Update issue-17383.rs

Author: notriddle

src/test/parse-fail/issue-17383.rs

@@ -12,7 +12,7 @@
 
 enum X {
     A =
-        b'a' //~ ERROR discriminator values can only be used with a c-like enum
+        b'a' //~ ERROR discriminator values can only be used with a field-less enum
     ,
     B(isize)
 }