discord.js/packages/api-extractor/src/analyzer/AstSymbolTable.ts

// Copyright (c) Microsoft Corporation. All rights reserved. Licensed under the MIT license.
// See LICENSE in the project root for license information.

// for ts.SymbolFlags

import { type PackageJsonLookup, InternalError } from '@rushstack/node-core-library';
import * as ts from 'typescript';
import type { MessageRouter } from '../collector/MessageRouter';
import { AstDeclaration } from './AstDeclaration.js';
import type { AstEntity } from './AstEntity.js';
import type { AstModule, AstModuleExportInfo } from './AstModule.js';
import { AstNamespaceImport } from './AstNamespaceImport.js';
import { AstSymbol } from './AstSymbol.js';
import { ExportAnalyzer } from './ExportAnalyzer.js';
import { PackageMetadataManager } from './PackageMetadataManager.js';
import { SourceFileLocationFormatter } from './SourceFileLocationFormatter.js';
import { SyntaxHelpers } from './SyntaxHelpers.js';
import { TypeScriptHelpers } from './TypeScriptHelpers.js';
import { TypeScriptInternals, type IGlobalVariableAnalyzer } from './TypeScriptInternals.js';

/**
 * Options for `AstSymbolTable._fetchAstSymbol()`
 */
export interface IFetchAstSymbolOptions {
	/**
	 * True while populating the `AstSymbolTable`; false if we're doing a passive lookup
	 * without adding anything new to the table
	 */
	addIfMissing: boolean;
	/**
	 * The symbol after any symbol aliases have been followed using TypeScriptHelpers.followAliases()
	 */
	followedSymbol: ts.Symbol;

	/**
	 * If true, symbols with AstSymbol.nominalAnalysis=true will be returned.
	 * Otherwise `undefined` will be returned for such symbols.
	 */
	includeNominalAnalysis: boolean;

	/**
	 * True if followedSymbol is not part of the working package
	 */
	isExternal: boolean;

	/**
	 * A hint to help `_fetchAstSymbol()` determine the `AstSymbol.localName`.
	 */
	localName?: string;
}

/**
 * AstSymbolTable is the workhorse that builds AstSymbol and AstDeclaration objects.
 * It maintains a cache of already constructed objects.  AstSymbolTable constructs
 * AstModule objects, but otherwise the state that it maintains is agnostic of
 * any particular entry point.  (For example, it does not track whether a given AstSymbol
 * is "exported" or not.)
 *
 * Internally, AstSymbolTable relies on ExportAnalyzer to crawl import statements and determine where symbols
 * are declared (i.e. the AstImport information needed to import them).
 */
export class AstSymbolTable {
	private readonly _program: ts.Program;

	private readonly _typeChecker: ts.TypeChecker;

	private readonly _messageRouter: MessageRouter;

	private readonly _globalVariableAnalyzer: IGlobalVariableAnalyzer;

	private readonly _packageMetadataManager: PackageMetadataManager;

	private readonly _exportAnalyzer: ExportAnalyzer;

	private readonly _alreadyWarnedGlobalNames: Set<string>;

	/**
	 * A mapping from ts.Symbol --\> AstSymbol
	 * NOTE: The AstSymbol.followedSymbol will always be a lookup key, but additional keys
	 * are possible.
	 *
	 * After following type aliases, we use this map to look up the corresponding AstSymbol.
	 */
	private readonly _astSymbolsBySymbol: Map<ts.Symbol, AstSymbol> = new Map<ts.Symbol, AstSymbol>();

	/**
	 * A mapping from ts.Declaration --\> AstDeclaration
	 */
	private readonly _astDeclarationsByDeclaration: Map<ts.Node, AstDeclaration> = new Map<ts.Node, AstDeclaration>();

