[analyzer] Prepare to rename error codes to camelCase.

A temporary script is added,
`pkg/analyzer/tool/messages/rename_error_constants.dart`, which will
rename every error code in the analyzer (and related packages) from
SCREAMING_CAPS to camelCase.

Also, the error message code generator is enhanced so that it can
generate error codes using either SCREAMING_CAPS or camelCase, based
on the setting of a temporary constant, `_useLowerCamelCaseNames`. The
constant is currently set to `false`; `rename_error_constants.dart`
will change it to `true`.

There are a few references to the old SCREAMING_CAPS names that won't
be able to be automatically addressed by the script. To avoid
breakages, a mechanism has been added to the error message code
generator to preserve those names after the migration, as deprecated
aliases. The names that will be preserved are listed in the
`ErrorClassInfo.deprecatedSnakeCaseNames` field, in
`error_code_info.dart`. These will be cleaned up in future CLs.

Once the rename is complete, the temporary script and constant will be
removed.

Change-Id: I6a6a69640b077c6bc4da92cec97686e4b2c3b906
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/444920
Reviewed-by: Konstantin Shcheglov <[email protected]>
Reviewed-by: Moritz Sümmermann <[email protected]>
Commit-Queue: Paul Berry <[email protected]>

Author: stereotype441

pkg/analyzer/lib/src/utilities/extensions/string.dart

@@ -160,6 +160,33 @@ extension StringExtension on String {
     }
   }
 
+  /// Converts `SCREAMING_SNAKE_CASE` or `snake_case` to `camelCase`.
+  String toCamelCase() {
+    var parts = toLowerCase().split('_');
+    var buffer = StringBuffer();
+    var i = 0;
+    // Preserve initial '_'s
+    while (i < parts.length - 1 && parts[i].isEmpty) {
+      buffer.write('_');
+      ++i;
+    }
+    if (i < parts.length) {
+      // Convert first word to lower case
+      buffer.write(parts[i].toLowerCase());
+      ++i;
+      // Convert remaining words to initial upper case
+      while (i < parts.length) {
+        var part = parts[i];
+        if (part.isNotEmpty) {
+          buffer.write(part[0].toUpperCase());
+          buffer.write(part.substring(1));
+        }
+        ++i;
+      }
+    }
+    return buffer.toString();
+  }
+
   /// Converts `camelCase` / `PascalCase` to `SCREAMING_SNAKE_CASE`.
   /// Examples:
   ///  - camelCase        -> CAMEL_CASE

pkg/analyzer/pubspec.yaml

@@ -31,6 +31,7 @@ dependencies:
 # See also https://dart.dev/tools/pub/dependencies.
 dev_dependencies:
   analysis_server_client: any
+  analyzer_plugin: any
   analyzer_testing: any
   analyzer_utilities: any
   args: any

pkg/analyzer/test/src/utilities/extensions/string_test.dart

@@ -197,6 +197,18 @@ class StringExtensionTest {
     expect('01234'.removeSuffix('5'), isNull);
   }
 
+  void test_toCamelCase() {
+    expect('CAMEL_CASE'.toCamelCase(), 'camelCase');
+    expect('alreadyCamel_case'.toCamelCase(), 'alreadycamelCase');
+    expect('FOO_123_BAR'.toCamelCase(), 'foo123Bar');
+    expect('FOO'.toCamelCase(), 'foo');
+    expect('___'.toCamelCase(), '___');
+    expect(''.toCamelCase(), '');
+    expect('_FOO_BAR'.toCamelCase(), '_fooBar');
+    expect('FOO__BAR'.toCamelCase(), 'fooBar');
+    expect('FOO_BAR_'.toCamelCase(), 'fooBar');
+  }
+
   void test_toScreamingSnake() {
     expect('camelCase'.toScreamingSnake(), 'CAMEL_CASE');
     expect('HTTPRequest'.toScreamingSnake(), 'HTTP_REQUEST');

