Remove rustc_cfg dependency

Cargo.lock

@@ -132,7 +132,6 @@ dependencies = [
  "redox-path",
  "redox_syscall",
  "rmm",
- "rustc-cfg",
  "rustc-demangle",
  "sbi-rt",
  "slab",
@@ -226,15 +225,6 @@ dependencies = [
 name = "rmm"
 version = "0.1.0"
 
-[[package]]
-name = "rustc-cfg"
-version = "0.5.0"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "9ddf7a5e441e8003a5a88aab97f1c6113043ddde252d789ef9dea3871b78633a"
-dependencies = [
- "thiserror",
-]
-
 [[package]]
 name = "rustc-demangle"
 version = "0.1.26"
@@ -341,26 +331,6 @@ dependencies = [
  "unicode-ident",
 ]
 
-[[package]]
-name = "thiserror"
-version = "1.0.69"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b6aaf5339b578ea85b50e080feb250a3e8ae8cfcdff9a461c9ec2904bc923f52"
-dependencies = [
- "thiserror-impl",
-]
-
-[[package]]
-name = "thiserror-impl"
-version = "1.0.69"
-source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4fee6c4efc90059e10f81e6d42c60a18f76588c3d74cb83a0b242a2b6c7504c1"
-dependencies = [
- "proc-macro2",
- "quote",
- "syn",
-]
-
 [[package]]
 name = "toml"
 version = "0.8.23"

Cargo.toml

@@ -6,7 +6,6 @@ edition = "2024"
 
 [build-dependencies]
 cc = "1.0"
-rustc-cfg = "0.5"
 toml = "0.8"
 
 [dependencies]

build.rs

@@ -1,4 +1,3 @@
-use rustc_cfg::Cfg;
 use std::{env, path::Path, process::Command};
 use toml::Table;
 
@@ -53,10 +52,9 @@ fn main() {
     println!("cargo::rustc-check-cfg=cfg(dtb)");
 
     let out_dir = env::var("OUT_DIR").unwrap();
-    let cfg = Cfg::of(env::var("TARGET").unwrap().as_str()).unwrap();
-    let arch_str = cfg.target_arch.as_str();
+    let arch_str = env::var("CARGO_CFG_TARGET_ARCH").unwrap();
 
-    match arch_str {
+    match &*arch_str {
         "aarch64" => {
             println!("cargo::rustc-cfg=dtb");
         }
@@ -96,5 +94,5 @@ fn main() {
         _ => (),
     }
 
-    let _ = parse_kconfig(arch_str);
+    let _ = parse_kconfig(&*arch_str);
 }