	// Note that this is a mapping from specific AST nodes that we analyzed, based on the underlying symbol
	// for that node.
	private readonly _entitiesByNode: Map<ts.Identifier | ts.ImportTypeNode, AstEntity | undefined> = new Map<
		ts.Identifier,
		AstEntity | undefined
	>();

	public constructor(
		program: ts.Program,
		typeChecker: ts.TypeChecker,
		packageJsonLookup: PackageJsonLookup,
		bundledPackageNames: ReadonlySet<string>,
		messageRouter: MessageRouter,
	) {
		this._program = program;
		this._typeChecker = typeChecker;
		this._messageRouter = messageRouter;
		this._globalVariableAnalyzer = TypeScriptInternals.getGlobalVariableAnalyzer(program);
		this._packageMetadataManager = new PackageMetadataManager(packageJsonLookup, messageRouter);

		this._exportAnalyzer = new ExportAnalyzer(this._program, this._typeChecker, bundledPackageNames, {
			analyze: this.analyze.bind(this),
			fetchAstSymbol: this._fetchAstSymbol.bind(this),
		});

		this._alreadyWarnedGlobalNames = new Set<string>();
	}

	/**
	 * Used to analyze an entry point that belongs to the working package.
	 */
	public fetchAstModuleFromWorkingPackage(sourceFile: ts.SourceFile): AstModule {
		return this._exportAnalyzer.fetchAstModuleFromSourceFile(sourceFile, undefined, false);
	}

	/**
	 * This crawls the specified entry point and collects the full set of exported AstSymbols.
	 */
	public fetchAstModuleExportInfo(astModule: AstModule): AstModuleExportInfo {
		return this._exportAnalyzer.fetchAstModuleExportInfo(astModule);
	}

	/**
	 * Attempts to retrieve an export by name from the specified `AstModule`.
	 * Returns undefined if no match was found.
	 */
	public tryGetExportOfAstModule(exportName: string, astModule: AstModule): AstEntity | undefined {
		return this._exportAnalyzer.tryGetExportOfAstModule(exportName, astModule);
	}

	/**
	 * Ensures that AstSymbol.analyzed is true for the provided symbol.  The operation
	 * starts from the root symbol and then fills out all children of all declarations, and
	 * also calculates AstDeclaration.referencedAstSymbols for all declarations.
	 * If the symbol is not imported, any non-imported references are also analyzed.
	 *
	 * @remarks
	 * This is an expensive operation, so we only perform it for top-level exports of an
	 * the AstModule.  For example, if some code references a nested class inside
	 * a namespace from another library, we do not analyze any of that class's siblings
	 * or members.  (We do always construct its parents however, since AstDefinition.parent
	 * is immutable, and needed e.g. to calculate release tag inheritance.)
	 */
	public analyze(astEntity: AstEntity): void {
		if (astEntity instanceof AstSymbol) {
			this._analyzeAstSymbol(astEntity);
			return;
		}

		if (astEntity instanceof AstNamespaceImport) {
			this._analyzeAstNamespaceImport(astEntity);
		}
	}

	/**
	 * For a given astDeclaration, this efficiently finds the child corresponding to the
	 * specified ts.Node.  It is assumed that AstDeclaration.isSupportedSyntaxKind() would return true for
	 * that node type, and that the node is an immediate child of the provided AstDeclaration.
	 */
	// NOTE: This could be a method of AstSymbol if it had a backpointer to its AstSymbolTable.
	public getChildAstDeclarationByNode(node: ts.Node, parentAstDeclaration: AstDeclaration): AstDeclaration {
		if (!parentAstDeclaration.astSymbol.analyzed) {
			throw new Error('getChildDeclarationByNode() cannot be used for an AstSymbol that was not analyzed');
		}

		const childAstDeclaration: AstDeclaration | undefined = this._astDeclarationsByDeclaration.get(node);
		if (!childAstDeclaration) {
			throw new Error('Child declaration not found for the specified node');
		}

		if (childAstDeclaration.parent !== parentAstDeclaration) {
			throw new InternalError('The found child is not attached to the parent AstDeclaration');
		}

