From 00a7a261bcf4438b06984879185e0e7c02da0bd2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=E3=81=AA=E3=81=A4=E3=81=8D?= <i@ntk.me>
Date: Tue, 16 Apr 2024 21:49:21 -0700
Subject: [PATCH] Emulate base importer inside LegacyImporterWrapper to track
 access to containingUrl

---
 lib/src/legacy/importer.ts | 26 +++++++++++++++++++++++++-
 lib/src/legacy/index.ts    | 19 ++++++++++++++-----
 2 files changed, 39 insertions(+), 6 deletions(-)

diff --git a/lib/src/legacy/importer.ts b/lib/src/legacy/importer.ts
index 97ef9117..5977a3d5 100644
--- a/lib/src/legacy/importer.ts
+++ b/lib/src/legacy/importer.ts
@@ -86,10 +86,34 @@ export class LegacyImporterWrapper<sync extends 'sync' | 'async'>
 
   canonicalize(
     url: string,
-    options: {fromImport: boolean}
+    options: {fromImport: boolean; containingUrl: URL | null}
   ): PromiseOr<URL | null, sync> {
     if (url.startsWith(endOfLoadProtocol)) return new URL(url);
 
+    // Emulate a base importer instead of using a real base importer,
+    // because we want to mark containingUrl as used, which is impossible
+    // in a real base importer.
+    if (options.containingUrl !== null) {
+      try {
+        const absoluteUrl = new URL(url, options.containingUrl).toString();
+        const resolved = this.canonicalize(absoluteUrl, {
+          fromImport: options.fromImport,
+          containingUrl: null,
+        });
+        if (resolved !== null) return resolved;
+      } catch (error: unknown) {
+        if (
+          error instanceof TypeError &&
+          isErrnoException(error) &&
+          error.code === 'ERR_INVALID_URL'
+        ) {
+          // ignore
+        } else {
+          throw error;
+        }
+      }
+    }
+
     if (
       url.startsWith(legacyImporterProtocolPrefix) ||
       url.startsWith(legacyImporterProtocol)
diff --git a/lib/src/legacy/index.ts b/lib/src/legacy/index.ts
index 404937cf..d7543e35 100644
--- a/lib/src/legacy/index.ts
+++ b/lib/src/legacy/index.ts
@@ -184,11 +184,20 @@ function convertStringOptions<sync extends 'sync' | 'async'>(
 ): StringOptions<sync> & {legacy: true} {
   const modernOptions = convertOptions(options, sync);
 
-  // Find the first non-NodePackageImporter to pass as legacy `importer` option.
-  // NodePackageImporter will be passed in `modernOptions.importers`.
-  const importer = modernOptions.importers?.find(
-    _importer => !(_importer instanceof NodePackageImporter)
-  ) as Importer<sync> | FileImporter<sync>;
+  // Use a no-op base importer, because the LegacyImporterWrapper will emulate
+  // the base importer by itself in order to mark containingUrl as accessed.
+  const importer = modernOptions.importers?.some(
+    importer => importer instanceof LegacyImporterWrapper
+  )
+    ? {
+        canonicalize() {
+          return null;
+        },
+        load() {
+          return null;
+        },
+      }
+    : undefined;
 
   return {
     ...modernOptions,