E0459 Update error format #35933

- Fixes #35933
- Part of #35233

r? @jonathandturner

Author: gavinb

src/librustc_metadata/creader.rs

@@ -977,8 +977,9 @@ impl<'a> LocalCrateReader<'a> {
             let n = match n {
                 Some(n) => n,
                 None => {
-                    span_err!(self.sess, m.span, E0459,
-                              "#[link(...)] specified without `name = \"foo\"`");
+                    struct_span_err!(self.sess, m.span, E0459,
+                                     "#[link(...)] specified without `name = \"foo\"`")
+                        .span_label(m.span, &format!("missing `name` argument")).emit();
                     InternedString::new("foo")
                 }
             };

src/test/compile-fail/E0459.rs

@@ -9,6 +9,7 @@
 // except according to those terms.
 
 #[link(kind = "dylib")] extern {} //~ ERROR E0459
+                                  //~| NOTE missing `name` argument
 
 fn main() {
 }