Building examples

[yanboti]

Hi, I would like to selectively choose which examples to compile. In particular, I would like to build only Kyber.
Furthermore, I would like to build only modules that I require. As such, I'm trying to configure with the following command:
./configure.py
-cc=gcc -cxxflags=-std=c++20
--with-os-features=getentropy
--with-external-includedir=/usr/include
--with-external-includedir=/usr/include/x86-64-linux-gnu
--with-external-libdir=/usr/lib
--with-external-libdir=/usr/lib/x86-64-linux-gnu
--minimized-build
--enable-modules=kyber
--enable-modules=keccak
--enable-system_rng
--build-targets=static
--build-targets=shared
--build-targets=examples

But this runs into problems examples will try to build all the examples in the /src/examples folder. What should I do? I've tried renaming the example source files too, but that created other warnings with dependencies in the makefile.

[securitykernel]

I am sorry you experience issues with the build system. The examples are currently all-or-nothing, you can not selectively enable or disable single or multiple examples. Some require boost, so all currently require boost, as you noted that in #3790. With #3787 merged yesterday, configure.py checks that now and fails if boost isn't enabled with the examples.

What you could do instead, is do your minimized kyber-only build, and then compile the kyber example on your own, for example:

$ ./configure.py --enable-modules=kyber ... [all your additional options]
$ g++ kyber.cpp -o kyber -L. -lbotan-3 -Ibuild/include -std=c++20

[lieser]

@yanboti you are missing the hkdf and sha2_64 module.

[randombit]

This looks like a bug - we should not segfault if the KDF is not available

[lieser]

This looks like a bug - we should not segfault if the KDF is not available

Because of that I tried to reproduce it, but was unable. I think this was "just" an unhandled LookupError exception because of the hkdf and sha2_64 module.

[randombit]

OK looks like we don't segfault, it just exits with an uncaught exception

[yanboti]

Hello good people of botan, you are right that I didn't seg fault and what happened was that an abort signal was detected. I also subsequently realised that I was missing hkdf and sha2 modules. Thank you for your help!