Release patched LLVM 15

[alan-j-hu]

I talked with @jberdine and we think that getting the LLVM 15 fork with the OCaml 5 support released on OPAM is more important than details of specific build systems. We think that LLVM 15 should just be released now in the same manner that LLVM 14 was.

My personal feeling after looking into Dune is that:

• Integrating Dune into LLVM upstream will make life harder for the predominantly C++ programmers maintaining LLVM. Therefore, I don't see a path going forward that would transition away from a separate Dune LLVM repo.
• Having the option of dynamic versus static linking to LLVM is much hackier with Dune than with OCamlfind. In general, I think Dune is opinionated in a way that is not good for multi-language projects. Perhaps this should be feedback for the Dune developers.

The ball is in the court of @kit-ty-kate to decide whether to accept this PR. Please let me know if you have any disagreement or concerns.

[jberdine]

I seem to recall that the conf-llvm package only needs to have the right major version, and the rest are superfluous. I don't remember where in the code I got that impression from though. It might be tidier to release conf-llvm.15 instead.

[jberdine]

Should this be llvm-devel-15, based on https://packages.fedoraproject.org/pkgs/llvm/llvm-devel/fedora-37.html ?

[alan-j-hu]

I do not know, as I am not a Fedora user. I am just copying over the naming convention from conf-llvm.14. Does the naming on that webpage, llvm-devel-15.0.0-1.fc37, imply that I would type dnf install llvm-devel-15 to install the package on Fedora?

I also found https://packages.fedoraproject.org/pkgs/llvm15/llvm15-devel/index.html.

[jberdine]

I am not familiar with the fedora naming scheme either, but am just guessing from the log of a failing CI job that says Error: Unable to find a match: llvm15-devel.

[alan-j-hu]

The CI seems to use Fedora 36. According to https://pkgs.org/download/llvm-devel, Fedora 26 has llvm-devel-14. On the other hand, https://pkgs.org/download/llvm15-devel says that llvm15-devel is available for Fedora 38 but not Fedora 36.

[jberdine]

The macos-homebrew-*-arm64 CI jobs fail with ld: library not found for -lzstd but the llvm@15 homebrew package does require zstd, so the failure is odd. I don't know if there is something nonstandard about the CI worker setup.

[alan-j-hu]

The relevant change being backported is https://reviews.llvm.org/D136400. My fork of LLVM also fixes various functions that were removed between LLVM 15 and LLVM 16 (and therefore not included in the linked patch) to work with OCaml 5. In addition, my fork of LLVM 15 adds deprecation annotations to various functions that were replaced between LLVM 15 and LLVM 16.

Compared to LLVM 14, the opam package file in this PR removes the conflicts with nnp and changes the tarball URL and hash.

[Kakadu]

@alan-j-hu Could you remind me, if there any easy ways to test this package without disabling the whole default opam repository? I have some trouble with https://discuss.ocaml.org/t/dynlinking-plugin-which-references-llvm-stubs/12596 and it would be great, if I could test LLVM 15.

[alan-j-hu]

@Kakadu The LLVM OCaml bindings README gives some instructions on how to install the bindings while linking to the already-installed LLVM: https://github.com/llvm/llvm-project/tree/main/llvm/bindings/ocaml

However, I'm not too experienced with this. I just tested the bindings by running the LLVM tests. IIRC CMake actually installed some of the files in the wrong place in the .opam folder and I had to manually move them, but I don't remember the details.

You can also try adding this branch of my fork as another opam repository, as seen with the example here: https://github.com/janestreet/opam-repository. However, I've never done this before.

[Kakadu]

You can also try adding this branch of my fork as another opam repository, as seen with the example here: https://github.com/janestreet/opam-repository. However, I've never done this before.

Build is currently failing:

#=== ERROR while compiling conf-llvm.15.0.7 ===================================#
Bad hash for   - /home/opam/.opam/repo/default/packages/conf-llvm/conf-llvm.15.0.7/files/configure.sh

[Kakadu]

It seem that "%{conf-llvm:config}%" is being expanded into empty string on my machine. I don't understand why this variable should have non-empty value. Is new release of llvm depends on minimal version of OPAM or something? I'm using 2.1.2

➜  asp opam install llvm.15.0.7 --verbose -y                                                        llvm15
The following actions will be performed:
∗ install llvm 15.0.7

<><> Processing actions <><><><><><><><><><><><><><><><><><><><><><><><><><><><>
⬇ retrieved llvm.15.0.7  (cached)
[llvm: patch] applying fix-shared.patch
[llvm: patch] applying fix-macos.patch
[llvm: patch] applying fix-rhel.patch
+ /mnt/mand/.opam/opam-init/hooks/sandbox.sh "build" "bash" "-ex" "install.sh" "" "/mnt/mand/.opam/llvm15/lib" "cmake" "make" "build" (CWD=/mnt/mand/.opam/llvm15/.opam-switch/build/llvm.15.0.7)
- + llvm_config=
- + libdir=/mnt/mand/.opam/llvm15/lib
- + cmake=cmake
- + make=make
- + action=build
- + case "$action" in
- + '' --link-static --libs
- install.sh: line 55: : command not found
- + '' --link-static --libs
- install.sh: line 59: : command not found
- + '' --link-shared --libs
- install.sh: line 62: : command not found
- + echo 'Link mode not recognized'
- Link mode not recognized
- + exit 1
[ERROR] The compilation of llvm.15.0.7 failed at "bash -ex install.sh  /mnt/mand/.opam/llvm15/lib cmake
make build".

[kit-ty-kate]

Superseded by #24268