Move lifetime_to_string to Display impl

src/libsyntax/ast.rs

@@ -50,11 +50,17 @@ impl fmt::Debug for Lifetime {
             f,
             "lifetime({}: {})",
             self.id,
-            pprust::lifetime_to_string(self)
+            self
         )
     }
 }
 
+impl fmt::Display for Lifetime {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        write!(f, "{}", self.ident.name.as_str())
+    }
+}
+
 /// A "Path" is essentially Rust's notion of a name.
 ///
 /// It's represented as a sequence of identifiers,

src/libsyntax/print/pprust.rs

@@ -326,10 +326,6 @@ pub fn expr_to_string(e: &ast::Expr) -> String {
     to_string(|s| s.print_expr(e))
 }
 
-pub fn lifetime_to_string(lt: &ast::Lifetime) -> String {
-    to_string(|s| s.print_lifetime(*lt))
-}
-
 pub fn tt_to_string(tt: tokenstream::TokenTree) -> String {
     to_string(|s| s.print_tt(tt, false))
 }