use let-else

Author: fengys1996

library/std/build.rs

@@ -198,6 +198,7 @@ BACKTRACE_RS_ANDROID_APIVERSION __ANDROID_API__
     // Create `android-api.c` on demand.
     let out_dir = env::var_os("OUT_DIR").unwrap();
     let android_api_c = Path::new(&out_dir).join("android-api.c");
+
     std::fs::write(&android_api_c, ANDROID_API_C).unwrap();
 
     let expansion = match cc::Build::new().file(&android_api_c).try_expand() {
@@ -207,23 +208,25 @@ BACKTRACE_RS_ANDROID_APIVERSION __ANDROID_API__
             return;
         }
     };
-    let expansion = match std::str::from_utf8(&expansion) {
-        Ok(s) => s,
-        Err(_) => return,
+
+    let Ok(expansion) = std::str::from_utf8(&expansion) else {
+        return;
     };
+
     eprintln!("expanded android version detection:\n{expansion}");
-    let i = match expansion.find(MARKER) {
-        Some(i) => i,
-        None => return,
+
+    let Some(i) = expansion.find(MARKER) else {
+        return;
     };
-    let version = match expansion[i + MARKER.len() + 1..].split_whitespace().next() {
-        Some(s) => s,
-        None => return,
+
+    let Some(version) = expansion[i + MARKER.len() + 1..].split_whitespace().next() else {
+        return;
     };
-    let version = match version.parse::<u32>() {
-        Ok(n) => n,
-        Err(_) => return,
+
+    let Ok(version) = version.parse::<u32>() else {
+        return;
     };
+
     if version >= 21 {
         println!("cargo:rustc-cfg=feature=\"dl_iterate_phdr\"");
     }