From f39befcbad57052240d9f55385a4b99d63c8ce5e Mon Sep 17 00:00:00 2001
From: ttwards <xuwenxi0517@gmail.com>
Date: Mon, 13 Oct 2025 21:19:59 +0800
Subject: [PATCH] fix(zephyr-sys): bindgen stddef.h not found error

Fix bindgen build failure caused by missing system headers by:

- Pass CC environment variable from CMake to cargo build/doc commands
- Dynamically detect GCC toolchain path and version from CC variable
- Add GCC include directory to clang arguments for bindgen
- Create dummy arm_acle.h header to avoid ARM ACLE parsing errors

The root cause was that bindgen couldn't find stddef.h and other GCC
builtin headers because:
1. CC variable was not passed to cargo, preventing toolchain detection
2. GCC include path was not provided to clang
3. ARM ACLE headers caused constant expression errors in bindgen

Tested on: qemu_cortex_m3, Zephyr SDK 0.17.2
Signed-off-by: ttwards <xuwenxi0517@gmail.com>
---
 CMakeLists.txt      |  2 ++
 zephyr-sys/build.rs | 33 +++++++++++++++++++++++++++++++--
 2 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 75ece41..6bf427f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -173,6 +173,7 @@ ${config_paths}
       WRAPPER_FILE="${WRAPPER_FILE}"
       DT_AUGMENTS="${DT_AUGMENTS}"
       BINARY_DIR_INCLUDE_GENERATED="${BINARY_DIR_INCLUDE_GENERATED}"
+      CC=${CMAKE_C_COMPILER}
       cargo build
       ${rust_build_type_arg}
 
@@ -217,6 +218,7 @@ ${config_paths}
       WRAPPER_FILE="${WRAPPER_FILE}"
       DT_AUGMENTS="${DT_AUGMENTS}"
       BINARY_DIR_INCLUDE_GENERATED="${BINARY_DIR_INCLUDE_GENERATED}"
+      CC=${CMAKE_C_COMPILER}
       cargo doc
       ${rust_build_type_arg}
 
diff --git a/zephyr-sys/build.rs b/zephyr-sys/build.rs
index 5d6a93f..880a6ed 100644
--- a/zephyr-sys/build.rs
+++ b/zephyr-sys/build.rs
@@ -53,8 +53,31 @@ fn main() -> Result<()> {
     let out_path = PathBuf::from(env::var("OUT_DIR").unwrap());
     let wrapper_path = PathBuf::from(env::var("WRAPPER_FILE").unwrap());
 
+    // Get GCC toolchain info to find stddef.h
+    let cc = env::var("CC").unwrap_or_default();
+    let gcc_include = if !cc.is_empty() {
+        let cc_path = Path::new(&cc);
+        let toolchain_path = cc_path.parent().and_then(|p| p.parent()).unwrap();
+        let target_triple = cc_path.file_name().unwrap().to_str().unwrap()
+            .strip_suffix("-gcc").unwrap_or("arm-zephyr-eabi");
+        let gcc_version = std::process::Command::new(&cc)
+            .arg("-dumpversion")
+            .output().ok()
+            .and_then(|o| String::from_utf8(o.stdout).ok())
+            .map(|v| v.trim().to_string())
+            .unwrap_or("12.2.0".to_string());
+        format!("{}/lib/gcc/{}/{}/include", toolchain_path.display(), target_triple, gcc_version)
+    } else {
+        String::new()
+    };
+
+    // Create dummy ARM headers to avoid ACLE errors
+    let dummy_headers = out_path.join("dummy_headers");
+    std::fs::create_dir_all(&dummy_headers).ok();
+    std::fs::write(dummy_headers.join("arm_acle.h"), "").ok();
+
     // Bindgen everything.
-    let bindings = Builder::default()
+    let mut bindings = Builder::default()
         .header(
             Path::new("wrapper.h")
                 .canonicalize()
@@ -63,7 +86,13 @@ fn main() -> Result<()> {
                 .unwrap(),
         )
         .use_core()
-        .clang_arg(&target_arg);
+        .clang_arg(&target_arg)
+        .clang_arg(format!("-I{}", dummy_headers.display()));
+    
+    if !gcc_include.is_empty() {
+        bindings = bindings.clang_arg(format!("-I{}", gcc_include));
+    }
+    
     let bindings = define_args(bindings, "-I", "INCLUDE_DIRS");
     let bindings = define_args(bindings, "-D", "INCLUDE_DEFINES");
     let bindings = bindings