		return childAstDeclaration;
	}

	/**
	 * For a given ts.Identifier that is part of an AstSymbol that we analyzed, return the AstEntity that
	 * it refers to.  Returns undefined if it doesn't refer to anything interesting.
	 *
	 * @remarks
	 * Throws an Error if the ts.Identifier is not part of node tree that was analyzed.
	 */
	public tryGetEntityForNode(identifier: ts.Identifier | ts.ImportTypeNode): AstEntity | undefined {
		if (!this._entitiesByNode.has(identifier)) {
			throw new InternalError('tryGetEntityForIdentifier() called for an identifier that was not analyzed');
		}

		return this._entitiesByNode.get(identifier);
	}

	/**
	 * Builds an AstSymbol.localName for a given ts.Symbol.  In the current implementation, the localName is
	 * a TypeScript-like expression that may be a string literal or ECMAScript symbol expression.
	 *
	 * ```ts
	 * class X {
	 *   // localName="identifier"
	 *   public identifier: number = 1;
	 *   // localName="\"identifier\""
	 *   public "quoted string!": number = 2;
	 *   // localName="[MyNamespace.MySymbol]"
	 *   public [MyNamespace.MySymbol]: number = 3;
	 * }
	 * ```
	 */
	public static getLocalNameForSymbol(symbol: ts.Symbol): string {
		// TypeScript binds well-known ECMAScript symbols like "[Symbol.iterator]" as "__@iterator".
		// Decode it back into "[Symbol.iterator]".
		const wellKnownSymbolName: string | undefined = TypeScriptHelpers.tryDecodeWellKnownSymbolName(symbol.escapedName);
		if (wellKnownSymbolName) {
			return wellKnownSymbolName;
		}

		const isUniqueSymbol: boolean = TypeScriptHelpers.isUniqueSymbolName(symbol.escapedName);

		// We will try to obtain the name from a declaration; otherwise we'll fall back to the symbol name.
		let unquotedName: string = symbol.name;

		for (const declaration of symbol.declarations ?? []) {
			// Handle cases such as "export default class X { }" where the symbol name is "default"
			// but the local name is "X".
			const localSymbol: ts.Symbol | undefined = TypeScriptInternals.tryGetLocalSymbol(declaration);
			if (localSymbol) {
				unquotedName = localSymbol.name;
			}

			// If it is a non-well-known symbol, then return the late-bound name.  For example, "X.Y.z" in this example:
			//
			//   namespace X {
			//     export namespace Y {
			//       export const z: unique symbol = Symbol("z");
			//     }
			//  }
			//
			//  class C {
			//    public [X.Y.z](): void { }
			//  }
			//
			if (isUniqueSymbol) {
				const declarationName: ts.DeclarationName | undefined = ts.getNameOfDeclaration(declaration);
				if (declarationName && ts.isComputedPropertyName(declarationName)) {
					const lateBoundName: string | undefined = TypeScriptHelpers.tryGetLateBoundName(declarationName);
					if (lateBoundName) {
						// Here the string may contain an expression such as "[X.Y.z]".  Names starting with "[" are always
						// expressions.  If a string literal contains those characters, the code below will JSON.stringify() it
						// to avoid a collision.
						return lateBoundName;
					}
				}
			}
		}

		// Otherwise that name may come from a quoted string or pseudonym like `__constructor`.
		// If the string is not a safe identifier, then we must add quotes.
		// Note that if it was quoted but did not need to be quoted, here we will remove the quotes.
		if (!SyntaxHelpers.isSafeUnquotedMemberIdentifier(unquotedName)) {
			// For API Extractor's purposes, a canonical form is more appropriate than trying to reflect whatever
			// appeared in the source code.  The code is not even guaranteed to be consistent, for example:
			//
			//   class X {
			//     public "f1"(x: string): void;
			//     public f1(x: boolean): void;
			//     public 'f1'(x: string | boolean): void { }
			//   }
			return JSON.stringify(unquotedName);
		}

		return unquotedName;
	}

	private _analyzeAstNamespaceImport(astNamespaceImport: AstNamespaceImport): void {
		if (astNamespaceImport.analyzed) {
			return;
		}