pkg/analyzer/tool/messages/error_code_info.dart

@@ -34,6 +34,13 @@ const List<ErrorClassInfo> errorClasses = [
     file: codesFile,
     name: 'CompileTimeErrorCode',
     type: 'COMPILE_TIME_ERROR',
+    deprecatedSnakeCaseNames: {
+      'IMPORT_INTERNAL_LIBRARY', // Referenced by `verify_docs.dart`.
+      'INSTANCE_ACCESS_TO_STATIC_MEMBER', // Referenced by `messages.yaml`.
+      'INVALID_OVERRIDE', // Referenced by `messages.yaml`.
+      'TYPE_ARGUMENT_NOT_MATCHING_BOUNDS', // Referenced by `messages.yaml`.
+      'UNDEFINED_CLASS', // Referenced by `messages.yaml`.
+    },
   ),
   ErrorClassInfo(
     file: scannerErrorFile,
@@ -51,19 +58,35 @@ const List<ErrorClassInfo> errorClasses = [
     name: 'WarningCode',
     type: 'STATIC_WARNING',
     severity: 'WARNING',
+    deprecatedSnakeCaseNames: {
+      'UNUSED_ELEMENT', // Referenced by `verify_docs.dart`.
+      'UNUSED_IMPORT', // Referenced by `verify_docs.dart`.
+      'UNUSED_LOCAL_VARIABLE', // Referenced by `verify_docs.dart`.
+    },
   ),
   ErrorClassInfo(
     file: ffiCodesFile,
     name: 'FfiCode',
     type: 'COMPILE_TIME_ERROR',
   ),
-  ErrorClassInfo(file: hintCodesFile, name: 'HintCode', type: 'HINT'),
+  ErrorClassInfo(
+    file: hintCodesFile,
+    name: 'HintCode',
+    type: 'HINT',
+    deprecatedSnakeCaseNames: {
+      'UNNECESSARY_IMPORT', // Referenced by `verify_docs.dart`.
+    },
+  ),
   ErrorClassInfo(
     file: syntacticErrorsFile,
     name: 'ParserErrorCode',
     type: 'SYNTACTIC_ERROR',
     severity: 'ERROR',
     includeCfeMessages: true,
+    deprecatedSnakeCaseNames: {
+      'EXPERIMENT_NOT_ENABLED', // Referenced by `messages.yaml`.
+      'UNEXPECTED_TOKEN', // Referenced by `package:dart_style`.
+    },
   ),
   ErrorClassInfo(
     file: manifestWarningCodeFile,
@@ -492,6 +515,11 @@ class ErrorClassInfo {
   /// The type of errors in this class.
   final String type;
 
+  /// The names of any errors which are relied upon by analyzer clients, and
+  /// therefore will need their "snake case" form preserved (with a deprecation
+  /// notice) after migration to camel case error codes.
+  final Set<String> deprecatedSnakeCaseNames;
+
   const ErrorClassInfo({
     this.extraImports = const [],
     required this.file,
@@ -500,6 +528,7 @@ class ErrorClassInfo {
     this.severity,
     this.superclass = 'DiagnosticCode',
     required this.type,
+    this.deprecatedSnakeCaseNames = const {},
   });
 
   /// Generates the code to compute the severity of errors of this class.

pkg/analyzer/tool/messages/generate.dart

@@ -19,6 +19,7 @@ library;
 import 'dart:convert';
 import 'dart:io';
 
+import 'package:analyzer/src/utilities/extensions/string.dart';
 import 'package:analyzer_testing/package_root.dart' as pkg_root;
 import 'package:analyzer_utilities/tools.dart';
 import 'package:collection/collection.dart';
@@ -34,6 +35,14 @@ Future<void> main() async {
     ..printSummary();
 }
 
+/// Whether the error constants that should be generated should use camel-case
+/// names.
+///
+/// This is a temporary flag to allow the codebase to be transitioned to using
+/// camel-case error constants. TODO(paulberry): once the transition is
+/// complete, remove this constant.
+const _useLowerCamelCaseNames = false;
+
 /// A list of all targets generated by this code generator.
 final List<GeneratedContent> allTargets = _analyzerGeneratedFiles();
 
