Introduce RUSTC_STATIC_CLANG_RT_PATH and RUSTC_STATIC_UNWIND_PATH envs

Cargo.lock

@@ -4995,6 +4995,7 @@ version = "0.0.0"
 dependencies = [
  "addr2line",
  "alloc",
+ "build_helper",
  "cfg-if 0.1.10",
  "compiler_builtins",
  "core",
@@ -5662,6 +5663,7 @@ dependencies = [
 name = "unwind"
 version = "0.0.0"
 dependencies = [
+ "build_helper",
  "cc",
  "cfg-if 0.1.10",
  "compiler_builtins",

compiler/rustc_llvm/build.rs

@@ -2,7 +2,7 @@ use std::env;
 use std::path::{Path, PathBuf};
 use std::process::Command;
 
-use build_helper::{output, tracked_env_var_os};
+use build_helper::{maybe_static_library, output, tracked_env_var_os};
 
 fn detect_llvm_link() -> (&'static str, &'static str) {
     // Force the link mode we want, preferring static by default, but
@@ -307,4 +307,6 @@ fn main() {
     if target.contains("windows-gnu") {
         println!("cargo:rustc-link-lib=static:-bundle=pthread");
     }
+
+    maybe_static_library("RUSTC_STATIC_CLANG_RT_PATH", "clang_rt");
 }

library/std/Cargo.toml

@@ -84,3 +84,6 @@ heap_size = 0x8000000
 name = "stdbenches"
 path = "benches/lib.rs"
 test = true
+
+[build-dependencies]
+build_helper = { path = "../../src/build_helper" }

library/std/build.rs

@@ -1,5 +1,7 @@
 use std::env;
 
+use build_helper::maybe_static_library;
+
 fn main() {
     println!("cargo:rerun-if-changed=build.rs");
     let target = env::var("TARGET").expect("TARGET was not set");
@@ -47,4 +49,6 @@ fn main() {
     }
     println!("cargo:rustc-env=STD_ENV_ARCH={}", env::var("CARGO_CFG_TARGET_ARCH").unwrap());
     println!("cargo:rustc-cfg=backtrace_in_libstd");
+
+    maybe_static_library("RUSTC_STATIC_CLANG_RT_PATH", "clang_rt");
 }

library/unwind/Cargo.toml

@@ -20,6 +20,7 @@ compiler_builtins = "0.1.0"
 cfg-if = "0.1.8"
 
 [build-dependencies]
+build_helper = { path = "../../src/build_helper" }
 cc = "1.0.69"
 
 [features]

library/unwind/build.rs

@@ -1,9 +1,15 @@
 use std::env;
 
+use build_helper::maybe_static_library;
+
 fn main() {
     println!("cargo:rerun-if-changed=build.rs");
     let target = env::var("TARGET").expect("TARGET was not set");
 
+    if maybe_static_library("RUSTC_STATIC_UNWIND_PATH", "unwind") {
+        return;
+    }
+
     if target.contains("android") {
         let build = cc::Build::new();
 

src/build_helper/lib.rs

@@ -203,3 +203,25 @@ fn fail(s: &str) -> ! {
     println!("\n\n{}\n\n", s);
     std::process::exit(1);
 }
+
+/// if you need for some reason to statically inject some library, like clang_rt
+/// here a good place. Anyway, you should use only thin .a file on macOS.
+/// You may extract it like:
+///   lipo -thin x86_64 -output libclang_rt.a /path/to/llvm/lib/../libclang_rt.osx.a
+///
+/// It returns true, when it had injected static library.
+pub fn maybe_static_library(env_path_name: &str, library_name: &str) -> bool {
+    println!("cargo:rerun-if-env-changed={}", env_path_name);
+
+    if let Ok(path) = env::var(env_path_name) {
+        let target = env::var("TARGET").expect("TARGET was not set");
+        println!("cargo:rerun-if-env-changed=TARGET");
+
+        println!("cargo:rustc-link-search=native={}", path);
+        println!("cargo:rustc-link-search=native={}/{}", path, target);
+        println!("cargo:rustc-link-lib=static={}", library_name);
+        return true;
+    }
+
+    return false;
+}