Alternatively, if the project is under git SC, run git clean -xdf command in cmd/ps, everything which is not under source control gets deleted, except for Microsoft.Bcl.Build.Tasks.dll.

Expected Behavior: packages folder gets deleted. VS should release the handle to resource in user space, when there is no user-driven operation going on.

Actual Behavior: packages\Microsoft.Bcl.Build.1.0.21\build\Microsoft.Bcl.Build.Tasks.dll - Access is denied. VS2015 does not release handle to this particular file unless we close the solution and kill devenv and wait for like 20 extra seconds before user gets a chance to remove the packages folder.

Copied from original issue: dotnet/roslyn#9554

[davkean]

This won’t be backported to VS14. CPS is the “Common Project System”, the base infrastructure that we’re building the new project system on.

The new project system hasn’t been turned on in VS15 yet - so there’s nothing to verify yet - here’s our roadmap of when it will be enabled: https://github.com/dotnet/roslyn-project-system/blob/master/docs/Roadmap.md

[davkean]

I’m going to mark this as completed - there’s really no other work that we plan on doing around this. C#/VB CPS-based projects perform out-of-proc design-time and official builds - devenv.exe will no longer lock tasks when using those project types.

The legacy project system still performs design-time builds in-proc, and still suffers from this problem - there are no plans to change that design. In a future Visual Studio version, all C#/VB project types will replaced by the new project system, see the roadmap: https://github.com/dotnet/roslyn-project-system/blob/master/docs/repo/roadmap.md.