Remove support for fixes and --fix. (#1564)

The tools that come with the Dart SDK provide two ways to apply automated changes to code: `dart format --fix` and `dart fix`. The former is older and used to be faster. But it can only apply a few fixes and hasn't been maintained in many years. The `dart fix` command is actively maintained, can apply all of the fixes that `dart format --fix` could apply and many many more.

In order to avoid duplicate engineering effort, we decided to consolidate on `dart fix` as the one way to make automated changes that go beyond the simple formatting and style changes that `dart format` applies.

The ability to apply fixes is also removed from the `DartFormatter()` library API.

Author: munificent

CHANGELOG.md

@@ -1,6 +1,38 @@
 ## 3.0.0-wip
 
-* Make the language version parameter to `DartFormatter()` mandatory.
+* **Remove support for fixes and `--fix`.** The tools that come with the Dart
+  SDK provide two ways to apply automated changes to code: `dart format --fix`
+  and `dart fix`. The former is older and used to be faster. But it can only
+  apply a few fixes and hasn't been maintained in many years. The `dart fix`
+  command is actively maintained, can apply all of the fixes that
+  `dart format --fix` could apply and many many more.
+
+  In order to avoid duplicate engineering effort, we decided to consolidate on
+  `dart fix` as the one way to make automated changes that go beyond the simple
+  formatting and style changes that `dart format` applies.
+
+  The ability to apply fixes is also removed from the `DartFormatter()` library
+  API.
+
+* **Make the language version parameter to `DartFormatter()` mandatory.** This
+  way, the formatter always knows what language version the input is intended
+  to be treated as. Note that a `// @dart=` language version comment if present
+  overrides the specified language version. You can think of the version passed
+  to the `DartFormatter()` constructor as a "default" language version which
+  the file's contents may then override.
+
+  If you don't particularly care about the version of what you're formatting,
+  you can pass in `DartFormatter.latestLanguageVersion` to unconditionally get
+  the latest language version that the formatter supports. Note that doing so
+  means you will also implicitly opt into the new tall style when that style
+  becomes available.
+
+  This change only affects the library API. When using the formatter from the
+  command line, you can use `--language-version=` to specify a language version
+  or pass `--language-version=latest` to use the latest supported version. If
+  omitted, the formatter will look up the surrounding directories for a package
+  config file and infer the language version for the package from that, similar
+  to how other Dart tools behave like `dart analyze` and `dart run`.
 
 ## 2.3.7
 

README.md

@@ -32,29 +32,6 @@ if (tag == 'style' ||
 The formatter will never break your code—you can safely invoke it
 automatically from build and presubmit scripts.
 
-## Style fixes
-
-The formatter can also apply non-whitespace changes to make your code
-consistently idiomatic. You must opt into these by passing either `--fix` which
-applies all style fixes, or any of the `--fix-`-prefixed flags to apply specific
-fixes.
-
-For example, running with `--fix-named-default-separator` changes this:
-
-```dart
-greet(String name, {String title: "Captain"}) {
-  print("Greetings, $title $name!");
-}
-```
-
-into:
-
-```dart
-greet(String name, {String title = "Captain"}) {
-  print("Greetings, $title $name!");
-}
-```
-
 ## Using the formatter
 
 The formatter is part of the unified [`dart`][] developer tool included in the

bin/format.dart

@@ -10,7 +10,6 @@ import 'package:dart_style/src/cli/output.dart';
 import 'package:dart_style/src/cli/show.dart';
 import 'package:dart_style/src/cli/summary.dart';
 import 'package:dart_style/src/io.dart';
-import 'package:dart_style/src/short/style_fix.dart';
 
 void main(List<String> args) async {
   var parser = ArgParser(allowTrailingOptions: true);
@@ -108,18 +107,6 @@ void main(List<String> args) async {
 
   var followLinks = argResults['follow-links'] as bool;
 
-  var fixes = <StyleFix>[];
-  if (argResults['fix'] as bool) fixes.addAll(StyleFix.all);
-  for (var fix in StyleFix.all) {
-    if (argResults['fix-${fix.name}'] as bool) {
-      if (argResults['fix'] as bool) {
-        usageError(parser, '--fix-${fix.name} is redundant with --fix.');
-      }
-
-      fixes.add(fix);
-    }
-  }
-
   if (argResults.wasParsed('stdin-name') && argResults.rest.isNotEmpty) {
     usageError(parser, 'Cannot pass --stdin-name when not reading from stdin.');
   }
@@ -128,7 +115,6 @@ void main(List<String> args) async {
       indent: indent,
       pageWidth: pageWidth,
       followLinks: followLinks,
-      fixes: fixes,
       show: show,
       output: output,
       summary: summary,

example/format.dart

@@ -76,7 +76,6 @@ Future<void> _runTest(String path, int line,
       languageVersion: formatTest.languageVersion,
       pageWidth: testFile.pageWidth,
       indent: formatTest.leadingIndent,
-      fixes: formatTest.fixes,
       experimentFlags: tall
           ? const ['inline-class', tallStyleExperimentFlag]
           : const ['inline-class']);

lib/dart_style.dart

@@ -3,5 +3,4 @@
 // BSD-style license that can be found in the LICENSE file.
 export 'src/dart_formatter.dart';
 export 'src/exceptions.dart';
-export 'src/short/style_fix.dart';
 export 'src/source_code.dart';

lib/src/cli/format_command.dart

@@ -8,7 +8,6 @@ import 'package:pub_semver/pub_semver.dart';
 
 import '../dart_formatter.dart';
 import '../io.dart';
-import '../short/style_fix.dart';
 import 'formatter_options.dart';
 import 'options.dart';
 import 'output.dart';
@@ -116,18 +115,6 @@ class FormatCommand extends Command<int> {
           '"${argResults['indent']}".');
     }
 
