Compilation behaviour

[edg2411]

Platform

ESP32

IDE / Tooling

pioarduino

What happened?

I found a strange behavior when trying to compile a project using this library.
If I include it but don’t include the header in the program, it gives a compilation error — but if I do include it, it compiles fine, even without actually using it. It was tested with different platform versions and with different LDF modes.

Stack Trace

including the header:

Compiling .pio/build/esp32dev/lib452/WebServer/Parsing.cpp.o
Compiling .pio/build/esp32dev/lib452/WebServer/WebServer.cpp.o
Linking .pio/build/esp32dev/firmware.elf
Retrieving maximum program size .pio/build/esp32dev/firmware.elf
Checking size .pio/build/esp32dev/firmware.elf
Advanced Memory Usage is available via "PlatformIO Home > Project Inspect"
RAM: [= ] 6.2% (used 20328 bytes from 327680 bytes)
Flash: [== ] 22.7% (used 297765 bytes from 1310720 bytes)
Building .pio/build/esp32dev/firmware.bin
esptool.py v4.8.1.1
Creating esp32 image...
Merged 2 ELF sections
Successfully created esp32 image.

without including the header:
Processing esp32dev (platform: https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip; board: esp32doit-devkit-v1; framework: arduino)

Verbose mode can be enabled via -v, --verbose option
CONFIGURATION: https://docs.platformio.org/page/boards/espressif32/esp32doit-devkit-v1.html
PLATFORM: Espressif 32 (51.3.6) > DOIT ESP32 DEVKIT V1
HARDWARE: ESP32 240MHz, 320KB RAM, 4MB Flash
DEBUG: Current (cmsis-dap) External (cmsis-dap, esp-bridge, esp-prog, iot-bus-jtag, jlink, minimodule, olimex-arm-usb-ocd, olimex-arm-usb-ocd-h, olimex-arm-usb-tiny-h, olimex-jtag-tiny, tumpa)
PACKAGES:

• framework-arduinoespressif32 @ 3.0.7
• framework-arduinoespressif32-libs @ 5.1.0+sha.632e0c2a9f
• tool-esptoolpy @ 4.8.1
• tool-mklittlefs @ 3.2.0
• tool-riscv32-esp-elf-gdb @ 12.1.0+20221002
• tool-xtensa-esp-elf-gdb @ 12.1.0+20221002
• toolchain-xtensa-esp32 @ 12.2.0+20230208
  LDF: Library Dependency Finder -> https://bit.ly/configure-pio-ldf
  LDF Modes: Finder ~ chain, Compatibility ~ strict
  Found 42 compatible libraries
  Scanning dependencies...
  Dependency Graph
  |-- AsyncTCP @ 3.4.9
  |-- ESPAsyncWebServer @ 3.8.1
  Building in release mode
  Compiling .pio/build/esp32dev/src/main.cpp.o
  Compiling .pio/build/esp32dev/lib452/WebServer/Parsing.cpp.o
  Compiling .pio/build/esp32dev/lib452/WebServer/WebServer.cpp.o
  /home/ezedg/.platformio/packages/framework-arduinoespressif32/libraries/WebServer/src/Parsing.cpp:24:10: fatal error: NetworkServer.h: No such file or directory

---

• Looking for NetworkServer.h dependency? Check our library registry!
• CLI > platformio lib search "header:NetworkServer.h"
• Web > https://registry.platformio.org/search?q=header:NetworkServer.h

---

24 | #include "NetworkServer.h"
| ^~~~~~~~~~~~~~~~~
compilation terminated.
/home/ezedg/.platformio/packages/framework-arduinoespressif32/libraries/WebServer/src/WebServer.cpp:28:10: fatal error: NetworkServer.h: No such file or directory

---

• Looking for NetworkServer.h dependency? Check our library registry!
• CLI > platformio lib search "header:NetworkServer.h"
• Web > https://registry.platformio.org/search?q=header:NetworkServer.h

---

28 | #include "NetworkServer.h"
| ^~~~~~~~~~~~~~~~~
compilation terminated.
*** [.pio/build/esp32dev/lib452/WebServer/Parsing.cpp.o] Error 1
*** [.pio/build/esp32dev/lib452/WebServer/WebServer.cpp.o] Error 1

Minimal Reproductible Example (MRE)

main.cpp (with and without the line commented)
#include <Arduino.h>

// #include <ESPAsyncWebServer.h>

void setup() {
Serial.begin(9600);
Serial.println("Hello, Arduino!");
}

void loop() {
// Your main code would go here
}

[env:esp32dev]
platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
board = esp32doit-devkit-v1
framework = arduino
monitor_speed = 115200
board_build.filesystem = littlefs
; build_flags = -DCORE_DEBUG_LEVEL=ARDUHAL_LOG_LEVEL_NONE
lib_compat_mode = strict
lib_ldf_mode = chain
lib_deps =
ESP32Async/AsyncTCP
ESP32Async/ESPAsyncWebServer

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]

@edg2411 : Hi, please open a support ticket next time or search ;-) 99% of time user think there is an issue in the lib, there is actually a problem in user code.

In that case, yes this is known.

Happens when you are compiling a program with ESP32Async/ESPAsyncWebServer in the compile classpath but without using it, that's why. Either remove the libs or include the header.

Or add WiFi.h (or something adding NetworkServer.h).

Also, maybe try to work on a reproductible use case because looking at the compile steps:

Compiling .pio/build/esp32dev/lib452/WebServer/WebServer.cpp.o
/home/ezedg/.platformio/packages/framework-arduinoespressif32/libraries/WebServer/src/Parsing.cpp:24:10: fatal error: NetworkServer.h: No such file or directory

it does not even reach the ESP32Async libs....

It seems more linked to the use of some Arduino includes in files that are compiled but not included in main.cpp maybe ?

FYI, ESP32Async libs do not import NetworkServer.h directly. It comes transitively through others.

[edg2411]

Hi, thanks for replying. I just wanted to know if this was normal behavior. I know the library works — in fact, I use it. As for providing a reproducible example, what I shared already clearly shows what I’m trying to point out. This hasn’t happened with other libraries; I just wanted to ask to understand why.

[mathieucarbou]

I suspect because you do not have WiFi.h (or another network header) in your main.cpp.
The compiler still tries to compile the libs and its cpp files since the lib is still included even if not used (see the dependency graph output). Even if at the end the linker should discard.
You can try including WiFi.h in main.cpp: it should work I think because the compile path would now contain arduino network libs.

[edg2411]

Ok thank you very much for clarifying that to me

[vortigont]

You can also include ‘WebServer‘ in platformio's ‘lib_ignore‘, it is a platformio's ldf issue