Update link branches to main (#146558)

- Update CS and googlesource.com link branches
- Update GitHub /blob/ and /tree/ links

Tested links manually and fixes a few broken or deprecated links

Added a test that validates that `master` isn't used, except for
specified repos.

Part of flutter/flutter#121564

## Pre-launch Checklist

- [x] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [x] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [x] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [x] I signed the [CLA].
- [x] I listed at least one issue that this PR fixes in the description
above.
- [x] I updated/added relevant documentation (doc comments with `///`).
- [x] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [x] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [x] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#overview
[Tree Hygiene]: https://github.com/flutter/flutter/wiki/Tree-hygiene
[test-exempt]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/wiki/Style-guide-for-Flutter-repo#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/wiki/Tree-hygiene#handling-breaking-changes
[Discord]: https://github.com/flutter/flutter/wiki/Chat
[Data Driven Fixes]:
https://github.com/flutter/flutter/wiki/Data-driven-Fixes

Author: guidezpl

.github/workflows/easy-cp.yml

@@ -53,7 +53,7 @@ jobs:
       # TODO(xilaizhang): remove this step once the template is available on release branches.
       - name: Get CP Template
         run: |
-          curl -o PULL_REQUEST_CP_TEMPLATE.md https://raw.githubusercontent.com/flutter/flutter/master/.github/PR_TEMPLATE/PULL_REQUEST_CP_TEMPLATE.md
+          curl -o PULL_REQUEST_CP_TEMPLATE.md https://raw.githubusercontent.com/flutter/flutter/main/.github/PR_TEMPLATE/PULL_REQUEST_CP_TEMPLATE.md
       - name: Create PR on CP success
         if: ${{ steps.attempt-cp.conclusion == 'success' }}
         working-directory: ./flutter

README.md

@@ -25,7 +25,7 @@ open source.
 * [Install Flutter](https://flutter.dev/get-started/)
 * [Flutter documentation](https://docs.flutter.dev/)
 * [Development wiki](https://github.com/flutter/flutter/wiki)
-* [Contributing to Flutter](https://github.com/flutter/flutter/blob/master/CONTRIBUTING.md)
+* [Contributing to Flutter](https://github.com/flutter/flutter/blob/main/CONTRIBUTING.md)
 
 For announcements about new releases, follow the
 [flutter-announce@googlegroups.com](https://groups.google.com/forum/#!forum/flutter-announce)
@@ -121,5 +121,5 @@ Information on how to get started can be found in our
 [macOS FFI]: https://docs.flutter.dev/development/platform-integration/macos/c-interop
 [Windows FFI]: https://docs.flutter.dev/development/platform-integration/windows/building#integrating-with-windows
 [platform channels]: https://docs.flutter.dev/development/platform-integration/platform-channels
-[interop example]: https://github.com/flutter/flutter/tree/master/examples/platform_channel
+[interop example]: https://github.com/flutter/flutter/tree/main/examples/platform_channel
 [Impeller]: https://docs.flutter.dev/perf/impeller

dev/bots/README.md

@@ -61,7 +61,7 @@ actions through `recipe_modules`. Searching the builder config in [infra](https:
 will indicate the recipe used for a test.
 
 Recipes are just Python with some limitations on what can be imported. They are
-[documented](https://github.com/luci/recipes-py/blob/master/doc/user_guide.md)
+[documented](https://github.com/luci/recipes-py/blob/main/doc/user_guide.md)
 by the [luci/recipes-py GitHub project](https://github.com/luci/recipes-py).
 
