chore(ci): add installation step for LLVM 18

bindgen requires Clang 9 and above. Add the libclang-dev and clang
packages from LLVM 18 toolchain and its dependencies.

Author: jorge-ortega

.github/workflows/rust.yml

@@ -5,6 +5,8 @@ on:
     paths-ignore:
       - "**.md"
   push:
+    branches:
+      - main
     paths-ignore:
       - "**.md"
 
@@ -80,7 +82,7 @@ jobs:
           sudo apt-get install -y libssl-dev
           sudo apt-get install -y libcurl4-openssl-dev
 
-      - name: Install LLVM 7
+      - name: Install LLVM 7 (for NVVM backend)
         if: contains(matrix.os, 'ubuntu')
         run: |
           mkdir -p ~/llvm7 && cd ~/llvm7
@@ -92,6 +94,17 @@ jobs:
           sudo apt-get install -y ./*.deb
           sudo ln -s /usr/bin/llvm-config-7 /usr/local/bin/llvm-config
 
+      - name: Install LLVM 18 (for bindgen)
+        if: matrix.os == 'ubuntu-24.04'
+        run: |
+          sudo apt-get update
+          sudo apt-get install -y gnupg
+          sudo apt-get install -y build-essential
+          wget -O - https://apt.llvm.org/llvm-snapshot.gpg.key | gpg --dearmor | tee /usr/share/keyrings/llvm-archive-keyring.gpg > /dev/null
+          echo "deb [signed-by=/usr/share/keyrings/llvm-archive-keyring.gpg] https://apt.llvm.org/jammy/ llvm-toolchain-jammy-18 main" | sudo tee /etc/apt/sources.list.d/llvm.list
+          sudo apt-get update && sudo apt-get install -y libclang-18-dev clang-18
+          export LIBCLANG_PATH=/usr/lib/llvm-18/lib
+
       - name: Load Rust Cache
         uses: Swatinem/rust-cache@v2.7.7
         with: