WebSocket - void send_P() is deprecated

[mikrocoder]

Hello,

Edit
Excuse me. I just realized that the deprecated warning did not come directly from the compiler, instead it came from the C++ source code. So it was set to deprecated by yourself. I apologize for this.
/Edit

Platform

ESP32

IDE / Tooling

Arduino (IDE/CLI)

What happened?

When I compile the WebSocket example I get a deprecated warning. I think this should be changed at some point. I am using the Espressif Core 3.1.1 with the Arduino IDE 2.3.4 with C++20 (23) and Windows 11

Stack Trace

"C:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\tools\\esp-x32\\2405/bin/xtensa-esp32s3-elf-g++" -MMD -c "@C:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\tools\\esp32-arduino-libs\\idf-release_v5.3-cfea4f7c-v1\\esp32s3/flags/cpp_flags" -std=gnu++23 -Wno-volatile -Os -Werror=return-type -DF_CPU=240000000L -DARDUINO=10607 -DARDUINO_XIAO_ESP32S3 -DARDUINO_ARCH_ESP32 "-DARDUINO_BOARD=\"XIAO_ESP32S3\"" "-DARDUINO_VARIANT=\"XIAO_ESP32S3\"" -DARDUINO_PARTITION_default_8MB "-DARDUINO_HOST_OS=\"windows\"" "-DARDUINO_FQBN=\"esp32:esp32:XIAO_ESP32S3:UploadSpeed=921600,USBMode=hwcdc,CDCOnBoot=default,MSCOnBoot=default,DFUOnBoot=default,UploadMode=default,CPUFreq=240,FlashMode=qio,FlashSize=8M,PartitionScheme=default_8MB,DebugLevel=none,PSRAM=disabled,LoopCore=1,EventsCore=1,EraseFlash=none,JTAGAdapter=default\"" -DESP32=ESP32 -DCORE_DEBUG_LEVEL=0 -DARDUINO_RUNNING_CORE=1 -DARDUINO_EVENT_RUNNING_CORE=1 -DARDUINO_USB_MODE=1 -DARDUINO_USB_CDC_ON_BOOT=1 -DARDUINO_USB_MSC_ON_BOOT=0 -DARDUINO_USB_DFU_ON_BOOT=0 "@C:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\tools\\esp32-arduino-libs\\idf-release_v5.3-cfea4f7c-v1\\esp32s3/flags/defines" "-IC:\\Users\\Worker\\AppData\\Local\\Temp\\.arduinoIDE-unsaved202528-9912-xh4lir.zrgbi\\WebSocket" -iprefix "C:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\tools\\esp32-arduino-libs\\idf-release_v5.3-cfea4f7c-v1\\esp32s3/include/" "@C:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\tools\\esp32-arduino-libs\\idf-release_v5.3-cfea4f7c-v1\\esp32s3/flags/includes" "-IC:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\tools\\esp32-arduino-libs\\idf-release_v5.3-cfea4f7c-v1\\esp32s3/qio_qspi/include" "-IC:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\3.1.1\\cores\\esp32" "-IC:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\3.1.1\\variants\\XIAO_ESP32S3" "-Ig:\\Arduino IDE v2.3.4\\portable\\sketchbook\\libraries\\credentials" "-IC:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\3.1.1\\libraries\\WiFi\\src" "-IC:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\3.1.1\\libraries\\Network\\src" "-Ig:\\Arduino IDE v2.3.4\\portable\\sketchbook\\libraries\\Async_TCP\\src" "-Ig:\\Arduino IDE v2.3.4\\portable\\sketchbook\\libraries\\ESP_Async_WebServer\\src" "-IC:\\Users\\Worker\\AppData\\Local\\Arduino15\\packages\\esp32\\hardware\\esp32\\3.1.1\\libraries\\FS\\src" "@C:\\Users\\Worker\\AppData\\Local\\arduino\\sketches\\D65EAF21176EFB3E025EFC79F0AA7AAC/build_opt.h" "@C:\\Users\\Worker\\AppData\\Local\\arduino\\sketches\\D65EAF21176EFB3E025EFC79F0AA7AAC/file_opts" "C:\\Users\\Worker\\AppData\\Local\\arduino\\sketches\\D65EAF21176EFB3E025EFC79F0AA7AAC\\sketch\\WebSocket.ino.cpp" -o "C:\\Users\\Worker\\AppData\\Local\\arduino\\sketches\\D65EAF21176EFB3E025EFC79F0AA7AAC\\sketch\\WebSocket.ino.cpp.o"
C:\Users\Worker\AppData\Local\Temp\.arduinoIDE-unsaved202528-9912-xh4lir.zrgbi\WebSocket\WebSocket.ino: In lambda function:
C:\Users\Worker\AppData\Local\Temp\.arduinoIDE-unsaved202528-9912-xh4lir.zrgbi\WebSocket\WebSocket.ino:140:20: warning: 'void AsyncWebServerRequest::send_P(int, const String&, const char*, AwsTemplateProcessor)' is deprecated: Replaced by send(int code, const String& contentType, const char* content = asyncsrv::empty, AwsTemplateProcessor callback = nullptr) [-Wdeprecated-declarations]
In file included from C:\Users\Worker\AppData\Local\Temp\.arduinoIDE-unsaved202528-9912-xh4lir.zrgbi\WebSocket\WebSocket.ino:5:
g:\Arduino IDE v2.3.4\portable\sketchbook\libraries\ESP_Async_WebServer\src/ESPAsyncWebServer.h:423:8: note: declared here
  423 |   void send_P(int code, const String &contentType, PGM_P content, AwsTemplateProcessor callback = nullptr) {
      |        ^~~~~~
Bibliotheken werden kompiliert ...

