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rustc: collect upvars from HIR, instead of during name resolution.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,104 @@ | ||
| //! Upvar (closure capture) collection from cross-body HIR uses of `Res::Local`s. | ||
| use crate::hir::{self, HirId}; | ||
| use crate::hir::def::Res; | ||
| use crate::hir::intravisit::{self, Visitor, NestedVisitorMap}; | ||
| use crate::ty::TyCtxt; | ||
| use crate::ty::query::Providers; | ||
| use syntax_pos::Span; | ||
| use rustc_data_structures::fx::{FxIndexMap, FxHashSet}; | ||
|
|
||
| pub fn provide(providers: &mut Providers<'_>) { | ||
| providers.upvars = |tcx, def_id| { | ||
| if !tcx.is_closure(def_id) { | ||
| return None; | ||
| } | ||
|
|
||
| let node_id = tcx.hir().as_local_node_id(def_id).unwrap(); | ||
| let body = tcx.hir().body(tcx.hir().maybe_body_owned_by(node_id)?); | ||
|
|
||
| let mut local_collector = LocalCollector::default(); | ||
| local_collector.visit_body(body); | ||
|
|
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| let mut capture_collector = CaptureCollector { | ||
| tcx, | ||
| locals: &local_collector.locals, | ||
| upvars: FxIndexMap::default(), | ||
| }; | ||
| capture_collector.visit_body(body); | ||
|
|
||
| if !capture_collector.upvars.is_empty() { | ||
| Some(tcx.arena.alloc(capture_collector.upvars)) | ||
| } else { | ||
| None | ||
| } | ||
| }; | ||
| } | ||
|
|
||
| #[derive(Default)] | ||
| struct LocalCollector { | ||
| // FIXME(eddyb) perhaps use `ItemLocalId` instead? | ||
| locals: FxHashSet<HirId>, | ||
| } | ||
|
|
||
| impl Visitor<'tcx> for LocalCollector { | ||
| fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> { | ||
| NestedVisitorMap::None | ||
| } | ||
|
|
||
| fn visit_pat(&mut self, pat: &'tcx hir::Pat) { | ||
| if let hir::PatKind::Binding(_, hir_id, ..) = pat.node { | ||
| self.locals.insert(hir_id); | ||
| } | ||
| intravisit::walk_pat(self, pat); | ||
| } | ||
| } | ||
|
|
||
| struct CaptureCollector<'a, 'tcx> { | ||
| tcx: TyCtxt<'a, 'tcx, 'tcx>, | ||
| locals: &'a FxHashSet<HirId>, | ||
| upvars: FxIndexMap<HirId, hir::Upvar>, | ||
| } | ||
|
|
||
| impl CaptureCollector<'_, '_> { | ||
| fn visit_local_use(&mut self, var_id: HirId, span: Span) { | ||
| if !self.locals.contains(&var_id) { | ||
| self.upvars.entry(var_id).or_insert(hir::Upvar { span }); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl Visitor<'tcx> for CaptureCollector<'a, 'tcx> { | ||
| fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> { | ||
| NestedVisitorMap::None | ||
| } | ||
|
|
||
| fn visit_path(&mut self, path: &'tcx hir::Path, _: hir::HirId) { | ||
| if let Res::Local(var_id) = path.res { | ||
| self.visit_local_use(var_id, path.span); | ||
| } | ||
|
|
||
| intravisit::walk_path(self, path); | ||
| } | ||
|
|
||
| fn visit_expr(&mut self, expr: &'tcx hir::Expr) { | ||
| if let hir::ExprKind::Closure(..) = expr.node { | ||
| let closure_def_id = self.tcx.hir().local_def_id_from_hir_id(expr.hir_id); | ||
| if let Some(upvars) = self.tcx.upvars(closure_def_id) { | ||
| // Every capture of a closure expression is a local in scope, | ||
| // that is moved/copied/borrowed into the closure value, and | ||
| // for this analysis they are like any other access to a local. | ||
| // | ||
| // E.g. in `|b| |c| (a, b, c)`, the upvars of the inner closure | ||
| // are `a` and `b`, and while `a` is not directly used in the | ||
| // outer closure, it needs to be an upvar there too, so that | ||
| // the inner closure can take it (from the outer closure's env). | ||
| for (&var_id, upvar) in upvars { | ||
| self.visit_local_use(var_id, upvar.span); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| intravisit::walk_expr(self, expr); | ||
| } | ||
| } |
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