From aace364df38db741efe964e068f72d4e4b0bdef3 Mon Sep 17 00:00:00 2001
From: Tobias Koppers <tobias.koppers@googlemail.com>
Date: Fri, 21 Feb 2020 11:15:20 +0100
Subject: [PATCH] avoid crashing when exports info contains a circular
 reference

e. g. when using

import * as self from "./self";
export { self }
---
 lib/ModuleInfoHeaderPlugin.js                 | 62 ++++++++++++++++---
 ...armonyExportImportedSpecifierDependency.js | 14 ++++-
 2 files changed, 65 insertions(+), 11 deletions(-)

diff --git a/lib/ModuleInfoHeaderPlugin.js b/lib/ModuleInfoHeaderPlugin.js
index 1cef3d88a..e799e61a2 100644
--- a/lib/ModuleInfoHeaderPlugin.js
+++ b/lib/ModuleInfoHeaderPlugin.js
@@ -28,9 +28,36 @@ const joinIterableWithComma = iterable => {
 	return str;
 };
 
-const printExportsInfoToSource = (source, indent, exportsInfo) => {
-	let hasExports = false;
+const printExportsInfoToSource = (
+	source,
+	indent,
+	exportsInfo,
+	alreadyPrinted = new Set()
+) => {
+	const otherExportsInfo = exportsInfo.otherExportsInfo;
+
+	let alreadyPrintedExports = 0;
+
+	// determine exports to print
+	const printedExports = [];
 	for (const exportInfo of exportsInfo.orderedExports) {
+		if (!alreadyPrinted.has(exportInfo)) {
+			alreadyPrinted.add(exportInfo);
+			printedExports.push(exportInfo);
+		} else {
+			alreadyPrintedExports++;
+		}
+	}
+	let showOtherExports = false;
+	if (!alreadyPrinted.has(otherExportsInfo)) {
+		alreadyPrinted.add(otherExportsInfo);
+		showOtherExports = true;
+	} else {
+		alreadyPrintedExports++;
+	}
+
+	// print the exports
+	for (const exportInfo of printedExports) {
 		source.add(
 			Template.toComment(
 				`${indent}export ${JSON.stringify(exportInfo.name).slice(
@@ -40,20 +67,39 @@ const printExportsInfoToSource = (source, indent, exportsInfo) => {
 			) + "\n"
 		);
 		if (exportInfo.exportsInfo) {
-			printExportsInfoToSource(source, indent + "  ", exportInfo.exportsInfo);
+			printExportsInfoToSource(
+				source,
+				indent + "  ",
+				exportInfo.exportsInfo,
+				alreadyPrinted
+			);
 		}
-		hasExports = true;
 	}
 
-	const otherExportsInfo = exportsInfo.otherExportsInfo;
-	if (otherExportsInfo.provided !== false || otherExportsInfo.used !== false) {
-		const title = hasExports ? "other exports" : "exports";
+	if (alreadyPrintedExports) {
 		source.add(
 			Template.toComment(
-				`${indent}${title} [${otherExportsInfo.getProvidedInfo()}] [${otherExportsInfo.getUsedInfo()}]`
+				`${indent}... (${alreadyPrintedExports} already listed exports)`
 			) + "\n"
 		);
 	}
+
+	if (showOtherExports) {
+		if (
+			otherExportsInfo.provided !== false ||
+			otherExportsInfo.used !== false
+		) {
+			const title =
+				printedExports.length > 0 || alreadyPrintedExports > 0
+					? "other exports"
+					: "exports";
+			source.add(
+				Template.toComment(
+					`${indent}${title} [${otherExportsInfo.getProvidedInfo()}] [${otherExportsInfo.getUsedInfo()}]`
+				) + "\n"
+			);
+		}
+	}
 };
 
 class ModuleInfoHeaderPlugin {
diff --git a/lib/dependencies/HarmonyExportImportedSpecifierDependency.js b/lib/dependencies/HarmonyExportImportedSpecifierDependency.js
index 31dc373b3..130809661 100644
--- a/lib/dependencies/HarmonyExportImportedSpecifierDependency.js
+++ b/lib/dependencies/HarmonyExportImportedSpecifierDependency.js
@@ -40,16 +40,23 @@ const EMPTY_MAP = new Map();
 const EMPTY_SET = new Set();
 
 /**
- *
  * @param {string[][]} referencedExports list of referenced exports, will be added to
  * @param {string[]} prefix export prefix
  * @param {ExportInfo} exportInfo the export info
+ * @param {Set<ExportInfo>} alreadyVisited already visited export info (to handle circular reexports)
  */
-const processExportInfo = (referencedExports, prefix, exportInfo) => {
+const processExportInfo = (
+	referencedExports,
+	prefix,
+	exportInfo,
+	alreadyVisited = new Set()
+) => {
 	if (!exportInfo) {
 		referencedExports.push(prefix);
 		return;
 	}
+	if (alreadyVisited.has(exportInfo)) return;
+	alreadyVisited.add(exportInfo);
 	if (exportInfo.used === UsageState.Unused) return;
 	if (
 		exportInfo.used !== UsageState.OnlyPropertiesUsed ||
@@ -64,7 +71,8 @@ const processExportInfo = (referencedExports, prefix, exportInfo) => {
 		processExportInfo(
 			referencedExports,
 			prefix.concat(exportInfo.name),
-			exportInfo
+			exportInfo,
+			alreadyVisited
 		);
 	}
 };