@@ -44,7 +53,7 @@ List<GeneratedContent> _analyzerGeneratedFiles() {
   for (var errorClassInfo in errorClasses) {
     (classesByFile[errorClassInfo.file] ??= []).add(errorClassInfo);
   }
-  var generatedCodes = <String>[];
+  var generatedCodes = <(String, String)>[];
   return [
     for (var entry in classesByFile.entries)
       GeneratedFile(entry.key.path, (pkgRoot) async {
@@ -72,7 +81,7 @@ class _AnalyzerErrorGenerator {
 
   final List<ErrorClassInfo> errorClasses;
 
-  final List<String> generatedCodes;
+  final List<(String, String)> generatedCodes;
 
   final StringBuffer out = StringBuffer('''
 // Copyright (c) 2021, the Dart project authors. Please see the AUTHORS file
@@ -154,15 +163,26 @@ library;
             );
             out.writeln('${errorCodeInfo.aliasFor};');
           } else {
-            generatedCodes.add('${errorClass.name}.$errorName');
-            out.writeln('  static const ${errorClass.name} $errorName =');
+            generatedCodes.add((errorClass.name, errorName));
+            var constantName =
+                _useLowerCamelCaseNames ? errorName.toCamelCase() : errorName;
+            out.writeln('  static const ${errorClass.name} $constantName =');
             out.writeln(
               errorCodeInfo.toAnalyzerCode(
                 errorClass,
                 errorName,
                 useExplicitConst: file.shouldUseExplicitConst,
               ),
             );
+
+            if (_useLowerCamelCaseNames &&
+                errorClass.deprecatedSnakeCaseNames.contains(errorName)) {
+              out.writeln();
+              out.writeln('  @Deprecated("Please use $constantName")');
+              out.writeln(
+                '  static const ${errorClass.name} $errorName = $constantName;',
+              );
+            }
           }
         } catch (e, st) {
           Error.throwWithStackTrace(
@@ -205,14 +225,17 @@ library;
     out.writeln('final fastaAnalyzerErrorCodes = <DiagnosticCode?>[');
     for (var entry in cfeToAnalyzerErrorCodeTables.indexToInfo) {
       var name = cfeToAnalyzerErrorCodeTables.infoToAnalyzerCode[entry];
+      if (_useLowerCamelCaseNames) {
+        name = name?.toCamelCase();
+      }
       out.writeln('${name == null ? 'null' : 'ParserErrorCode.$name'},');
     }
     out.writeln('];');
   }
 }
 
 class _DiagnosticCodeValuesGenerator {
-  final List<String> generatedCodes;
+  final List<(String, String)> generatedCodes;
 
   final StringBuffer out = StringBuffer('''
 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file
@@ -239,12 +262,12 @@ class _DiagnosticCodeValuesGenerator {
     // The scanner error codes are not yet being generated, so we need to add
     // them to the list explicitly.
     generatedCodes.addAll([
-      'TodoCode.TODO',
-      'TodoCode.FIXME',
-      'TodoCode.HACK',
-      'TodoCode.UNDONE',
+      ('TodoCode', 'TODO'),
+      ('TodoCode', 'FIXME'),
+      ('TodoCode', 'HACK'),
+      ('TodoCode', 'UNDONE'),
     ]);
-    generatedCodes.sort();
+    generatedCodes.sortBy((x) => '${x.$1}.${x.$2}');
 
     out.writeln();
     out.writeln(r'''
@@ -261,8 +284,11 @@ import 'package:analyzer/src/pubspec/pubspec_warning_code.dart';
       "@AnalyzerPublicApi(message: 'exported by lib/error/error.dart')",
     );
     out.writeln('const List<DiagnosticCode> diagnosticCodeValues = [');
-    for (var name in generatedCodes) {
-      out.writeln('  $name,');
+    for (var (className, errorName) in generatedCodes) {
+      if (_useLowerCamelCaseNames) {
+        errorName = errorName.toCamelCase();
+      }
+      out.writeln('  $className.$errorName,');
     }
     out.writeln('];');
     out.writeln();