 The typical cycle for editing a recipe is:

dev/bots/analyze.dart

@@ -109,9 +109,12 @@ Future<void> run(List<String> arguments) async {
   printProgress('Debug mode instead of checked mode...');
   await verifyNoCheckedMode(flutterRoot);
 
-  printProgress('Links for creating GitHub issues');
+  printProgress('Links for creating GitHub issues...');
   await verifyIssueLinks(flutterRoot);
 
+  printProgress('Links to GitHub...');
+  await verifyGitHubLinks(flutterRoot);
+
   printProgress('Unexpected binaries...');
   await verifyNoBinaries(flutterRoot);
 
@@ -1220,7 +1223,7 @@ String _bullets(String value) => ' * $value';
 Future<void> verifyIssueLinks(String workingDirectory) async {
   const String issueLinkPrefix = 'https://github.com/flutter/flutter/issues/new';
   const Set<String> stops = <String>{ '\n', ' ', "'", '"', r'\', ')', '>' };
-  assert(!stops.contains('.')); // instead of "visit https://foo." say "visit: https://", it copy-pastes better
+  assert(!stops.contains('.')); // instead of "visit https://foo." say "visit: https://foo", it copy-pastes better
   const String kGiveTemplates =
     'Prefer to provide a link either to $issueLinkPrefix/choose (the list of issue '
     'templates) or to a specific template directly ($issueLinkPrefix?template=...).\n';
@@ -1291,6 +1294,68 @@ Future<void> verifyIssueLinks(String workingDirectory) async {
   }
 }
 
+Future<void> verifyGitHubLinks(String workingDirectory) async {
+  const Set<String> stops = <String>{ '\n', ' ', "'", '"', r'\', ')', '>' };
+  assert(!stops.contains('.')); // instead of "visit https://foo." say "visit: https://foo", it copy-pastes better
+
+  // Repos whose default branch is still 'master'
+  const Set<String> repoExceptions = <String>{
+    'clojure/clojure',
+    'dart-lang/test', // TODO(guidezpl): remove when https://github.com/dart-lang/test/issues/2209 is closed
+    'eseidelGoogle/bezier_perf',
+    'flutter/devtools', // TODO(guidezpl): remove when https://github.com/flutter/devtools/issues/7551 is closed
+    'flutter/flutter_gallery_assets', // TODO(guidezpl): remove when subtask in https://github.com/flutter/flutter/issues/121564 is complete
+    'flutter/flutter-intellij', // TODO(guidezpl): remove when https://github.com/flutter/flutter-intellij/issues/7342 is closed
+    'flutter/platform_tests', // TODO(guidezpl): remove when subtask in https://github.com/flutter/flutter/issues/121564 is complete
+    'glfw/glfw',
+    'material-components/material-components-android', // TODO(guidezpl): remove when https://github.com/material-components/material-components-android/issues/4144 is closed
+    'torvalds/linux',
+    'tpn/winsdk-10',
+  };
+
+  const List<String> linkPrefixes = <String>[
+    'https://raw.githubusercontent.com/',
+    'https://github.com/',
+  ];
+
+  final List<String> problems = <String>[];
+  final Set<String> suggestions = <String>{};
+  final List<File> files = await _gitFiles(workingDirectory);
+  for (final File file in files) {
+    for (final String linkPrefix in linkPrefixes) {
+      final Uint8List bytes = file.readAsBytesSync();
+      // We allow invalid UTF-8 here so that binaries don't trip us up.
+      // There's a separate test in this file that verifies that all text
+      // files are actually valid UTF-8 (see verifyNoBinaries below).
+      final String contents = utf8.decode(bytes, allowMalformed: true);
+      int start = 0;
+      while ((start = contents.indexOf(linkPrefix, start)) >= 0) {
+        int end = start + linkPrefixes.length;
+        while (end < contents.length && !stops.contains(contents[end])) {
+          end += 1;
+        }
+        final String url = contents.substring(start, end);
+        if (url.startsWith(linkPrefix) && !repoExceptions.any(url.contains)) {
+          if (url.contains('master')) {
+            problems.add('${file.path} contains $url, which uses the banned "master" branch.');
+            suggestions.add('Change the URLs above to the expected pattern by '
+              'using the "main" branch if it exists, otherwise adding the '
+              'repository to the list of exceptions in analyze.dart.');
+          }
+        }
+        start = end;
+      }
+    }
+  }
+  assert(problems.isEmpty == suggestions.isEmpty);
+  if (problems.isNotEmpty) {
+    foundError(<String>[
+      ...problems,
+      ...suggestions,
+    ]);
+  }
+}
+
 @immutable
 class Hash256 {
   const Hash256(this.a, this.b, this.c, this.d);

dev/bots/codelabs_build_test.sh

@@ -29,7 +29,7 @@ if [ ${PIPESTATUS[0]} -eq 0 ] || is_expected_failure "$log_file"; then
   rm "$log_file"
 else
   all_builds_ok=0
-  echo "View https://github.com/flutter/flutter/blob/master/dev/bots/README.md for steps to resolve this failed build test." >> ${log_file}
+  echo "View https://github.com/flutter/flutter/blob/main/dev/bots/README.md for steps to resolve this failed build test." >> ${log_file}
   echo
   echo "Log left in $log_file."
   echo

dev/conductor/core/bin/cli.dart

@@ -13,7 +13,7 @@ import 'package:file/local.dart';
 import 'package:platform/platform.dart';
 import 'package:process/process.dart';
 
-const String readmeUrl = 'https://github.com/flutter/flutter/tree/master/dev/conductor/README.md';
+const String readmeUrl = 'https://github.com/flutter/flutter/tree/main/dev/conductor/README.md';
 
 Future<void> main(List<String> args) async {
   const FileSystem fileSystem = LocalFileSystem();

dev/customer_testing/run_tests.dart

@@ -60,7 +60,7 @@ Future<bool> run(List<String> arguments) async {
   void printHelp() {
     print('run_tests.dart [options...] path/to/file1.test path/to/file2.test...');
     print('For details on the test registry format, see:');
-    print('  https://github.com/flutter/tests/blob/master/registry/template.test');
+    print('  https://github.com/flutter/tests/blob/main/registry/template.test');
     print('');
     print(argParser.usage);
     print('');

dev/devicelab/README.md

@@ -217,7 +217,7 @@ _TASK_- the name of your test that also matches the name of the
   file in `bin/tasks` without the `.dart` extension.
 
 1. Add target to
-   [.ci.yaml](https://github.com/flutter/flutter/blob/master/.ci.yaml)
+   [.ci.yaml](https://github.com/flutter/flutter/blob/main/.ci.yaml)
    * Mirror an existing one that has the recipe `devicelab_drone`
 
 If your test needs to run on multiple operating systems, create a separate
@@ -237,7 +237,7 @@ and the test will run based on the artifact against a testbed with a device.
 
 Steps:
 
-1. Update the task class to extend [`BuildTestTask`](https://github.com/flutter/flutter/blob/master/dev/devicelab/lib/tasks/build_test_task.dart)
+1. Update the task class to extend [`BuildTestTask`](https://github.com/flutter/flutter/blob/main/dev/devicelab/lib/tasks/build_test_task.dart)
    - Override function `getBuildArgs`
    - Override function `getTestArgs`
    - Override function `parseTaskResult`

dev/devicelab/lib/framework/devices.dart

@@ -649,7 +649,7 @@ class AndroidDevice extends Device {
 
   /// Retrieves device's wakefulness state.
   ///
-  /// See: https://android.googlesource.com/platform/frameworks/base/+/master/core/java/android/os/PowerManagerInternal.java
+  /// See: https://android.googlesource.com/platform/frameworks/base/+/main/core/java/android/os/PowerManagerInternal.java
   Future<String> _getWakefulness() async {
     final String powerInfo = await shellEval('dumpsys', <String>['power']);
     // A motoG4 phone returns `mWakefulness=Awake`.

dev/integration_tests/deferred_components_test/run_release_test.sh

@@ -9,7 +9,7 @@
 #
 # In CI, this script currently depends on a modified version of bundletool because
 # ddmlib which bundletool depends on does not yet support detecting QEMU emulator device
-# density system properties. See https://android.googlesource.com/platform/tools/base/+/refs/heads/master/ddmlib/src/main/java/com/android/ddmlib/IDevice.java#46
+# density system properties. See https://android.googlesource.com/platform/tools/base/+/refs/heads/main/ddmlib/src/main/java/com/android/ddmlib/IDevice.java#46
 #
 # The modified bundletool which waives the density requirement is at:
 # https://chrome-infra-packages.appspot.com/p/flutter/android/bundletool/+/vFt1jA0cUeZLmUCVR5NG2JVB-SgJ18GH_pVYKMOlfUIC