Check for `llvm-config` (without a version suffix)

[smoelius]

Additionally, on Arch Linux the current officially supported LLVM version is 16.0.6 so llvm-config command comes without a version prefix but the build script fails because it invokes llvm-config-16 --version instead of llvm-config --version. I had to create a symbolic link in order to fix this but it would be better if the build script checked llvm-config --version first before invoking the command with a specific prefix.

Originally posted by @a1akris in #434 (comment)

[h49nakxs]

Hi there,

Adding my 2 cents to the issue.

llvm-config command exists in two situations :

• LLVM has been installed using the distribution default package.
• LLVM has been built from source and then installed system-wide (by the way, AFLplusplus@9f6b012 cannot be build with LLVM 20).

But if a later version has been installed using another distribution package, e.g. llvm-17, llvm-18, then the command will be llvm-config-xx.

So I think you better retrieve the correct command using something like :
which llvm-config > /dev/null 2>&1 && echo 'llvm-config' || ls /usr/bin | grep -o 'llvm-config-[0-9][0-9]' | sort -r | head -1

[smoelius]

Thanks very much for these observations, @h49nakxs.

[vanhauser-thc]

Hi!

Thanks for the notice about the recent change in LLVM 20, fixed that in the dev branch.

Note that the current nightly is on LLVM 19, so that is the llvm version that needs to be installed (and matched against with llvm-config).