[dynamic_modules] Add support for deduplicating library prefixes to dart2wasm

Change-Id: I325e4e1e3aff25c4e894bc2f3f23fcf02f15da16
Fixes: https://github.com/dart-lang/sdk/issues/62828
Tested: Dynamic module tests.
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/485980
Commit-Queue: Alexander Markov <alexmarkov@google.com>
Reviewed-by: Alexander Markov <alexmarkov@google.com>
Auto-Submit: Nate Biggs <natebiggs@google.com>

pkg/dart2bytecode/lib/dart2bytecode.dart

@@ -15,7 +15,7 @@ import 'package:front_end/src/api_unstable/vm.dart'
         parseExperimentalArguments,
         parseExperimentalFlags,
         resolveInputUri;
-import 'package:kernel/ast.dart' show Component, Library, Source;
+import 'package:kernel/ast.dart' show Component;
 import 'package:vm/kernel_front_end.dart'
     show
         badUsageExitCode,
@@ -30,6 +30,8 @@ import 'package:vm/kernel_front_end.dart'
         parseCommandLineDefines,
         successExitCode,
         writeDepfile;
+import 'package:vm/transformations/prefix_library_uris.dart'
+    as prefix_library_uris;
 
 import 'bytecode_serialization.dart' show BytecodeSizeStatistics;
 import 'bytecode_generator.dart' show generateBytecode;
@@ -260,8 +262,8 @@ Future<int> runCompilerWithOptions({
   if (errorDetector.hasCompilationErrors || component == null) {
     return compileTimeErrorExitCode;
   }
-  component =
-      prefixLibraryUris(component, results.loadedLibraries, libraryUrisPrefix);
+  component = prefix_library_uris.prefixLibraryUris(
+      component, results.loadedLibraries, libraryUrisPrefix);
   if (bytecodeOptions.showBytecodeSizeStatistics) {
     BytecodeSizeStatistics.reset();
   }
@@ -291,57 +293,3 @@ Future<int> runCompilerWithOptions({
 
   return successExitCode;
 }
-
-Component prefixLibraryUris(Component component, Set<Library> loadedLibraries,
-    String libraryUrisPrefix) {
-  if (libraryUrisPrefix.isEmpty) {
-    return component;
-  }
-  final prefixSegments = libraryUrisPrefix.split('/');
-  final importUriReplacements = <Uri, Uri>{};
-
-  for (final lib in component.libraries) {
-    // Skip libraries that come from the host app or the SDK.
-    if (loadedLibraries.contains(lib)) {
-      continue;
-    }
-    final newImportUri = prefixUri(lib.importUri, prefixSegments);
-    importUriReplacements[lib.importUri] = newImportUri;
-    lib.importUri = newImportUri;
-  }
-
-  // Update import uris in sources.
-  final allSourceFileUris = component.uriToSource.keys.toSet();
-  for (final fileUri in allSourceFileUris) {
-    final source = component.uriToSource[fileUri]!;
-    final importUriReplacement = importUriReplacements[source.importUri];
-    if (importUriReplacement == null) {
-      continue;
-    }
-
-    // Rewrite the source with the new import URI.
-    component.uriToSource[fileUri] = Source(
-      source.lineStarts,
-      source.source,
-      importUriReplacement,
-      source.fileUri,
-    )
-      ..cachedText = source.cachedText
-      ..constantCoverageConstructors = source.constantCoverageConstructors;
-  }
-
-  return component;
-}
-
-Uri prefixUri(Uri uri, List<String> prefixSegments) {
-  if (uri.scheme == 'package') {
-    // For package URIs, the first segment is dot-separated package path, so
-    // we prepend the prefix to the first segment.
-    final pathSegments = uri.pathSegments.toList();
-    pathSegments[0] = [...prefixSegments, pathSegments.first].join('.');
-    return uri.replace(pathSegments: pathSegments);
-  }
-
-  // For other schemes, we just prepend the prefix to the path segments.
-  return uri.replace(pathSegments: prefixSegments.followedBy(uri.pathSegments));
-}

pkg/dart2bytecode/test/dart2bytecode_test.dart

@@ -1,18 +0,0 @@
-// Copyright (c) 2026, the Dart project authors.  Please see the AUTHORS file
-// for details. All rights reserved. Use of this source code is governed by a
-// BSD-style license that can be found in the LICENSE file.
-import 'package:dart2bytecode/dart2bytecode.dart' show prefixUri;
-import 'package:test/test.dart';
-
-void main() {
-  group('prefixUri', () {
-    test('prefixes file URIs', () {
-      expect(prefixUri(Uri.parse('file:///foo/bar.dart'), ['pre', 'fix']),
-          Uri.parse('file:///pre/fix/foo/bar.dart'));
-    });
-    test('prefixes package URIs', () {
-      expect(prefixUri(Uri.parse('package:foo/bar.dart'), ['pre', 'fix']),
-          Uri.parse('package:pre.fix.foo/bar.dart'));
-    });
-  });
-}