Rollup merge of #120516 - Nadrieril:cleanup-impls, r=compiler-errors

pattern_analysis: cleanup manual impls

https://github.com/rust-lang/rust/pull/120420 introduced some unneeded manual impls. I remove them here.

r? ```@Nilstrieb```

1 files changed, 2 insertions, 12 deletions

diff --git a/compiler/rustc_pattern_analysis/src/usefulness.rs b/compiler/rustc_pattern_analysis/src/usefulness.rs
index 3d45d032a99..f729f0aa41b 100644
--- a/compiler/rustc_pattern_analysis/src/usefulness.rs
+++ b/compiler/rustc_pattern_analysis/src/usefulness.rs
@@ -1207,6 +1207,7 @@ impl<'p, Cx: TypeCx> fmt::Debug for Matrix<'p, Cx> {
 /// The final `Pair(Some(_), true)` is then the resulting witness.
 ///
 /// See the top of the file for more detailed explanations and examples.
+#[derive(Debug)]
 struct WitnessStack<Cx: TypeCx>(Vec<WitnessPat<Cx>>);
 
 impl<Cx: TypeCx> Clone for WitnessStack<Cx> {
@@ -1215,12 +1216,6 @@ impl<Cx: TypeCx> Clone for WitnessStack<Cx> {
     }
 }
 
-impl<Cx: TypeCx> fmt::Debug for WitnessStack<Cx> {
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt.debug_tuple("WitnessStack").field(&self.0).finish()
-    }
-}
-
 impl<Cx: TypeCx> WitnessStack<Cx> {
     /// Asserts that the witness contains a single pattern, and returns it.
     fn single_pattern(self) -> WitnessPat<Cx> {
@@ -1265,6 +1260,7 @@ impl<Cx: TypeCx> WitnessStack<Cx> {
 ///
 /// Just as the `Matrix` starts with a single column, by the end of the algorithm, this has a single
 /// column, which contains the patterns that are missing for the match to be exhaustive.
+#[derive(Debug)]
 struct WitnessMatrix<Cx: TypeCx>(Vec<WitnessStack<Cx>>);
 
 impl<Cx: TypeCx> Clone for WitnessMatrix<Cx> {
@@ -1273,12 +1269,6 @@ impl<Cx: TypeCx> Clone for WitnessMatrix<Cx> {
     }
 }
 
-impl<Cx: TypeCx> fmt::Debug for WitnessMatrix<Cx> {
-    fn fmt(&self, fmt: &mut fmt::Formatter<'_>) -> fmt::Result {
-        fmt.debug_tuple("WitnessMatrix").field(&self.0).finish()
-    }
-}
-
 impl<Cx: TypeCx> WitnessMatrix<Cx> {
     /// New matrix with no witnesses.
     fn empty() -> Self {