Confusing LLVM versions

[phischu]

When running effekt --backend=llvm and entering 1 + 1 (or anthing really) or when I try to compile a file I with the LLVM backend I get:

error: Opaque pointers are only supported in -opaque-pointers mode (Producer: 'LLVM18.1.8' Reader: 'LLVM 14.0.0')
1 error generated.

I have

> clang --version
Ubuntu clang version 14.0.0-1ubuntu1.1
Target: x86_64-pc-linux-gnu
Thread model: posix
InstalledDir: /usr/bin

[jiribenes]

After #964, we likely require LLVM & Clang on version 18?

[marvinborner]

In #887 (comment) it was decided that Debian/Ubuntu users will have to do a "manual" LLVM installation via the LLVM APT repo.

[b-studios]

The question really is: do we want to support better error messages in this case or just ignore this issue?

[phischu]

I do have clang-18 too, which should be used. I believe we should swap the search order between clang-18 and clang (and also on the following two lines) here

effekt/effekt/jvm/src/main/scala/effekt/Runner.scala

Line 275 in db62053

lazy val clangCmd = discoverExecutable(List("clang", "clang-18"), List("--version"))

[jiribenes]

I agree provided that we flip all of them: preferring the foo-version over plain foo as a general rule.

[b-studios]

As discussed on Slack it does not solve it for me since I have a weird mix of unprefixed commands and also no version 18, but 19