error: expected identifier before string constant

[dirkt68]

Description
Hello everyone,

I am currently using the single header file version of the library to try and do some basic serialization, and unfortunately I am having trouble with some errors coming up. I am assuming it is Visual Studio Code's fault, as the header file compiles fine on Programiz's Online Compiler. There are three spots marked as "errors" but which are valid syntax:

line 589 -> SizedRamString(const char* str, size_t sz) : str_(str), size_(sz) {} -> "expected identifier" (squiggle on the "s" in str_)
line 527 -> ZeroTerminatedRamString(const char* str) : str_(str) {} -> same problem
line 888/889 -> FlashString(const __FlashStringHelper* str, size_t sz) : str_(reinterpret_cast<const char*>(str)), size_(sz) {} -> same problem

Thank you all for your help!

Troubleshooter's report

1. The program uses ArduinoJson 6
2. The issue happens at compile time
3. The error is not in the list

Environment

• Microcontroller: RAK4631
• Core/Framework: Latest offical Arduino plugin on Visual Studio Code, WisBlock RUI3 RAK4361 Core
• IDE: Visual Studio Code Version 1.82.3(user setting)

Reproduction code

#include <ArduinoJson.h>

void setup(){}

void loop(){}

Remarks
This also occurs in a blank project simply by including the header, so I do not believe it is code related. There are also a lot of undefined functions and other errors around the header file, but those three cause red squiggles. As a test, adding this header to a CLion PlatformIO project shows no errors whatsoever and compiles correctly.

[bblanchon]

Hi @dirkt68,

Please share the complete compiler output.

Best regards,
Benoit

[bblanchon]

I compiled JsonGeneratorExample.ino successfully with the following setup:

• Arduino IDE 2.2.1
• Core RAK-nRF52-Arduino (board manager url)
• Board WisBlock RAF4631 (FQBN: rakwireless:nrf52:WisCoreRAK4631Board)

I only had to add #include <Adafruit_TinyUSB.h> at the top of the file.

[dirkt68]

Benoit,

Thank you for responding so quickly, I am attaching the compiler output from the most recent one, apologies for the length.
compiler_output.txt

I am using the same version of the Arduino IDE, and I think there might be a difference between your test and my environment, as my FQBN is rak_rui:nrf52:WisCoreRAK4631Board, not rakwireless:nrf52:WisCoreRAK4631Board. RAK Wireless has two different methods of using their boards in Arduino, so maybe the rui version could be causing this issue? I tried compiling this file in a random ESP32 sketch and that worked fine on the same Arduino IDE.

Thank you for your time,
Dirk

[bblanchon]

Hi Dirk,

I could not install the RUI boards on the Arduino IDE.
I used the following boards url, but it didn't add any new boards to the IDE:
https://github.com/RAKWireless/RAKwireless-Arduino-BSP-Index/blob/main/package_rakwireless_index.json

How did you do?

Best regards,
Benoit

[bblanchon]

I was able to reproduce the issue by adding the following line at the top of the file:

#define str_(s) #s

I found this macro in:

• RAK-STM32-RUI
• RAK-nRF52-RUI
• RAK-APOLLO3-RUI

[dirkt68]

Oh wow, would adding a check and #undef solve the issue if put in the header?

[bblanchon]

As a workaround, you can #undef, but it's better to rename the macro.
I'll open issues on the corresponding repos.

[dirkt68]

Benoit,

Thanks so much for your quick help with all of this, renaming all instance of str_ in ArduinoJson.h to str_json_ solves the problem for me. While not the permanent solution of course, this will do for me!

Sincerely,
Dirk