ESPAsyncWebServer.h:1107:49: error: passing 'const AsyncServer' as 'this' argument discards qualifiers [-fpermissive]

[rob040]

Platform

ESP32

IDE / Tooling

Arduino (IDE/CLI)

What happened?

Compilation error on this library internal member function:

e:\develop\Arduino\libraries\ESP_Async_WebServer\src/ESPAsyncWebServer.h: In member function 'tcp_state AsyncWebServer::state() const':
e:\develop\Arduino\libraries\ESP_Async_WebServer\src/ESPAsyncWebServer.h:1107:49: error: passing 'const AsyncServer' as 'this' argument discards qualifiers [-fpermissive]
1107 | return static_cast<tcp_state>(_server.status());
| ~~~~~~~~~~~~~~^~

Using latest version of ESPAsyncWebServer v3.7.6
Using latest version of AsyncTCP v3.3.6
Using latest Arduino IDE version v2.3.6
Using ArduinoESP32 Arduino Release v3.2.0 based on ESP-IDF v5.4.1

Stack Trace

See compiler output above

Minimal Reproductible Example (MRE)

From Arduino library AsyncEspFsWebserver v2.0.2 (latest) by Tolentino Cotesta, compile example customOptions, without any modifications

I confirm that:

• I have read the documentation.
• I have searched for similar discussions.
• I have searched for similar issues.
• I have looked at the examples.
• I have upgraded to the lasted version of ESPAsyncWebServer (and AsyncTCP for ESP32).

[mathieucarbou]

@rob040 : there is probably an issue in your project regarding dependencies. This error tells that
uint8_t AsyncServer::status() const { in your version that is compiled is not const (not immutable).

Try to compile the ServerState.ino example of the project, only using ESpAsyncWS and AsyncTCP.
Make sure you cleanup your libs and only have those 2 at their latest version.

This is what our CI is doing, and it works.

I suspect something brings a conflict in your project maybe ?

[rob040]

This was indeed caused by duplicate library AsyncTCP v1.1.4 by me-no-dev and [email protected] by ESP32Async.

I removed the former one, which probably will kill the compilation of some older project, that will require more time investment to get compiled with latest API . On the other hand, no big issue, as I should not use Arduino IDE for meaningful projects, as its library handling is a PITA. I should and will only use Arduino IDE for quick trials.

wrt this issue, the Arduino IDE does not help me to identify that the culprit function was external to this library, while I estimated it was fully internal but maybe compiler setting/version related.

[mathieucarbou]

IMO, Arduino IDE is not an IDE.
It is much more an editor with added features around Arduino to help quick one-ino-file PoC.
A real IDE like Vscode, coupled with a better build system like pioarduino PlatformIO extension is required as soon as you want stability and reliability around dependency resolution in your project.

[mathieucarbou]

You are not alone to have this issue sadly... A lot of people do not understand how bad is Arduino IDE for dependency management.

[mathieucarbou]

Marking this as duplicate of #142

[rob040]

Totally agree.
My preferred IDE is also VScode with PlatformIO.
'pioarduino' is new to me, I'll have a look at that.

[mathieucarbou]

pioarduino is the vscode extension that replaces PlatformIO.

It enables to user Arduino Core 3 with PlatformIO Tooling, since PlatformIO dropped supporting the espressif platform.

https://github.com/pioarduino/platform-espressif32