1 files changed, 11 insertions, 3 deletions
diff --git a/compiler/rustc_pattern_analysis/src/lib.rs b/compiler/rustc_pattern_analysis/src/lib.rs
index 4fd01b5e638..a55d53dfdac 100644
--- a/compiler/rustc_pattern_analysis/src/lib.rs
+++ b/compiler/rustc_pattern_analysis/src/lib.rs
@@ -101,15 +101,23 @@ pub trait TypeCx: Sized + fmt::Debug {
 
     /// The types of the fields for this constructor. The result must have a length of
     /// `ctor_arity()`.
-    fn ctor_sub_tys(&self, ctor: &Constructor<Self>, ty: &Self::Ty) -> &[Self::Ty];
+    fn ctor_sub_tys<'a>(
+        &'a self,
+        ctor: &'a Constructor<Self>,
+        ty: &'a Self::Ty,
+    ) -> impl Iterator<Item = Self::Ty> + ExactSizeIterator + Captures<'a>;
 
     /// The set of all the constructors for `ty`.
     ///
     /// This must follow the invariants of `ConstructorSet`
     fn ctors_for_ty(&self, ty: &Self::Ty) -> Result<ConstructorSet<Self>, Self::Error>;
 
-    /// Best-effort `Debug` implementation.
-    fn debug_pat(f: &mut fmt::Formatter<'_>, pat: &DeconstructedPat<'_, Self>) -> fmt::Result;
+    /// Write the name of the variant represented by `pat`. Used for the best-effort `Debug` impl of
+    /// `DeconstructedPat`. Only invoqued when `pat.ctor()` is `Struct | Variant(_) | UnionField`.
+    fn write_variant_name(
+        f: &mut fmt::Formatter<'_>,
+        pat: &crate::pat::DeconstructedPat<'_, Self>,
+    ) -> fmt::Result;
 
     /// Raise a bug.
     fn bug(&self, fmt: fmt::Arguments<'_>) -> !;