fix(csharp): resolve fluent-chain receivers, generic member names, and type twins for call recall

[vitali87]

What

Round 1 of the C# calls-recall campaign (follows the dead-code dogfood, #782/#784/#785/#786): three resolution gaps behind Polly's fluent-API surface. The retrieval eval gains 280 true call edges with zero new false positives: tp 3113 -> 3393, recall 0.7828 -> 0.8532, f1 0.8781 -> 0.9208, precision stays 1.0000. The dead-code report is unchanged at its single verified true positive.

Root causes and fixes

1. Generic member names never matched (+242 edges). Policy.Handle<InvalidOperationException>() keeps its type arguments through both call-name extraction and the member resolver, while methods register generic-free, so Polly's whole fluent entry point emitted nothing. Both paths now strip the type-argument list.
2. Object-creation and invocation receivers were untypable. new Builder().Add() and Policy.Handle<T>().Wrap(...) hand the resolver receiver nodes it had no branch for. An object-creation receiver IS its type; an invocation receiver types the next hop through the resolved inner call's recorded return type (new csharp_method_return_types, recorded at both the member-ingest and #if-recovery paths from the returns field, which is the C# grammar's return-type field; there is no type field on methods). Mirrors the existing C++ chained-factory typing.
3. Generic/non-generic type twins killed the chain and extension binding. ResiliencePipelineBuilder and ResiliencePipelineBuilder<TResult> share a simple name, so the receiver-type sweep returned None (ambiguity) and the extension matcher's unqualified-ambiguity guard refused to bind. Class declarations now record their type-parameter count (csharp_class_generic_arity); the type sweep filters candidates by the reference's written arity, and the extension guard treats same-name declarations that all differ by generic arity as non-ambiguous (a compilable call binds the unique matching extension; true N1.Widget/N2.Widget namespace splits, same arity, stay guarded).

Validation

• RED demonstrated in commit history for all three fixes (generic member call, object-creation receiver, chained-return receiver, twins disambiguation).
• Full suite green; all 143 C# tests pass.
• C# retrieval eval (full Polly, Roslyn oracle): tp 3113 -> 3393, fp 0 -> 0, precision 1.0000, recall 0.7828 -> 0.8532.
• Polly dead-code: unchanged at 1 (the verified PolicyBuilder true positive), zero new findings.

Remaining recall tail (~584)

Dominated by two classes for follow-up rounds: BCL-name collisions in the eval reduction (Cancel, Add, Dispose, ToString on BCL receivers that share a simple name with first-party declarations; needs eval-semantics investigation before touching the graph) and deeper chains through field-typed or awaited receivers.

[gemini-code-assist]

Code Review

This pull request enhances C# type inference and call resolution, particularly for generic types and fluent/chained method calls. It introduces tracking of C# class generic arity and method return types during ingestion. These additions allow the type inference engine to resolve chained invocations (such as Policy.Handle<T>().Wrap(...)), handle object creation expressions as receivers, and disambiguate same-name classes that differ by generic arity (e.g., Builder vs. Builder<TResult>). Corresponding unit tests have been added to verify these improvements. I have no feedback to provide as there are no review comments.

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[greptile-apps]

Greptile Summary

This PR improves C# call recall for fluent APIs and generic type variants. The main changes are:

• Generic member call names are normalized before resolver lookup.
• Object-creation and chained invocation receivers are typed for follow-up calls.
• C# method return types and class generic arity are recorded during ingestion.
• Extension method matching now includes receiver generic arity.
• Tests cover generic member calls, fluent chained calls, object-creation receivers, and generic/plain type twin cases.

Confidence Score: 5/5

This PR appears safe to merge with low risk.

No blocking correctness or security issues were identified in the changed C# inference paths. The updated code includes focused tests for the main resolver cases changed by this PR. Previously reported arity-context issues appear addressed in the reviewed code.

No files require special attention.

T-Rex Logs

What T-Rex did

• Reviewed the focused pytest blocker log captured after C# parser dependencies were installed.
• Verified that the fallback parser-level validation completed with EXIT_CODE: 0 and all C# parser smoke checks passed.
• Inspected the generated executable harness used for the fallback parser-level validation.

_{Ran code and verified through T-Rex}

Important Files Changed

Filename	Overview
codebase_rag/parsers/csharp/type_inference.py	Extends C# call resolution for generic member names, object-creation receivers, invocation-chain return types, and generic-arity disambiguation.
codebase_rag/parsers/csharp/utils.py	Adds C# type normalization and generic-arity helpers and includes extension receiver arity in the extension index.
codebase_rag/parsers/class_ingest/mixin.py	Records C# class generic arity and method return types during normal member ingestion.
codebase_rag/parsers/function_ingest.py	Records C# method return types for recovered/truncated member ingestion paths.
codebase_rag/tests/test_csharp_type_inference.py	Adds tests for object creation, chained return receivers, and generic/plain builder disambiguation.
codebase_rag/tests/test_csharp_extension_methods.py	Adds tests preventing generic receivers from binding non-generic extension receivers.
codebase_rag/tests/test_csharp_calls.py	Adds tests for generic member calls on class receivers.

Sequence Diagram

%%{init: {'theme': 'neutral'}}%%
sequenceDiagram
participant Ingest as C# ingestion
participant Indexes as Arity/return-type indexes
participant Resolver as Type inference resolver
participant Calls as CALLS edge emission

Ingest->>Indexes: Record class generic arity and method return types
Ingest->>Indexes: Index extension receiver type and arity
Resolver->>Resolver: Strip generic call-name type arguments
Resolver->>Indexes: Resolve object creation or inner invocation receiver
Indexes-->>Resolver: Return receiver type and generic arity
Resolver->>Calls: Emit matching instance or extension method edge

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sequenceDiagram
participant Ingest as C# ingestion
participant Indexes as Arity/return-type indexes
participant Resolver as Type inference resolver
participant Calls as CALLS edge emission

Ingest->>Indexes: Record class generic arity and method return types
Ingest->>Indexes: Index extension receiver type and arity
Resolver->>Resolver: Strip generic call-name type arguments
Resolver->>Indexes: Resolve object creation or inner invocation receiver
Indexes-->>Resolver: Return receiver type and generic arity
Resolver->>Calls: Emit matching instance or extension method edge

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_{Reviews (3): Last reviewed commit: "fix(csharp): keep caller context when re..." | Re-trigger Greptile}

[vitali87]

@greptile review

[vitali87]

@greptile review

[sonarqubecloud]

Quality Gate passed

Issues
1 New issue
0 Accepted issues

Measures
0 Security Hotspots
85.7% Coverage on New Code
2.8% Duplication on New Code

See analysis details on SonarQube Cloud