put up a facade so that features are tested earlier

compiler/rustc_hir_analysis/src/check/scope_map.rs

@@ -2,7 +2,7 @@ use hir::intravisit::Visitor;
 use rustc_hir as hir;
 use rustc_index::Idx;
 use rustc_middle::{
-    middle::region::{BodyScopeMap, FirstStatementIndex, Scope, ScopeData},
+    middle::region::{BodyScopeMap, FirstStatementIndex, Scope, ScopeData, ScopeMapFacade},
     ty::TyCtxt,
 };
 use rustc_span::source_map;
@@ -493,17 +493,28 @@ impl<'tcx> Visitor<'tcx> for ScopeCollector<'tcx> {
     }
 }
 
-pub fn body_scope_map(tcx: TyCtxt<'_>, def_id: hir::def_id::DefId) -> &BodyScopeMap {
+pub fn body_scope_map<'tcx>(
+    tcx: TyCtxt<'tcx>,
+    def_id: hir::def_id::DefId,
+) -> &'tcx ScopeMapFacade<'tcx> {
     let typeck_root_def_id = tcx.typeck_root_def_id(def_id);
-    if typeck_root_def_id != def_id {
-        return tcx.body_scope_map(typeck_root_def_id);
-    }
-    let map = if let Some(body_id) = tcx.hir().maybe_body_owned_by(def_id.expect_local()) {
-        let mut collector = ScopeCollector::new(tcx);
-        collector.visit_body(tcx.hir().body(body_id));
-        BodyScopeMap { expr_scope: collector.expr_scope, new_var_scope: collector.new_var_scope }
+    if tcx.sess.at_least_rust_2024() && tcx.features().new_temp_lifetime {
+        if typeck_root_def_id != def_id {
+            return tcx.body_scope_map(typeck_root_def_id);
+        }
+        let map = if let Some(body_id) = tcx.hir().maybe_body_owned_by(def_id.expect_local()) {
+            let mut collector = ScopeCollector::new(tcx);
+            collector.visit_body(tcx.hir().body(body_id));
+            BodyScopeMap {
+                expr_scope: collector.expr_scope,
+                new_var_scope: collector.new_var_scope,
+            }
+        } else {
+            BodyScopeMap { expr_scope: <_>::default(), new_var_scope: <_>::default() }
+        };
+        let map = tcx.arena.alloc(map);
+        tcx.arena.alloc(ScopeMapFacade::Edition2024(map))
     } else {
-        BodyScopeMap { expr_scope: <_>::default(), new_var_scope: <_>::default() }
-    };
-    tcx.arena.alloc(map)
+        tcx.arena.alloc(ScopeMapFacade::Classical(tcx.region_scope_tree(typeck_root_def_id)))
+    }
 }

compiler/rustc_middle/src/arena.rs

@@ -40,6 +40,7 @@ macro_rules! arena_types {
             [] const_allocs: rustc_middle::mir::interpret::Allocation,
             [] region_scope_tree: rustc_middle::middle::region::ScopeTree,
             [] body_scope_map: rustc_middle::middle::region::BodyScopeMap,
+            [] scope_map_facade: rustc_middle::middle::region::ScopeMapFacade<'tcx>,
             // Required for the incremental on-disk cache
             [] mir_keys: rustc_hir::def_id::DefIdSet,
             [] dropck_outlives:

compiler/rustc_middle/src/middle/region.rs

@@ -6,7 +6,7 @@
 //!
 //! [rustc dev guide]: https://rustc-dev-guide.rust-lang.org/borrow_check.html
 
-use crate::ty::TyCtxt;
+use crate::ty::{RvalueScopes, TyCtxt};
 use rustc_data_structures::fx::FxIndexMap;
 use rustc_data_structures::unord::UnordMap;
 use rustc_hir as hir;
@@ -410,11 +410,39 @@ pub struct BodyScopeMap {
 }
 
 impl BodyScopeMap {
-    pub fn var_scope_new(&self, var_id: hir::ItemLocalId) -> Option<Scope> {
+    pub fn var_scope(&self, var_id: hir::ItemLocalId) -> Option<Scope> {
         self.new_var_scope.get(&var_id).copied().flatten()
     }
 
