Fix non local definition in rustfmt

src/tools/rustfmt/src/source_file.rs

@@ -16,6 +16,17 @@ use crate::formatting::FileRecord;
 
 use rustc_data_structures::sync::Lrc;
 
+impl From<&FileName> for rustc_span::FileName {
+    fn from(filename: &FileName) -> rustc_span::FileName {
+        match filename {
+            FileName::Real(path) => {
+                rustc_span::FileName::Real(rustc_span::RealFileName::LocalPath(path.to_owned()))
+            }
+            FileName::Stdin => rustc_span::FileName::Custom("stdin".to_owned()),
+        }
+    }
+}
+
 // Append a newline to the end of each file.
 pub(crate) fn append_newline(s: &mut String) {
     s.push('\n');
@@ -66,17 +77,6 @@ where
         }
     }
 
-    impl From<&FileName> for rustc_span::FileName {
-        fn from(filename: &FileName) -> rustc_span::FileName {
-            match filename {
-                FileName::Real(path) => {
-                    rustc_span::FileName::Real(rustc_span::RealFileName::LocalPath(path.to_owned()))
-                }
-                FileName::Stdin => rustc_span::FileName::Custom("stdin".to_owned()),
-            }
-        }
-    }
-
     // SourceFile's in the SourceMap will always have Unix-style line endings
     // See: https://github.com/rust-lang/rustfmt/issues/3850
     // So if the user has explicitly overridden the rustfmt `newline_style`