/** Slice 4 — `union kind=result|option` validator.
 *
 *  Spec: docs/language/result-option-spec.md
 *
 *  Walks every `union` node and rejects:
 *    1. `kind=<other>` — only `result` and `option` are recognised in slice 4.
 *       Empty string and ExprObject `kind={{ ... }}` also error per the
 *       slice 6 effects pattern (the prop is a literal-only string).
 *    2. `kind=result` shape — the union must declare exactly two variants
 *       named `ok` and `err` (either order). Any other variant set is a
 *       `KIND_SHAPE_VIOLATION`.
 *    3. `kind=option` shape — exactly two variants named `some` and `none`.
 *    4. `discriminant != 'kind'` on `kind=result|option` — the spec mandates
 *       `discriminant=kind` so slice 7's `?` / `!` propagation operators can
 *       check `r.kind === 'err'` uniformly across targets.
 *
 *  These rules are what make the slice 4 stdlib helpers safe — `map`,
 *  `unwrapOr`, etc. assume `x.kind === 'ok'` / `x.value` / `x.error`. The
 *  schema enforces the shape so the helpers don't need defensive checks.
 *
 *  Does NOT change codegen — unions that pass the walker emit unchanged. */
import type { ParseState } from './parser-diagnostics.js';
import { type IRNode } from './types.js';
export declare function validateUnionKind(state: ParseState, root: IRNode): void;