UndocumentedApi: support enumerations without name

samples:
```C++
enum /*unnamed-enum*/ {
};

enum /*unnamed-enum*/ : int {
};

/** doc */
typedef enum /*unnamed-enum*/ {
} type_name_3;

typedef enum /*unnamed-enum*/ {
} type_name_4; ///< doc

/** doc */
typedef enum /*unnamed-enum*/ : int {
} type_name_5;

typedef enum /*unnamed-enum*/ : int {
} type_name_6; ///< doc
```

Author: guwirth

cxx-squid/src/main/java/org/sonar/cxx/visitors/AbstractCxxPublicApiVisitor.java

@@ -795,24 +795,51 @@ private void visitAliasDeclaration(AstNode aliasDeclNode) {
     }
   }
 
-  private void visitEnumSpecifier(AstNode enumSpecifierNode) {
-    var enumIdNode = enumSpecifierNode.getFirstDescendant(GenericTokenType.IDENTIFIER);
+  private static List<Token> getTypedefInlineComment(AstNode typedef) {
+    var commentTokens = new ArrayList<Token>();
+    var node = typedef.getFirstAncestor(CxxGrammarImpl.declaration);
+    node = node.getNextAstNode();
+
+    // search for first child with a comment
+    while (node != null) {
+      for (var trivia : node.getToken().getTrivia()) {
+        if (trivia.isComment()) {
+          commentTokens.add(trivia.getToken());
+          return commentTokens;
+        }
+      }
+      node = node.getFirstChild();
+    }
 
-    String enumId = (enumIdNode == null) ? UNNAMED_ENUM_ID : enumIdNode.getTokenValue();
+    return commentTokens;
+  }
 
+  private void visitEnumSpecifier(AstNode enumSpecifierNode) {
     if (!isPublicApiMember(enumSpecifierNode)) {
-      // not in public API
-      return;
+      return; // not in public API
     }
 
-    // deal with typedef enum: documentation is on typedef node
-    AstNode docNode = getTypedefNode(enumSpecifierNode);
+    var docNode = getTypedefNode(enumSpecifierNode);
+    AstNode idNode;
     if (docNode == null) {
-      docNode = enumSpecifierNode;
+      // enum ...
+      idNode = enumSpecifierNode.getFirstDescendant(CxxGrammarImpl.enumHeadName);
+      if (idNode != null) {
+        visitPublicApi(enumSpecifierNode, idNode.getTokenValue(), getBlockDocumentation(enumSpecifierNode));
+      }
+    } else {
+      // typedef enum ...
+      var declaration = enumSpecifierNode.getFirstAncestor(CxxGrammarImpl.declaration);
+      idNode = declaration.getFirstDescendant(CxxGrammarImpl.declaratorId);
+      if (idNode != null) {
+        List<Token> comments = getBlockDocumentation(docNode);
+        if (comments.isEmpty()) { // documentation may be inlined
+          comments = getTypedefInlineComment(docNode);
+        }
+        visitPublicApi(enumSpecifierNode, idNode.getTokenValue(), comments);
+      }
     }
 
-    visitPublicApi(enumSpecifierNode, enumId, getBlockDocumentation(docNode));
-
     // deal with enumeration values
     AstNode enumeratorList = enumSpecifierNode.getFirstDescendant(CxxGrammarImpl.enumeratorList);
 

cxx-squid/src/test/java/org/sonar/cxx/visitors/CxxPublicApiVisitorTest.java

@@ -98,7 +98,7 @@ public void unnamed_class() throws IOException {
 
   @Test
   public void unnamed_enum() throws IOException {
-    assertThat(verifyPublicApiOfFile("src/test/resources/metrics/unnamed_enum.h")).isEqualTo(tuple(1, 1));
+    assertThat(verifyPublicApiOfFile("src/test/resources/metrics/unnamed_enum.h")).isEqualTo(tuple(8, 0));
   }
 
   @Test

cxx-squid/src/test/resources/metrics/unnamed_enum.h

@@ -1,3 +1,39 @@
-enum /*anonymous enum*/ {
+// enum ...
+
+/** doc */
+enum named_enum_1 {
+};
+
+enum /*unnamed-enum*/ {
+};
+
+/** doc */
+enum named_enum_2 : int {
+};
+
+enum /*unnamed-enum*/ : int {
 };
 
+// typedef ...
+
+/** doc */
+typedef enum named_enum_3 {
+} type_name_1;
+
+/** doc */
+typedef enum named_enum_4 : int {
+} type_name_2;
+
+/** doc */
+typedef enum /*unnamed-enum*/ {
+} type_name_3;
+
+typedef enum /*unnamed-enum*/ {
+} type_name_4; ///< doc
+
+/** doc */
+typedef enum /*unnamed-enum*/ : int {
+} type_name_5;
+
+typedef enum /*unnamed-enum*/ : int {
+} type_name_6; ///< doc