Fix commas.

Author: smmalis37

src/librustc_typeck/astconv.rs

@@ -3080,7 +3080,7 @@ impl<'o, 'tcx> dyn AstConv<'tcx> + 'o {
                 tcx.sess,
                 decl.output.span(),
                 E0581,
-                "return type references {} which is not constrained by the fn input types",
+                "return type references {}, which is not constrained by the fn input types",
                 br_name
             )
         });

src/test/ui/issues/issue-47511.stderr

@@ -1,4 +1,4 @@
-error[E0581]: return type references an anonymous lifetime which is not constrained by the fn input types
+error[E0581]: return type references an anonymous lifetime, which is not constrained by the fn input types
   --> $DIR/issue-47511.rs:5:15
    |
 LL | fn f(_: X) -> X {