openwrt-packages/lang/rust/patches/0002-rustc-bootstrap-cache.patch

--- a/src/bootstrap/bootstrap.py
+++ b/src/bootstrap/bootstrap.py
@@ -557,7 +557,7 @@ class RustBuild(object):
                 shutil.rmtree(bin_root)
 
             key = self.stage0_compiler.date
-            cache_dst = os.path.join(self.build_dir, "cache")
+            cache_dst = os.getenv('OPENWRT_RUSTC_BOOTSTRAP_CACHE', os.path.join(self.build_dir, "cache"))
             rustc_cache = os.path.join(cache_dst, key)
             if not os.path.exists(rustc_cache):
                 os.makedirs(rustc_cache)
--- a/src/bootstrap/download.rs
+++ b/src/bootstrap/download.rs
@@ -211,7 +211,13 @@ impl Config {
             Some(other) => panic!("unsupported protocol {other} in {url}"),
             None => panic!("no protocol in {url}"),
         }
-        t!(std::fs::rename(&tempfile, dest_path));
+        match std::fs::rename(&tempfile, dest_path) {
+            Ok(v) => v,
+            Err(_) => {
+                t!(std::fs::copy(&tempfile, dest_path));
+                t!(std::fs::remove_file(&tempfile));
+            }
+        }
     }
 
     fn download_http_with_retries(&self, tempfile: &Path, url: &str, help_on_error: &str) {
@@ -529,7 +535,10 @@ impl Config {
         key: &str,
         destination: &str,
     ) {
-        let cache_dst = self.out.join("cache");
+        let cache_dst = match env::var_os("OPENWRT_RUSTC_BOOTSTRAP_CACHE") {
+            Some(v) => PathBuf::from(v),
+            None => self.out.join("cache"),
+        };
         let cache_dir = cache_dst.join(key);
         if !cache_dir.exists() {
             t!(fs::create_dir_all(&cache_dir));
@@ -656,7 +665,10 @@ download-rustc = false
         let llvm_assertions = self.llvm_assertions;
 
         let cache_prefix = format!("llvm-{llvm_sha}-{llvm_assertions}");
-        let cache_dst = self.out.join("cache");
+        let cache_dst = match env::var_os("OPENWRT_RUSTC_BOOTSTRAP_CACHE") {
+            Some(v) => PathBuf::from(v),
+            None => self.out.join("cache"),
+        };
         let rustc_cache = cache_dst.join(cache_prefix);
         if !rustc_cache.exists() {
             t!(fs::create_dir_all(&rustc_cache));