fix: #24765 SAM conversion for extension method from self-based types

[halotukozak]

Fixes #24765

Enter type members into the anonymous class scope before creating term forwarders, so allOverriddenSymbols can resolve type aliases (like Self = Int) when matching method signatures.

How much have you relied on LLM-based tools in this contribution?

Claude helped me find the root cause.

How was the solution tested?

i24765.scala added

Additional notes

[Copilot]

Pull request overview

Fixes SAM conversion for extension methods in self-based type classes by ensuring type members are entered into the anonymous class scope early enough for override-resolution to see type aliases (e.g., type Self = Int), and adds a regression test for #24765.

Changes:

• Adjust anonymous class generation to enter synthetic type members before creating term forwarders (so allOverriddenSymbols can match signatures through aliases).
• Add tests/pos/i24765.scala regression test covering given Int is B = x => x where B uses a Self type member.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 1 comment.

File	Description
tests/pos/i24765.scala	Adds a positive regression test for SAM conversion with Self-based extension methods.
compiler/src/dotty/tools/dotc/ast/tpd.scala	Reorders construction to enter type members before generating forwarder methods.

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[Copilot]

This code relies on evaluation order: typeMembers are entered via .entered before calling fwdMeth.allOverriddenSymbols in forwarder, otherwise overridden-signature matching can miss type aliases (as in #24765). Please add a short comment (or refactor to make the ordering/side effect explicit) so a future cleanup doesn’t accidentally revert the fix by inlining/reordering the maps.

Suggested change

	}
	}
	// Important: `typeMembers` must be entered before calling `allOverriddenSymbols` in `forwarder`,
	// otherwise overridden-signature matching can miss type aliases (see scala/bug#24765).

[halotukozak]

I am not sure of the convention in this repo. I will commit this suggestion if the human reviewer asks for it