weird error in arduino.h on makeWord () with core 3.0.0

[stef-ladefense]

hi,
i have a weird error in arduino.h on makeWord ().
I use word (h, l) in my code and with core 3.0.0 it gives a fatal error during compilation.

In file included from C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.0\libraries\ESP8266WiFi\src/WiFiClient.h:25,
                 from C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.0\libraries\ESP8266WiFi\src/ESP8266WiFi.h:39,

C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.0\cores\esp8266/Arduino.h:247:19: error: 'uint16_t makeWord' redeclared as different kind of entity
  247 | uint16_t makeWord(byte h, byte l);
      |                   ^~~~
C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.0\cores\esp8266/Arduino.h:246:10: note: previous declaration 'uint16_t makeWord(uint16_t)'
  246 | uint16_t makeWord(uint16_t w);
      |          ^~~~~~~~
C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.0\cores\esp8266/Arduino.h:247:19: error: reference to 'byte' is ambiguous
  247 | uint16_t makeWord(byte h, byte l);
      |                   ^~~~

i got around the problem by changing in arduino.h

uint16_t makeWord (byte h, byte l); -> uint16_t makeWord (uint8_t h, uint8_t l);

What do you think ?

[d-a-v]

Are you using a git installation, and in that case did you upgrade the toolchain with the script tools/get.py ?

(normally I should close because you deleted the issue template and the answers of my question would be in it after you filled the fields)

[stef-ladefense]

hi,
no i use classic install with boards manager
(oh escuse me)

[d-a-v]

We need a way to reproduce, with a MCVE.
@stef-ladefense can you provide one simple example that would allow us to reproduce, without your changes in Arduino.h ?

side note to maintainers:
the core need this change to match Arduino.h (to avoid undefined reference to '_Z8makeWordt')
(but that won't solve your issue @stef-ladefense) (core is updated)

[dok-net]

I've a few observations. The use of the identifier "byte" is a bit onerous. In Arduino.h, there is a typedef uint8_t byte;, whereas core_esp8266_si2c.cpp and Esp.cpp use byte as object identifier. On top of that, the signature in Arduino.h is not just different for makeWord(unsigned int), but also literally different for uint16_t makeWord(byte h, byte l); (Arduino.h) vs. unsigned int makeWord(unsigned char h, unsigned char l) (WMath.cpp).
According to https://en.cppreference.com/w/cpp/types/byte , this also was introduced as an official type in the std namespace with C++17.
As a typename, byte is hardly ever used in ESP8266 Core for Arduino (trivial to fix one-time slip being in core_esp8266_main.cpp). In libraries/ESP8266WiFiMesh/src/TypeConversionFunctions.cpp, it also is used in error, as libraries/ESP8266WiFiMesh/src/TypeConversionFunctions.h specifies the affected 2 functions using uint8_t.

I'm providing PR #8090 as a suggested fix to this, including @d-a-v's change.

[stef-ladefense]

first I apologize for not following the issue template, but I did not imagine the benefit.
I'm happy with the outcome, it's going in the right direction
thank you all

[dok-net]

With the PR, this compiles fine now:

byte h = 0;
byte l = 0;

void setup()
{
	Serial.begin(74880);
	delay(500);
	Serial.println("makeword");
	auto w1 = word(1025);
	h = w1 >> 8;
	l = w1 & 0xff;
	auto w2 = word(h, l);
	if (w1 == w2)
		Serial.println("OK");
	else
		Serial.println("oops");
}

void loop()
{
}

@earlephilhower Is this convincing proof that uint8_tin uint16_t makeWord(uint8_t h, uint8_t l) is non-breaking vs. Arduino AVR?

[dok-net]

@d-a-v #8097 builds and works with byte, uint8_t, and unsigned char for the makeWord(h, l) arguments. I'm keeping #8090 for the time being, in case someone considers removing byte has any value of itself after all.

[earlephilhower]

Closing as no feedback and a merged PR which we believe fixes things.

[Sai-Kiran-31]

thank you all

Sir, How did you resolve the problem I too facing the same

[earlephilhower]

@Sai-Kiran-31 you need to either use the git master branch, or wait for 3.0.1 to be released to get the change incorporated.

[bill-orange]

I re-tested with 3.0.1 and the noted error still exists. Thoughts? 2.7.4 works fine.

