[Q] literals.h compile error

[andg1]

I'm getting a compiler error about reassignment in literals.h
Replacing
#pragma once
with
#ifndef LITERALS_H
#define LITERALS_H
.
.
.
#endif

Fixes the error

[mathieucarbou]

@vortigont : could you please have a look at this issue ?

I suspect this is caused by compiler flags, maybe we should not use pragma for this project.

what do you think ?

Though, I find this a bit weird...

[mathieucarbou]

@andg1 : can you please show us the issue with the compilation flags ?

[andg1]

I'm using Arduino IDE anyway I think those are the compiler flags

/home/andrea/.arduino15/packages/esp32/tools/esp-xs3/2302/bin/xtensa-esp32s3-elf-g++ -c @/home/andrea/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.1-bd2b9390ef/esp32s3/flags/cpp_flags -w -Os -w -x c++ -E -CC -DF_CPU=240000000L -DARDUINO=10607 -DARDUINO_ESP32S3_DEV -DARDUINO_ARCH_ESP32 -DARDUINO_BOARD="ESP32S3_DEV" -DARDUINO_VARIANT="esp32s3" -DARDUINO_PARTITION_app3M_fat9M_16MB -DARDUINO_HOST_OS="linux" -DARDUINO_FQBN="esp32:esp32:esp32s3:UploadSpeed=921600,USBMode=hwcdc,CDCOnBoot=cdc,MSCOnBoot=default,DFUOnBoot=default,UploadMode=default,CPUFreq=240,FlashMode=qio,FlashSize=16M,PartitionScheme=app3M_fat9M_16MB,DebugLevel=none,PSRAM=opi,LoopCore=1,EventsCore=1,EraseFlash=none,JTAGAdapter=default,ZigbeeMode=default" -DESP32 -DCORE_DEBUG_LEVEL=0 -DARDUINO_RUNNING_CORE=1 -DARDUINO_EVENT_RUNNING_CORE=1 -DBOARD_HAS_PSRAM -DARDUINO_USB_MODE=1 -DARDUINO_USB_CDC_ON_BOOT=1 -DARDUINO_USB_MSC_ON_BOOT=0 -DARDUINO_USB_DFU_ON_BOOT=0 @/home/andrea/.arduino15/packages/esp32/tools/esp32-arduino-libs/idf-release_v5.1-bd2b9390ef/esp32s3/flags/defines -I/home/andrea/

[vortigont]

but what's the error actually?

[vortigont]

I do not like that #ifndef style, it makes sense if there could be cases where you can redefine declarations. Other than this, better to figure out the root cause of the problem.

[andg1]

Compilation error: redefinition of 'constexpr const char* const asyncsrv::T_100_CONTINUE', is trowing errors for every assignment about esp32
error: redefinition of 'constexpr const char* const asyncsrv::T_100_CONTINUE'
10 | static constexpr const char* T_100_CONTINUE = "100-continue";
| ^~~~~~~~~~~~~~
In file included from /.../ESPAsyncWebServer.h:46,
from /.../AsyncEventSource.h:43,
from /.../AsyncEventSource.cpp:24:
/.../literals.h:10:30: note: 'constexpr const char* const asyncsrv::T_100_CONTINUE' previously defined here
10 | static constexpr const char* T_100_CONTINUE = "100-continue";

[mathieucarbou]

@andg1 : is it possible that you have a mix of libraries ? can you show us your .pio/libdeps folder if you use pio, or if using arduino ide, maybe cleanup your lib and redownload them ?

Because you see this line:

In file included from /.../ESPAsyncWebServer.h:46,

It is also surrounded with #ifndef _ESPAsyncWebServer_H_

[vortigont]

agreed with mathieucarbou, pls recheck if by any chance you have two instances of literals.h files somewhere under .pio or other include dirs

also note this:
/.../literals.h:10:30: note: 'constexpr const char* const asyncsrv::T_100_CONTINUE'
error message mentions line 10, while in current instance of literals.h T_100_CONTINUE is defined in line 6.

[andg1]

The line is different because I've commented out the ifdef lines and added back pragma, also in a different computer I'm getting the same error on arduino ide. Will fix it in my side if no other user is getting the same error. Thank you anyway

[mathieucarbou]

The line is different because I've commented out the ifdef lines and added back pragma, also in a different computer I'm getting the same error on arduino ide. Will fix it in my side if no other user is getting the same error. Thank you anyway

You can try to use PlatformIO, and also you can try to compile an exemple in the project, using platformuio, or Arduino IDE, but first cleanup your dependency folder and start fresh. It really looks like an IDE / env issue. Platformio is correctly handling dependencies, not like Arduino IDE.

[Pablo2048]

@andg1 you can also try to install Arduino in portable mode (unfortunately only Arduino 1.x) https://docs.arduino.cc/software/ide-v1/tutorials/PortableIDE/ and try to compile to avoid library space poisoning.