A field-wise Clone grant does not entail Clone for an open-row record

LIMIT-TYPE-INFERENCE-011

An owned generic row with where all R: Clone cannot clone the entire open-row value inside its body.

Lifecycle

resolved

Owner

metel-frontend

Scope

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

Origin

v0.14.0 sensitive release-matrix probe; metel-core#1420

Affects · linked records

spec.types.generics.field-wise-row-constraints.legality-1language spec rule

spec.types.generics.rigid-type-parameters.legality-1language spec rule

limitationKnown limitations ↗

Limitation

A generic function with an owned parameter { id: i64, ..R } and where all R: Clone was rejected with T0035 when its body called value.clone(). Generic method entailment now accounts for the fixed row fields and carries the declared field-wise requirement to the open tail. The regression evaluator/records/release_matrix_bounded_clone_residual_callback.mtl passes without a skip. The fix merged in metel-core PR #1422.

Impact

Previously, generic code could not use field-wise Clone to duplicate an owned anonymous row, even when every field was known to satisfy Clone.

Affects

• spec.types.generics.field-wise-row-constraints.legality-1
• spec.types.generics.rigid-type-parameters.legality-1

Resolution

Implemented in metel-core commit 5f038b189cb67c5ec40e51d16a3e11a831a4535e (PR #1422), with executable empty/nonempty tails and residual/callback coverage, plus neg_release_matrix_clone_fixed_field_not_clone; tracked by metel-core#1420. The remaining generic move-analysis skip is separate and remains tracked by metel-core#273.