revive llvm builder utility (#154)

Pre-eliminary support for LLVM releases and resolc binary releases by streamlining the build process for all supported hosts platforms.

- Introduce the revive-llvm-builder crate with the revive-llvm builder utilty.
- Do not rely on the LLVM dependency in $PATH to decouple the system LLVM installation from the LLVM host dependency.
- Fix the emscripten build by decoupling the host and native LLVM dependencies. Thus allowing a single LLVM emscripten release that can be used on any host platform.
- An example Dockerfile building an alpine container with a fully statically linked resolc ELF binary.
- Remove the Debian builder utilities and workflow.

crates/lld-sys/Cargo.toml

@@ -13,3 +13,4 @@ libc = { workspace = true }
 
 [build-dependencies]
 cc = { workspace = true }
+revive-build-utils = { workspace = true }

crates/lld-sys/build.rs

@@ -1,34 +1,16 @@
-use std::{
-    env,
-    path::{Path, PathBuf},
-};
+fn set_rustc_link_flags() {
+    let llvm_lib_path = match std::env::var(revive_build_utils::REVIVE_LLVM_TARGET_PREFIX) {
+        Ok(path) => std::path::PathBuf::from(path).join("lib"),
+        _ => revive_build_utils::llvm_lib_dir(),
+    };
 
-const LLVM_LINK_PREFIX: &str = "LLVM_LINK_PREFIX";
-
-fn locate_llvm_config() -> PathBuf {
-    let prefix = env::var_os(LLVM_LINK_PREFIX)
-        .map(|p| PathBuf::from(p).join("bin"))
-        .unwrap_or_default();
-    prefix.join("llvm-config")
-}
-
-fn llvm_config(llvm_config_path: &Path, arg: &str) -> String {
-    let output = std::process::Command::new(llvm_config_path)
-        .args([arg])
-        .output()
-        .unwrap_or_else(|_| panic!("`llvm-config {arg}` failed"));
-
-    String::from_utf8(output.stdout)
-        .unwrap_or_else(|_| panic!("output of `llvm-config {arg}` should be utf8"))
-}
-
-fn set_rustc_link_flags(llvm_config_path: &Path) {
     println!(
         "cargo:rustc-link-search=native={}",
-        llvm_config(llvm_config_path, "--libdir")
+        llvm_lib_path.to_string_lossy()
     );
 
     for lib in [
+        // These are required by ld.lld
         "lldELF",
         "lldCommon",
         "lldMachO",
@@ -91,18 +73,27 @@ fn set_rustc_link_flags(llvm_config_path: &Path) {
     }
 
     let target_os = std::env::var("CARGO_CFG_TARGET_OS").unwrap_or_default();
+    let target_env = std::env::var("CARGO_CFG_TARGET_ENV").unwrap_or_default();
     if target_os == "linux" {
-        println!("cargo:rustc-link-lib=dylib=stdc++");
-        println!("cargo:rustc-link-lib=tinfo");
+        if target_env == "musl" {
+            println!("cargo:rustc-link-lib=static=c++");
+        } else {
+            println!("cargo:rustc-link-lib=dylib=stdc++");
+        }
     }
 }
 
 fn main() {
-    println!("cargo:rerun-if-env-changed={}", LLVM_LINK_PREFIX);
+    println!(
+        "cargo:rerun-if-env-changed={}",
+        revive_build_utils::REVIVE_LLVM_HOST_PREFIX
+    );
+    println!(
+        "cargo:rerun-if-env-changed={}",
+        revive_build_utils::REVIVE_LLVM_TARGET_PREFIX
+    );
 
-    let llvm_config_path = locate_llvm_config();
-
-    llvm_config(&llvm_config_path, "--cxxflags")
+    revive_build_utils::llvm_cxx_flags()
         .split_whitespace()
         .fold(&mut cc::Build::new(), |builder, flag| builder.flag(flag))
         .flag("-Wno-unused-parameter")
@@ -110,7 +101,7 @@ fn main() {
         .file("src/linker.cpp")
         .compile("liblinker.a");
 
-    set_rustc_link_flags(&llvm_config_path);
+    set_rustc_link_flags();
 
     println!("cargo:rerun-if-changed=build.rs");
 }