A record literal accepts at most one row spread
Gap
{ ..a, ..b } places two rows in one record. Its row is well-formed only if the two rows
share no label. For concrete rows that is a check by inspection; for abstract rows
({ ..R } and { ..S }) the declared bounds can state per-label absence (R: !{ x }) but
not that two rows are disjoint as wholes. RFC-0178 therefore allows one spread per literal.
Nesting does not work around it, since each spread still needs its own absence proof.
Impact
Visible to Metel programmers: merging two generic records into one has no spelling. Merge concrete records field by field.
Affects
Resolution
Not scheduled. Needs a row-disjointness bound (for example R # S), which would be its own
RFC.