Support ForInvocationWithName in incremental source generators

[captainsafia]

Background and Motivation

Many source generators in the ASP.NET Core ecosystem use invocations of minimal API's Map method calls as entrypoints for type discovery that eventually feeds into the source generator. Some generators also look for invocations of methods that they will intercept with source generated implementations. Currently, we rely on using the SyntaxProvider.CreateSyntaxProvider API to discover the desired invocations and intercept them.

Given the frequency of this pattern and its usability in conjunction with interceptors, we should consider an API ala ForAttributeWithMetadata name for them.
 

Proposed API

namespace Microsoft.CodeAnalysis;

public partial struct SyntaxValueProvider
{
+   public IncrementalValuesProvider<T> ForInvocationWIthName<T>(
+         string fullyQualifiedMetadataTypeName,
+         string methodName,
+          Func<SyntaxNode, CancellationToken, bool> predicate,
+         Func<InvocationExpressionSyntaxContext, CancellationToken, T> transform)
}

+ public readonly struct InvocationExpressionSyntaxContext
+ {
+    public SyntaxNode TargetNode { get; }
+    public ISymbol TargetSymbol { get; }
+    public SemanticModel SemanticModel { get; }
+ }

Usage Examples

var addOpenApiInvocations = context.
  .ForInvocationWithMetadataName("Microsoft.Extensions.DependencyInjection.AddOpenApi", ..., ...);

Alternative Designs

• The context object for this new API has many of the same properties as the GeneratorAttributeSyntaxContext. We may consider an abstract class + concrete implementation pattern for this if we anticipate keying on more shapes.

[captainsafia]

cc: @CyrusNajmabadi I couldn't find an issue in the backlog proposing this API so I've gone ahead and created this here.

Feel free to close this if one already exists.

[CyrusNajmabadi]

fullyQualifiedMetadataName

I'm wary about this. Especially as the FQN for a method is exceedingl complex (and i don't know if we actually have a parser for this).

We could instead of Have something like fullyQualifiedMetadataTypeName and then something like the string methodName. and you'd find calls to any and all overloads of such a method with that name from inside that type.

[captainsafia]

I'm wary about this. Especially as the FQN for a method is exceedingl complex (and i don't know if we actually have a parser for this).

Yep, I share your reservation here but I overindexed on the existing API in the proposal.

We could instead of Have something like fullyQualifiedMetadataTypeName and then something like the string methodName. and you'd find calls to any and all overloads of such a method with that name from inside that type.

That makes sense. So the invocation would become something like this:

context.ForInvocation("Microsoft.Extensions.DependencyInjection.OpenApiServiceCollectionExtensions", "AddOpenApi", ..., ...);

I've renamed it to ForInvocation because I'm not quite sure what a better name would be. Maybe ForInvocationWithName is fine?

[CyrusNajmabadi]

ForInvocationWithName

Yes. That seems pretty reasonable.

[RikkiGibson]

looks good though I am confused by the struct named InvocationExpressionAttributeSyntax. Maybe it was meant to be InvocationExpressionSyntaxContext?

[captainsafia]

looks good though I am confused by the struct named InvocationExpressionAttributeSyntax. Maybe it was meant to be InvocationExpressionSyntaxContext?

Yes, it was a copy pasta issue. Fixed.