fix: remove use_ros_shim. Let user pass compiler flag to specify the ROS distro

rclrs/Cargo.toml

@@ -43,18 +43,13 @@ tempfile = "3.3.0"
 tokio = { version = "1", features = ["rt", "time", "macros"] }
 
 [build-dependencies]
-# Needed for FFI
-bindgen = "0.70"
 # Needed for uploading documentation to docs.rs
-cfg-if = "1.0.0"
+rustflags = "0.1"
 
 [features]
 default = []
 dyn_msg = ["ament_rs", "libloading"]
 serde = ["dep:serde", "dep:serde-big-array", "rosidl_runtime_rs/serde"]
-# This feature is solely for the purpose of being able to generate documetation without a ROS installation
-# The only intended usage of this feature is for docs.rs builders to work, and is not intended to be used by end users
-use_ros_shim = ["rosidl_runtime_rs/use_ros_shim"]
 
 [package.metadata.docs.rs]
-features = ["use_ros_shim"]
+rustc-args = ["--cfg", "ros_distro=humble"]

rclrs/build.rs

@@ -1,12 +1,11 @@
 use std::{
     env,
-    fs::read_dir,
-    path::{Path, PathBuf},
+    path::Path,
 };
+use rustflags::Flag;
 
 const AMENT_PREFIX_PATH: &str = "AMENT_PREFIX_PATH";
 const ROS_DISTRO: &str = "ROS_DISTRO";
-const BINDGEN_WRAPPER: &str = "src/rcl_wrapper.h";
 
 fn get_env_var_or_abort(env_var: &'static str) -> String {
     if let Ok(value) = env::var(env_var) {
@@ -23,16 +22,20 @@ fn main() {
     let ros_distro = if let Ok(value) = env::var(ROS_DISTRO) {
         value
     } else {
-        let error_msg =
-            "ROS_DISTRO environment variable not set - please source ROS 2 installation first.";
-        cfg_if::cfg_if! {
-            if #[cfg(feature="use_ros_shim")] {
-                println!("{}", error_msg);
-                return;
-            } else {
-                panic!("{}", error_msg);
+        // Look for --cfg ros_distro=<ros_distro>
+        for flag in rustflags::from_env() {
+            if matches!(flag, Flag::Cfg { ref name, value : _ } if name == "ros_distro") {
+                if let Flag::Cfg {name:_, value: flag_value} = flag {
+                    println!("cargo:rustc-cfg=ros_distro={}", flag_value.unwrap());
+                    return;
+                } else {
+                    continue;
+                }
             }
         }
+        let error_msg =
+            "ROS_DISTRO environment variable not set - please source ROS 2 installation first.";
+        panic!("{}", error_msg);
     };
 
     println!("cargo:rustc-check-cfg=cfg(ros_distro, values(\"humble\", \"jazzy\", \"rolling\"))");

rclrs/src/rcl_bindings.rs

@@ -12,28 +12,26 @@
 #![allow(missing_docs)]
 
 cfg_if::cfg_if! {
-    if #[cfg(feature="use_ros_shim")] {
-        include!(
-            concat!(
-                env!("CARGO_MANIFEST_DIR"),
-                "/src/rcl_bindings_generated_",
-                "rolling", // rolling will always be a valid ROS distro
-                ".rs",
-            )
-        );
-
+    let ros_distro = if #[cfg(ros_distro="humble")] {
+        "humble"
+    } else if #[cfg(ros_distro="jazzy")] {
+        "jazzy"
+    } else if #[cfg(ros_distro="kilted")] {
+        "kilted"
+    } else if #[cfg(ros_distro="rolling")] {
+        "rolling"
     } else {
-        include!(
-            concat!(
-                env!("CARGO_MANIFEST_DIR"),
-                "/src/rcl_bindings_generated_",
-                env!("ROS_DISTRO"),
-                ".rs",
+        panic!("Unsupported ROS distribution");
+    }
+    include!(
+        concat!(
+            env!("CARGO_MANIFEST_DIR"),
+            "/src/rcl_bindings_generated_",
+            ros_distro,
+            ".rs",
             )
         );
-
-        pub const RMW_GID_STORAGE_SIZE: usize = rmw_gid_storage_size_constant;
-    }
+    pub const RMW_GID_STORAGE_SIZE: usize = rmw_gid_storage_size_constant;
 }
 
 /// Wrapper around [`std::slice::from_raw_parts`] that accommodates the rcl