Fix boxed_local
suggestion
Don't warn about an argument that is moved into a closure. ExprUseVisitor doesn't walk into nested bodies so use a new visitor that collects the variables that are moved into closures. Fixes #3739
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@ -1,11 +1,12 @@
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use crate::utils::span_lint;
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use rustc::hir::intravisit as visit;
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use rustc::hir::intravisit::{walk_expr, NestedVisitorMap, Visitor};
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use rustc::hir::*;
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use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
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use rustc::middle::expr_use_visitor::*;
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use rustc::middle::mem_categorization::{cmt_, Categorization};
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use rustc::ty::layout::LayoutOf;
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use rustc::ty::{self, Ty};
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use rustc::ty::{self, Ty, UpvarCapture};
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use rustc::util::nodemap::NodeSet;
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use rustc::{declare_tool_lint, lint_array};
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use syntax::ast::NodeId;
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@ -88,11 +89,17 @@ impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Pass {
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let region_scope_tree = &cx.tcx.region_scope_tree(fn_def_id);
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ExprUseVisitor::new(&mut v, cx.tcx, cx.param_env, region_scope_tree, cx.tables, None).consume_body(body);
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for node in v.set {
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let mut capture_visitor = CaptureVisitor {
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cx,
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moved: NodeSet::default(),
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};
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capture_visitor.visit_body(body);
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for node in v.set.difference(&capture_visitor.moved) {
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span_lint(
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cx,
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BOXED_LOCAL,
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cx.tcx.hir().span(node),
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cx.tcx.hir().span(*node),
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"local variable doesn't need to be boxed here",
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);
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}
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@ -192,3 +199,32 @@ impl<'a, 'tcx> EscapeDelegate<'a, 'tcx> {
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}
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}
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}
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struct CaptureVisitor<'a, 'tcx: 'a> {
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cx: &'a LateContext<'a, 'tcx>,
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moved: NodeSet,
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}
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impl<'a, 'tcx> Visitor<'tcx> for CaptureVisitor<'a, 'tcx> {
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fn visit_expr(&mut self, expr: &'tcx Expr) {
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if let ExprKind::Closure(..) = expr.node {
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if let ty::Closure(def_id, _) = &self.cx.tables.expr_ty(expr).sty {
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if let Some(upvar_list) = &self.cx.tables.upvar_list.get(&def_id) {
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for upvar_id in upvar_list.iter() {
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if let UpvarCapture::ByValue = self.cx.tables.upvar_capture(*upvar_id) {
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let hir_id = upvar_id.var_path.hir_id;
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let id = &self.cx.tcx.hir().hir_to_node_id(hir_id);
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self.moved.insert(*id);
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}
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}
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}
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}
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} else {
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walk_expr(self, expr);
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}
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}
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fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
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NestedVisitorMap::None
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}
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}
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@ -148,3 +148,23 @@ trait MyTrait {
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impl<T> MyTrait for Box<T> {
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fn do_sth(self) {}
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}
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// Issue #3739 - capture in closures
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mod issue_3739 {
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use super::A;
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fn consume<T>(_: T) {}
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fn borrow<T>(_: &T) {}
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fn closure_consume(x: Box<A>) {
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let _ = move || {
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consume(x);
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};
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}
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fn closure_borrow(x: Box<A>) {
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let _ = || {
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borrow(&x);
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};
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}
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}
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@ -12,5 +12,11 @@ error: local variable doesn't need to be boxed here
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LL | pub fn new(_needs_name: Box<PeekableSeekable<&()>>) -> () {}
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| ^^^^^^^^^^^
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error: aborting due to 2 previous errors
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error: local variable doesn't need to be boxed here
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--> $DIR/escape_analysis.rs:165:23
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LL | fn closure_borrow(x: Box<A>) {
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| ^
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error: aborting due to 3 previous errors
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