1 files changed, 37 insertions, 0 deletions
diff --git a/src/tools/rustfmt/src/emitter/files.rs b/src/tools/rustfmt/src/emitter/files.rs
new file mode 100644
index 000000000..6360b73ee
--- /dev/null
+++ b/src/tools/rustfmt/src/emitter/files.rs
@@ -0,0 +1,37 @@
+use super::*;
+use std::fs;
+
+#[derive(Debug, Default)]
+pub(crate) struct FilesEmitter {
+    print_misformatted_file_names: bool,
+}
+
+impl FilesEmitter {
+    pub(crate) fn new(print_misformatted_file_names: bool) -> Self {
+        Self {
+            print_misformatted_file_names,
+        }
+    }
+}
+
+impl Emitter for FilesEmitter {
+    fn emit_formatted_file(
+        &mut self,
+        output: &mut dyn Write,
+        FormattedFile {
+            filename,
+            original_text,
+            formatted_text,
+        }: FormattedFile<'_>,
+    ) -> Result<EmitterResult, io::Error> {
+        // Write text directly over original file if there is a diff.
+        let filename = ensure_real_path(filename);
+        if original_text != formatted_text {
+            fs::write(filename, formatted_text)?;
+            if self.print_misformatted_file_names {
+                writeln!(output, "{}", filename.display())?;
+            }
+        }
+        Ok(EmitterResult::default())
+    }
+}