Add llvm20 and use for rust recipe

recipes/dev/llvm20/native.cmake

@@ -0,0 +1,2 @@
+set(CMAKE_C_COMPILER cc)
+set(CMAKE_CXX_COMPILER c++)

recipes/dev/llvm20/recipe.toml

@@ -0,0 +1,72 @@
+[source]
+git = "https://gitlab.redox-os.org/redox-os/llvm-project.git"
+upstream = "https://github.com/rust-lang/llvm-project.git"
+branch = "redox-2025-10-03"
+shallow_clone = true
+
+[build]
+template = "custom"
+dependencies = [
+    "zlib"
+]
+script = """
+DYNAMIC_INIT
+
+# https://llvm.org/docs/CMake.html
+case "${TARGET}" in
+    x86-unknown-redox)
+        LLVM_TARGETS_TO_BUILD="X86"
+        ;;
+    x86_64-unknown-redox)
+        LLVM_TARGETS_TO_BUILD="X86"
+        ;;
+    aarch64-unknown-redox)
+        LLVM_TARGETS_TO_BUILD="AArch64"
+        ;;
+    riscv64gc-unknown-redox)
+        LLVM_TARGETS_TO_BUILD="RISCV"
+        ;;
+    *)
+        LLVM_TARGETS_TO_BUILD="host"
+        ;;
+esac
+
+COOKBOOK_CMAKE_FLAGS+=(
+    -DCMAKE_CXX_FLAGS="--std=gnu++11"
+    -DBUILD_SHARED_LIBS=False
+    -DLLVM_LINK_LLVM_DYLIB=On
+    -DCROSS_TOOLCHAIN_FLAGS_NATIVE="-DCMAKE_TOOLCHAIN_FILE=$(realpath "${COOKBOOK_RECIPE}/native.cmake")"
+    -DLLVM_BUILD_BENCHMARKS=Off
+    -DLLVM_BUILD_EXAMPLES=Off
+    -DLLVM_BUILD_TESTS=Off
+    -DLLVM_BUILD_UTILS=Off
+    -DLLVM_DEFAULT_TARGET_TRIPLE="${TARGET}"
+    -DLLVM_ENABLE_LTO=Off
+    -DLLVM_ENABLE_RTTI=On
+    -DLLVM_ENABLE_THREADS=On
+    -DLLVM_ENABLE_ZSTD=Off
+    -DLLVM_INCLUDE_BENCHMARKS=Off
+    -DLLVM_INCLUDE_EXAMPLES=Off
+    -DLLVM_INCLUDE_TESTS=Off
+    -DLLVM_INCLUDE_UTILS=Off
+    -DLLVM_OPTIMIZED_TABLEGEN=On
+    -DLLVM_TARGET_ARCH="$(echo "${TARGET}" | cut -d - -f1)"
+    -DLLVM_TARGETS_TO_BUILD="${LLVM_TARGETS_TO_BUILD}"
+    -DLLVM_TOOL_LLVM_COV_BUILD=Off
+    -DLLVM_TOOL_LLVM_LTO_BUILD=Off
+    -DLLVM_TOOL_LLVM_LTO2_BUILD=Off
+    -DLLVM_TOOL_LLVM_PROFDATA_BUILD=Off
+    -DLLVM_TOOL_LLVM_RTDYLD_BUILD=Off
+    -DLLVM_TOOL_LLVM_XRAY_BUILD=Off
+    -DLLVM_TOOL_LLI_BUILD=Off
+    -DLLVM_TOOL_LTO_BUILD=Off
+    -DLLVM_TOOLS_INSTALL_DIR=bin
+    -DLLVM_UTILS_INSTALL_DIR=bin
+    -DUNIX=1
+    -DLLVM_ENABLE_PROJECTS="llvm"
+)
+
+# Native tablegen build fails with too many jobs, limit to 16
+COOKBOOK_MAKE_JOBS="$(( ${COOKBOOK_MAKE_JOBS} > 16 ? 16 : ${COOKBOOK_MAKE_JOBS} ))"
+cookbook_cmake "${COOKBOOK_SOURCE}/llvm"
+"""

recipes/dev/rust/recipe.toml

@@ -8,7 +8,7 @@ shallow_clone = true
 [build]
 template = "custom"
 dependencies = [
-    "llvm18",
+    "llvm20",
     "zlib"
 ]
 script = """