Improve the WitnessPat: Debug impl

compiler/rustc_pattern_analysis/src/lib.rs

@@ -120,7 +120,8 @@ pub trait PatCx: Sized + fmt::Debug {
     /// `DeconstructedPat`. Only invoqued when `pat.ctor()` is `Struct | Variant(_) | UnionField`.
     fn write_variant_name(
         f: &mut fmt::Formatter<'_>,
-        pat: &crate::pat::DeconstructedPat<Self>,
+        ctor: &crate::constructor::Constructor<Self>,
+        ty: &Self::Ty,
     ) -> fmt::Result;
 
     /// Raise a bug.