[linter] Prepare to rename lint codes to camelCase.

In https://dart-review.googlesource.com/c/sdk/+/444921, which renames
analyzer diagnostics from `SCREAMING_CAPS` to `camelCase`, I failed to
notice that the lint codes use `lower_snake_case`, so they were not
renamed.

This change updates the `rename_error_constants.dart` script so that
it will also rename diagnostics from `lower_snake_case` form. It also
adds a `_useLowerCamelCaseNames` boolean to the linter's error code
generator, so after the updated script is run, the generated code will
match up with the renamed lint error codes.

Change-Id: I6a6a6964d32a17a605947feb4dc07a0677b77191
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/445111
Reviewed-by: Konstantin Shcheglov <[email protected]>
Reviewed-by: Samuel Rawlins <[email protected]>
Commit-Queue: Paul Berry <[email protected]>

Author: stereotype441

pkg/analyzer/tool/messages/rename_error_constants.dart

@@ -6,10 +6,11 @@
 /// camelCase.
 ///
 /// This script analyzes `pkg/analyzer` (and related packages), and renames
-/// every static const error code declaration from SCREAMING_CAPS format to
-/// camelCase format. It also flips the constant `_useLowerCamelCaseNames`
-/// (in `messages/generate.dart`) from `false` to `true`, so that error message
-/// code generation will start generating error codes in camelCase format.
+/// every static const error code declaration from SCREAMING_CAPS or
+/// lower_snake_case format to camelCase format. It also flips the constant
+/// `_useLowerCamelCaseNames` (in `messages/generate.dart` and
+/// `generate_lints.dart`) from `false` to `true`, so that error message code
+/// generation will start generating errorcodes in camelCase format.
 ///
 /// This script will be run once to change the format of all the analyzer error
 /// codes, and then it will be removed from the codebase.
@@ -86,6 +87,8 @@ void main() async {
   }
 }
 
+final _lowerSnakeCaseRegExp = RegExp(r'^[a-z0-9][A-Za-z0-9]*_[A-Za-z0-9_]+$');
+
 final _screamingCapsRegExp = RegExp(r'^[A-Z0-9_]+$');
 
 class _Elements {
@@ -104,8 +107,7 @@ class _Visitor extends RecursiveAstVisitor {
 
   @override
   visitSimpleIdentifier(SimpleIdentifier node) {
-    if (_isScreamingCaps(node.name) &&
-        _isDiagnosticCodeConstant(node.element)) {
+    if (_isSnakeCase(node.name) && _isDiagnosticCodeConstant(node.element)) {
       _edits.add(SourceEdit(node.offset, node.length, node.name.toCamelCase()));
     }
     return super.visitSimpleIdentifier(node);
@@ -114,11 +116,14 @@ class _Visitor extends RecursiveAstVisitor {
   @override
   visitVariableDeclaration(VariableDeclaration node) {
     if (node.name.lexeme == '_useLowerCamelCaseNames' &&
-        path.basename(_file) == 'generate.dart') {
+        const {
+          'generate.dart',
+          'generate_lints.dart',
+        }.contains(path.basename(_file))) {
       _edits.add(
         SourceEdit(node.initializer!.offset, node.initializer!.length, 'true'),
       );
-    } else if (_isScreamingCaps(node.name.lexeme) &&
+    } else if (_isSnakeCase(node.name.lexeme) &&
         _isDiagnosticCodeConstant(node.declaredFragment?.element)) {
       _edits.add(
         SourceEdit(
@@ -148,5 +153,6 @@ class _Visitor extends RecursiveAstVisitor {
     );
   }
 
-  bool _isScreamingCaps(String s) => _screamingCapsRegExp.hasMatch(s);
+  bool _isSnakeCase(String s) =>
+      _screamingCapsRegExp.hasMatch(s) || _lowerSnakeCaseRegExp.hasMatch(s);
 }

pkg/linter/tool/generate_lints.dart

@@ -6,6 +6,7 @@
 /// the entries in `pkg/linter/messages.yaml`.
 library;
 
+import 'package:analyzer/src/utilities/extensions/string.dart';
 import 'package:analyzer_testing/package_root.dart' as pkg_root;
 import 'package:analyzer_utilities/tools.dart';
 
@@ -34,6 +35,14 @@ const linterLintCodeInfo = ErrorClassInfo(
   type: 'LINT',
 );
 
+/// 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;
+
 GeneratedFile get generatedCodesFile =>
     GeneratedFile(generatedCodesPath, (pkgRoot) async {
       var out = StringBuffer('''
@@ -69,7 +78,9 @@ class LinterLintCode extends LintCode {
         if (codeInfo.deprecatedMessage case var deprecatedMessage?) {
           out.writeln('  @Deprecated("$deprecatedMessage")');
         }
-        out.writeln('  static const LintCode $errorName =');
+        var constantName =
+            _useLowerCamelCaseNames ? errorName.toCamelCase() : errorName;
+        out.writeln('  static const LintCode $constantName =');
         out.writeln(
           codeInfo.toAnalyzerCode(
             linterLintCodeInfo,
@@ -81,11 +92,13 @@ class LinterLintCode extends LintCode {
         out.writeln();
       }
 
+      var removedLintName =
+          _useLowerCamelCaseNames ? 'removedLint' : 'removed_lint';
       out.writeln('''
   /// A lint code that removed lints can specify as their `lintCode`.
   ///
   /// Avoid other usages as it should be made unnecessary and removed.
-  static const LintCode removed_lint = LinterLintCode(
+  static const LintCode $removedLintName = LinterLintCode(
     'removed_lint',
     'Removed lint.',
   );