Fix a bug in comment parsing (#879)

Fixes #871.

protoc_plugin/CHANGELOG.md

@@ -1,3 +1,10 @@
+## 21.1.2-dev
+
+* Fix a bug in comment parsing ([#871], [#879]).
+
+[#871]: https://github.com/google/protobuf.dart/issues/871
+[#879]: https://github.com/google/protobuf.dart/pull/879
+
 ## 21.1.1
 
 * Rename a local variable used with message constructors to avoid potential

protoc_plugin/lib/src/shared.dart

@@ -38,8 +38,8 @@ String? toDartComment(String value) {
 
   var lines = LineSplitter.split(value).toList();
 
-  // Find any leading spaces in the first line.
-  // If all of the lines have the same leading spaces, remove them all.
+  // Find any leading spaces in the first line. If all of the lines have the
+  // same leading spaces, remove them all.
   final leadingSpaces = _leadingSpaces.firstMatch(lines.first);
   if (leadingSpaces != null) {
     final prefix = leadingSpaces.group(0)!;
@@ -48,11 +48,16 @@ String? toDartComment(String value) {
     }
   }
 
-  // Remove empty, trailing lines
-  while (lines.last.isEmpty) {
+  // Remove empty, trailing lines.
+  while (lines.isNotEmpty && lines.last.trim().isEmpty) {
     lines.removeLast();
   }
 
+  // Don't generate a documentation comment if all lines are empty.
+  if (lines.isEmpty) {
+    return null;
+  }
+
   return lines.map((e) => '/// $e'.trimRight()).join('\n');
 }
 

protoc_plugin/pubspec.yaml

@@ -1,5 +1,5 @@
 name: protoc_plugin
-version: 21.1.1
+version: 21.1.2-dev
 description: A protobuf protoc compiler plugin used to generate Dart code.
 repository: https://github.com/google/protobuf.dart/tree/master/protoc_plugin
 

protoc_plugin/test/shared_test.dart

@@ -7,6 +7,10 @@ void main() {
       expect(toDartComment(''), null);
     });
 
+    test('just space', () {
+      expect(toDartComment(' '), null);
+    });
+
     test('indent', () {
       expect(
         toDartComment('''