libdill appears to be unmaintained and installation has failed

[lihaidong-GSLZ]

I have been studying from your book "Modern Fortran" during this time. It is a good book. I have learned a lot of new knowledge from the first ten chapters, and I am very grateful for it.
In Chapter 11 I ran into a problem. I was stuck at the beginning. The problem is with the installation of libdill.
I compiled and executed the following code on WSL,

git clone https://github.com/modern-fortran/tcp-client-server
cd tcp-client-server
make

However, I encountered an error during the process:

cd libdill && ./autogen.sh && ./configure && make && cp .libs/libdill.a ..
autoreconf: export WARNINGS=
autoreconf: Entering directory '.'
autoreconf: configure.ac: not using Gettext
autoreconf: running: aclocal --force -I m4
autoreconf: configure.ac: tracing
autoreconf: running: libtoolize --copy --force
libtoolize: putting auxiliary files in '.'.
libtoolize: copying file './ltmain.sh'
libtoolize: putting macros in AC_CONFIG_MACRO_DIRS, 'm4'.
libtoolize: copying file 'm4/libtool.m4'
libtoolize: copying file 'm4/ltoptions.m4'
libtoolize: copying file 'm4/ltsugar.m4'
libtoolize: copying file 'm4/ltversion.m4'
libtoolize: copying file 'm4/lt~obsolete.m4'
autoreconf: configure.ac: not using Intltool
autoreconf: configure.ac: not using Gtkdoc
autoreconf: running: aclocal --force -I m4
autoreconf: running: /usr/bin/autoconf --force
configure.ac:59: warning: The macro `AC_PROG_CC_C99' is obsolete.
configure.ac:59: You should run autoupdate.
./lib/autoconf/c.m4:1659: AC_PROG_CC_C99 is expanded from...
configure.ac:59: the top level
configure.ac:210: warning: AC_OUTPUT should be used without arguments.
configure.ac:210: You should run autoupdate.
configure.ac:119: error: possibly undefined macro: AC_CHECK_LIB
      If this token and others are legitimate, please use m4_pattern_allow.
      See the Autoconf documentation.
configure.ac:127: error: possibly undefined macro: AC_MSG_ERROR
autoreconf: error: /usr/bin/autoconf failed with exit status: 1
make: *** [Makefile:24: libdill.a] Error 1

I attempted to seek help on the official libdill website (https://libdill.org/), but it seems the project is no longer actively maintained.

I learned that this library was written and maintained by a senior expert, but was abandoned for unknown reasons, and now even the documentation cannot be viewed.

I wanted to bring this issue to your attention and seek guidance on how to proceed. Any assistance or suggestions would be greatly appreciated.

Thank you

[jnorrid]

Just went to http://libdill.org and yes, it appears that the website is no longer available. That said, the documentation appears to have moved to GitHub Pages and is located here: https://sustrik.github.io/libdill/index.html. It might make sense to update the README.md for this repo to point to https://sustrik.github.io/libdill/index.html for libdill docs and possibly also add the GH repo for it here: https://github.com/sustrik/libdill.

[milancurcic]

I agree, and thanks for finding the correct current URL. I can update the README early next week, unless one of you wishes to open a PR sooner. Thanks!

[jnorrid]

PR submitted. thanks for writing this book - it is VERY well done!