Ok, I'd like to report that with the patch you sent me privately, I was able to compile https://github.com/hebisch/gpc

combined with ftp://ftp.gnu.org/gnu/gcc/gcc-3.4.6/gcc-core-3.4.6.tar.bz2 using Ubuntu 20.10 compiler:

was to say default but:

gcc (GCC) 9.3.1 20200430 (for GNAT Community 2020 20200818)

paul@jacko:~/gpc$ gpc --version

gpc 20070904, based on gcc-3.4.6

paul@jacko:~/gpc$ /usr/local/bin/gcc --version

gcc (GCC) 3.4.6

I did had to edit p/doc/hr/gpc.texi to begins:

--------------------------------------------------

\input texinfo

@setfilename gpc-hr.info

@documentencoding iso-8859-2

@settitle GNU Pascal priru<E8>nik.

@c We use Latin 2 charset for hr_HR language.

@set charset iso-8859-2

-----------------

and p/doc/es/gpcs.texi to begins:

-----------------------

\input texinfo

@setfilename gpcs.info

@documentencoding iso-8859-1

@settitle Est<E1>ndar de Codificaci<F3>n GNU Pascal

@c Copyright (C) 2001-2006 Free Software Foundation, Inc.

@c

@c Authors: Frank Heckenbach <frank@pascal.gnu.de>

@c          Peter Gerwinski <peter@gerwinski.de>

@c          Nicola Girardi <nicola@g-n-u.de>

@c

@c Remember to update this when you save

@set lastupdate 2006-02-02

@direntry

* Est<E1>ndares de Codificaci<F3>n Pascal: (gpcs).   Est<E1>ndares de codificaci<F3>n GNU Pascal.

@end direntry

-----------------------------

So I moved @documentencoding before @settitle when it was using some special characters... but I now see emacs did transform the characters in the document too.

And now I can:

paul@jacko:~/gpc$ rm a.out hello

paul@jacko:~/gpc$ gpc -o hello ../gpc2/gcc-3.4.6/gcc/p/demos/hello.pas

paul@jacko:~/gpc$ ls -lh

total 548K

-rwxrwxr-x 1 paul paul 546K mar  6 14:21 hello

paul@jacko:~/gpc$ ./hello

Hello, world.

paul@jacko:~/gpc$ gpc ../gpc2/gcc-3.4.6/gcc/p/demos/readdirdemo.pas

../gpc2/gcc-3.4.6/gcc/p/demos/readdirdemo.pas:31: erreur: module/unit interface `GPC' could not be imported

paul@jacko:~/gpc$ LANG=C gpc ../gpc2/gcc-3.4.6/gcc/p/demos/readdirdemo.pas

../gpc2/gcc-3.4.6/gcc/p/demos/readdirdemo.pas:31: error: module/unit interface `GPC' could not be imported

paul@jacko:~/gpc$

Will need to figure out what to do to make that working.