Analyzer complaining about not disposing object (False positives)

[roywill]

    <PackageReference Include="Microsoft.CodeAnalysis.NetAnalyzers" Version="5.0.3">
      <PrivateAssets>all</PrivateAssets>
      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
    </PackageReference>

Describe the bug

var item = new ItemData(scannedFileName: filePath);
return parseChannel.Writer.WriteAsync(item);

The class ItemData is indeed IDisposable and WriteAsync can throw, so yep I would an IDisposable error, which there is.

Changing to:

So, to address the issue I change that to this.

var item = new ItemData(scannedFileName: filePath);
try
{
var parseTask = parseChannel.Writer.WriteAsync(item);
item = null;
return parseTask;
}
finally
{
item?.Dispose();
}

Only results in:

Severity	Code	Description	Project	File	Line	Suppression State	Tool
Warning	CA1508	'item' is always 'null'. Remove or refactor the condition(s) to avoid dead code.	ItemCheck	...	636	Active	Microsoft.CodeAnalysis.NetAnalyzers

Severity	Code	Description	Project	File	Line	Suppression State	Tool
Warning	CA2000	Call System.IDisposable.Dispose on object created by 'new ItemData(scannedFileName: filePath)' before all references to it are out of scope	ItemCheck	...	627	Active	Microsoft.CodeAnalysis.NetAnalyzers

[N-Olbert]

The 1508 also occurs with the official example from the CA2000-docs.

public SerialPort OpenPort2(string portName)
{
   SerialPort tempPort = null;
   SerialPort port = null;
   try
   {
      tempPort = new SerialPort(portName);
      tempPort.Open();
      SomeMethod();
      //Add any other methods above this line
      port = tempPort;
      tempPort = null;

   }
   finally
   {
      if (tempPort != null) // BOOM
      {
         tempPort.Close();
      }
   }
   return port;
}