From 1da5e60ac59661bca0d09b50839600fe0deeb0aa Mon Sep 17 00:00:00 2001 From: Mara Bos Date: Wed, 26 Mar 2025 14:48:14 +0100 Subject: [PATCH 1/4] Don't record child scopes for patterns. They are unused. --- compiler/rustc_hir_analysis/src/check/region.rs | 2 -- 1 file changed, 2 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/check/region.rs b/compiler/rustc_hir_analysis/src/check/region.rs index 255f5fee52a80..c81f75eb31982 100644 --- a/compiler/rustc_hir_analysis/src/check/region.rs +++ b/compiler/rustc_hir_analysis/src/check/region.rs @@ -221,8 +221,6 @@ fn resolve_arm<'tcx>(visitor: &mut ScopeResolutionVisitor<'tcx>, arm: &'tcx hir: } fn resolve_pat<'tcx>(visitor: &mut ScopeResolutionVisitor<'tcx>, pat: &'tcx hir::Pat<'tcx>) { - visitor.record_child_scope(Scope { local_id: pat.hir_id.local_id, data: ScopeData::Node }); - // If this is a binding then record the lifetime of that binding. if let PatKind::Binding(..) = pat.kind { record_var_lifetime(visitor, pat.hir_id.local_id); From 227f93395a2cc86f6f66d26a68fdbd7955a8ec51 Mon Sep 17 00:00:00 2001 From: Mara Bos Date: Wed, 26 Mar 2025 14:49:07 +0100 Subject: [PATCH 2/4] Simplify RvalueCandidateType. There is no difference between the Patternand Borrow cases. Reduce it to a simple struct. --- .../rustc_hir_analysis/src/check/region.rs | 10 ++---- .../rustc_hir_typeck/src/rvalue_scopes.rs | 12 +++---- compiler/rustc_middle/src/middle/region.rs | 31 ++++++++----------- 3 files changed, 19 insertions(+), 34 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/check/region.rs b/compiler/rustc_hir_analysis/src/check/region.rs index c81f75eb31982..a7007c5d831b3 100644 --- a/compiler/rustc_hir_analysis/src/check/region.rs +++ b/compiler/rustc_hir_analysis/src/check/region.rs @@ -623,10 +623,7 @@ fn resolve_local<'tcx>( if is_binding_pat(pat) { visitor.scope_tree.record_rvalue_candidate( expr.hir_id, - RvalueCandidateType::Pattern { - target: expr.hir_id.local_id, - lifetime: blk_scope, - }, + RvalueCandidate { target: expr.hir_id.local_id, lifetime: blk_scope }, ); } } @@ -731,10 +728,7 @@ fn resolve_local<'tcx>( record_rvalue_scope_if_borrow_expr(visitor, subexpr, blk_id); visitor.scope_tree.record_rvalue_candidate( subexpr.hir_id, - RvalueCandidateType::Borrow { - target: subexpr.hir_id.local_id, - lifetime: blk_id, - }, + RvalueCandidate { target: subexpr.hir_id.local_id, lifetime: blk_id }, ); } hir::ExprKind::Struct(_, fields, _) => { diff --git a/compiler/rustc_hir_typeck/src/rvalue_scopes.rs b/compiler/rustc_hir_typeck/src/rvalue_scopes.rs index 98d7f777d6b8a..973dc7141e64d 100644 --- a/compiler/rustc_hir_typeck/src/rvalue_scopes.rs +++ b/compiler/rustc_hir_typeck/src/rvalue_scopes.rs @@ -2,7 +2,7 @@ use hir::Node; use hir::def_id::DefId; use rustc_hir as hir; use rustc_middle::bug; -use rustc_middle::middle::region::{RvalueCandidateType, Scope, ScopeTree}; +use rustc_middle::middle::region::{RvalueCandidate, Scope, ScopeTree}; use rustc_middle::ty::RvalueScopes; use tracing::debug; @@ -55,15 +55,11 @@ fn record_rvalue_scope_rec( fn record_rvalue_scope( rvalue_scopes: &mut RvalueScopes, expr: &hir::Expr<'_>, - candidate: &RvalueCandidateType, + candidate: &RvalueCandidate, ) { debug!("resolve_rvalue_scope(expr={expr:?}, candidate={candidate:?})"); - match candidate { - RvalueCandidateType::Borrow { lifetime, .. } - | RvalueCandidateType::Pattern { lifetime, .. } => { - record_rvalue_scope_rec(rvalue_scopes, expr, *lifetime) - } // FIXME(@dingxiangfei2009): handle the candidates in the function call arguments - } + record_rvalue_scope_rec(rvalue_scopes, expr, candidate.lifetime) + // FIXME(@dingxiangfei2009): handle the candidates in the function call arguments } pub(crate) fn resolve_rvalue_scopes<'a, 'tcx>( diff --git a/compiler/rustc_middle/src/middle/region.rs b/compiler/rustc_middle/src/middle/region.rs index 