See also: https://bugs.gentoo.org/706366
gcc-10 and above flipped a default from -fcommon to -fno-common:
https://gcc.gnu.org/PR85678
Usually all it takes is to add a few 'extern' declarations and
move definitions from header files to modules. I've port iverilog
to gcc-10 accroding to this guide:
https://wiki.gentoo.org/wiki/Gcc_10_porting_notes/fno_common
To fix this, I analyzed the code, and found ``pli_trace`` has been
defined at here:
https://github.com/steveicarus/iverilog/blob/v10_3/libveriuser/priv.c#L24
So I changed ``FILE* pli_trace;`` to ``extern FILE* pli_trace;``.
The var ``current_file`` only in ``cfparse_misc.h``, I changed it
from ``char *current_file;`` to ``extern char *current_file;`` and
declaring it in cflexor.lex
And then it works.
Signed-off-by: Huang Rui <vowstar@gmail.com>