Using a ** wildcard in an F# project causes Visual Studio to refuse to load the project - visual-studio

Question

I've got an F# project with several additional files stored in many nested folders, creating a complex folder structure. The compiler doesn't need to know about them: all I need to do is to have them copied into the output directory at the end of the build process.
I tried adding my files using the ** wildcard:
<ItemGroup>
    <FilesToCopyToOutput Include="additionalData\**\*.*"/>
</ItemGroup>
It works fine when running MSBuild manually from PowerShell. However, when I attempt to open my project in Visual Studio (v. 2015), I get the following error message:
Cannot open F# project . This project uses
wildcards in the item specification. Wildcards in F# projects are not
currently supported.
Similarly, a C# project with the wildcards works just fine. I guess this has something to do with the fact that the order of files in an F# project matters and using the wildcards causes a problem if a user wants to reorder the files.
However, I'm wondering if there's anything that can be done in my particular case: I don't care if the files are available in VS or not: I just want them to be copied to the output folder.

Answer 1

Using a ** wildcard in an F# project causes Visual Studio to refuse to load the project
Indeed, Visual Studio 2017 is a good choose. I have test the ** wildcard in the Visual Studio 2015 and 2017, it works fine in the Visual Studio 2017 but not in the Visual Studio 2015, got the same error as you.
Since you could not change the tech stack to use Visual Studio 2017, I would like provide a workaround for this issue, you can check if it works for you.
Since you do not care if the files are available in VS or not, you just want them to be copied to the output folder, you can use a power shell script to copy the additionalData folder to the output folder, like:
Copy-Item -Path "ThePathForAdditionalData\additionalData" -Destination "ThePathForProject\bin\Debug" -recurse -Force
Then execute this power shell script with MSBuild task after build:
<Target Name="CopyMyFiles" AfterTargets="Build">
<Message Text="Copying files..."/>
<Exec Command="C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe -NonInteractive -executionpolicy Unrestricted -command "& { .\YourCopyFiles.ps1 } "" ></Exec>
</Target>
Hope this helps.

Answer 2

I assume FilesToCopyToOutput is the name you gave to an item collection, and the question is how to stop the old F# compiler from thinking it should handle it?
I suspect what you want to do though is to treat an entire folder as content items and copy them to the output folder :
<Content Include="additionalData\**\*.*">
<CopyToOutputDirectory>Always</CopyToOutputDirectory>
</Content>
Copy Task
If you want to copy items with an MSBuild task you can use Copy. You should be able to write :
<ItemGroup>
<MyAdditionalData Include="additionalData\**\*.*" />
</ItemGroup>
<Target Name="CopyFiles">
<Copy
SourceFiles="#(MyAdditionalData)"
DestinationFolder="$(OutputPath)"
/>
</Target>
The Include attribute allows selecting multiple files that can be used as arguments to a task. Exclude is used to exclude files. You can specify a Condition attribute too, eg to run the task only for Release or Debug configuration. $(OutputPath) is one of the MSBuild properties that can be used in paths.
How to: Exclude Files from the Build shows how you can combine all those attributes to process specific items in a directory, eg:
<JPGFile
Include="Images\**\*.jpg"
Exclude = "Images\**\Version2\*.jpg"/>
This will include all files in the Images directory except those in Version2
Using Post-build events
Most people though didn't use MSBuild until the latest simplified format.
The most common way to copy files after build is to use a post-build event from the project's property pages, eg :
xcopy $(ProjectDir)additionalData\*.* $(TargetDir) /s /e
$(ProjectDir) and $(TargetDir) are replacement macros that point to the projects' folder and output folder. The list of all macros is available in Pre-build Event/Post-build Event Command Line Dialog Box.