Merge pull request #523 from sanxiyn/escape-arg

Extend escape analysis to arguments

1 files changed, 14 insertions, 1 deletions

diff --git a/src/escape.rs b/src/escape.rs
index 079fdcf09a0..8ef64aee84c 100644
--- a/src/escape.rs
+++ b/src/escape.rs
@@ -31,6 +31,13 @@ pub struct EscapePass;
 /// ```
 declare_lint!(pub BOXED_LOCAL, Warn, "using Box<T> where unnecessary");
 
+fn is_box(ty: ty::Ty) -> bool {
+    match ty.sty {
+        ty::TyBox(..) => true,
+        _ => false
+    }
+}
+
 struct EscapeDelegate<'a, 'tcx: 'a> {
     cx: &'a LateContext<'a, 'tcx>,
     set: NodeSet,
@@ -77,6 +84,12 @@ impl<'a, 'tcx: 'a> Delegate<'tcx> for EscapeDelegate<'a, 'tcx> {
     }
     fn matched_pat(&mut self, _: &Pat, _: cmt<'tcx>, _: MatchMode) {}
     fn consume_pat(&mut self, consume_pat: &Pat, cmt: cmt<'tcx>, _: ConsumeMode) {
+        if self.cx.tcx.map.is_argument(consume_pat.id) {
+            if is_box(cmt.ty) {
+                self.set.insert(consume_pat.id);
+            }
+            return;
+        }
         if let Categorization::Rvalue(..) = cmt.cat {
             if let Some(Node::NodeStmt(st)) = self.cx
                                                   .tcx
@@ -86,7 +99,7 @@ impl<'a, 'tcx: 'a> Delegate<'tcx> for EscapeDelegate<'a, 'tcx> {
                     if let DeclLocal(ref loc) = decl.node {
                         if let Some(ref ex) = loc.init {
                             if let ExprBox(..) = ex.node {
-                                if let ty::TyBox(..) = cmt.ty.sty {
+                                if is_box(cmt.ty) {
                                     // let x = box (...)
                                     self.set.insert(consume_pat.id);
                                 }