From 3bae9276fa13f0b7c39a1d1e1c39aba0fd96bf8d Mon Sep 17 00:00:00 2001
From: Nicholas Nethercote <n.nethercote@gmail.com>
Date: Tue, 28 Nov 2023 12:19:17 +1100
Subject: [PATCH] Add `LoweringContext::new`.

---
 compiler/rustc_ast_lowering/src/item.rs | 38 +----------------------
 compiler/rustc_ast_lowering/src/lib.rs  | 40 +++++++++++++++++++++++++
 2 files changed, 41 insertions(+), 37 deletions(-)

diff --git a/compiler/rustc_ast_lowering/src/item.rs b/compiler/rustc_ast_lowering/src/item.rs
index bdb2d58167f..2d395179a95 100644
--- a/compiler/rustc_ast_lowering/src/item.rs
+++ b/compiler/rustc_ast_lowering/src/item.rs
@@ -7,7 +7,6 @@ use hir::definitions::DefPathData;
 use rustc_ast::ptr::P;
 use rustc_ast::visit::AssocCtxt;
 use rustc_ast::*;
-use rustc_data_structures::sorted_map::SortedMap;
 use rustc_errors::ErrorGuaranteed;
 use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
@@ -55,42 +54,7 @@ impl<'a, 'hir> ItemLowerer<'a, 'hir> {
         owner: NodeId,
         f: impl FnOnce(&mut LoweringContext<'_, 'hir>) -> hir::OwnerNode<'hir>,
     ) {
-        let allow_gen_future = Some(if self.tcx.features().async_fn_track_caller {
-            [sym::gen_future, sym::closure_track_caller][..].into()
-        } else {
-            [sym::gen_future][..].into()
-        });
-        let mut lctx = LoweringContext {
-            // Pseudo-globals.
-            tcx: self.tcx,
-            resolver: self.resolver,
-            arena: self.tcx.hir_arena,
-
-            // HirId handling.
-            bodies: Vec::new(),
-            attrs: SortedMap::default(),
-            children: Vec::default(),
-            current_hir_id_owner: hir::CRATE_OWNER_ID,
-            item_local_id_counter: hir::ItemLocalId::new(0),
-            node_id_to_local_id: Default::default(),
-            trait_map: Default::default(),
-
-            // Lowering state.
-            catch_scope: None,
-            loop_scope: None,
-            is_in_loop_condition: false,
-            is_in_trait_impl: false,
-            is_in_dyn_type: false,
-            coroutine_kind: None,
-            task_context: None,
-            current_item: None,
-            impl_trait_defs: Vec::new(),
-            impl_trait_bounds: Vec::new(),
-            allow_try_trait: Some([sym::try_trait_v2, sym::yeet_desugar_details][..].into()),
-            allow_gen_future,
-            generics_def_id_map: Default::default(),
-            host_param_id: None,
-        };
+        let mut lctx = LoweringContext::new(self.tcx, self.resolver);
         lctx.with_hir_id_owner(owner, |lctx| f(lctx));
 
         for (def_id, info) in lctx.children {
diff --git a/compiler/rustc_ast_lowering/src/lib.rs b/compiler/rustc_ast_lowering/src/lib.rs
index 129cfa8a910..d3f832284ea 100644
--- a/compiler/rustc_ast_lowering/src/lib.rs
+++ b/compiler/rustc_ast_lowering/src/lib.rs
@@ -144,6 +144,46 @@ struct LoweringContext<'a, 'hir> {
     host_param_id: Option<LocalDefId>,
 }
 
+impl<'a, 'hir> LoweringContext<'a, 'hir> {
+    fn new(tcx: TyCtxt<'hir>, resolver: &'a mut ResolverAstLowering) -> Self {
+        Self {
+            // Pseudo-globals.
+            tcx,
+            resolver: resolver,
+            arena: tcx.hir_arena,
+
+            // HirId handling.
+            bodies: Vec::new(),
+            attrs: SortedMap::default(),
+            children: Vec::default(),
+            current_hir_id_owner: hir::CRATE_OWNER_ID,
+            item_local_id_counter: hir::ItemLocalId::new(0),
+            node_id_to_local_id: Default::default(),
+            trait_map: Default::default(),
+
+            // Lowering state.
+            catch_scope: None,
+            loop_scope: None,
+            is_in_loop_condition: false,
+            is_in_trait_impl: false,
+            is_in_dyn_type: false,
+            coroutine_kind: None,
+            task_context: None,
+            current_item: None,
+            impl_trait_defs: Vec::new(),
+            impl_trait_bounds: Vec::new(),
+            allow_try_trait: Some([sym::try_trait_v2, sym::yeet_desugar_details][..].into()),
+            allow_gen_future: Some(if tcx.features().async_fn_track_caller {
+                [sym::gen_future, sym::closure_track_caller][..].into()
+            } else {
+                [sym::gen_future][..].into()
+            }),
+            generics_def_id_map: Default::default(),
+            host_param_id: None,
+        }
+    }
+}
+
 trait ResolverAstLoweringExt {
     fn legacy_const_generic_args(&self, expr: &Expr) -> Option<Vec<usize>>;
     fn get_partial_res(&self, id: NodeId) -> Option<PartialRes>;