Fix mixed dartdoc processing

This change should fix the failing ResynthesizeAstStrongTest.test_class_documented_mix test.

Change-Id: I0b89fa5ddbb4725ec0115836e8b5e801d18678c5
Reviewed-on: https://dart-review.googlesource.com/68900
Commit-Queue: Dan Rubel <danrubel@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>

pkg/analyzer/lib/src/fasta/ast_builder.dart

@@ -2608,10 +2608,15 @@ class AstBuilder extends StackListener {
 
     // Build and return the comment
     List<CommentReference> references = parseCommentReferences(dartdoc);
-    List<Token> tokens = <Token>[];
-    while (dartdoc != null) {
-      tokens.add(dartdoc);
+    List<Token> tokens = <Token>[dartdoc];
+    if (dartdoc.lexeme.startsWith('///')) {
       dartdoc = dartdoc.next;
+      while (dartdoc != null) {
+        if (dartdoc.lexeme.startsWith('///')) {
+          tokens.add(dartdoc);
+        }
+        dartdoc = dartdoc.next;
+      }
     }
     return ast.documentationComment(tokens, references);
   }

pkg/analyzer/test/generated/parser_test.dart

@@ -13373,7 +13373,10 @@ class C<@Foo.bar(const [], const [1], const{"":r""}, 0xFF + 2, .3, 4.5) T> {}
     expectNotNullIfNoErrors(unit);
     assertNoErrors();
     ClassDeclaration declaration = unit.declarations[0];
-    expect(declaration.documentationComment, isNotNull);
+    Comment comment = declaration.documentationComment;
+    expect(comment.isDocumentation, isTrue);
+    expect(comment.tokens, hasLength(1));
+    expect(comment.tokens[0].lexeme, '/** 2 */');
     expect(declaration.metadata, hasLength(1));
   }
 
@@ -13438,6 +13441,103 @@ class C<@Foo.bar(const [], const [1], const{"":r""}, 0xFF + 2, .3, 4.5) T> {}
     expect(declaration.metadata, hasLength(2));
   }
 
+  void test_parseCommentAndMetadata_mix1() {
+    createParser(r'''
+/**
+ * aaa
+ */
+/**
+ * bbb
+ */
+class A {}
+''');
+    CompilationUnit unit = parser.parseCompilationUnit2();
+    expectNotNullIfNoErrors(unit);
+    assertNoErrors();
+    ClassDeclaration declaration = unit.declarations[0];
+    expect(declaration.metadata, hasLength(0));
+    List<Token> tokens = declaration.documentationComment.tokens;
+    expect(tokens, hasLength(1));
+    expect(tokens[0].lexeme, contains('bbb'));
+  }
+
+  void test_parseCommentAndMetadata_mix2() {
+    createParser(r'''
+/**
+ * aaa
+ */
+/// bbb
+/// ccc
+class B {}
+''');
+    CompilationUnit unit = parser.parseCompilationUnit2();
+    expectNotNullIfNoErrors(unit);
+    assertNoErrors();
+    ClassDeclaration declaration = unit.declarations[0];
+    expect(declaration.metadata, hasLength(0));
+    List<Token> tokens = declaration.documentationComment.tokens;
+    expect(tokens, hasLength(2));
+    expect(tokens[0].lexeme, contains('bbb'));
+    expect(tokens[1].lexeme, contains('ccc'));
+  }
+
+  void test_parseCommentAndMetadata_mix3() {
+    createParser(r'''
+/// aaa
+/// bbb
+/**
+ * ccc
+ */
+class C {}
+''');
+    CompilationUnit unit = parser.parseCompilationUnit2();
+    expectNotNullIfNoErrors(unit);
+    assertNoErrors();
+    ClassDeclaration declaration = unit.declarations[0];
+    expect(declaration.metadata, hasLength(0));
+    List<Token> tokens = declaration.documentationComment.tokens;
+    expect(tokens, hasLength(1));
+    expect(tokens[0].lexeme, contains('ccc'));
+  }
+
+  test_parseCommentAndMetadata_mix4() {
+    createParser(r'''
+/// aaa
+/// bbb
+/**
+ * ccc
+ */
+/// ddd
+class D {}
+''');
+    CompilationUnit unit = parser.parseCompilationUnit2();
+    expectNotNullIfNoErrors(unit);
+    assertNoErrors();
+    ClassDeclaration declaration = unit.declarations[0];
+    expect(declaration.metadata, hasLength(0));
+    List<Token> tokens = declaration.documentationComment.tokens;
+    expect(tokens, hasLength(1));
+    expect(tokens[0].lexeme, contains('ddd'));
+  }
+
+  test_parseCommentAndMetadata_mix5() {
+    createParser(r'''
+/**
+ * aaa
+ */
+// bbb
+class E {}
+''');
+    CompilationUnit unit = parser.parseCompilationUnit2();
+    expectNotNullIfNoErrors(unit);
+    assertNoErrors();
+    ClassDeclaration declaration = unit.declarations[0];
+    expect(declaration.metadata, hasLength(0));
+    List<Token> tokens = declaration.documentationComment.tokens;
+    expect(tokens, hasLength(1));
+    expect(tokens[0].lexeme, contains('aaa'));
+  }
+
   void test_parseCommentAndMetadata_none() {
     createParser('class C {}');
     CompilationUnit unit = parser.parseCompilationUnit2();

pkg/front_end/lib/src/fasta/parser/parser.dart

@@ -5836,14 +5836,22 @@ class Parser {
   /// or `null` if no dartdoc token is found.
   Token findDartDoc(Token token) {
     Token comments = token.precedingComments;
+    Token dartdoc = null;
+    bool isMultiline = false;
     while (comments != null) {
       String lexeme = comments.lexeme;
-      if (lexeme.startsWith('/**') || lexeme.startsWith('///')) {
-        break;
+      if (lexeme.startsWith('///')) {
+        if (!isMultiline) {
+          dartdoc = comments;
+          isMultiline = true;
+        }
+      } else if (lexeme.startsWith('/**')) {
+        dartdoc = comments;
+        isMultiline = false;
       }
       comments = comments.next;
     }
-    return comments;
+    return dartdoc;
   }
 
   /// Parse the comment references in a sequence of comment tokens