Exhaustively match on the mutability and nestedness

Author: oli-obk

compiler/rustc_const_eval/src/interpret/validity.rs

@@ -483,12 +483,14 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                         }
                         // Return alloc mutability. For "root" statics we look at the type to account for interior
                         // mutability; for nested statics we have no type and directly use the annotated mutability.
-                        match self.ecx.tcx.def_kind(did) {
-                            DefKind::Static { mutability: Mutability::Mut, .. } => Mutability::Mut,
-                            DefKind::Static { mutability: Mutability::Not, nested: true } => {
-                                Mutability::Not
-                            }
-                            DefKind::Static { mutability: Mutability::Not, nested: false }
+                        let DefKind::Static { mutability, nested } = self.ecx.tcx.def_kind(did)
+                        else {
+                            bug!()
+                        };
+                        match (mutability, nested) {
+                            (Mutability::Mut, _) => Mutability::Mut,
+                            (Mutability::Not, true) => Mutability::Not,
+                            (Mutability::Not, false)
                                 if !self
                                     .ecx
                                     .tcx
@@ -499,7 +501,7 @@ impl<'rt, 'mir, 'tcx: 'mir, M: Machine<'mir, 'tcx>> ValidityVisitor<'rt, 'mir, '
                             {
                                 Mutability::Mut
                             }
-                            _ => Mutability::Not,
+                            (Mutability::Not, false) => Mutability::Not,
                         }
                     }
                     GlobalAlloc::Memory(alloc) => alloc.inner().mutability,