llvmPackages_18: init

[RossComputerGuy]

Description of changes

Closes #293866

Adding LLVM 18 to Nixpkgs, opening as a draft while I work on this.

Things done

• Update patches
• Test if working

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin
• For non-Linux: Is sandboxing enabled in nix.conf? (See Nix manual)
  • sandbox = relaxed
  • sandbox = true
• Tested, as applicable:
  • NixOS test(s) (look inside nixos/tests)
  • and/or package tests
  • or, for functions and "core" functionality, tests in lib/tests or pkgs/test
  • made sure NixOS tests are linked to the relevant packages
• Tested compilation of all packages that depend on this change using nix-shell -p nixpkgs-review --run "nixpkgs-review rev HEAD". Note: all changes have to be committed, also see nixpkgs-review usage
• Tested basic functionality of all binary files (usually in ./result/bin/)
• 24.05 Release Notes (or backporting 23.05 and 23.11 Release notes)
  • (Package updates) Added a release notes entry if the change is major or breaking
  • (Module updates) Added a release notes entry if the change is significant
  • (Module addition) Added a release notes entry if adding a new NixOS module
• Fits CONTRIBUTING.md.

---

Add a 👍 reaction to pull requests you find important.

[ghost]

PR #292043 which is currently in staging-next made changes to the LLVMs specifically, merging libcxxabi into libcxx.

Please start with a LLVM which has those changes when copying all the files into llvm/18

thanks.

[RossComputerGuy]

@a-n-n-a-l-e-e Alright, I'll rebase this with that. I didn't see that since I'm at NixCon NA and there's WiFi issues here lol.

[ghost]

are these files copied from llvm_git or llvm_17? looks like llvm_17.

[ghost]

@a-n-n-a-l-e-e Alright, I'll rebase this with that. I didn't see that since I'm at NixCon NA and there's WiFi issues here lol.

you might want to be on staging-next and then rebase to master once it merges into master because c++ code will not compile with this toolchain on master currently.

[RossComputerGuy]

@a-n-n-a-l-e-e Yes it is copied from 17, I couldn't pull almost anything at NixCon NA but now that I'm back home, I can do that. I'll trying to do that here in a bit.

[ghost]

I think that leaving libunwind as a separate component is a mistake as it is no longer supported. i think it should be combined into libcxx as it is coupled to libcxxabi i believe. have to look at this a little more tho.

I'll look into this tonight.

so i think standalone libunwind is fine libcxx just errors when LIBCXXABI_USE_LLVM_UNWINDER=ON using an external libunwind. we could try to just specify libunwind as the system unwinder, that's what we did with libcxxabi but resulted in using the wrong linker flags on darwin, but looking over the cmake files it seems less of an issue for libunwind.

so the change in libcxx/default.nix would be.

diff --git a/pkgs/development/compilers/llvm/18/libcxx/default.nix b/pkgs/development/compilers/llvm/18/libcxx/default.nix
index a865c27f4845..a071bcbf1e20 100644
--- a/pkgs/development/compilers/llvm/18/libcxx/default.nix
+++ b/pkgs/development/compilers/llvm/18/libcxx/default.nix
@@ -1,5 +1,5 @@
 { lib, stdenv, llvm_meta
-, monorepoSrc, runCommand, fetchpatch
+, monorepoSrc, runCommand
 , cmake, lndir, ninja, python3, fixDarwinDylibNames, version
 , cxxabi ? if stdenv.hostPlatform.isFreeBSD then libcxxrt else null
 , libcxxrt, libunwind
@@ -19,10 +19,10 @@ let
   # Note: useLLVM is likely false for Darwin but true under pkgsLLVM
   useLLVM = stdenv.hostPlatform.useLLVM or false;
 
-  cxxabiCMakeFlags = lib.optionals (useLLVM && !stdenv.hostPlatform.isWasm) [
-    "-DLIBCXXABI_USE_LLVM_UNWINDER=ON"
-  ] ++ lib.optionals (lib.versionAtLeast version "18" && !(useLLVM && !stdenv.hostPlatform.isWasm)) [
+  cxxabiCMakeFlags = [
     "-DLIBCXXABI_USE_LLVM_UNWINDER=OFF"
+  ] ++ lib.optionals (useLLVM && !stdenv.hostPlatform.isWasm) [
+    "-DLIBCXXABI_ADDITIONAL_LIBRARIES=unwind"
   ] ++ lib.optionals stdenv.hostPlatform.isWasm [
     "-DLIBCXXABI_ENABLE_THREADS=OFF"
     "-DLIBCXXABI_ENABLE_EXCEPTIONS=OFF"
@@ -86,18 +86,6 @@ stdenv.mkDerivation rec {
   patches = lib.optionals (stdenv.isDarwin && lib.versionOlder stdenv.hostPlatform.darwinMinVersion "10.13") [
     # https://github.com/llvm/llvm-project/issues/64226
     ./0001-darwin-10.12-mbstate_t-fix.patch
-  ] ++ lib.optionals (cxxabi == null && lib.versionAtLeast version "18") [
-    # Allow building libcxxabi alone when using LLVM unwinder
-    (fetchpatch {
-      url = "https://github.com/llvm/llvm-project/commit/77610dd10454e87bb387040d2b51100a17ac5755.patch";
-      revert = true;
-      hash = "sha256-jFbC3vBY3nKfjknJ7UzaPyoy0iSYdD3+jUmOFeOaVcA=";
-    })
-    (fetchpatch {
-      url = "https://github.com/llvm/llvm-project/commit/48e5b5ea92674ded69b998cf35724d9012c0f57d.patch";
-      revert = true;
-      hash = "sha256-WN63L4T3GxVozPZb6kx21AgNe4rwwSUOeeryIGsvQYY=";
-    })
   ];
 
   postPatch = ''

[RossComputerGuy]

I think that leaving libunwind as a separate component is a mistake as it is no longer supported. i think it should be combined into libcxx as it is coupled to libcxxabi i believe. have to look at this a little more tho.

