Getting error: "reference to 'byte' is ambiguous" when using with "Keypad.h" or "MFRC522.h"

[outsu]

I'm not sure if this is a bug or if I didn't dope it. So I'm sorry if I opened a wrong ticket here.

I need to use FirebaseClient with Keypad.h and MRFC522. But since they use the byte to define, (like rows and cols for Keypad.h and "key.keyByte[i] = 0xFF;" for key at MRFC"). This is so weird, but when we import the new libraries, "FirebaseClient" and "ArduinoJson"; the keypad sections gives an error for bytes. When I change the bytes to uint8_t, I just get another type of error because Keypad.h is written to work with bytes for define.

Here's an example that just after I implemented FirebaseClient:

C:\Users\xxxxxxx\AppData\Local\Arduino15\packages\esp32\hardware\esp32\3.0.3\cores\esp32/Arduino.h:149:17: note:                 'typedef uint8_t byte'
  149 | typedef uint8_t byte;
      |                 ^~~~
In file included from C:\Users\xxxxxxx\Documents\Arduino\real_main\real_main.ino:2:
C:\Users\xxxxxxx\Documents\Arduino\real_main\real_main.ino:35:35: error: 'keys' was not declared in this scope; did you mean 'key'?
   35 | Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
      |                                   ^~~~
c:\Users\xxxxxxx\Documents\Arduino\libraries\Keypad\src/Keypad.h:71:31: note: in definition of macro 'makeKeymap'
   71 | #define makeKeymap(x) ((char*)x)
      |                               ^
C:\Users\xxxxxxx\Documents\Arduino\real_main\real_main.ino:35:42: error: 'rowPins' was not declared in this scope
   35 | Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
      |                                          ^~~~~~~
C:\Users\xxxxxxx\Documents\Arduino\real_main\real_main.ino:35:51: error: 'colPins' was not declared in this scope
   35 | Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
      |                                                   ^~~~~~~
C:\Users\xxxxxxx\Documents\Arduino\real_main\real_main.ino:35:60: error: 'ROWS' was not declared in this scope
   35 | Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
      |                                                            ^~~~
C:\Users\xxxxxxx\Documents\Arduino\real_main\real_main.ino:35:66: error: 'COLS' was not declared in this scope
   35 | Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);
      |                                                                  ^~~~
Compilation error: reference to 'byte' is ambiguous

The part of where I use FirebaseClient:

#include "get_expert_list.h"

#define WIFI_SSID "xxx"
#define WIFI_PASSWORD "xxx"

// The API key can be obtained from Firebase console > Project Overview > Project settings.
#define API_KEY "xxx"

// User Email and password that already registerd or added in your project.
#define USER_EMAIL "xxx"
#define USER_PASSWORD "xxx"
#define DATABASE_URL "xxx"

#define FIREBASE_PROJECT_ID "xxx"

DefaultNetwork network;
UserAuth user_auth(API_KEY, USER_EMAIL, USER_PASSWORD);
FirebaseApp app;

WiFiClientSecure ssl_client;
using AsyncClient = AsyncClientClass;
AsyncClient aClient(ssl_client, getNetwork(network));
Firestore::Documents Docs;
AsyncResult aResult_no_callback;

void setupFirebase() {
    WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

    Serial.print("Connecting to Wi-Fi");

    while (WiFi.status() != WL_CONNECTED) {
      Serial.print(".");
      delay(300);
    }

    Serial.println();
    Serial.print("Connected with IP: ");
    Serial.println(WiFi.localIP());

    Firebase.printf("Firebase Client v%s\n", FIREBASE_CLIENT_VERSION);
    Serial.println("Initialize app...");
    ssl_client.setInsecure();

    initializeApp(aClient, app, getAuth(user_auth), aResult_no_callback);
    authHandler();

    app.getApp<Firestore::Documents>(Docs);
    aClient.setAsyncResult(aResult_no_callback);
}

void getExpertList() {
    authHandler();

    Docs.loop();

    String colExpert = "experts";

    Serial.println("Get all documents in collection experts");

    ListDocumentsOptions listDocsOptions;
    listDocsOptions.mask(DocumentMask("name"));

    String payload = Docs.list(aClient, Firestore::Parent(FIREBASE_PROJECT_ID), colExpert, listDocsOptions);

    if (aClient.lastError().code() == 0) {
        DynamicJsonDocument doc(1024);
        DeserializationError error = deserializeJson(doc, payload);

        if (error) {
            Serial.print("deserializeJson() failed: ");
            Serial.println(error.c_str());
            return;
        }

        JsonArray documents = doc["documents"].as<JsonArray>();
        for (JsonObject document : documents) {
            String name = document["name"];
            String id = name.substring(name.lastIndexOf('/') + 1);
            String expertName = document["fields"]["name"]["stringValue"];

            Serial.print("Document ID: ");
            Serial.println(id);
            Serial.print("Name: ");
            Serial.println(expertName);
        }
    } else {
        printError(aClient.lastError().code(), aClient.lastError().message());
    }
}

void authHandler() {
    unsigned long ms = millis();
    while (app.isInitialized() && !app.ready() && millis() - ms < 120 * 1000) {
        JWT.loop(app.getAuth());
        printResult(aResult_no_callback);
    }
}

void printResult(AsyncResult &aResult) {
    if (aResult.isEvent()) {
        Firebase.printf("Event task: %s, msg: %s, code: %d\n", aResult.uid().c_str(), aResult.appEvent().message().c_str(), aResult.appEvent().code());
    }

    if (aResult.isDebug()) {
        Firebase.printf("Debug task: %s, msg: %s\n", aResult.uid().c_str(), aResult.debug().c_str());
    }

    if (aResult.isError()) {
        Firebase.printf("Error task: %s, msg: %s, code: %d\n", aResult.uid().c_str(), aResult.error().message().c_str(), aResult.error().code());
    }

    if (aResult.available()) {
        Firebase.printf("task: %s, payload: %s\n", aResult.uid().c_str(), aResult.c_str());
    }
}

void printError(int code, const String &msg) {
    Firebase.printf("Error, msg: %s, code: %d\n", msg.c_str(), code);
}

