Regression test for identity_conversion

Author: flip1995

tests/ui/identity_conversion_fp.rs

@@ -0,0 +1,13 @@
+// compile-pass
+
+// Tracking issue: #3913
+
+use std::fs;
+use std::path::Path;
+
+fn main() -> Result<(), std::io::Error> {
+    let path = Path::new(".");
+    for _ in fs::read_dir(path)? {}
+
+    Ok(())
+}