We are trying to use the Roslyn APIs to analyse an existing application with a view to be able to write tools to asses it for quality.
In the code below we are trying to use the APIs to get the IOperation for a particular method being called via async/await call:
if (toEvaluate is AwaitExpressionSyntax awaitExpressionSyntax)
{
if (awaitExpressionSyntax.Expression is InvocationExpressionSyntax invocationExpressionSyntax)
{
var operation = semanticModel.GetOperation(invocationExpressionSyntax);
// Analyse the operation
}
}
We are seeing this work in most circumstances but for one particular method call GetOperation is return an IOperation with a Kind of OperationKind.Invalid.
Since we are analysing code from a working application we know the code itself isn’t invalid.
What can cause GetOperation to return OperationKind.Invalid?
Is there any debugging information that can be used to understand what the operation is deemed invalid?
In the end we were able to get a bit of a clue as to what the problem was by looking at the output from semanticModel.GetDiagnostics() which indicated that the model was missing a reference to netstandard.dll.
Adding the missing DLL does seem to have fixed the problem.
Its not entirely clear why this was working for other methods as even for methods where semanticModel.GetOperation(invocationExpressionSyntax) returned successfully (i.e. OperationKind wasn’t Invalid) the errors in the diagnostics were still there.