[BUG] Multiple definition of u8g_bitData, u8g_bitNotData, etc

[roobre]

Bug Description

While trying to compile with latest u8glib, I get linker errors regarding multiple u8glib-related variables, defined here:

Marlin/Marlin/src/HAL/AVR/u8g_com_HAL_AVR_sw_spi.cpp

Lines 67 to 68 in c352aeb

	uint8_t u8g_bitData, u8g_bitNotData, u8g_bitClock, u8g_bitNotClock;
	volatile uint8_t *u8g_outData, *u8g_outClock;

These variables collide with some with the same name in u8glib:

https://github.com/olikraus/U8glib_Arduino/blob/f17d404d8a20831bfb07ef5de0d225cada2adaef/src/clib/u8g_com_arduino_sw_spi.c#L62

These symbols do not seem to be used outside their compilation unit neither in U8glib, nor in Marlin, at least as far as I could grep. I have solved this locally by patching Marlin and unexport them. See the diff here:

roobre/Marlin-E5P@2.0.x...roobre:fix-u8glib-exported

I am running Marlin on my printer with this patch and I haven't found issues so far.

My Configurations

Configuration is basically the sample in the current 2.0.x branch with some tweaks for the Ender 5 Pro. A diff can be found here: roobre/Marlin-E5P@fix-u8glib-exported...roobre:2.0.x-e5p

Perhaps the most relevant changes are:

#define MOTHERBOARD BOARD_MELZI_CREALITY
#define CR10_STOCKDISPLAY

Steps to Reproduce

1. Download Marlin
2. Download U8glib either manually or from the Arduino IDE
3. Attempt to build using the Arduino IDE

Expected behavior: Build succeeds

Actual behavior: Linking fails due to multiple definitions.

Additional Information

It could be that I am not building Marlin correctly, if that is the case please tell me. Otherwise, the patch I linked above is working for me so I could happily create a PR for it.

I also think that it would be better practice to unexport this in U8glib, rather than in Marlin, but since U8g v1 seems to be long unmaintained I think I'd have better success by submitting a patch here.

[boelle]

tried with vscode+plaform.io ?

[roobre]

tried with vscode+plaform.io ?

No, sorry, I do not have VSC or PIO on my laptop. It might work with that setup.

[boelle]

i use that... but be warned: its highly addictive, once you tried you will never go back to arduino ide

[roobre]

i use that... but be warned: its highly addictive, once you tried you will never go back to arduino ide

Yeah, Arduino IDE is quite simple and limited, I'm not particularly a fan. I usually use arduino-mk for my projects, but honestly I was not able to get Marlin's makefile to work...

In any case, I'd like to have some feedback regarding the patch, just to see if it is worth to create a PR for it :)

[roobre]

I wanted to add that I tried (in fact, switched to) PIO, which pulls a different u8glib (https://github.com/MarlinFirmware/U8glib-HAL). I cannot reproduce this using PIO setup.

When I was using Arduino for compiling, I tried to use the library mentioned above instead for compilation, but it did not work to me. Unfortunately, I do not have the exact output right now, but I can try to get it if you think it may help.

However, I still think that it would be a good idea to keep those symbols private, as they seem to be internal and are conflicting on at least one build environment. Is there a reason I'm not seeing them for keeping them exported?

[sjasonsmith]

@roobre it might be more effective to just post the PR, they will usually be responded to within a couple days. Just be sure to post it against the bugfix-2.0.x branch.

I haven't responded before now because I don't know anything about these u8g libraries, or why there is a custom version for Marlin and we have these duplicated functions.

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