Review comments

Author: jackh726

compiler/rustc_middle/src/traits/chalk.rs

@@ -112,43 +112,39 @@ impl<'tcx> chalk_ir::interner::Interner for RustInterner<'tcx> {
         match application_ty.name {
             chalk_ir::TypeName::Ref(mutbl) => {
                 let data = application_ty.substitution.interned();
-                let lifetime = match &**data[0].interned() {
-                    chalk_ir::GenericArgData::Lifetime(t) => t,
+                match (&**data[0].interned(), &**data[1].interned()) {
+                    (
+                        chalk_ir::GenericArgData::Lifetime(lifetime),
+                        chalk_ir::GenericArgData::Ty(ty),
+                    ) => Some(match mutbl {
+                        chalk_ir::Mutability::Not => write!(fmt, "(&{:?} {:?})", lifetime, ty),
+                        chalk_ir::Mutability::Mut => write!(fmt, "(&{:?} mut {:?})", lifetime, ty),
+                    }),
                     _ => unreachable!(),
-                };
-                let ty = match &**data[1].interned() {
-                    chalk_ir::GenericArgData::Ty(t) => t,
-                    _ => unreachable!(),
-                };
-                return Some(match mutbl {
-                    chalk_ir::Mutability::Not => write!(fmt, "(&{:?} {:?})", lifetime, ty),
-                    chalk_ir::Mutability::Mut => write!(fmt, "(&{:?} mut {:?})", lifetime, ty),
-                });
+                }
             }
             chalk_ir::TypeName::Array => {
                 let data = application_ty.substitution.interned();
-                let ty = match &**data[0].interned() {
-                    chalk_ir::GenericArgData::Ty(t) => t,
-                    _ => unreachable!(),
-                };
-                let len = match &**data[1].interned() {
-                    chalk_ir::GenericArgData::Const(t) => t,
+                match (&**data[0].interned(), &**data[1].interned()) {
+                    (chalk_ir::GenericArgData::Ty(ty), chalk_ir::GenericArgData::Const(len)) => {
+                        Some(write!(fmt, "[{:?}; {:?}]", ty, len))
+                    }
                     _ => unreachable!(),
-                };
-                return Some(write!(fmt, "[{:?}; {:?}]", ty, len));
+                }
             }
             chalk_ir::TypeName::Slice => {
                 let data = application_ty.substitution.interned();
                 let ty = match &**data[0].interned() {
                     chalk_ir::GenericArgData::Ty(t) => t,
                     _ => unreachable!(),
                 };
-                return Some(write!(fmt, "[{:?}]", ty));
+                Some(write!(fmt, "[{:?}]", ty))
+            }
+            _ => {
+                let chalk_ir::ApplicationTy { name, substitution } = application_ty;
+                Some(write!(fmt, "{:?}{:?}", name, chalk_ir::debug::Angle(substitution.interned())))
             }
-            _ => {}
         }
-        let chalk_ir::ApplicationTy { name, substitution } = application_ty;
-        Some(write!(fmt, "{:?}{:?}", name, chalk_ir::debug::Angle(substitution.interned())))
     }
 
     fn debug_substitution(