66861519e17c8..66ece8f0e52fd 100644 --- a/compiler/rustc_middle/src/middle/region.rs +++ b/compiler/rustc_middle/src/middle/region.rs @@ -224,7 +224,7 @@ pub struct ScopeTree { /// and not the enclosing *statement*. Expressions that are not present in this /// table are not rvalue candidates. The set of rvalue candidates is computed /// during type check based on a traversal of the AST. - pub rvalue_candidates: HirIdMap, + pub rvalue_candidates: HirIdMap, /// Backwards incompatible scoping that will be introduced in future editions. /// This information is used later for linting to identify locals and @@ -308,15 +308,14 @@ pub struct ScopeTree { pub yield_in_scope: UnordMap>, } -/// Identifies the reason that a given expression is an rvalue candidate -/// (see the `rvalue_candidates` field for more information what rvalue -/// candidates in general). In constants, the `lifetime` field is None -/// to indicate that certain expressions escape into 'static and -/// should have no local cleanup scope. +/// See the `rvalue_candidates` field for more information on rvalue +/// candidates in general. +/// The `lifetime` field is None to indicate that certain expressions escape +/// into 'static and should have no local cleanup scope. #[derive(Debug, Copy, Clone, HashStable)] -pub enum RvalueCandidateType { - Borrow { target: hir::ItemLocalId, lifetime: Option }, - Pattern { target: hir::ItemLocalId, lifetime: Option }, +pub struct RvalueCandidate { + pub target: hir::ItemLocalId, + pub lifetime: Option, } #[derive(Debug, Copy, Clone, HashStable)] @@ -344,16 +343,12 @@ impl ScopeTree { self.var_map.insert(var, lifetime); } - pub fn record_rvalue_candidate(&mut self, var: HirId, candidate_type: RvalueCandidateType) { - debug!("record_rvalue_candidate(var={var:?}, type={candidate_type:?})"); - match &candidate_type { - RvalueCandidateType::Borrow { lifetime: Some(lifetime), .. } - | RvalueCandidateType::Pattern { lifetime: Some(lifetime), .. } => { - assert!(var.local_id != lifetime.local_id) - } - _ => {} + pub fn record_rvalue_candidate(&mut self, var: HirId, candidate: RvalueCandidate) { + debug!("record_rvalue_candidate(var={var:?}, candidate={candidate:?})"); + if let Some(lifetime) = &candidate.lifetime { + assert!(var.local_id != lifetime.local_id) } - self.rvalue_candidates.insert(var, candidate_type); + self.rvalue_candidates.insert(var, candidate); } /// Returns the narrowest scope that encloses `id`, if any. From 0ad0142a5be5c6aab4d0b5a897a7d11c78fbea12 Mon Sep 17 00:00:00 2001 From: Mara Bos Date: Wed, 26 Mar 2025 16:07:14 +0100 Subject: [PATCH 3/4] Don't set cx.parent to None; it seems unnecessary. --- compiler/rustc_hir_analysis/src/check/region.rs | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/check/region.rs b/compiler/rustc_hir_analysis/src/check/region.rs index a7007c5d831b3..4e4b975573659 100644 --- a/compiler/rustc_hir_analysis/src/check/region.rs +++ b/compiler/rustc_hir_analysis/src/check/region.rs @@ -849,13 +849,12 @@ impl<'tcx> Visitor<'tcx> for ScopeResolutionVisitor<'tcx> { self.enter_body(body.value.hir_id, |this| { if this.tcx.hir_body_owner_kind(owner_id).is_fn_or_closure() { // The arguments and `self` are parented to the fn. - this.cx.var_parent = this.cx.parent.take(); + this.cx.var_parent = this.cx.parent; for param in body.params { this.visit_pat(param.pat); } // The body of the every fn is a root scope. - this.cx.parent = this.cx.var_parent; this.visit_expr(body.value) } else { // Only functions have an outer terminating (drop) scope, while From 2cc3fa32ef0ac964c3c99b14d0cbc422a10788bb Mon Sep 17 00:00:00 2001 From: Mara Bos Date: Wed, 26 Mar 2025 17:13:49 +0100 Subject: [PATCH 4/4] Remove ScopeDepth from var_parent. It was never used. --- .../rustc_hir_analysis/src/check/region.rs | 26 ++++++++++++------- 1 file changed, 16 insertions(+), 10 deletions(-) diff --git a/compiler/rustc_hir_analysis/src/check/region.rs b/compiler/rustc_hir_analysis/src/check/region.rs index 4e4b975573659..ba8124b11fc13 100644 --- a/compiler/rustc_hir_analysis/src/check/region.rs +++ b/compiler/rustc_hir_analysis/src/check/region.rs @@ -25,12 +25,18 @@ use tracing::debug; struct Context { /// The scope that contains any new variables declared, plus its depth in /// the scope tree. - var_parent: Option<(Scope, ScopeDepth)>, + var_parent: Option, /// Region parent of expressions, etc., plus its depth in the scope tree. parent: Option<(Scope, ScopeDepth)>, } +impl Context { + fn set_var_parent(&mut self) { + self.var_parent = self.parent.map(|(p, _)| p); + } +} + struct ScopeResolutionVisitor<'tcx> { tcx: TyCtxt<'tcx>, @@ -78,7 +84,7 @@ fn record_var_lifetime(visitor: &mut ScopeResolutionVisitor<'_>, var_id: hir::It // // extern fn isalnum(c: c_int) -> c_int } - Some((parent_scope, _)) => visitor.scope_tree.record_var_scope(var_id, parent_scope), + Some(parent_scope) => visitor.scope_tree.record_var_scope(var_id, parent_scope), } } @@ -113,7 +119,7 @@ fn resolve_block<'tcx>(visitor: &mut ScopeResolutionVisitor<'tcx>, blk: &'tcx hi // itself has returned. visitor.enter_node_scope_with_dtor(blk.hir_id.local_id); - visitor.cx.var_parent = visitor.cx.parent; + visitor.cx.set_var_parent(); { // This block should be kept approximately in sync with @@ -132,7 +138,7 @@ fn resolve_block<'tcx>(visitor: &mut ScopeResolutionVisitor<'tcx>, blk: &'tcx hi local_id: blk.hir_id.local_id, data: ScopeData::Remainder(FirstStatementIndex::new(i)), }); - visitor.cx.var_parent = visitor.cx.parent; + visitor.cx.set_var_parent(); visitor.visit_stmt(statement); // We need to back out temporarily to the last enclosing scope // for the `else` block, so that even the temporaries receiving @@ -157,7 +163,7 @@ fn resolve_block<'tcx>(visitor: &mut ScopeResolutionVisitor<'tcx>, blk: &'tcx hi local_id: blk.hir_id.local_id, data: ScopeData::Remainder(FirstStatementIndex::new(i)), }); - visitor.cx.var_parent = visitor.cx.parent; + visitor.cx.set_var_parent(); visitor.visit_stmt(statement) } hir::StmtKind::Item(..) => { @@ -207,7 +213,7 @@ fn resolve_arm<'tcx>(visitor: &mut ScopeResolutionVisitor<'tcx>, arm: &'tcx hir: visitor.terminating_scopes.insert(arm.hir_id.local_id); visitor.enter_node_scope_with_dtor(arm.hir_id.local_id); - visitor.cx.var_parent = visitor.cx.parent; + visitor.cx.set_var_parent(); if let Some(expr) = arm.guard && !has_let_expr(expr) @@ -484,7 +490,7 @@ fn resolve_expr<'tcx>(visitor: &mut ScopeResolutionVisitor<'tcx>, expr: &'tcx hi ScopeData::IfThen }; visitor.enter_scope(Scope { local_id: then.hir_id.local_id, data }); - visitor.cx.var_parent = visitor.cx.parent; + visitor.cx.set_var_parent(); visitor.visit_expr(cond); visitor.visit_expr(then); visitor.cx = expr_cx; @@ -499,7 +505,7 @@ fn resolve_expr<'tcx>(visitor: &mut ScopeResolutionVisitor<'tcx>, expr: &'tcx hi ScopeData::IfThen }; visitor.enter_scope(Scope { local_id: then.hir_id.local_id, data }); - visitor.cx.var_parent = visitor.cx.parent; + visitor.cx.set_var_parent(); visitor.visit_expr(cond); visitor.visit_expr(then); visitor.cx = expr_cx; @@ -558,7 +564,7 @@ fn resolve_local<'tcx>( ) { debug!("resolve_local(pat={:?}, init={:?})", pat, init); - let blk_scope = visitor.cx.var_parent.map(|(p, _)| p); + let blk_scope = visitor.cx.var_parent; // As an exception to the normal rules governing temporary // lifetimes, initializers in a let have a temporary lifetime @@ -849,7 +855,7 @@ impl<'tcx> Visitor<'tcx> for ScopeResolutionVisitor<'tcx> { self.enter_body(body.value.hir_id, |this| { if this.tcx.hir_body_owner_kind(owner_id).is_fn_or_closure() { // The arguments and `self` are parented to the fn. - this.cx.var_parent = this.cx.parent; + this.cx.set_var_parent(); for param in body.params { this.visit_pat(param.pat); }