Minimal Reproductible Example (MRE)

WebSocket Example from ESP32 Async WebServer Library

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]

There is no warning when compiling with this lib on Arduino 3.
Pleas have a look at the CI.

https://github.com/ESP32Async/ESPAsyncWebServer/actions/runs/13674993269/job/38233414438#step:6:4841

You might have something wrong in your environment?

[me-no-dev]

@mathieucarbou method is deprecated on ESP32: https://github.com/ESP32Async/ESPAsyncWebServer/blob/main/src/ESPAsyncWebServer.h#L422

[me-no-dev]

@mikrocoder this is not an issue. Methods do get deprecated from time to time. You should move to the suggested send instead

[mikrocoder]

Why should my Arduino IDE 2.3.4 not work with the Lib example. With Espressif Core 3.1.1 and C++20 I get the mentioned deprecated warning.
Surely this can be changed in the lib?
If the change is to make sense, then it must be changed in the lib. Otherwise a lib makes no sense. I just want to give you a hint.

[mathieucarbou]

Surely this can be changed in the lib?

the lib is fine.
this is a compiler warning telling you to not use this method anymore.
this is not a compiler error.

there is nothing to fix in the lib.

also, depending on the platform used (i.e. pioarduino, old platform espressif, esp8266, etc) all are using different compile flags. But that's not the lib problem. Up to the user to correctly set its compile flags.

[mikrocoder]

Excuse me. Of course it's your Lib's problem. You wrote the method. Now the compiler warns you about a future problem and you want to ignore it completely? Very strange behavior.

[mathieucarbou]

Excuse me. Of course it's your Lib's problem. You wrote the method. Now the compiler warns you about a future problem and you want to ignore it completely? Very strange behavior.

No that's the way around: developers are marking methods as deprecated because the goal is to warn library users that such method will be moved in a future major release.

In this case, the compiler tells you that it has detected a usage of send_P, and we marked this method as deprecated because it will be removed soon. This is a way to warn users before removal. The compiler instead asks you to check your code because there is a usage of send_P somewhere, and we marked it as being deprecated for removal soon.

Look, we are expert developers here and even if this is totally possible that there are some bugs in the library, from what I saw from the 2 last issues you opened, I really think you might refrain from writing such assertions like above and instead ramp up your developer skills and take advices from people around. You actually needed help / support for these 2 things: they are not library issues.

[mathieucarbou]

I am locking the discussion. The solution and explanations have already been provided.