-    pub fn temporary_scope_new(&self, expr_id: hir::ItemLocalId) -> Option<Scope> {
+    pub fn temporary_scope(&self, expr_id: hir::ItemLocalId) -> Option<Scope> {
         self.expr_scope.get(&expr_id).copied().flatten()
     }
 }
+
+/// Facade to switch between classical, pre-2024, temporary lifetime rules
+/// and Edition 2024 rules.
+#[derive(Clone, Debug, HashStable)]
+pub enum ScopeMapFacade<'tcx> {
+    Classical(&'tcx ScopeTree),
+    Edition2024(&'tcx BodyScopeMap),
+}
+
+impl<'tcx> ScopeMapFacade<'tcx> {
+    pub fn var_scope(&self, var_id: hir::ItemLocalId) -> Option<Scope> {
+        match self {
+            ScopeMapFacade::Classical(map) => map.var_scope(var_id),
+            ScopeMapFacade::Edition2024(map) => map.var_scope(var_id),
+        }
+    }
+
+    pub fn temporary_scope(
+        &self,
+        rvalue_scopes: &RvalueScopes,
+        expr_id: hir::ItemLocalId,
+    ) -> Option<Scope> {
+        match self {
+            ScopeMapFacade::Classical(map) => rvalue_scopes.temporary_scope(map, expr_id),
+            ScopeMapFacade::Edition2024(map) => map.temporary_scope(expr_id),
+        }
+    }
+}

compiler/rustc_middle/src/query/mod.rs

@@ -1140,7 +1140,7 @@ rustc_queries! {
 
     /// Per-body `region::BodyScopeMap`. The `DefId` should point to the owner of the body;
     /// in the case of closures, this will be redirected to the enclosing function.
-    query body_scope_map(def_id: DefId) -> &'tcx crate::middle::region::BodyScopeMap {
+    query body_scope_map(def_id: DefId) -> &'tcx crate::middle::region::ScopeMapFacade<'tcx> {
         desc { |tcx| "computing drop scopes and temporary lifetime for `{}`", tcx.def_path_str(def_id) }
     }
 

compiler/rustc_mir_build/src/build/matches/mod.rs

@@ -798,11 +798,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         self.cfg.push(block, Statement { source_info, kind: StatementKind::StorageLive(local_id) });
         // Although there is almost always scope for given variable in corner cases
         // like #92893 we might get variable with no scope.
-        let scope = if let Some(scope_map) = self.scope_map {
-            scope_map.var_scope_new(var.0.local_id)
-        } else {
-            self.region_scope_tree.var_scope(var.0.local_id)
-        };
+        let scope = self.scope_map.var_scope(var.0.local_id);
         if let Some(region_scope) = scope
             && schedule_drop
         {
@@ -818,11 +814,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
         for_guard: ForGuard,
     ) {
         let local_id = self.var_local_id(var, for_guard);
-        let scope = if let Some(scope_map) = self.scope_map {
-            scope_map.var_scope_new(var.0.local_id)
-        } else {
-            self.region_scope_tree.var_scope(var.0.local_id)
-        };
+        let scope = self.scope_map.var_scope(var.0.local_id);
         if let Some(region_scope) = scope {
             self.schedule_drop(span, region_scope, local_id, DropKind::Value);
         }

compiler/rustc_mir_build/src/build/mod.rs

@@ -167,7 +167,7 @@ struct Builder<'a, 'tcx> {
     tcx: TyCtxt<'tcx>,
     infcx: InferCtxt<'tcx>,
     region_scope_tree: &'tcx region::ScopeTree,
-    scope_map: Option<&'tcx region::BodyScopeMap>,
+    scope_map: &'tcx region::ScopeMapFacade<'tcx>,
     param_env: ty::ParamEnv<'tcx>,
 
     thir: &'a Thir<'tcx>,
@@ -753,8 +753,7 @@ impl<'a, 'tcx> Builder<'a, 'tcx> {
             tcx,
             infcx,
             region_scope_tree: tcx.region_scope_tree(def),
-            scope_map: (tcx.sess.at_least_rust_2024() && tcx.features().new_temp_lifetime)
-                .then(|| tcx.body_scope_map(def)),
+            scope_map: tcx.body_scope_map(def),
             param_env,
             def_id: def,
             hir_id,

compiler/rustc_mir_build/src/thir/cx/expr.rs

@@ -236,11 +236,8 @@ impl<'tcx> Cx<'tcx> {
     fn make_mirror_unadjusted(&mut self, expr: &'tcx hir::Expr<'tcx>) -> Expr<'tcx> {
         let tcx = self.tcx;
         let expr_ty = self.typeck_results().expr_ty(expr);
-        let temp_lifetime = if let Some(scope_map) = self.scope_map {
-            scope_map.temporary_scope_new(expr.hir_id.local_id)
-        } else {
-            self.rvalue_scopes.temporary_scope(self.region_scope_tree, expr.hir_id.local_id)
-        };
+        let temp_lifetime =
+            self.scope_map.temporary_scope(self.rvalue_scopes, expr.hir_id.local_id);
 