I'll look into this tonight.

so i think standalone libunwind is fine libcxx just errors when LIBCXXABI_USE_LLVM_UNWINDER=ON using an external libunwind. we could try to just specify libunwind as the system unwinder, that's what we did with libcxxabi but resulted in using the wrong linker flags on darwin, but looking over the cmake files it seems less of an issue for libunwind.
so the change in libcxx/default.nix would be.

diff --git a/pkgs/development/compilers/llvm/18/libcxx/default.nix b/pkgs/development/compilers/llvm/18/libcxx/default.nix
index a865c27f4845..a071bcbf1e20 100644
--- a/pkgs/development/compilers/llvm/18/libcxx/default.nix
+++ b/pkgs/development/compilers/llvm/18/libcxx/default.nix
@@ -1,5 +1,5 @@
 { lib, stdenv, llvm_meta
-, monorepoSrc, runCommand, fetchpatch
+, monorepoSrc, runCommand
 , cmake, lndir, ninja, python3, fixDarwinDylibNames, version
 , cxxabi ? if stdenv.hostPlatform.isFreeBSD then libcxxrt else null
 , libcxxrt, libunwind
@@ -19,10 +19,10 @@ let
   # Note: useLLVM is likely false for Darwin but true under pkgsLLVM
   useLLVM = stdenv.hostPlatform.useLLVM or false;
 
-  cxxabiCMakeFlags = lib.optionals (useLLVM && !stdenv.hostPlatform.isWasm) [
-    "-DLIBCXXABI_USE_LLVM_UNWINDER=ON"
-  ] ++ lib.optionals (lib.versionAtLeast version "18" && !(useLLVM && !stdenv.hostPlatform.isWasm)) [
+  cxxabiCMakeFlags = [
     "-DLIBCXXABI_USE_LLVM_UNWINDER=OFF"
+  ] ++ lib.optionals (useLLVM && !stdenv.hostPlatform.isWasm) [
+    "-DLIBCXXABI_ADDITIONAL_LIBRARIES=unwind"
   ] ++ lib.optionals stdenv.hostPlatform.isWasm [
     "-DLIBCXXABI_ENABLE_THREADS=OFF"
     "-DLIBCXXABI_ENABLE_EXCEPTIONS=OFF"
@@ -86,18 +86,6 @@ stdenv.mkDerivation rec {
   patches = lib.optionals (stdenv.isDarwin && lib.versionOlder stdenv.hostPlatform.darwinMinVersion "10.13") [
     # https://github.com/llvm/llvm-project/issues/64226
     ./0001-darwin-10.12-mbstate_t-fix.patch
-  ] ++ lib.optionals (cxxabi == null && lib.versionAtLeast version "18") [
-    # Allow building libcxxabi alone when using LLVM unwinder
-    (fetchpatch {
-      url = "https://github.com/llvm/llvm-project/commit/77610dd10454e87bb387040d2b51100a17ac5755.patch";
-      revert = true;
-      hash = "sha256-jFbC3vBY3nKfjknJ7UzaPyoy0iSYdD3+jUmOFeOaVcA=";
-    })
-    (fetchpatch {
-      url = "https://github.com/llvm/llvm-project/commit/48e5b5ea92674ded69b998cf35724d9012c0f57d.patch";
-      revert = true;
-      hash = "sha256-WN63L4T3GxVozPZb6kx21AgNe4rwwSUOeeryIGsvQYY=";
-    })
   ];
 
   postPatch = ''

Alright, I've implemented this

[RossComputerGuy]

Just fixed a conflict.

[ghost]

the libunwind change in libcxx looks like it got reverted on the last update.

[theoparis]

I think once MLIR is added, these options should be enabled by default, with vulkan being optional.

-DMLIR_ENABLE_VULKAN_RUNNER=ON \
-DMLIR_ENABLE_SPIRV_CPU_RUNNER=ON \
-DMLIR_ENABLE_EXECUTION_ENGINE=ON \

[RossComputerGuy]

the libunwind change in libcxx looks like it got reverted on the last update.

It looks to be present still. It was only needed for git.

[ghost]

the libunwind change in libcxx looks like it got reverted on the last update.

It looks to be present still. It was only needed for git.

it should be in both. 18 is reverting two commits to make libunwind work the old way.

[RossComputerGuy]

the libunwind change in libcxx looks like it got reverted on the last update.

It looks to be present still. It was only needed for git.

it should be in both. 18 is reverting two commits to make libunwind work the old way.

Alright, done.

[ghost]

diffed changes against llvm17. looks good. missing one patch in lld but perhaps it was already incorporated upstream.

[ghost]

compared to llvm17 this is missing ./add-table-base.patch. is it no longer needed?

[RossComputerGuy]

I believe so

[ghost]

ok. diffed 18 against git. looks good except for libcxx/default.nix.

git/libcxx/default.nix is not correct and should be refreshed from the one from 18/libcxx/default.nix

also noticed that 18/libcxx/default.nix is missing a flag (comment inline) so that should be added as well.

[RossComputerGuy]

Added @Artturin's update-git.py commit as they stated on Matrix.