Store less information for destruction scopes

Author: Aaron1011

compiler/rustc_middle/src/middle/region.rs

@@ -228,7 +228,7 @@ pub struct ScopeTree {
     var_map: FxHashMap<hir::ItemLocalId, Scope>,
 
     /// Maps from a `NodeId` to the associated destruction scope (if any).
-    destruction_scopes: FxHashMap<(hir::ItemLocalId, bool), Scope>,
+    destruction_scopes: FxHashMap<hir::ItemLocalId, Scope>,
 
     /// `rvalue_scopes` includes entries for those expressions whose
     /// cleanup scope is larger than the default. The map goes from the
@@ -341,15 +341,12 @@ impl ScopeTree {
 
         // Record the destruction scopes for later so we can query them.
         if let ScopeData::Destruction = child.data {
-            assert_eq!(
-                self.destruction_scopes.insert((child.item_local_id(), child.for_stmt), child),
-                None
-            );
+            assert_eq!(self.destruction_scopes.insert(child.item_local_id(), child), None);
         }
     }
 
-    pub fn opt_destruction_scope(&self, n: hir::ItemLocalId, for_stmt: bool) -> Option<Scope> {
-        self.destruction_scopes.get(&(n, for_stmt)).cloned()
+    pub fn opt_destruction_scope(&self, n: hir::ItemLocalId) -> Option<Scope> {
+        self.destruction_scopes.get(&n).cloned()
     }
 
     pub fn record_var_scope(&mut self, var: hir::ItemLocalId, lifetime: Scope) {

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

@@ -13,7 +13,7 @@ impl<'tcx> Cx<'tcx> {
         // in order to get the lexical scoping correctly.
         let stmts = self.mirror_stmts(block.hir_id.local_id, block.stmts);
         let opt_destruction_scope =
-            self.region_scope_tree.opt_destruction_scope(block.hir_id.local_id, false);
+            self.region_scope_tree.opt_destruction_scope(block.hir_id.local_id);
         Block {
             targeted_by_break: block.targeted_by_break,
             region_scope: region::Scope {
@@ -47,8 +47,11 @@ impl<'tcx> Cx<'tcx> {
             .enumerate()
             .filter_map(|(index, stmt)| {
                 let hir_id = stmt.kind.hir_id();
-                let opt_dxn_ext =
-                    self.region_scope_tree.opt_destruction_scope(hir_id.local_id, true);
+                let dxn_scope = region::Scope {
+                    id: hir_id.local_id,
+                    data: region::ScopeData::Destruction,
+                    for_stmt: true,
+                };
                 match stmt.kind {
                     hir::StmtKind::Expr(ref expr) | hir::StmtKind::Semi(ref expr) => {
                         let stmt = Stmt {
@@ -60,7 +63,7 @@ impl<'tcx> Cx<'tcx> {
                                 },
                                 expr: self.mirror_expr(expr),
                             },
-                            opt_destruction_scope: opt_dxn_ext,
+                            opt_destruction_scope: Some(dxn_scope),
                         };
                         Some(self.thir.stmts.push(stmt))
                     }
@@ -111,7 +114,7 @@ impl<'tcx> Cx<'tcx> {
                                 initializer: local.init.map(|init| self.mirror_expr(init)),
                                 lint_level: LintLevel::Explicit(local.hir_id),
                             },
-                            opt_destruction_scope: opt_dxn_ext,
+                            opt_destruction_scope: Some(dxn_scope),
                         };
                         Some(self.thir.stmts.push(stmt))
                     }

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

@@ -62,7 +62,7 @@ impl<'tcx> Cx<'tcx> {
 
         // Finally, create a destruction scope, if any.
         if let Some(region_scope) =
-            self.region_scope_tree.opt_destruction_scope(hir_expr.hir_id.local_id, false)
+            self.region_scope_tree.opt_destruction_scope(hir_expr.hir_id.local_id)
         {
             expr = Expr {
                 temp_lifetime,