         let kind = match expr.kind {
             // Here comes the interesting stuff:
@@ -717,11 +714,8 @@ impl<'tcx> Cx<'tcx> {
             },
             hir::ExprKind::Loop(body, ..) => {
                 let block_ty = self.typeck_results().node_type(body.hir_id);
-                let temp_lifetime = if let Some(scope_map) = self.scope_map {
-                    scope_map.temporary_scope_new(body.hir_id.local_id)
-                } else {
-                    self.rvalue_scopes.temporary_scope(self.region_scope_tree, body.hir_id.local_id)
-                };
+                let temp_lifetime =
+                    self.scope_map.temporary_scope(self.rvalue_scopes, body.hir_id.local_id);
                 let block = self.mirror_block(body);
                 let body = self.thir.exprs.push(Expr {
                     ty: block_ty,
@@ -830,11 +824,8 @@ impl<'tcx> Cx<'tcx> {
         span: Span,
         overloaded_callee: Option<Ty<'tcx>>,
     ) -> Expr<'tcx> {
-        let temp_lifetime = if let Some(scope_map) = self.scope_map {
-            scope_map.temporary_scope_new(expr.hir_id.local_id)
-        } else {
-            self.rvalue_scopes.temporary_scope(self.region_scope_tree, expr.hir_id.local_id)
-        };
+        let temp_lifetime =
+            self.scope_map.temporary_scope(self.rvalue_scopes, expr.hir_id.local_id);
         let (ty, user_ty) = match overloaded_callee {
             Some(fn_def) => (fn_def, None),
             None => {
@@ -920,11 +911,8 @@ impl<'tcx> Cx<'tcx> {
             // a constant reference (or constant raw pointer for `static mut`) in MIR
             Res::Def(DefKind::Static(_), id) => {
                 let ty = self.tcx.static_ptr_ty(id);
-                let temp_lifetime = if let Some(scope_map) = self.scope_map {
-                    scope_map.temporary_scope_new(expr.hir_id.local_id)
-                } else {
-                    self.rvalue_scopes.temporary_scope(self.region_scope_tree, expr.hir_id.local_id)
-                };
+                let temp_lifetime =
+                    self.scope_map.temporary_scope(self.rvalue_scopes, expr.hir_id.local_id);
                 let kind = if self.tcx.is_thread_local_static(id) {
                     ExprKind::ThreadLocalRef(id)
                 } else {
@@ -1003,11 +991,8 @@ impl<'tcx> Cx<'tcx> {
 
         // construct the complete expression `foo()` for the overloaded call,
         // which will yield the &T type
-        let temp_lifetime = if let Some(scope_map) = self.scope_map {
-            scope_map.temporary_scope_new(expr.hir_id.local_id)
-        } else {
-            self.rvalue_scopes.temporary_scope(self.region_scope_tree, expr.hir_id.local_id)
-        };
+        let temp_lifetime =
+            self.scope_map.temporary_scope(self.rvalue_scopes, expr.hir_id.local_id);
         let fun = self.method_callee(expr, span, overloaded_callee);
         let fun = self.thir.exprs.push(fun);
         let fun_ty = self.thir[fun].ty;
@@ -1027,11 +1012,8 @@ impl<'tcx> Cx<'tcx> {
         closure_expr: &'tcx hir::Expr<'tcx>,
         place: HirPlace<'tcx>,
     ) -> Expr<'tcx> {
-        let temp_lifetime = if let Some(scope_map) = self.scope_map {
-            scope_map.temporary_scope_new(closure_expr.hir_id.local_id)
-        } else {
-            self.rvalue_scopes.temporary_scope(self.region_scope_tree, closure_expr.hir_id.local_id)
-        };
+        let temp_lifetime =
+            self.scope_map.temporary_scope(self.rvalue_scopes, closure_expr.hir_id.local_id);
         let var_ty = place.base_ty;
 
