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rustc: Remove
used_mut_nodes from TyCtxt
This updates the borrowck query to return a result, and this result is then used to incrementally check for unused mutable nodes given sets of all the used mutable nodes. Closes #42384
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,31 @@ | ||
| // Copyright 2017 The Rust Project Developers. See the COPYRIGHT | ||
| // file at the top-level directory of this distribution and at | ||
| // http://rust-lang.org/COPYRIGHT. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
| // option. This file may not be copied, modified, or distributed | ||
| // except according to those terms. | ||
|
|
||
| use ich::StableHashingContext; | ||
| use hir::HirId; | ||
| use util::nodemap::FxHashSet; | ||
|
|
||
| use rustc_data_structures::stable_hasher::{HashStable, StableHasher, | ||
| StableHasherResult}; | ||
|
|
||
| pub struct BorrowCheckResult { | ||
| pub used_mut_nodes: FxHashSet<HirId>, | ||
| } | ||
|
|
||
| impl<'gcx> HashStable<StableHashingContext<'gcx>> for BorrowCheckResult { | ||
| fn hash_stable<W: StableHasherResult>(&self, | ||
| hcx: &mut StableHashingContext<'gcx>, | ||
| hasher: &mut StableHasher<W>) { | ||
| let BorrowCheckResult { | ||
| ref used_mut_nodes, | ||
| } = *self; | ||
| used_mut_nodes.hash_stable(hcx, hasher); | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,118 @@ | ||
| // Copyright 2017 The Rust Project Developers. See the COPYRIGHT | ||
| // file at the top-level directory of this distribution and at | ||
| // http://rust-lang.org/COPYRIGHT. | ||
| // | ||
| // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or | ||
| // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license | ||
| // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your | ||
| // option. This file may not be copied, modified, or distributed | ||
| // except according to those terms. | ||
|
|
||
| use rustc::hir::intravisit::{Visitor, NestedVisitorMap}; | ||
| use rustc::hir::{self, HirId}; | ||
| use rustc::lint::builtin::UNUSED_MUT; | ||
| use rustc::ty; | ||
| use rustc::util::nodemap::{FxHashMap, FxHashSet}; | ||
| use rustc_back::slice; | ||
| use syntax::ptr::P; | ||
|
|
||
| use borrowck::BorrowckCtxt; | ||
|
|
||
| pub fn check<'a, 'tcx>(bccx: &BorrowckCtxt<'a, 'tcx>, body: &'tcx hir::Body) { | ||
| let mut used_mut = bccx.used_mut_nodes.borrow().clone(); | ||
| UsedMutFinder { | ||
| bccx, | ||
| set: &mut used_mut, | ||
| }.visit_expr(&body.value); | ||
| let mut cx = UnusedMutCx { bccx, used_mut }; | ||
| for arg in body.arguments.iter() { | ||
| cx.check_unused_mut_pat(slice::ref_slice(&arg.pat)); | ||
| } | ||
| cx.visit_expr(&body.value); | ||
| } | ||
|
|
||
| struct UsedMutFinder<'a, 'tcx: 'a> { | ||
| bccx: &'a BorrowckCtxt<'a, 'tcx>, | ||
| set: &'a mut FxHashSet<HirId>, | ||
| } | ||
|
|
||
| struct UnusedMutCx<'a, 'tcx: 'a> { | ||
| bccx: &'a BorrowckCtxt<'a, 'tcx>, | ||
| used_mut: FxHashSet<HirId>, | ||
| } | ||
|
|
||
| impl<'a, 'tcx> UnusedMutCx<'a, 'tcx> { | ||
| fn check_unused_mut_pat(&self, pats: &[P<hir::Pat>]) { | ||
| let tcx = self.bccx.tcx; | ||
| let mut mutables = FxHashMap(); | ||
| for p in pats { | ||
| p.each_binding(|_, id, span, path1| { | ||
| let name = path1.node; | ||
|
|
||
| // Skip anything that looks like `_foo` | ||
| if name.as_str().starts_with("_") { | ||
| return | ||
| } | ||
|
|
||
| // Skip anything that looks like `&foo` or `&mut foo`, only look | ||
| // for by-value bindings | ||
| let hir_id = tcx.hir.node_to_hir_id(id); | ||
| let bm = match self.bccx.tables.pat_binding_modes().get(hir_id) { | ||
| Some(&bm) => bm, | ||
| None => span_bug!(span, "missing binding mode"), | ||
| }; | ||
| match bm { | ||
| ty::BindByValue(hir::MutMutable) => {} | ||
| _ => return, | ||
| } | ||
|
|
||
| mutables.entry(name).or_insert(Vec::new()).push((id, hir_id, span)); | ||
| }); | ||
| } | ||
|
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| for (_name, ids) in mutables { | ||
| // If any id for this name was used mutably then consider them all | ||
| // ok, so move on to the next | ||
| if ids.iter().any(|&(_, ref id, _)| self.used_mut.contains(id)) { | ||
| continue | ||
| } | ||
|
|
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| let mut_span = tcx.sess.codemap().span_until_char(ids[0].2, ' '); | ||
|
|
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| // Ok, every name wasn't used mutably, so issue a warning that this | ||
| // didn't need to be mutable. | ||
| tcx.struct_span_lint_node(UNUSED_MUT, | ||
| ids[0].0, | ||
| ids[0].2, | ||
| "variable does not need to be mutable") | ||
| .span_suggestion_short(mut_span, "remove this `mut`", "".to_owned()) | ||
| .emit(); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| impl<'a, 'tcx> Visitor<'tcx> for UnusedMutCx<'a, 'tcx> { | ||
| fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> { | ||
| NestedVisitorMap::OnlyBodies(&self.bccx.tcx.hir) | ||
| } | ||
|
|
||
| fn visit_arm(&mut self, arm: &hir::Arm) { | ||
| self.check_unused_mut_pat(&arm.pats) | ||
| } | ||
|
|
||
| fn visit_local(&mut self, local: &hir::Local) { | ||
| self.check_unused_mut_pat(slice::ref_slice(&local.pat)); | ||
| } | ||
| } | ||
|
|
||
| impl<'a, 'tcx> Visitor<'tcx> for UsedMutFinder<'a, 'tcx> { | ||
| fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> { | ||
| NestedVisitorMap::OnlyBodies(&self.bccx.tcx.hir) | ||
| } | ||
|
|
||
| fn visit_nested_body(&mut self, id: hir::BodyId) { | ||
| let def_id = self.bccx.tcx.hir.body_owner_def_id(id); | ||
| self.set.extend(self.bccx.tcx.borrowck(def_id).used_mut_nodes.iter().cloned()); | ||
| self.visit_body(self.bccx.tcx.hir.body(id)); | ||
| } | ||
| } |
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