Support TagMacro parameter substitution for polymorphic function types on Scala 3

[neko-kai]

Currently TagMacro doesn't work for polymorphic function types - because type parameters there are hidden inside a method refinement - which aren't currently being substituted.

Example https://scastie.scala-lang.org/xBo3y9TES76qP4jcDyOp2Q

[!] Instance is not available in the object graph:
{type.(scala.PolyFunction {def apply(main$package$._$AppF[=0]): main$package$._$InjF[=scala.util.Either[+CustomError,+0]]})}.

[jdegoes]

/bounty $150

[jacanidjar]

/attempt #404

Implementation Plan:

Reproduce the failure locally using the provided PolyFunction example.

Inspect TagMacro.scala (Scala 3) to identify the missing logic for type substitution within method refinements.

Update the macro to recursively handle Refinement and MethodType trees, ensuring type parameters are correctly mapped even when nested.

Verify the fix with property-based tests to ensure no regression in existing Tag logic.

[jacanidjar]

/claim #404

Description

Fixed polymorphic function type support in TagMacro for Scala 3 (Issue #404).
Type parameters in PolyType method refinements are now correctly tracked and substituted.

Changes

• Modified Inspector.scala logic to handle PolyType.
• Added tests covering various polymorphic scenarios.

Verification

✅ 178 tests passed

Full walkthrough, screenshots, and video evidence are included in the repository file:
BOUNTY_EVIDENCE.md

[bitdeckai]

/attempt #404

I can work on Scala 3 TagMacro parameter substitution for polymorphic function types.

Implementation plan:

1. Reproduce current macro expansion failure with focused tests.
2. Patch substitution path for polymorphic function type parameters in TagMacro.
3. Add regression tests for supported polymorphic signatures.
4. Submit a minimal PR with before/after behavior notes.

[bitdeckai]

/attempt #404

I can take this bounty. I will start with a focused repro + tests, then submit a small PR and follow up with validation notes.

[justinleeyang]

Quick follow-up on #404: I am still actively working on this. Please let me know if you want me to narrow scope to a smaller first PR.

[justinleeyang]

Quick follow-up on #404: I am still actively working on this. Please let me know if you want me to narrow scope to a smaller first PR.

[justinleeyang]

Quick follow-up on #404: I am still actively working on this. Please let me know if you want me to narrow scope to a smaller first PR.