I think I need a box.

src/parser/nom_context.rs

@@ -19,4 +19,14 @@ impl<'a> NomContext<'a> {
             can_match_link: true,
         }
     }
+
+    pub fn with_additional_fail_matcher<'o, 'c: 'a + 'o>(&self, other: &'o mut dyn FnMut(&str) -> IResult<&str, &str, VerboseError<&str>>) -> NomContext<'c> {
+        let new_matcher = alt((&self.fail_matcher, other));
+        NomContext {
+            fail_matcher: new_matcher,
+            can_match_bold: self.can_match_bold,
+            can_match_link: self.can_match_link
+        }
+        todo!()
+    }
 }