fails to compile on raspberry pi 4 raspberry os 64 bit about ch341ser

[sirlucjan]

First of all: I compiled and the program is built without problems:

lucjan@archlinux ~/Pobrane/roboczy/roboczy-2/CH341SER $ export LANG=c
lucjan@archlinux ~/Pobrane/roboczy/roboczy-2/CH341SER $ make
make -C /lib/modules/5.8.11.ll27-1-lucjan-git/build  M=/home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER 
make[1]: Entering directory '/usr/lib/modules/5.8.11.ll27-1-lucjan-git/build'
  AR      /home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER/built-in.a
  CC [M]  /home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER/ch34x.o
  MODPOST /home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER/Module.symvers
  CC [M]  /home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER/ch34x.mod.o
  LD [M]  /home/lucjan/Pobrane/roboczy/roboczy-2/CH341SER/ch34x.ko
make[1]: Leaving directory '/usr/lib/modules/5.8.11.ll27-1-lucjan-git/build'

Secondly: Why do you compile on your root account? This is highly inadvisable.

Thirdly: Check on another gcc version, you have a bit out of date (the latest of the gcc8 line is 8.4).