		// mark before actual analyzing, to handle module cyclic reexport
		astNamespaceImport.analyzed = true;

		const exportedLocalEntities: Map<string, AstEntity> = this.fetchAstModuleExportInfo(
			astNamespaceImport.astModule,
		).exportedLocalEntities;

		for (const exportedEntity of exportedLocalEntities.values()) {
			this.analyze(exportedEntity);
		}
	}

	private _analyzeAstSymbol(astSymbol: AstSymbol): void {
		if (astSymbol.analyzed) {
			return;
		}

		if (astSymbol.nominalAnalysis) {
			// We don't analyze nominal symbols
			astSymbol._notifyAnalyzed();
			return;
		}

		// Start at the root of the tree
		const rootAstSymbol: AstSymbol = astSymbol.rootAstSymbol;

		// Calculate the full child tree for each definition
		for (const astDeclaration of rootAstSymbol.astDeclarations) {
			this._analyzeChildTree(astDeclaration.declaration, astDeclaration);
		}

		rootAstSymbol._notifyAnalyzed();

		if (!astSymbol.isExternal) {
			// If this symbol is non-external (i.e. it belongs to the working package), then we also analyze any
			// referencedAstSymbols that are non-external.  For example, this ensures that forgotten exports
			// get analyzed.
			rootAstSymbol.forEachDeclarationRecursive((astDeclaration: AstDeclaration) => {
				for (const referencedAstEntity of astDeclaration.referencedAstEntities) {
					// Walk up to the root of the tree, looking for any imports along the way
					if (referencedAstEntity instanceof AstSymbol && !referencedAstEntity.isExternal) {
						this._analyzeAstSymbol(referencedAstEntity);
					}

					if (referencedAstEntity instanceof AstNamespaceImport && !referencedAstEntity.astModule.isExternal) {
						this._analyzeAstNamespaceImport(referencedAstEntity);
					}
				}
			});
		}
	}

	/**
	 * Used by analyze to recursively analyze the entire child tree.
	 */
	private _analyzeChildTree(node: ts.Node, governingAstDeclaration: AstDeclaration): void {
		switch (node.kind) {
			case ts.SyntaxKind.JSDocComment: // Skip JSDoc comments - TS considers @param tags TypeReference nodes
				return;

			// Is this a reference to another AstSymbol?
			case ts.SyntaxKind.TypeReference: // general type references
			case ts.SyntaxKind.ExpressionWithTypeArguments: // special case for e.g. the "extends" keyword
			case ts.SyntaxKind.ComputedPropertyName: // used for EcmaScript "symbols", e.g. "[toPrimitive]".
			case ts.SyntaxKind.TypeQuery: // represents for "typeof X" as a type
				{
					// Sometimes the type reference will involve multiple identifiers, e.g. "a.b.C".
					// In this case, we only need to worry about importing the first identifier,
					// so do a depth-first search for it:
					const identifierNode: ts.Identifier | undefined = TypeScriptHelpers.findFirstChildNode(
						node,
						ts.SyntaxKind.Identifier,
					);

					if (identifierNode) {
						let referencedAstEntity: AstEntity | undefined = this._entitiesByNode.get(identifierNode);
						if (!referencedAstEntity) {
							const symbol: ts.Symbol | undefined = this._typeChecker.getSymbolAtLocation(identifierNode);
							if (!symbol) {
								throw new Error('Symbol not found for identifier: ' + identifierNode.getText());
							}

