Windows: Test that deleting a running binary fails

Author: ChrisDenton

Diff for: std/src/sys/pal/windows/fs.rs

@@ -1239,8 +1239,10 @@ pub fn unlink(p: &Path) -> io::Result<()> {
             let mut opts = OpenOptions::new();
             opts.access_mode(c::DELETE);
             opts.custom_flags(c::FILE_FLAG_OPEN_REPARSE_POINT);
-            if File::open_native(&p_u16s, &opts).map(|f| f.posix_delete()).is_ok() {
-                return Ok(());
+            if let Ok(f) = File::open_native(&p_u16s, &opts) {
+                if f.posix_delete().is_ok() {
+                    return Ok(());
+                }
             }
         }
         // return the original error if any of the above fails.

Diff for: std/tests/win_delete_self.rs

@@ -0,0 +1,8 @@
+#![cfg(windows)]
+
+/// Attempting to delete a running binary should return an error on Windows.
+#[test]
+fn win_delete_self() {
+    let path = std::env::current_exe().unwrap();
+    assert!(std::fs::remove_file(path).is_err());
+}