         // The result of capture analysis in `rustc_hir_analysis/check/upvar.rs`represents a captured path
@@ -1086,11 +1068,8 @@ impl<'tcx> Cx<'tcx> {
         let upvar_capture = captured_place.info.capture_kind;
         let captured_place_expr =
             self.convert_captured_hir_place(closure_expr, captured_place.place.clone());
-        let temp_lifetime = if let Some(scope_map) = self.scope_map {
-            scope_map.temporary_scope_new(closure_expr.hir_id.local_id)
-        } else {
-            self.rvalue_scopes.temporary_scope(self.region_scope_tree, closure_expr.hir_id.local_id)
-        };
+        let temp_lifetime =
+            self.scope_map.temporary_scope(self.rvalue_scopes, closure_expr.hir_id.local_id);
 
         match upvar_capture {
             ty::UpvarCapture::ByValue => captured_place_expr,

compiler/rustc_mir_build/src/thir/cx/mod.rs

@@ -57,8 +57,7 @@ struct Cx<'tcx> {
 
     param_env: ty::ParamEnv<'tcx>,
 
-    region_scope_tree: &'tcx region::ScopeTree,
-    scope_map: Option<&'tcx region::BodyScopeMap>,
+    scope_map: &'tcx region::ScopeMapFacade<'tcx>,
     typeck_results: &'tcx ty::TypeckResults<'tcx>,
     rvalue_scopes: &'tcx RvalueScopes,
 
@@ -98,9 +97,7 @@ impl<'tcx> Cx<'tcx> {
             tcx,
             thir: Thir::new(body_type),
             param_env: tcx.param_env(def),
-            region_scope_tree: tcx.region_scope_tree(def),
-            scope_map: (tcx.sess.at_least_rust_2024() && tcx.features().new_temp_lifetime)
-                .then(|| tcx.body_scope_map(def)),
+            scope_map: tcx.body_scope_map(def),
             typeck_results,
             rvalue_scopes: &typeck_results.rvalue_scopes,
             body_owner: def.to_def_id(),

src/tools/clippy/clippy_lints/src/loops/needless_range_loop.rs

@@ -57,12 +57,7 @@ pub(super) fn check<'tcx>(
                 if let Some(indexed_extent) = indexed_extent {
                     let parent_def_id = cx.tcx.hir().get_parent_item(expr.hir_id);
                     let region_scope_tree = cx.tcx.region_scope_tree(parent_def_id);
-                    let var_scope = if cx.tcx.sess.at_least_rust_2024() && cx.tcx.features().new_temp_lifetime {
-                        let scope_map = cx.tcx.body_scope_map(parent_def_id);
-                        scope_map.var_scope_new(pat.hir_id.local_id)
-                    } else {
-                        region_scope_tree.var_scope(pat.hir_id.local_id)
-                    };
+                    let var_scope = cx.tcx.body_scope_map(parent_def_id).var_scope(pat.hir_id.local_id);
                     let pat_extent = var_scope.unwrap();
                     if region_scope_tree.is_subscope_of(indexed_extent, pat_extent) {
                         return;
@@ -262,13 +257,12 @@ impl<'a, 'tcx> VarVisitor<'a, 'tcx> {
             match res {
                 Res::Local(hir_id) => {
                     let parent_def_id = self.cx.tcx.hir().get_parent_item(expr.hir_id);
-                    let region_scope_tree = self.cx.tcx.region_scope_tree(parent_def_id);
-                    let extent = if self.cx.tcx.sess.at_least_rust_2024() && self.cx.tcx.features().new_temp_lifetime {
-                        self.cx.tcx.body_scope_map(parent_def_id).var_scope_new(hir_id.local_id)
-                    } else {
-                        region_scope_tree.var_scope(hir_id.local_id)
-                    }
-                    .unwrap();
+                    let extent = self
+                        .cx
+                        .tcx
+                        .body_scope_map(parent_def_id)
+                        .var_scope(hir_id.local_id)
+                        .unwrap();
                     if index_used_directly {
                         self.indexed_directly.insert(
                             seqvar.segments[0].ident.name,

src/tools/clippy/clippy_lints/src/shadow.rs

@@ -163,14 +163,7 @@ impl<'tcx> LateLintPass<'tcx> for Shadow {
 fn is_shadow(cx: &LateContext<'_>, owner: LocalDefId, first: ItemLocalId, second: ItemLocalId) -> bool {
     let def_id = owner.to_def_id();
     let scope_tree = cx.tcx.region_scope_tree(def_id);
-    let get_scope = |id| {
-        if cx.tcx.sess.at_least_rust_2024() && cx.tcx.features().new_temp_lifetime {
-            let scope_map = cx.tcx.body_scope_map(def_id);
-            scope_map.var_scope_new(id)
-        } else {
-            scope_tree.var_scope(id)
-        }
-    };
+    let get_scope = |id| cx.tcx.body_scope_map(def_id).var_scope(id);
     if let Some(first_scope) = get_scope(first) {
         if let Some(second_scope) = get_scope(second) {
             return scope_tree.is_subscope_of(second_scope, first_scope);