							// Normally we expect getSymbolAtLocation() to take us to a declaration within the same source
							// file, or else to an explicit "import" statement within the same source file.  But in certain
							// situations (e.g. a global variable) the symbol will refer to a declaration in some other
							// source file.  We'll call that case a "displaced symbol".
							//
							// For more info, see this discussion:
							// https://github.com/microsoft/rushstack/issues/1765#issuecomment-595559849
							let displacedSymbol = true;
							for (const declaration of symbol.declarations ?? []) {
								if (declaration.getSourceFile() === identifierNode.getSourceFile()) {
									displacedSymbol = false;
									break;
								}
							}

							if (displacedSymbol) {
								if (this._globalVariableAnalyzer.hasGlobalName(identifierNode.text)) {
									// If the displaced symbol is a global variable, then API Extractor simply ignores it.
									// Ambient declarations typically describe the runtime environment (provided by an API consumer),
									// so we don't bother analyzing them as an API contract.  (There are probably some packages
									// that include interesting global variables in their API, but API Extractor doesn't support
									// that yet; it would be a feature request.)

									if (this._messageRouter.showDiagnostics && !this._alreadyWarnedGlobalNames.has(identifierNode.text)) {
										this._alreadyWarnedGlobalNames.add(identifierNode.text);
										this._messageRouter.logDiagnostic(
											`Ignoring reference to global variable "${identifierNode.text}"` +
												` in ` +
												SourceFileLocationFormatter.formatDeclaration(identifierNode),
										);
									}
								} else {
									// If you encounter this, please report a bug with a repro.  We're interested to know
									// how it can occur.
									throw new InternalError(`Unable to follow symbol for "${identifierNode.text}"`);
								}
							} else {
								referencedAstEntity = this._exportAnalyzer.fetchReferencedAstEntity(
									symbol,
									governingAstDeclaration.astSymbol.isExternal,
								);

								this._entitiesByNode.set(identifierNode, referencedAstEntity);
							}
						}

						if (referencedAstEntity) {
							governingAstDeclaration._notifyReferencedAstEntity(referencedAstEntity);
						}
					}
				}

				break;

			// Is this the identifier for the governingAstDeclaration?
			case ts.SyntaxKind.Identifier:
				{
					const identifierNode: ts.Identifier = node as ts.Identifier;
					if (!this._entitiesByNode.has(identifierNode)) {
						const symbol: ts.Symbol | undefined = this._typeChecker.getSymbolAtLocation(identifierNode);

						let referencedAstEntity: AstEntity | undefined;

						if (symbol === governingAstDeclaration.astSymbol.followedSymbol) {
							referencedAstEntity = this._fetchEntityForNode(identifierNode, governingAstDeclaration);
						}

						this._entitiesByNode.set(identifierNode, referencedAstEntity);
					}
				}

				break;

			case ts.SyntaxKind.ImportType:
				{
					const importTypeNode: ts.ImportTypeNode = node as ts.ImportTypeNode;
					let referencedAstEntity: AstEntity | undefined = this._entitiesByNode.get(importTypeNode);

					if (!this._entitiesByNode.has(importTypeNode)) {
						referencedAstEntity = this._fetchEntityForNode(importTypeNode, governingAstDeclaration);

						if (!referencedAstEntity) {
							// This should never happen
							throw new Error('Failed to fetch entity for import() type node: ' + importTypeNode.getText());
						}

						this._entitiesByNode.set(importTypeNode, referencedAstEntity);
					}

					if (referencedAstEntity) {
						governingAstDeclaration._notifyReferencedAstEntity(referencedAstEntity);
					}
				}

				break;

			default:
				break;
		}

		// Is this node declaring a new AstSymbol?
		const newGoverningAstDeclaration: AstDeclaration | undefined = this._fetchAstDeclaration(
			node,
			governingAstDeclaration.astSymbol.isExternal,
		);

		for (const childNode of node.getChildren()) {
			this._analyzeChildTree(childNode, newGoverningAstDeclaration ?? governingAstDeclaration);
		}
	}

