Reword error hint

src/libsyntax/parse/parser.rs

@@ -6002,7 +6002,8 @@ fn parse_foreign_item(&mut self) -> PResult<'a, Option<ForeignItem>> {
             if self.token.is_keyword(keywords::Const) {
                 self.diagnostic()
                     .struct_span_err(self.span, "extern items cannot be `const`")
-                    .span_label(self.span, "use `static` instead").emit();
+                    .span_suggestion(self.span, "instead try using", "static".to_owned())
+                    .emit();
             }
             self.bump(); // `static` or `const`
             return Ok(Some(self.parse_item_foreign_static(visibility, lo, attrs)?));

src/test/ui/extern-const.stderr

@@ -2,7 +2,7 @@ error: extern items cannot be `const`
   --> $DIR/extern-const.rs:14:5
    |
 14 |     const C: u8; //~ ERROR extern items cannot be `const`
-   |     ^^^^^ use `static` instead
+   |     ^^^^^ help: instead try using: `static`
 
 error: aborting due to previous error