Name the forbidden character in the port name error

include/behaviortree_cpp/basic_types.h

@@ -370,6 +370,9 @@ struct Timestamp
 /// and control characters (ASCII 0-31, 127). UTF-8 multibyte sequences are allowed.
 [[nodiscard]] char findForbiddenChar(StringView name);
 
+/// Describes a character returned by findForbiddenChar() for an error message.
+[[nodiscard]] std::string formatForbiddenChar(char c);
+
 class TypeInfo
 {
 public:
@@ -468,6 +471,11 @@ template <typename T = AnyTypeAllowed>
   auto sname = static_cast<std::string>(name);
   if(!IsAllowedPortName(sname))
   {
+    if(const char c = findForbiddenChar(sname); c != '\0')
+    {
+      throw RuntimeError("Port name '", sname, "' contains forbidden character ",
+                         formatForbiddenChar(c));
+    }
     throw RuntimeError("The name of a port must not be `name` or `ID` "
                        "and must start with an alphabetic character. "
                        "Underscore is reserved.");

src/basic_types.cpp

@@ -613,6 +613,15 @@ char findForbiddenChar(StringView name)
   return '\0';
 }
 
+std::string formatForbiddenChar(char c)
+{
+  if(c < 32 || c == 127)
+  {
+    return "control character (ASCII " + std::to_string(static_cast<int>(c)) + ")";
+  }
+  return std::string("'") + c + "'";
+}
+
 Any convertFromJSON(StringView json_text, std::type_index type)
 {
   const nlohmann::json json = nlohmann::json::parse(json_text);

src/xml_parsing.cpp

@@ -103,16 +103,6 @@ auto StrEqual = [](const char* str1, const char* str2) -> bool {
   return strcmp(str1, str2) == 0;
 };
 
-// Helper to format forbidden character for error messages
-std::string formatForbiddenChar(char c)
-{
-  if(c < 32 || c == 127)
-  {
-    return "control character (ASCII " + std::to_string(static_cast<int>(c)) + ")";
-  }
-  return std::string("'") + c + "'";
-}
-
 void validateModelName(const std::string& name, int line_number)
 {
   const auto line_str = std::to_string(line_number);

tests/gtest_name_validation.cpp

@@ -120,6 +120,32 @@ TEST(NameValidation, IsAllowedPortName_Invalid)
   EXPECT_FALSE(IsAllowedPortName("port<T>"));    // angle brackets
 }
 
+TEST(NameValidation, CreatePort_NamesForbiddenChar)
+{
+  try
+  {
+    (void)InputPort<std::string>("goal.pose");
+    FAIL() << "Expected RuntimeError to be thrown";
+  }
+  catch(const RuntimeError& e)
+  {
+    const std::string msg = e.what();
+    EXPECT_NE(msg.find("goal.pose"), std::string::npos) << msg;
+    EXPECT_NE(msg.find("forbidden character '.'"), std::string::npos) << msg;
+  }
+
+  try
+  {
+    (void)InputPort<std::string>("goal\tpose");
+    FAIL() << "Expected RuntimeError to be thrown";
+  }
+  catch(const RuntimeError& e)
+  {
+    const std::string msg = e.what();
+    EXPECT_NE(msg.find("control character (ASCII 9)"), std::string::npos) << msg;
+  }
+}
+
 // ============== Tests for XML parsing validation ==============
 
 class NameValidationXMLTest : public testing::Test