Protobuf: "protoc-gen-dart: Plugin output is unparseable" #58199

models.proto:

syntax = "proto2";
package proto;

message MessageEnvelope {
}

I run these commands: brew install protobuf flutter pub global activate protoc_plugin export PATH="$PATH:/Users/gintas/flutter/.pub-cache/bin" protoc --dart_out=. ./lib/models/protobuf/models.proto -I=.

I get this garbage:

--dart_out: protoc-gen-dart: Plugin output is unparseable: \rz\354\014\n\"lib/models/protobuf/models.pb.dartz\305\014///\n// Generated code. Do not modify.\n// source: lib/models/protobuf/models.proto\n//\n// @dart = 2.3\n// ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type\n\nimport \'dart:core\' as $core;\n\nimport \'package:protobuf/protobuf.dart\' as $pb;\n\nclass MessageEnvelope extends $pb.GeneratedMessage {\n static final $pb.BuilderInfo i = $pb.BuilderInfo(\'MessageEnvelope\', package: const $pb.PackageName(\'proto\'), createEmptyInstance: create)\n ..hasRequiredFields = false\n ;\n\n MessageEnvelope.() : super();\n factory MessageEnvelope() => create();\n factory MessageEnvelope.fromBuffer($core.List<$core.int> i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromBuffer(i, r);\n factory MessageEnvelope.fromJson($core.String i, [$pb.ExtensionRegistry r = $pb.ExtensionRegistry.EMPTY]) => create()..mergeFromJson(i, r);\n MessageEnvelope clone() => MessageEnvelope()..mergeFromMessage(this);\n MessageEnvelope copyWith(void Function(MessageEnvelope) updates) => super.copyWith((message) => updates(message as MessageEnvelope));\n $pb.BuilderInfo get info_ => i;\n @$core.pragma(\'dart2js:noInline\')\n static MessageEnvelope create() => MessageEnvelope.();\n MessageEnvelope createEmptyInstance() => create();\n static $pb.PbList createRepeated() => $pb.PbList();\n @$core.pragma(\'dart2js:noInline\')\n static MessageEnvelope getDefault() => _defaultInstance ??= $pb.GeneratedMessage.$_defaultFor(create);\n static MessageEnvelope _defaultInstance;\n}\n\nz\235\002\n&lib/models/protobuf/models.pbenum.dartz\362\001///\n// Generated code. Do not modify.\n// source: lib/models/protobuf/models.proto\n//\n// @dart = 2.3\n// ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type\n\nz\340\002\n&lib/models/protobuf/models.pbjson.dartz\265\002///\n// Generated code. Do not modify.\n// source: lib/models/protobuf/models.proto\n//\n// @dart = 2.3\n// ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type\n\nconst MessageEnvelope$json = const {\n \'1\': \'MessageEnvelope\',\n};\n\nz\271\002\n(lib/models/protobuf/models.pbserver.dartz\214\002///\n// Generated code. Do not modify.\n// source: lib/models/protobuf/models.proto\n//\n// @dart = 2.3\n// ignore_for_file: camel_case_types,non_constant_identifier_names,library_prefixes,unused_import,unused_shown_name,return_of_invalid_type\n\nexport \'models.pb.dart\';\n\n

flutter doctor -v
[✓] Flutter (Channel master, 1.19.0-2.0.pre.173, on Mac OS X 10.15.4 19E287, locale en-GB)
    • Flutter version 1.19.0-2.0.pre.173 at /Users/gintas/flutter
    • Framework revision 5663e02645 (23 hours ago), 2020-05-27 18:32:01 -0400
    • Engine revision 2663be8370
    • Dart version 2.9.0 (build 2.9.0-11.0.dev e007545c42)

[✓] Android toolchain - develop for Android devices (Android SDK version 29.0.3)
    • Android SDK at /Users/gintas/Library/Android/sdk
    • Platform android-29, build-tools 29.0.3
    • Java binary at: /Applications/Android Studio.app/Contents/jre/jdk/Contents/Home/bin/java
    • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b4-5784211)
    • All Android licenses accepted.

[✓] Xcode - develop for iOS and macOS (Xcode 11.4.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Xcode 11.4.1, Build version 11E503a
    • CocoaPods version 1.9.1

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] Android Studio (version 3.6)
    • Android Studio at /Applications/Android Studio.app/Contents
    • Flutter plugin version 45.1.1
    • Dart plugin version 192.7761
    • Java version OpenJDK Runtime Environment (build 1.8.0_212-release-1586-b4-5784211)

[!] VS Code (version 1.43.2)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    ✗ Flutter extension not installed; install from
      https://marketplace.visualstudio.com/items?itemName=Dart-Code.flutter

[✓] Connected device (3 available)
    • macOS      • macOS      • darwin-x64     • Mac OS X 10.15.4 19E287
    • Web Server • web-server • web-javascript • Flutter Tools
    • Chrome     • chrome     • web-javascript • Google Chrome 83.0.4103.61

! Doctor found issues in 1 category.

If I do protoc --java_out=. ./lib/models/protobuf/models.proto -I=., then Java file is generated ok without error

google / protobuf.dart

Protobuf: "protoc-gen-dart: Plugin output is unparseable" #58199 #375