Exception at IncrementalBuild.fs Line 813: The input array was empty. (Parameter 'array')

[jcoder58]

Please provide a succinct description of the issue.

Called ParseAndCheckProject with small fs project and got exception in title

Repro steps

See attached zip file.

cd Test
dotnet run ..\Game\Game.fsproj

Expected behavior

No exception.

Actual behavior

> dotnet run ..\Game\Game.fsproj
Arguments passed to function : [|"..\Game\Game.fsproj"|] C:\UnrealEngine\Test\Test\Test
Unhandled exception. System.AggregateException: One or more errors occurred. (The input array was empty. (Parameter 'array'))
 ---> System.ArgumentException: The input array was empty. (Parameter 'array')
   at FSharp.Compiler.CodeAnalysis.IncrementalBuilderHelpers.FinalizeTypeCheckTask@752-10.Invoke(FSharpOption`1[] latestImplFiles) in D:\a\_work\1\s\src\Compiler\Service\IncrementalBuild.fs:line 758
   at FSharp.Compiler.BuildGraph.Bind@61-1.Invoke(T x) in D:\a\_work\1\s\src\Compiler\Facilities\BuildGraph.fs:line 62
   at Microsoft.FSharp.Control.AsyncPrimitives.CallThenInvokeNoHijackCheck[a,b](AsyncActivation`1 ctxt, b result1, FSharpFunc`2 userCode) in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 528
   at Microsoft.FSharp.Control.Trampoline.Execute(FSharpFunc`2 firstAction) in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 112
   --- End of inner exception stack trace ---
   at Microsoft.FSharp.Control.AsyncResult`1.Commit() in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 454
   at Microsoft.FSharp.Control.AsyncPrimitives.QueueAsyncAndWaitForResultSynchronously[a](CancellationToken token, FSharpAsync`1 computation, FSharpOption`1 timeout) in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 1140
   at Microsoft.FSharp.Control.AsyncPrimitives.RunSynchronously[T](CancellationToken cancellationToken, FSharpAsync`1 computation, FSharpOption`1 timeout) in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 1167
   at Microsoft.FSharp.Control.FSharpAsync.RunSynchronously[T](FSharpAsync`1 computation, FSharpOption`1 timeout, FSharpOption`1 cancellationToken) in D:\a\_work\1\s\src\FSharp.Core\async.fs:line 1511
   at Program.compile(String projPath) in C:\UnrealEngine\Test\Test\Test\Program.fs:line 10
   at Program.main(String[] args) in C:\UnrealEngine\Test\Test\Test\Program.fs:line 19

Known workarounds

FSharp.Compiler.Service 42.7.101 runs to completion.

Related information

Provide any related information (optional):

Windows 11
.NET 8.0

Test.zip

[majocha]

I think you need to pass the list of files in args:

    let projectOptions = checker.GetProjectOptionsFromCommandLineArgs(
        projPath, [| "Library.fs" |])

As for the exception, this does not look right.
There is a silent assumption that we have at least one source file, when creating a builder. Obviously this is not covered by tests.
I don't know what is best to do in such case. Maybe we should return a diagnostic error?

[jcoder58]

I think you need to pass the list of files in args:

Why is that? I assumed that if a project file was give as an argument, the file would be used as a source for all the files and references.

[vzarytovskii]

I think you need to pass the list of files in args:

Why is that? I assumed that if a project file was give as an argument, the file would be used as a source for all the files and references.

Compiler doesn't do any parsing or evaluation of project files. It's something for project loading/msbuild to do.