/**
 * Semantic union member discovery — alias-preserving.
 *
 * This module provides union member analysis for semantic consumers:
 * guard detection, branch type reasoning, predicate matching.
 *
 * The key difference from runtime-unions.ts expansion:
 * - Authored alias identity is preserved as a single member.
 *   `PathSpec | MiddlewareLike` yields two members, not their expanded contents.
 * - Explicit `unionType` nodes are flattened (they are structural, not aliases).
 * - Nullish types are stripped (same as runtime path).
 *
 * Runtime carrier construction (buildRuntimeUnionFrame, buildRuntimeUnionLayout)
 * still uses full expansion via getCanonicalRuntimeUnionMembers. That is correct
 * for lowering — the carrier needs the expanded member set.
 *
 * Semantic consumers must use these helpers so that analysis results are
 * stable regardless of whether moduleMap / typeAliasIndex are populated.
 */
import { IrType } from "@tsonic/frontend";
import type { EmitterContext } from "../../types.js";
/**
 * Discover the semantic union members of a type.
 *
 * Flattens explicit `unionType` structure and strips nullish members,
 * but preserves authored alias references (referenceType nodes) as
 * single members. This ensures that `PathSpec | MiddlewareLike` yields
 * exactly two members regardless of what those aliases expand to at
 * lowering time.
 *
 * Returns undefined if the type is not a union or has fewer than 2
 * non-nullish members.
 */
export declare const getSemanticUnionMembers: (type: IrType, context: EmitterContext) => readonly IrType[] | undefined;
/**
 * Find the index of a semantic union member that matches a target type.
 *
 * Uses context-aware type equivalence to find which authored member
 * corresponds to the predicate target. This avoids raw-name comparison and
 * requires deterministic nominal/CLR/structural identity before matching
 * reference types.
 *
 * Returns the 0-based index, or undefined if no match or multiple matches.
 */
export declare const findSemanticUnionMemberIndex: (members: readonly IrType[], target: IrType, context: EmitterContext) => number | undefined;
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