	private _fetchEntityForNode(
		node: ts.Identifier | ts.ImportTypeNode,
		governingAstDeclaration: AstDeclaration,
	): AstEntity | undefined {
		let referencedAstEntity: AstEntity | undefined = this._entitiesByNode.get(node);
		if (!referencedAstEntity) {
			if (node.kind === ts.SyntaxKind.ImportType) {
				referencedAstEntity = this._exportAnalyzer.fetchReferencedAstEntityFromImportTypeNode(
					node,
					governingAstDeclaration.astSymbol.isExternal,
				);
			} else {
				const symbol: ts.Symbol | undefined = this._typeChecker.getSymbolAtLocation(node);
				if (!symbol) {
					throw new Error('Symbol not found for identifier: ' + node.getText());
				}

				referencedAstEntity = this._exportAnalyzer.fetchReferencedAstEntity(
					symbol,
					governingAstDeclaration.astSymbol.isExternal,
				);
			}

			this._entitiesByNode.set(node, referencedAstEntity);
		}

		return referencedAstEntity;
	}

	private _fetchAstDeclaration(node: ts.Node, isExternal: boolean): AstDeclaration | undefined {
		if (!AstDeclaration.isSupportedSyntaxKind(node.kind)) {
			return undefined;
		}

		const symbol: ts.Symbol | undefined = TypeScriptHelpers.getSymbolForDeclaration(
			node as ts.Declaration,
			this._typeChecker,
		);
		if (!symbol) {
			throw new InternalError('Unable to find symbol for node');
		}

		const astSymbol: AstSymbol | undefined = this._fetchAstSymbol({
			followedSymbol: symbol,
			isExternal,
			includeNominalAnalysis: true,
			addIfMissing: true,
		});

		if (!astSymbol) {
			return undefined;
		}

		const astDeclaration: AstDeclaration | undefined = this._astDeclarationsByDeclaration.get(node);

		if (!astDeclaration) {
			throw new InternalError('Unable to find constructed AstDeclaration');
		}

		return astDeclaration;
	}

	private _fetchAstSymbol(options: IFetchAstSymbolOptions): AstSymbol | undefined {
		const followedSymbol: ts.Symbol = options.followedSymbol;

		// Filter out symbols representing constructs that we don't care about
		const arbitraryDeclaration: ts.Declaration | undefined = TypeScriptHelpers.tryGetADeclaration(followedSymbol);
		if (!arbitraryDeclaration) {
			return undefined;
		}

		if (
			followedSymbol.flags & (ts.SymbolFlags.TypeParameter | ts.SymbolFlags.TypeLiteral | ts.SymbolFlags.Transient) &&
			!TypeScriptInternals.isLateBoundSymbol(followedSymbol)
		) {
			return undefined;
		}

		// API Extractor doesn't analyze ambient declarations at all
		if (
			TypeScriptHelpers.isAmbient(followedSymbol, this._typeChecker) && // We make a special exemption for ambient declarations that appear in a source file containing
			// an "export=" declaration that allows them to be imported as non-ambient.
			!this._exportAnalyzer.isImportableAmbientSourceFile(arbitraryDeclaration.getSourceFile())
		) {
			return undefined;
		}

		// Make sure followedSymbol isn't an alias for something else
		if (TypeScriptHelpers.isFollowableAlias(followedSymbol, this._typeChecker)) {
			// We expect the caller to have already followed any aliases
			throw new InternalError('AstSymbolTable._fetchAstSymbol() cannot be called with a symbol alias');
		}

		let astSymbol: AstSymbol | undefined = this._astSymbolsBySymbol.get(followedSymbol);

		if (!astSymbol) {
			// None of the above lookups worked, so create a new entry...
			let nominalAnalysis = false;

			if (options.isExternal) {
				// If the file is from an external package that does not support AEDoc, normally we ignore it completely.
				// But in some cases (e.g. checking star exports of an external package) we need an AstSymbol to
				// represent it, but we don't need to analyze its sibling/children.
				const followedSymbolSourceFileName: string = arbitraryDeclaration.getSourceFile().fileName;

				if (!this._packageMetadataManager.isAedocSupportedFor(followedSymbolSourceFileName)) {
					nominalAnalysis = true;

					if (!options.includeNominalAnalysis) {
						return undefined;
					}
				}
			}

			let parentAstSymbol: AstSymbol | undefined;

			if (!nominalAnalysis) {
				for (const declaration of followedSymbol.declarations ?? []) {
					if (!AstDeclaration.isSupportedSyntaxKind(declaration.kind)) {
						throw new InternalError(
							`The "${followedSymbol.name}" symbol has a` +
								` ts.SyntaxKind.${ts.SyntaxKind[declaration.kind]} declaration which is not (yet?)` +
								` supported by API Extractor`,
						);
					}
				}

				// We always fetch the entire chain of parents for each declaration.
				// (Children/siblings are only analyzed on demand.)