Some example of usage "byte" in Keypad:

const byte ROWS = 4;
const byte COLS = 3;
char keys[ROWS][COLS] = {
  {'1','2','3'},
  {'4','5','6'},
  {'7','8','9'},
  {'*','0','#'}
};
byte rowPins[ROWS] = {32, 33, 25, 26}; // Suitable for input/output
byte colPins[COLS] = {14, 27, 13};     // Suitable for input/output
Keypad keypad = Keypad(makeKeymap(keys), rowPins, colPins, ROWS, COLS);

[mobizt]

It is your code issue which you should debug it yourself.

[outsu]

I think I need to be clearer, the problem is not in my code. My code is trivial, I didn't want to debug it, I put it just in case, but I didn't need to. Let's say there is a code, it contains byte definition, it works without any problem. Even if I add the line "#include <FirebaseClient.h>", and nothing else. All byte definitions give the error "reference to 'byte' is ambiguous".

Let's say this is the code, which works fine obviously:

const byte Avariable = 1;
byte AnotherVariable = 0;

void setup() {
}

I just add "#include <FirebaseClient.h>":

#include <FirebaseClient.h>
const byte Avariable = 1;
byte AnotherVariable = 0;

void setup() {
}

Conclusion:

C:\Users\xxxxxxx\AppData\Local\Temp\.arduinoIDE-unsaved202473-27892-1lmgvi4.otzg\sketch_aug3f\sketch_aug3f.ino:3:7: error: reference to 'byte' is ambiguous
    3 | const byte Avariable = 1;
      |       ^~~~
In file included from c:\users\xxxxxxx\appdata\local\arduino15\packages\esp32\tools\esp-x32\2302\xtensa-esp32-elf\include\c++\12.2.0\cmath:42,
                 from c:\users\xxxxxxx\appdata\local\arduino15\packages\esp32\tools\esp-x32\2302\xtensa-esp32-elf\include\c++\12.2.0\math.h:36,
                 from C:\Users\xxxxxxx\AppData\Local\Arduino15\packages\esp32\hardware\esp32\3.0.3\cores\esp32/esp32-hal.h:30,
                 from C:\Users\xxxxxxx\AppData\Local\Arduino15\packages\esp32\hardware\esp32\3.0.3\cores\esp32/Arduino.h:36,
                 from C:\Users\xxxxxxx\AppData\Local\Temp\arduino\sketches\640C8824C24A9EE9A34D23C1A6E5C69B\sketch\sketch_aug3f.ino.cpp:1:
c:\users\xxxxxxx\appdata\local\arduino15\packages\esp32\tools\esp-x32\2302\xtensa-esp32-elf\include\c++\12.2.0\bits\cpp_type_traits.h:406:30: note: candidates are: 'enum class std::byte'
  406 |   enum class byte : unsigned char;
      |                              ^~~~
C:\Users\xxxxxxx\AppData\Local\Arduino15\packages\esp32\hardware\esp32\3.0.3\cores\esp32/Arduino.h:149:17: note:                 'typedef uint8_t byte'
  149 | typedef uint8_t byte;
      |                 ^~~~
C:\Users\xxxxxxx\AppData\Local\Temp\.arduinoIDE-unsaved202473-27892-1lmgvi4.otzg\sketch_aug3f\sketch_aug3f.ino:4:1: error: reference to 'byte' is ambiguous
    4 | byte AnotherVariable = 0;
      | ^~~~
c:\users\xxxxxxx\appdata\local\arduino15\packages\esp32\tools\esp-x32\2302\xtensa-esp32-elf\include\c++\12.2.0\bits\cpp_type_traits.h:406:30: note: candidates are: 'enum class std::byte'
  406 |   enum class byte : unsigned char;
      |                              ^~~~
C:\Users\xxxxxxx\AppData\Local\Arduino15\packages\esp32\hardware\esp32\3.0.3\cores\esp32/Arduino.h:149:17: note:                 'typedef uint8_t byte'
  149 | typedef uint8_t byte;
      |                 ^~~~

exit status 1

Compilation error: reference to 'byte' is ambiguous

I need to use the "byte" type with several libraries, which prevents me from using FirebaseClient. I can't use uint8_t, the other libraries gives an error in this time.

[mobizt]

As I wrote, you have to debug your code.

It means you have to find the error in your code.

You have to understand the compiler log too.

The error in the compiler log is about the naming conflicts between byte data type defined in Arduino.h and the C++17 byte class name in cpp_type_traits.h.

This is not related to the library directly, but the Firebase library contains the unnecessary code of using namespace std that causes the error when user defines byte in his code and the compiler is confusing about that name meaning in ESP32 Arduino Core SDK v3.x.x that comes with C++17.

The library was updated by removing this using namespace std statement to allow you use byte (uint8_t) defined in Arduino.h.

But this can be the issue if you include any library or even your code as below that uses this statement using namespace std.

#include <Arduino.h>

using namespace std;

const byte Avariable = 1;

byte AnotherVariable = 0;

void setup()
{
}

void loop()
{
}

I recommend you should avoid using byte in the ESP32 Arduino Core SDK v3.x.x because of C++17 the byte naming conflicts.