feat(cargo): Set rustc-check-cfg for all config options

This squashes lint warnings for config options which are not
currently enabled.

See https://doc.rust-lang.org/cargo/reference/build-scripts.html\#rustc-check-cfg

Signed-off-by: Hayden Ball <[email protected]>

Author: ball-hayden

CMakeLists.txt

@@ -152,6 +152,17 @@ DT_AUGMENTS = \"${DT_AUGMENTS}\"
 ${config_paths}
 ")
 
+  add_custom_command(
+    OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/rust-kconfig-bool-options.json
+    COMMAND
+      ${CMAKE_COMMAND} -E
+      env ${COMMON_KCONFIG_ENV_SETTINGS}
+      ${RUST_MODULE_DIR}/scripts/kconfig-bool-options.py ${KCONFIG_ROOT} ${DOTCONFIG} > ${CMAKE_CURRENT_BINARY_DIR}/rust-kconfig-bool-options.json
+    DEPENDS ${DOTCONFIG}
+    COMMENT "Finding valid kconfig boolean options"
+    WORKING_DIRECTORY ${APPLICATION_SOURCE_DIR}
+  )
+
   # The block of environment variables below could theoretically be captured in a variable, but this
   # seems "challenging" in CMake (to be polite), as many of these contain spaces, and the quoting
   # rules in CMake are inconsistent, at best.
@@ -161,6 +172,7 @@ ${config_paths}
   add_custom_command(
     OUTPUT ${DUMMY_FILE}
     BYPRODUCTS ${RUST_LIBRARY} ${WRAPPER_FILE}
+    DEPENDS ${CMAKE_CURRENT_BINARY_DIR}/rust-kconfig-bool-options.json
     USES_TERMINAL
     COMMAND
       ${CMAKE_COMMAND} -E

samples/bench/src/lib.rs

@@ -2,10 +2,6 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #![no_std]
-// Cargo tries to detect configs that have typos in them.  Unfortunately, the Zephyr Kconfig system
-// uses a large number of Kconfigs and there is no easy way to know which ones might conceivably be
-// valid.  This prevents a warning about each cfg that is used.
-#![allow(unexpected_cfgs)]
 
 extern crate alloc;
 

samples/philosophers/src/lib.rs

@@ -2,10 +2,6 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #![no_std]
-// Cargo tries to detect configs that have typos in them.  Unfortunately, the Zephyr Kconfig system
-// uses a large number of Kconfigs and there is no easy way to know which ones might conceivably be
-// valid.  This prevents a warning about each cfg that is used.
-#![allow(unexpected_cfgs)]
 
 extern crate alloc;
 

samples/work-philosophers/src/lib.rs

@@ -2,10 +2,6 @@
 // SPDX-License-Identifier: Apache-2.0
 
 #![no_std]
-// Cargo tries to detect configs that have typos in them.  Unfortunately, the Zephyr Kconfig system
-// uses a large number of Kconfigs and there is no easy way to know which ones might conceivably be
-// valid.  This prevents a warning about each cfg that is used.
-#![allow(unexpected_cfgs)]
 
 extern crate alloc;
 

scripts/kconfig-bool-options.py

@@ -0,0 +1,48 @@
+#!/usr/bin/env python3
+
+# SPDX-License-Identifier: Apache-2.0
+
+import os
+import sys
+import argparse
+import json
+
+from itertools import chain
+
+sys.path.insert(0, str(os.path.join(os.environ["ZEPHYR_BASE"], "scripts", "kconfig")))
+from kconfiglib import Kconfig, _T_BOOL, _T_CHOICE
+
+
+def main():
+    args = parse_args()
+
+    kconf = Kconfig(args.kconfig_file)
+    kconf.load_config(args.dotconfig)
+
+    options = {}
+
+    for sym in chain(kconf.unique_defined_syms, kconf.unique_choices):
+        if not sym.name:
+            continue
+
+        if "-" in sym.name:
+            # Rust does not allow hyphens in cfg options.
+            continue
+
+        if sym.type in [_T_BOOL, _T_CHOICE]:
+            options[f"CONFIG_{sym.name}"] = sym.str_value
+
+    print(json.dumps(options))
+
+
+def parse_args():
+    parser = argparse.ArgumentParser(allow_abbrev=False)
+
+    parser.add_argument("kconfig_file", help="Top-level Kconfig file")
+    parser.add_argument("dotconfig", help="Path to dotconfig file")
+
+    return parser.parse_args()
+
+
+if __name__ == "__main__":
+    main()

zephyr-build/src/lib.rs

@@ -11,6 +11,7 @@
 // This builds a program that is run on the compilation host before the code is compiled.  It can
 // output configuration settings that affect the compilation.
 
+use std::collections::BTreeMap;
 use std::env;
 use std::fs::File;
 use std::io::{BufRead, BufReader, Write};
@@ -27,19 +28,26 @@ mod devicetree;
 /// Export boolean Kconfig entries.  This must happen in any crate that wishes to access the
 /// configuration settings.
 pub fn export_bool_kconfig() {
-    let dotconfig = env::var("DOTCONFIG").expect("DOTCONFIG must be set by wrapper");
+    let build_dir = env::var("BUILD_DIR").expect("BUILD_DIR must be set by wrapper");
 
-    // Ensure the build script is rerun when the dotconfig changes.
-    println!("cargo:rerun-if-env-changed=DOTCONFIG");
-    println!("cargo-rerun-if-changed={}", dotconfig);
+    let bool_options_path = Path::new(&build_dir)
+        .join("rust-kconfig-bool-options.json")
+        .to_str()
+        .unwrap()
+        .to_string();
 
-    let config_y = Regex::new(r"^(CONFIG_.*)=y$").unwrap();
+    // Ensure the build script is rerun when kconfig bool options change.
+    println!("cargo:rerun-if-changed={}", bool_options_path);
 
-    let file = File::open(&dotconfig).expect("Unable to open dotconfig");
-    for line in BufReader::new(file).lines() {
-        let line = line.expect("reading line from dotconfig");
-        if let Some(caps) = config_y.captures(&line) {
-            println!("cargo:rustc-cfg={}", &caps[1]);
+    let bool_options = File::open(&bool_options_path).expect("Unable to open bool options");
+    let bool_options: BTreeMap<String, String> =
+        serde_yaml_ng::from_reader(bool_options).expect("Unable to parse bool options");
+
+    for (key, value) in bool_options.iter() {
+        println!("cargo:rustc-check-cfg=cfg({})", key);
+
+        if value == "y" {
+            println!("cargo:rustc-cfg={}", key);
         }
     }
 }