fix: build on macos with asan (tlspuffin#302)

tlspuffin/build.rs

@@ -2,13 +2,12 @@ use std::process::Command;
 
 fn main() {
     if cfg!(feature = "asan") {
-        let output = Command::new("clang")
-            .args(["--print-resource-dir"])
-            .output()
-            .expect("failed to clang to get resource dir");
-        let clang: &str = std::str::from_utf8(&output.stdout).unwrap().trim();
-
-        println!("cargo:rustc-link-arg=-Wl,-rpath={}/lib/linux/", clang);
+        // NOTE adding compiler-rt to rpath for libasan is not straightforward
+        //
+        //     Unfortunately, passing `-frtlib-add-rpath` to clang doesn't add
+        //     the correct rpath on linux platforms. Instead, we find the folder
+        //     containing the compiler-rt runtime and add it to rpath ourselves.
+        println!("cargo:rustc-link-arg=-Wl,-rpath,{}", runtime_dir());
         println!("cargo:rustc-link-arg=-fsanitize=address");
         println!("cargo:rustc-link-arg=-shared-libasan");
     }
@@ -23,3 +22,61 @@ fn main() {
         println!("cargo:rustc-link-arg=-fcoverage-mapping");
     }
 }
+
+fn runtime_dir() -> String {
+    // NOTE the current process for finding the runtime-dir might be incomplete
+    //
+    //     We try the following in order:
+    //       - `clang --print-runtime-dir` (clang >= 13)
+    //       - `clang --print-resource-dir`/lib/<os>
+    //       - panic
+    //
+    //     Note that extracting the directory path directly from the result of
+    //     `--print-file-name=libclang_rt.asan-<arch>.<dylib_suffix>` would be
+    //     an alternative solution but it was broken for a long time on Apple
+    //     clang.
+    //
+    //     - see https://github.com/llvm/llvm-project/commit/aafc3f7be804d117a632365489a18c3e484a3931
+    let output = Command::new("clang")
+        .args(["--print-runtime-dir"])
+        .output()
+        .expect("failed to get runtime dir from `clang --print-runtime-dir`. Is clang in PATH?");
+
+    let clang_runtime_dir = output
+        .status
+        .success()
+        .then(|| std::str::from_utf8(&output.stdout).unwrap().trim())
+        .unwrap_or("");
+
+    if clang_runtime_dir.is_empty() {
+        return runtime_dir_fallback();
+    }
+
+    clang_runtime_dir.to_string()
+}
+
+fn runtime_dir_fallback() -> String {
+    let output = Command::new("clang")
+        .args(["--print-resource-dir"])
+        .output()
+        .expect("failed to get resource dir from `clang --print-resource-dir`. Is clang in PATH?");
+
+    let clang_resource_dir = output
+        .status
+        .success()
+        .then(|| std::str::from_utf8(&output.stdout).unwrap().trim())
+        .expect("failed to get resource dir from `clang --print-resource-dir`");
+
+    let clang_sysname = match std::env::consts::OS {
+        "macos" => "darwin",
+        "linux" => "linux",
+        _ => panic!("cannot get compiler runtime dir: unsupported os"),
+    };
+
+    let runtime_dir = format!("{}/lib/{}/", clang_resource_dir, clang_sysname);
+    if !std::path::Path::new(&runtime_dir).exists() {
+        panic!("failed to find clang runtime dir");
+    }
+
+    runtime_dir
+}