Use same file permissions for ar_archive_writer as the LLVM archive writer

compiler/rustc_codegen_ssa/src/back/archive.rs

@@ -13,7 +13,7 @@ use object::read::macho::FatArch;
 use tempfile::Builder as TempFileBuilder;
 
 use std::error::Error;
-use std::fs::File;
+use std::fs::{self, File};
 use std::io::{self, Write};
 use std::path::{Path, PathBuf};
 
@@ -280,22 +280,33 @@ impl<'a> ArArchiveBuilder<'a> {
         // This prevents programs (including rustc) from attempting to read a partial archive.
         // It also enables writing an archive with the same filename as a dependency on Windows as
         // required by a test.
-        let mut archive_tmpfile = TempFileBuilder::new()
+        // The tempfile crate currently uses 0o600 as mode for the temporary files and directories
+        // it creates. We need it to be the default mode for back compat reasons however. (See
+        // #107495) To handle this we are telling tempfile to create a temporary directory instead
+        // and then inside this directory create a file using File::create.
+        let archive_tmpdir = TempFileBuilder::new()
             .suffix(".temp-archive")
-            .tempfile_in(output.parent().unwrap_or_else(|| Path::new("")))
-            .map_err(|err| io_error_context("couldn't create a temp file", err))?;
+            .tempdir_in(output.parent().unwrap_or_else(|| Path::new("")))
+            .map_err(|err| {
+                io_error_context("couldn't create a directory for the temp file", err)
+            })?;
+        let archive_tmpfile_path = archive_tmpdir.path().join("tmp.a");
+        let mut archive_tmpfile = File::create_new(&archive_tmpfile_path)
+            .map_err(|err| io_error_context("couldn't create the temp file", err))?;
 
-        write_archive_to_stream(archive_tmpfile.as_file_mut(), &entries, archive_kind, false)?;
+        write_archive_to_stream(&mut archive_tmpfile, &entries, archive_kind, false)?;
 
         let any_entries = !entries.is_empty();
         drop(entries);
         // Drop src_archives to unmap all input archives, which is necessary if we want to write the
         // output archive to the same location as an input archive on Windows.
         drop(self.src_archives);
 
-        archive_tmpfile
-            .persist(output)
-            .map_err(|err| io_error_context("failed to rename archive file", err.error))?;
+        fs::rename(archive_tmpfile_path, output)
+            .map_err(|err| io_error_context("failed to rename archive file", err))?;
+        archive_tmpdir
+            .close()
+            .map_err(|err| io_error_context("failed to remove temporary directory", err))?;
 
         Ok(any_entries)
     }

tests/run-make/issue-107495-archive-permissions/foo.rs

@@ -0,0 +1 @@
+// Empty

tests/run-make/issue-107495-archive-permissions/rmake.rs

@@ -0,0 +1,31 @@
+#![feature(rustc_private)]
+
+#[cfg(unix)]
+extern crate libc;
+extern crate run_make_support;
+
+use run_make_support::{aux_build, tmp_dir};
+use std::fs;
+#[cfg(unix)]
+use std::os::unix::fs::PermissionsExt;
+use std::path::Path;
+
+fn main() {
+    #[cfg(unix)]
+    unsafe {
+        libc::umask(0o002);
+    }
+
+    aux_build().arg("foo.rs").run();
+    verify(&tmp_dir().join("libfoo.rlib"));
+}
+
+fn verify(path: &Path) {
+    let perm = fs::metadata(path).unwrap().permissions();
+
+    assert!(!perm.readonly());
+
+    // Check that the file is readable for everyone
+    #[cfg(unix)]
+    assert_eq!(perm.mode(), 0o100664);
+}