> C:\Users\William\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/Arduino.h:246:10: note: previous declaration 'uint16_t makeWord(uint16_t)'
> 
>   246 | uint16_t makeWord(uint16_t w);
> 
>       |          ^~~~~~~~
> 
> C:\Users\William\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/Arduino.h:247:19: error: reference to 'byte' is ambiguous
> 
>   247 | uint16_t makeWord(byte h, byte l);
> 
>       |                   ^~~~
> 
> In file included from c:\users\william\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\bits\stl_algobase.h:61,
> 

Plenty more of the same followed

[stef-ladefense]

tested 3.00 > 3.01 and bug

fixed with change uint16_t makeWord(uint8_t h, uint8_t l); in arduino.h

In file included from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NtpClientLib.h:59,
                 from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NTPClientLib.cpp:32:
C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/Arduino.h:247:19: error: 'uint16_t makeWord' redeclared as different kind of entity
  247 | uint16_t makeWord(byte h, byte l);
      |                   ^~~~
C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/Arduino.h:246:10: note: previous declaration 'uint16_t makeWord(uint16_t)'
  246 | uint16_t makeWord(uint16_t w);
      |          ^~~~~~~~
C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/Arduino.h:247:19: error: reference to 'byte' is ambiguous
  247 | uint16_t makeWord(byte h, byte l);
      |                   ^~~~
In file included from c:\users\stephane\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\bits\stl_algobase.h:61,
                 from c:\users\stephane\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\array:40,
                 from c:\users\stephane\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\tuple:39,
                 from c:\users\stephane\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\functional:54,
                 from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NtpClientLib.h:44,
                 from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NTPClientLib.cpp:32:
c:\users\stephane\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\bits\cpp_type_traits.h:404:30: note: candidates are: 'enum class std::byte'
  404 |   enum class byte : unsigned char;
      |                              ^~~~
In file included from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NtpClientLib.h:59,
                 from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NTPClientLib.cpp:32:
C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/Arduino.h:160:17: note:                 'typedef uint8_t byte'
  160 | typedef uint8_t byte;
      |                 ^~~~
In file included from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NtpClientLib.h:59,
                 from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NTPClientLib.cpp:32:
C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/Arduino.h:247:27: error: reference to 'byte' is ambiguous
  247 | uint16_t makeWord(byte h, byte l);
      |                           ^~~~
In file included from c:\users\stephane\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\bits\stl_algobase.h:61,
                 from c:\users\stephane\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\array:40,
                 from c:\users\stephane\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\tuple:39,
                 from c:\users\stephane\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\functional:54,
                 from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NtpClientLib.h:44,
                 from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NTPClientLib.cpp:32:
c:\users\stephane\appdata\local\arduino15\packages\esp8266\tools\xtensa-lx106-elf-gcc\3.0.3-gcc10.3-9bcba0b\xtensa-lx106-elf\include\c++\10.3.0\bits\cpp_type_traits.h:404:30: note: candidates are: 'enum class std::byte'
  404 |   enum class byte : unsigned char;
      |                              ^~~~
In file included from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NtpClientLib.h:59,
                 from C:\Users\stephane\Documents\Arduino\libraries\NtpClient-3.0.2-beta\src\NTPClientLib.cpp:32:
C:\Users\stephane\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\3.0.1\cores\esp8266/Arduino.h:160:17: note:                 'typedef uint8_t byte'
  160 | typedef uint8_t byte;
      |                 ^~~~
exit status 1
Erreur de compilation pour la carte Generic ESP8266 Module

[dok-net]

Food for thought, from NtpClientLib.h:

#if defined ESP8266 || defined ESP32
#include <functional>
using namespace std;

[...]

vs.
enum class byte : unsigned char {} ; (since C++17)
vs.
Arduino.h

typedef uint8_t byte;

[d-a-v]

I could reproduce.
That is because of using namespace std which is incompatible with byte.
See gmag11/NtpClient#115

edit:
Keeping this opened even if there's nothing to do anymore in this core,
but tracking PR from NtpClient library which is widely used.

[d-a-v]

It appears that there are a number of libraries with using namespace std; and using byte.
Arduino's byte and using namespace std; are incompatible.
The fix should be to remove all using namespace std; and use std::stuff instead of stuff where relevant but is is not possible to go and fix all external projects or libraries.
Removing Arduino's byte in favor of using std::byte; is not an option because std::byte test = 0; is an error (int incompatible with std::byte…)
I wonder whether there's another path than to patch the toolchain and make std::byte definition optional for this core.

[mcspr]

std::byte test{0}; is allowed (but might be looking foreign to anyone coming from C), and so is std::byte test = (std::byte)1; btw.

With the linked issue, the general problem is with using namespace std; in the global namespace, which should probably be discouraged instead of making it silently working with a ton of workarounds?
Also see https://www.cryptopp.com/wiki/Std::byte and this small comment here

[d-a-v]

I am now closing again this issue that I re-opened.
esp8266/Arduino maintainers won't be doing anything at all to try to keep backward compatibility with already existing codes which are broken when using this core-v3 with the introduction of c++17's std::byte when bad c++ practices are involved (such as using namespace std;).