Rollup merge of #141104 - PaulDance:fix-win7-test_eq_windows_file_type, r=ChrisDenton

Test(fs): Fix `test_eq_windows_file_type` for Windows 7

Would otherwise fail on:

```
thread 'fs::tests::test_eq_windows_file_type' panicked at library/std/src/test_helpers.rs:53:20:
called `Result::unwrap()` on an `Err` value: Os { code: 5, kind: PermissionDenied, message: "Access is denied." }
```

This came from the read-only attribute set on the test file. In order to fix this, instead of simply disabling the test, the attribute is reset before the test's end so it may still run successfully.

`@rustbot` label T-libs A-filesystem A-testsuite O-windows-7 O-windows-msvc

1 files changed, 23 insertions, 1 deletions

diff --git a/library/std/src/fs/tests.rs b/library/std/src/fs/tests.rs
index 8da6d75b73e..c81e3af2f0d 100644
--- a/library/std/src/fs/tests.rs
+++ b/library/std/src/fs/tests.rs
@@ -1782,8 +1782,30 @@ fn test_eq_windows_file_type() {
     // Change the readonly attribute of one file.
     let mut perms = file1.metadata().unwrap().permissions();
     perms.set_readonly(true);
-    file1.set_permissions(perms).unwrap();
+    file1.set_permissions(perms.clone()).unwrap();
+    #[cfg(target_vendor = "win7")]
+    let _g = ReadonlyGuard { file: &file1, perms };
     assert_eq!(file1.metadata().unwrap().file_type(), file2.metadata().unwrap().file_type());
+
+    // Reset the attribute before the `TmpDir`'s drop that removes the
+    // associated directory, which fails with a `PermissionDenied` error when
+    // running under Windows 7.
+    #[cfg(target_vendor = "win7")]
+    struct ReadonlyGuard<'f> {
+        file: &'f File,
+        perms: fs::Permissions,
+    }
+    #[cfg(target_vendor = "win7")]
+    impl<'f> Drop for ReadonlyGuard<'f> {
+        fn drop(&mut self) {
+            self.perms.set_readonly(false);
+            let res = self.file.set_permissions(self.perms.clone());
+
+            if !thread::panicking() {
+                res.unwrap();
+            }
+        }
+    }
 }
 
 /// Regression test for https://github.com/rust-lang/rust/issues/50619.