Auto merge of #96087 - Dylan-DPC:rollup-k6yzk55, r=Dylan-DPC

Rollup of 11 pull requests

Successful merges:

 - #94457 (Stabilize `derive_default_enum`)
 - #94461 (Create (unstable) 2024 edition)
 - #94849 (Check var scope if it exist)
 - #95194 (remove find_use_placement)
 - #95749 (only downgrade selection Error -> Ambiguous if type error is in predicate)
 - #96026 (couple of clippy::complexity fixes)
 - #96027 (remove function parameters only used in recursion)
 - #96034 ([test] Add test cases of untested functions for BTreeSet )
 - #96040 (Use u32 instead of i32 for futexes.)
 - #96062 (docs: Update tests chapter for Termination stabilization)
 - #96065 (Refactor: Use `format-args-capture` and remove unnecessary nested blocks in rustc_typeck)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

4 files changed, 7 insertions, 10 deletions

diff --git a/compiler/rustc_middle/src/hir/map/mod.rs b/compiler/rustc_middle/src/hir/map/mod.rs
index 65796fbc698..08cd40f38ef 100644
--- a/compiler/rustc_middle/src/hir/map/mod.rs
+++ b/compiler/rustc_middle/src/hir/map/mod.rs
@@ -584,7 +584,7 @@ impl<'hir> Map<'hir> {
             Some(OwnerNode::Item(&Item { span, kind: ItemKind::Mod(ref m), .. })) => {
                 (m, span, hir_id)
             }
-            Some(OwnerNode::Crate(item)) => (item, item.inner, hir_id),
+            Some(OwnerNode::Crate(item)) => (item, item.spans.inner_span, hir_id),
             node => panic!("not a module: {:?}", node),
         }
     }
@@ -1012,7 +1012,7 @@ impl<'hir> Map<'hir> {
             Node::Infer(i) => i.span,
             Node::Visibility(v) => bug!("unexpected Visibility {:?}", v),
             Node::Local(local) => local.span,
-            Node::Crate(item) => item.inner,
+            Node::Crate(item) => item.spans.inner_span,
         };
         Some(span)
     }
diff --git a/compiler/rustc_middle/src/lib.rs b/compiler/rustc_middle/src/lib.rs
index fd2b5f5335f..199b5fa0314 100644
--- a/compiler/rustc_middle/src/lib.rs
+++ b/compiler/rustc_middle/src/lib.rs
@@ -30,7 +30,7 @@
 #![feature(bool_to_option)]
 #![feature(box_patterns)]
 #![feature(core_intrinsics)]
-#![feature(derive_default_enum)]
+#![cfg_attr(bootstrap, feature(derive_default_enum))]
 #![feature(discriminant_kind)]
 #![feature(exhaustive_patterns)]
 #![feature(get_mut_unchecked)]
diff --git a/compiler/rustc_middle/src/middle/region.rs b/compiler/rustc_middle/src/middle/region.rs
index 98da20baf02..af16e5e3fc8 100644
--- a/compiler/rustc_middle/src/middle/region.rs
+++ b/compiler/rustc_middle/src/middle/region.rs
@@ -362,12 +362,9 @@ impl ScopeTree {
         self.parent_map.get(&id).cloned().map(|(p, _)| p)
     }
 
-    /// Returns the lifetime of the local variable `var_id`
-    pub fn var_scope(&self, var_id: hir::ItemLocalId) -> Scope {
-        self.var_map
-            .get(&var_id)
-            .cloned()
-            .unwrap_or_else(|| bug!("no enclosing scope for id {:?}", var_id))
+    /// Returns the lifetime of the local variable `var_id`, if any.
+    pub fn var_scope(&self, var_id: hir::ItemLocalId) -> Option<Scope> {
+        self.var_map.get(&var_id).cloned()
     }
 
     /// Returns the scope when the temp created by `expr_id` will be cleaned up.
diff --git a/compiler/rustc_middle/src/ty/inhabitedness/mod.rs b/compiler/rustc_middle/src/ty/inhabitedness/mod.rs
index 2c78c1f63d8..226456588e7 100644
--- a/compiler/rustc_middle/src/ty/inhabitedness/mod.rs
+++ b/compiler/rustc_middle/src/ty/inhabitedness/mod.rs
@@ -191,7 +191,7 @@ impl<'tcx> Ty<'tcx> {
         tcx: TyCtxt<'tcx>,
         param_env: ty::ParamEnv<'tcx>,
     ) -> DefIdForest<'tcx> {
-        tcx.type_uninhabited_from(param_env.and(self)).clone()
+        tcx.type_uninhabited_from(param_env.and(self))
     }
 }