Aspects typically do not have access to the underlying Roslyn code model of the current project. The most significant consequence of this limitation is that aspects cannot access the syntax tree of method implementation. Indeed, the Metalama.Framework.Code namespace only exposes declarations, not implementation syntax.
If your aspect requires access to the syntax tree, it can achieve this by using the Metalama SDK.
Using the Roslyn API
Step 1. Reference the Metalama SDK
To use the Roslyn API from an aspect, your project needs to reference the Metalama.Framework.Sdk package privately, in addition to the regular Metalama.Framework package:
<PackageReference Include="Metalama.Framework.Sdk" Version="$(MetalamaVersion)" PrivateAssets="all" />
<PackageReference Include="Metalama.Framework" Version="$(MetalamaVersion)" />
Step 2. Use the Roslyn API
Your aspect generally gets access to Roslyn types by using extension methods from the SymbolExtensions class. To get access to syntax, you can then use ISymbol.DeclaringSyntaxReferences.
As an example, you could use Roslyn API to get the documentation comment ID for a Metalama declaration like this:
static string? GetDocumentationCommentId(this IDeclaration metalamaDeclaration)
{
var roslynSymbol = metalamaDeclaration.GetSymbol();
return roslynSymbol.GetDocumentationCommentId();
}