Update LLVM from 21 to 22 (#505)

crates/llvm-builder/README.md

@@ -82,10 +82,10 @@ Obtain a compatible build for your host platform from the release section of thi
 
       Build artifacts end up in the `./target-llvm/gnu/target-final/` directory by default.
       The `gnu` directory depends on the supported archticture and will either be `gnu`, `musl` or `emscripten`.
-      You now need to export the final target directory `$LLVM_SYS_211_PREFIX`:
+      You now need to export the final target directory `$LLVM_SYS_221_PREFIX`:
 
       ```shell
-      export LLVM_SYS_211_PREFIX=${PWD}/target-llvm/gnu/target-final
+      export LLVM_SYS_221_PREFIX=${PWD}/target-llvm/gnu/target-final
       ```
 
       If built with the `--enable-tests` option, test tools will be in the `./target-llvm/gnu/build-final/` directory, along with copies of the build artifacts. For all supported build options, run `revive-llvm build --help`.

crates/llvm-builder/src/platforms/aarch64_linux_musl.rs

@@ -77,7 +77,6 @@ pub fn build(
         llvm_module_llvm.as_path(),
         llvm_build_final.as_path(),
         llvm_target_final.as_path(),
-        musl_target.as_path(),
         llvm_target_host.as_path(),
         enable_tests,
         enable_coverage,
@@ -269,7 +268,6 @@ fn build_target(
     source_directory: &Path,
     build_directory: &Path,
     target_directory: &Path,
-    musl_target_directory: &Path,
     host_target_directory: &Path,
     enable_tests: bool,
     enable_coverage: bool,
@@ -366,26 +364,21 @@ fn build_target(
 
     crate::utils::ninja(build_directory)?;
 
-    let mut musl_lib_directory = musl_target_directory.to_path_buf();
-    musl_lib_directory.push("lib/");
-
     let mut host_lib_directory = host_target_directory.to_path_buf();
     host_lib_directory.push("lib/aarch64-unknown-linux-musl/");
 
     let mut target_lib_directory = target_directory.to_path_buf();
     target_lib_directory.push("lib/");
 
+    // Stage libc++/libunwind alongside the LLVM archives so `LLVM_SYS_221_PREFIX`
+    // consumers can resolve the libc++ symbols they reference. The musl sysroot
+    // is not copied: it would shadow the host libc on the link search path.
     let copy_options = fs_extra::dir::CopyOptions {
         overwrite: true,
         copy_inside: true,
         content_only: true,
         ..Default::default()
     };
-    fs_extra::dir::copy(
-        musl_lib_directory,
-        target_lib_directory.as_path(),
-        &copy_options,
-    )?;
     fs_extra::dir::copy(
         host_lib_directory,
         target_lib_directory.as_path(),

crates/llvm-builder/src/platforms/x86_64_linux_musl.rs

@@ -80,7 +80,6 @@ pub fn build(
         llvm_module_llvm.as_path(),
         llvm_build_final.as_path(),
         llvm_target_final.as_path(),
-        musl_target.as_path(),
         llvm_target_host.as_path(),
         enable_tests,
         enable_coverage,
@@ -267,7 +266,6 @@ fn build_target(
     source_directory: &Path,
     build_directory: &Path,
     target_directory: &Path,
-    musl_target_directory: &Path,
     host_target_directory: &Path,
     enable_tests: bool,
     enable_coverage: bool,
@@ -366,26 +364,21 @@ fn build_target(
 
     crate::utils::ninja(build_directory)?;
 
-    let mut musl_lib_directory = musl_target_directory.to_path_buf();
-    musl_lib_directory.push("lib/");
-
     let mut host_lib_directory = host_target_directory.to_path_buf();
     host_lib_directory.push("lib/x86_64-pc-linux-musl/");
 
     let mut target_lib_directory = target_directory.to_path_buf();
     target_lib_directory.push("lib/");
 
+    // Stage libc++/libunwind alongside the LLVM archives so `LLVM_SYS_221_PREFIX`
+    // consumers can resolve the libc++ symbols they reference. The musl sysroot
+    // is not copied: it would shadow the host libc on the link search path.
     let copy_options = fs_extra::dir::CopyOptions {
         overwrite: true,
         copy_inside: true,
         content_only: true,
         ..Default::default()
     };
-    fs_extra::dir::copy(
-        musl_lib_directory,
-        target_lib_directory.as_path(),
-        &copy_options,
-    )?;
     fs_extra::dir::copy(
         host_lib_directory,
         target_lib_directory.as_path(),

crates/llvm-builder/src/revive_llvm/main.rs

@@ -7,9 +7,14 @@ use std::str::FromStr;
 
 use anyhow::Context;
 use clap::Parser;
+use revive_llvm_builder::target_env::TargetEnv;
 
 use self::arguments::{Arguments, Subcommand};
 
+/// RUSTFLAGS required when operating in a musl target environment so that the
+/// C runtime is linked dynamically rather than statically.
+const MUSL_RUSTFLAGS: &str = "-Ctarget-feature=-crt-static";
+
 fn main() {
     env_logger::init();
 
@@ -25,6 +30,10 @@ fn main() {
 fn main_inner() -> anyhow::Result<()> {
     let arguments = Arguments::parse();
 
+    if arguments.target_env == TargetEnv::MUSL {
+        std::env::set_var("RUSTFLAGS", MUSL_RUSTFLAGS);
+    }
+
     revive_llvm_builder::utils::directory_target_llvm(arguments.target_env);
 
     match arguments.subcommand {