Use a fixed rust-ar

Cargo.toml

@@ -33,7 +33,7 @@ core = { version = "1.0.0", optional = true, package = 'rustc-std-workspace-core
 
 [build-dependencies]
 cc = { optional = true, version = "1.0" }
-ar = { optional = true }
+ar = { optional = true, path = "../rust-ar" }
 
 [dev-dependencies]
 panic-handler = { path = 'crates/panic-handler' }

build.rs

@@ -504,16 +504,6 @@ mod c_system {
         r.to_string()
     }
 
-    // TODO: this really should be part of ar
-    fn clone_header(h0: &ar::Header) -> ar::Header {
-        let mut h = ar::Header::new(h0.identifier().to_vec(), h0.size());
-        h.set_mtime(h0.mtime());
-        h.set_uid(h0.uid());
-        h.set_gid(h0.gid());
-        h.set_mode(h0.mode());
-        h
-    }
-
     fn find_library<I>(dirs: I, libname: &str) -> Result<PathBuf, Vec<String>>
     where
         I: Iterator<Item = PathBuf>
@@ -600,11 +590,9 @@ mod c_system {
                     },
                 }
             };
-            orig.jump_to_entry(i).unwrap(); // Work around a stupid rust-ar bug
             let mut entry = orig.jump_to_entry(i).unwrap();
-            let header = clone_header(entry.header());
             // TODO: ar really should have an append_entry to avoid the clone
-            new.append(&header, &mut entry).unwrap();
+            new.append(&entry.header().clone(), &mut entry).unwrap();
             println!("cargo:rustc-cfg={}=\"optimized-c\"", sym);
         }