-    var fixes = <StyleFix>[];
-    if (argResults['fix'] as bool) fixes.addAll(StyleFix.all);
-    for (var fix in StyleFix.all) {
-      if (argResults['fix-${fix.name}'] as bool) {
-        if (argResults['fix'] as bool) {
-          usageException('--fix-${fix.name} is redundant with --fix.');
-        }
-
-        fixes.add(fix);
-      }
-    }
-
     List<int>? selection;
     try {
       selection = parseSelection(argResults, 'selection');
@@ -160,7 +147,6 @@ class FormatCommand extends Command<int> {
         indent: indent,
         pageWidth: pageWidth,
         followLinks: followLinks,
-        fixes: fixes,
         show: show,
         output: output,
         summary: summary,

lib/src/cli/formatter_options.dart

@@ -6,7 +6,6 @@ import 'dart:io';
 
 import 'package:pub_semver/pub_semver.dart';
 
-import '../short/style_fix.dart';
 import '../source_code.dart';
 import 'output.dart';
 import 'show.dart';
@@ -31,9 +30,6 @@ class FormatterOptions {
   /// Whether symlinks should be traversed when formatting a directory.
   final bool followLinks;
 
-  /// The style fixes to apply while formatting.
-  final List<StyleFix> fixes;
-
   /// Which affected files should be shown.
   final Show show;
 
@@ -55,14 +51,12 @@ class FormatterOptions {
       this.indent = 0,
       this.pageWidth = 80,
       this.followLinks = false,
-      Iterable<StyleFix>? fixes,
       this.show = Show.changed,
       this.output = Output.write,
       this.summary = Summary.none,
       this.setExitIfChanged = false,
       List<String>? experimentFlags})
-      : fixes = [...?fixes],
-        experimentFlags = [...?experimentFlags];
+      : experimentFlags = [...?experimentFlags];
 
   /// Called when [file] is about to be formatted.
   ///

lib/src/cli/options.dart

@@ -3,8 +3,6 @@
 // BSD-style license that can be found in the LICENSE file.
 import 'package:args/args.dart';
 
-import '../short/style_fix.dart';
-
 void defineOptions(ArgParser parser,
     {bool oldCli = false, bool verbose = false}) {
   if (oldCli) {
@@ -78,15 +76,6 @@ void defineOptions(ArgParser parser,
       negatable: false,
       help: 'Return exit code 1 if there are any formatting changes.');
 
-  if (verbose) parser.addSeparator('Non-whitespace fixes (off by default):');
-  parser.addFlag('fix',
-      negatable: false, help: 'Apply all style fixes.', hide: !verbose);
-
-  for (var fix in StyleFix.all) {
-    parser.addFlag('fix-${fix.name}',
-        negatable: false, help: fix.description, hide: !verbose);
-  }
-
   if (verbose) parser.addSeparator('Other options:');
 
   parser.addOption('line-length',

lib/src/dart_formatter.dart

@@ -18,7 +18,6 @@ import 'constants.dart';
 import 'exceptions.dart';
 import 'front_end/ast_node_visitor.dart';
 import 'short/source_visitor.dart';
-import 'short/style_fix.dart';
 import 'source_code.dart';
 import 'string_compare.dart' as string_compare;
 
@@ -46,8 +45,6 @@ class DartFormatter {
   /// The number of characters of indentation to prefix the output lines with.
   final int indent;
 
-  final Set<StyleFix> fixes;
-
   /// Flags to enable experimental language features.
   ///
   /// See dart.dev/go/experiments for details.
@@ -61,18 +58,14 @@ class DartFormatter {
   ///
   /// If [indent] is given, that many levels of indentation will be prefixed
   /// before each resulting line in the output.
-  ///
-  /// While formatting, also applies any of the given [fixes].
   DartFormatter(
       {required this.languageVersion,
       this.lineEnding,
       int? pageWidth,
       int? indent,
-      Iterable<StyleFix>? fixes,
       List<String>? experimentFlags})
       : pageWidth = pageWidth ?? 80,
         indent = indent ?? 0,
-        fixes = {...?fixes},
         experimentFlags = [...?experimentFlags];
 
   /// Formats the given [source] string containing an entire Dart compilation
@@ -193,8 +186,7 @@ class DartFormatter {
     }
 
     // Sanity check that only whitespace was changed if that's all we expect.
-    if (fixes.isEmpty &&
-        !string_compare.equalIgnoringWhitespace(source.text, output.text)) {
+    if (!string_compare.equalIgnoringWhitespace(source.text, output.text)) {
       throw UnexpectedOutputException(source.text, output.text);
     }
 

lib/src/io.dart

@@ -34,7 +34,6 @@ Future<void> formatStdin(
             options.languageVersion ?? DartFormatter.latestLanguageVersion,
         indent: options.indent,
         pageWidth: options.pageWidth,
-        fixes: options.fixes,
         experimentFlags: options.experimentFlags);
     try {
       options.beforeFile(null, name);
@@ -181,7 +180,6 @@ Future<bool> _processFile(
       languageVersion: languageVersion ?? DartFormatter.latestLanguageVersion,
       indent: options.indent,
       pageWidth: options.pageWidth,
-      fixes: options.fixes,
       experimentFlags: options.experimentFlags);
 
   try {