Avoid repeating the underlined type in the label

Author: dtolnay

syntax/check.rs

@@ -67,7 +67,8 @@ fn check_type_ident(cx: &mut Check, ident: &Ident) {
         && !cx.types.cxx.contains(ident)
         && !cx.types.rust.contains(ident)
     {
-        cx.error(ident, &format!("unsupported type: {}", ident));
+        let msg = format!("unsupported type: {}", ident);
+        cx.error(ident, &msg);
     }
 }
 

syntax/error.rs

@@ -21,6 +21,7 @@ pub static ERRORS: &[Error] = &[
     DISCRIMINANT_OVERFLOW,
     DOUBLE_UNDERSCORE,
     RUST_TYPE_BY_VALUE,
+    UNSUPPORTED_TYPE,
     USE_NOT_ALLOWED,
 ];
 
@@ -66,6 +67,12 @@ pub static RUST_TYPE_BY_VALUE: Error = Error {
     note: Some("hint: wrap it in a Box<>"),
 };
 
+pub static UNSUPPORTED_TYPE: Error = Error {
+    msg: "unsupported type: ",
+    label: Some("unsupported type"),
+    note: None,
+};
+
 pub static USE_NOT_ALLOWED: Error = Error {
     msg: "`use` items are not allowed within cxx bridge",
     label: Some("not allowed"),