A partial nominal residual cannot be coerced to a row-conditional dyn aspect

LIMIT-TYPE-INFERENCE-009

Row-conditional dispatch works on a partial nominal residual, but coercion of that receiver to dyn Aspect fails.

Lifecycle

resolved

Owner

metel-frontend

Scope

architecture/spec/type-inference.md#type-inference

Origin

v0.14.0 sensitive release-matrix probe; metel-core#1413

Affects · linked records

spec.types.generics.row-conditional-impls.legality-1language spec rule

spec.declarations.aspects.dyn-aspect.legality-6language spec rule

limitationKnown limitations ↗

Limitation

Row-conditional method dispatch succeeded on a partial nominal residual, but coercing that receiver to dyn Aspect failed with T0012; runtime coercion also assumed every value had a nominal type id, rejecting anonymous records. Dyn values now retain an optional nominal id and the concrete structural receiver type, and runtime dispatch routes structural values through record/pattern impl lookup. evaluator/records/release_matrix_residual_dyn_alias.mtl passes without a skip. The fix merged in metel-core PR #1422.

Impact

Previously, an otherwise available row-conditional implementation could not be used through the corresponding existential aspect type after record narrowing.

Affects

• spec.types.generics.row-conditional-impls.legality-1
• spec.declarations.aspects.dyn-aspect.legality-6

Resolution

Implemented in metel-core commit 5f038b189cb67c5ec40e51d16a3e11a831a4535e (PR #1422). The executable fixture above covers nominal residuals, anonymous rows, a transparent dyn alias, and captured dynamic dispatch; tracked by metel-core#1413.