				// Key assumptions behind this squirrely logic:
				//
				// IF a given symbol has two declarations D1 and D2; AND
				// If D1 has a parent P1, then
				// - D2 will also have a parent P2; AND
				// - P1 and P2's symbol will be the same
				// - but P1 and P2 may be different (e.g. merged namespaces containing merged interfaces)

				// Is there a parent AstSymbol?  First we check to see if there is a parent declaration:
				if (arbitraryDeclaration) {
					const arbitraryParentDeclaration: ts.Node | undefined =
						this._tryFindFirstAstDeclarationParent(arbitraryDeclaration);

					if (arbitraryParentDeclaration) {
						const parentSymbol: ts.Symbol = TypeScriptHelpers.getSymbolForDeclaration(
							arbitraryParentDeclaration as ts.Declaration,
							this._typeChecker,
						);

						parentAstSymbol = this._fetchAstSymbol({
							followedSymbol: parentSymbol,
							isExternal: options.isExternal,
							includeNominalAnalysis: false,
							addIfMissing: true,
						});
						if (!parentAstSymbol) {
							throw new InternalError('Unable to construct a parent AstSymbol for ' + followedSymbol.name);
						}
					}
				}
			}

			const localName: string | undefined = options.localName ?? AstSymbolTable.getLocalNameForSymbol(followedSymbol);

			astSymbol = new AstSymbol({
				followedSymbol,
				localName,
				isExternal: options.isExternal,
				nominalAnalysis,
				parentAstSymbol,
				rootAstSymbol: parentAstSymbol ? parentAstSymbol.rootAstSymbol : undefined,
			});

			this._astSymbolsBySymbol.set(followedSymbol, astSymbol);

			// Okay, now while creating the declarations we will wire them up to the
			// their corresponding parent declarations
			for (const declaration of followedSymbol.declarations ?? []) {
				let parentAstDeclaration: AstDeclaration | undefined;
				if (parentAstSymbol) {
					const parentDeclaration: ts.Node | undefined = this._tryFindFirstAstDeclarationParent(declaration);

					if (!parentDeclaration) {
						throw new InternalError('Missing parent declaration');
					}

					parentAstDeclaration = this._astDeclarationsByDeclaration.get(parentDeclaration);
					if (!parentAstDeclaration) {
						throw new InternalError('Missing parent AstDeclaration');
					}
				}

				const astDeclaration: AstDeclaration = new AstDeclaration({
					declaration,
					astSymbol,
					parent: parentAstDeclaration,
				});

				this._astDeclarationsByDeclaration.set(declaration, astDeclaration);
			}
		}

		if (options.isExternal !== astSymbol.isExternal) {
			throw new InternalError(
				`Cannot assign isExternal=${options.isExternal} for` +
					` the symbol ${astSymbol.localName} because it was previously registered` +
					` with isExternal=${astSymbol.isExternal}`,
			);
		}

		return astSymbol;
	}

	/**
	 * Returns the first parent satisfying isAstDeclaration(), or undefined if none is found.
	 */
	private _tryFindFirstAstDeclarationParent(node: ts.Node): ts.Node | undefined {
		let currentNode: ts.Node | undefined = node.parent;
		while (currentNode) {
			if (AstDeclaration.isSupportedSyntaxKind(currentNode.kind)) {
				return currentNode;
			}

			currentNode = currentNode.parent;
		}

		return undefined;
	}
}