[tannevaled]

Module#define_method conformance (MRI 4.0.6)

Advances core/module/define_method_spec.rb from 45 → 85 passing (of 88), with no regressions in the wider suite.

Changes

1. Lambda arity semantics (callProcMethod): a define_method body — from a block or a non-lambda Proc — now binds arguments with method/lambda arity: ArgumentError on a count mismatch, and no auto-splat of a lone Array. (+22 examples)
2. Visibility: the created method takes the receiver's current default visibility (public/private/protected), is public when defined from another module, and is always private for :initialize/:initialize_copy.
3. Name coercion: a non-Symbol/String name is coerced through #to_str; a #to_str returning a non-String raises the MRI TypeError.
4. method_added fires once after the method is installed.
5. Body/error paths: a Proc/Method/UnboundMethod argument takes precedence over a passed block; a non-Proc/Method/UnboundMethod body raises the MRI TypeError naming Proc/Method/UnboundMethod; a frozen receiver raises FrozenError.
6. Cross-class bind check: a transplanted Method/UnboundMethod owned by a Class (or singleton class) may only be re-homed onto that class or a subclass, else TypeError ("bind argument must be a subclass of …" / "can't bind singleton method to a different class"); Module-owned and the Object/BasicObject universal roots stay permissive.

Files

• internal/vm/object_model.go — callProcMethod lambda binding.
• internal/vm/builtins.go — define_method native rewrite.
• internal/vm/modulefunc.go — defineMethodName, defineMethodVis, checkTransplantBindable, fireMethodAdded helpers.
• internal/vm/define_method_conformance_test.go — new coverage.
• Two reflection tests corrected to the MRI cross-class bind rule.

Remaining 3 (out of scope for the define_method path)

• #to_str non-String message: rbgo emits MRI 4.0.6's exact "can't convert Object to String (…)"; the corpus regex expects the older "…into String".
• { |a,| } two-arg arity and redo: parser/compiler representation, outside modulefunc.go/object_model.go.

Verification

go test ./internal/vm/ and go test ./... green; GOOS=js GOARCH=wasm build OK; gofmt -l clean; MERGED coverage of all changed functions and the overall profile 100.0%.

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