keep our own self-name resolving

packages/core/src/module-resolver.ts

@@ -11,6 +11,7 @@ import { explicitRelative, RewrittenPackageCache } from '@embroider/shared-inter
 import makeDebug from 'debug';
 import assertNever from 'assert-never';
 import reversePackageExports from '@embroider/reverse-exports';
+import { exports as resolveExports } from 'resolve.exports';
 
 import {
   virtualExternalESModule,
@@ -946,13 +947,10 @@ export class Resolver {
             .withMeta({ originalFromFile: request.fromFile })
             .rehome(resolve(originalRequestingPkg.root, 'package.json'))
         );
-      }
-      // TODO is this the right check for this?
-      else if (packageName !== requestingPkg.name) {
+      } else {
         // requesting package was moved and we failed to find its target. We
         // can't let that accidentally succeed in the defaultResolve because we
         // could escape the moved package system.
-        // and it's not a self reference
         return logTransition('missing outbound request from moved package', request, request.notFound());
       }
     }
@@ -1018,6 +1016,26 @@ export class Resolver {
           request,
           request.alias(selfImportPath).rehome(resolve(pkg.root, 'package.json'))
         );
+      } else {
+        // v2 packages are supposed to use package.json `exports` to enable
+        // self-imports, but not all build tools actually follow the spec. This
+        // is a workaround for badly behaved packagers.
+        //
+        // Known upstream bugs this works around:
+        // - https://github.com/vitejs/vite/issues/9731
+        if (pkg.packageJSON.exports) {
+          let found = resolveExports(pkg.packageJSON, request.specifier, {
+            browser: true,
+            conditions: ['default', 'imports'],
+          });
+          if (found?.[0]) {
+            return logTransition(
+              `v2 self-import with package.json exports`,
+              request,
+              request.alias(found?.[0]).rehome(resolve(pkg.root, 'package.json'))
+            );
+          }
+        }
       }
     }
 

packages/core/src/node-resolve.ts

@@ -1,12 +1,10 @@
 import { virtualContent } from './virtual-content';
-import { dirname, join } from 'path';
-import { packageName as getPackageName } from '@embroider/shared-internals';
+import { dirname, resolve, isAbsolute } from 'path';
+import { explicitRelative } from '@embroider/shared-internals';
 import assertNever from 'assert-never';
-import { exports as resolveExports } from 'resolve.exports';
 
 // these would be circular, but they're type-only so it's fine
 import type { ModuleRequest, Resolution, Resolver } from './module-resolver';
-import { existsSync } from 'fs-extra';
 
 export class NodeModuleRequest implements ModuleRequest {
   constructor(
@@ -104,24 +102,12 @@ export class NodeModuleRequest implements ModuleRequest {
     // We can do the path adjustments before doing require.resolve.
     let { specifier } = request;
     let fromDir = dirname(request.fromFile);
-
-    let packageName = getPackageName(request.specifier);
-
-    let pkg = this.resolver.packageCache.ownerOfFile(request.fromFile);
-
-    // check for self reference
-    if (packageName && pkg?.name === packageName && pkg.packageJSON.exports) {
-      let found = resolveExports(pkg.packageJSON, request.specifier, {
-        browser: true,
-        conditions: ['default', 'imports'],
-      });
-      if (found?.[0]) {
-        let filename = join(pkg.root, found?.[0]);
-
-        // only resolve to this file if it exists, otherwise fallback to other behaviour
-        if (existsSync(filename)) {
-          return { type: 'found', filename, result: { type: 'real' as 'real', filename }, isVirtual: false };
-        }
+    if (!isAbsolute(specifier) && specifier.startsWith('.')) {
+      let targetPath = resolve(fromDir, specifier);
+      let newFromDir = dirname(targetPath);
+      if (fromDir !== newFromDir) {
+        specifier = explicitRelative(newFromDir, targetPath);
+        fromDir = newFromDir;
       }
     }