Revert "replace trait object BufRead by generic"

This reverts commit 037861e588.

src/features.rs

@@ -86,34 +86,25 @@ fn print_file(
     printer: &mut Printer,
     filename: Option<&str>,
 ) -> Result<()> {
-    printer.print_header(filename)?;
+    let stdin = io::stdin(); // TODO: this is not always needed
+    {
+        let reader: Box<BufRead> = match filename {
+            None => Box::new(stdin.lock()),
+            Some(filename) => Box::new(BufReader::new(File::open(filename)?)),
+        };
 
-    let highlighter = HighlightLines::new(syntax, theme);
-    match filename {
-        None => {
-            let stdin = io::stdin(); // TODO: this is not always needed
-            print_file_ranges(
-                printer,
-                stdin.lock(),
-                highlighter,
-                &printer.config.line_range,
-            )?;
-        }
-        Some(filename) => print_file_ranges(
-            printer,
-            BufReader::new(File::open(filename)?),
-            highlighter,
-            &printer.config.line_range,
-        )?,
+        let highlighter = HighlightLines::new(syntax, theme);
+
+        printer.print_header(filename)?;
+        print_file_ranges(printer, reader, highlighter, &printer.config.line_range)?;
+        printer.print_footer()?;
     }
-
-    printer.print_footer()?;
     Ok(())
 }
 
-fn print_file_ranges<T: BufRead>(
+fn print_file_ranges<'a>(
     printer: &mut Printer,
-    mut reader: T,
+    mut reader: Box<BufRead + 'a>,
     mut highlighter: HighlightLines,
     line_ranges: &Option<LineRange>,
 ) -> Result<()> {