chore: self-review misc fixes

Author: yannham

libdd-otel-thread-ctx-ffi/README.md

@@ -21,16 +21,16 @@ inline the C wrapper at link time. The requirements are:
 - `clang` is available to compile the C shim to LLVM IR (version requirements
   aren't clear -- tested with clang18 and clang20, but ideally the version
   should be the same or close to the LLVM version shipped with `rustc`)
-- Either the Rust toolchain ships lld or there's a system-wide lld install
+- Either the Rust toolchain ships `lld` or there's a system-wide `lld` install
   (Rust ships `rust-lld` for a long time, something like since 1.53+, however
-  some musl-based distro like Alpine might have Rust packages without LLD)
-- lld version is at least 19 (TLSDESC support)
+  some musl-based distro like Alpine might have the Rust toolchain without LLD)
+- `lld` version is at least 19 (TLSDESC support)
 
 If those requirements are met, you can use the small wrapper script provided in
 this directory to build an optimized release version where the C shim is
 inlined. A wrapper script is needed because cross-language LTO requires two
 `rustc` codegen flags (`-Clinker-plugin-lto` and `-Clinker=clang`) that cannot
-be set from a Cargo build script — they must come from `RUSTFLAGS` or
+be set from a Cargo build script: they must come from `RUSTFLAGS` or
 `.cargo/config.toml`. The script sets them via the target-scoped
 `CARGO_TARGET_<TRIPLE>_RUSTFLAGS` env var so they don't leak to build scripts
 or proc-macros.

libdd-otel-thread-ctx-ffi/build-optimized.sh

@@ -7,6 +7,7 @@
 # on every TLS access.
 #
 # Requirements: clang, lld (rust-lld from the toolchain is used automatically).
+# The requirements are checked by the build.rs script.
 #
 # Usage:
 #   ./build-optimized.sh              # auto-detect host triple
@@ -44,9 +45,9 @@ cargo build --release \
     -p libdd-otel-thread-ctx-ffi \
     "${EXTRA_ARGS[@]}"
 
-# Sanity-check that the C shim was actually inlined.
+# Sanity-check that the C shim was actually inlined, if `nm` is available.
 if ! command -v nm &>/dev/null; then
-    echo >&2 "WARNING: nm not found — skipping sanity check that the C TLS shim was inlined."
+		echo >&2 "WARNING: skipping sanity check that the C TLS shim was inlined (\`nm\` not found)"
 else
     SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
     REPO_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"

libdd-otel-thread-ctx-ffi/build.rs

@@ -3,9 +3,7 @@
 extern crate build_common;
 
 use build_common::generate_and_configure_header;
-use std::env;
-use std::path::PathBuf;
-use std::process::Command;
+use std::{env, path::PathBuf, process::Command};
 
 /// Locate the `gcc-ld/` shim directory shipped with the Rust toolchain.
 ///
@@ -86,22 +84,23 @@ fn main() {
 
     println!("cargo:rerun-if-env-changed=LIBDD_OTEL_THREAD_CTX_INLINE");
 
-    let inline_mode = env::var_os("LIBDD_OTEL_THREAD_CTX_INLINE").is_some();
+    let inline_mode = env::var("LIBDD_OTEL_THREAD_CTX_INLINE").unwrap();
     let manifest_dir = env::var("CARGO_MANIFEST_DIR").unwrap();
     let target_arch = env::var("CARGO_CFG_TARGET_ARCH").unwrap();
 
-    if inline_mode {
+    if &inline_mode == "1" {
         let rust_lld_dir = require_lld_for_inline(&target_arch);
 
         // Emit link args for ALL link types (not just cdylib) so that test
-        // binaries also link correctly when RUSTFLAGS sets clang as the linker.
+        // binaries also link correctly when RUSTFLAGS sets clang as the linker (although we should
+        // only build the shared object file in inline mode).
         if let Some(dir) = rust_lld_dir {
             println!("cargo:rustc-link-arg=-B{}", dir.display());
         }
         println!("cargo:rustc-link-arg=-fuse-ld=lld");
 
         // On x86-64, tell the LLVM backend to use TLSDESC during LTO codegen.
-        // On aarch64 TLSDESC is the only model, so no flag is needed.
+        // On aarch64 TLSDESC is the default and the only model.
         if target_arch == "x86_64" {
             println!("cargo:rustc-link-arg=-Wl,-mllvm,-enable-tlsdesc");
         }