From a9b929dbb6b8e86ccedf96a207a6253c0af1d6c9 Mon Sep 17 00:00:00 2001
From: Patrick Walton <pcwalton@mimiga.net>
Date: Thu, 11 Sep 2014 11:59:05 -0700
Subject: [PATCH] librustc: Make sure region bounds on closures outlive calls
to them.
This can break code like:
fn call_rec(f: |uint| -> uint) -> uint {
(|x| f(x))(call_rec(f))
}
Change this code to use a temporary instead of violating the borrow
rules:
fn call_rec(f: |uint| -> uint) -> uint {
let tmp = call_rec(|x| f(x)); f(tmp)
}
Closes #17144.
[breaking-change]
---
src/librustc/middle/typeck/check/regionck.rs | 4 ++++
.../region-bound-on-closure-outlives-call.rs | 16 ++++++++++++++++
2 files changed, 20 insertions(+)
create mode 100644 src/test/compile-fail/region-bound-on-closure-outlives-call.rs
diff --git a/src/librustc/middle/typeck/check/regionck.rs b/src/librustc/middle/typeck/check/regionck.rs
index c08401375ca..6ddb10cc8ca 100644
--- a/src/librustc/middle/typeck/check/regionck.rs
+++ b/src/librustc/middle/typeck/check/regionck.rs
@@ -1064,6 +1064,10 @@ fn constrain_callee(rcx: &mut Rcx,
};
rcx.fcx.mk_subr(infer::InvokeClosure(callee_expr.span),
call_region, region);
+
+ let region = closure_ty.bounds.region_bound;
+ rcx.fcx.mk_subr(infer::InvokeClosure(callee_expr.span),
+ call_region, region);
}
_ => {
// this should not happen, but it does if the program is
diff --git a/src/test/compile-fail/region-bound-on-closure-outlives-call.rs b/src/test/compile-fail/region-bound-on-closure-outlives-call.rs
new file mode 100644
index 00000000000..13ab7acaf48
--- /dev/null
+++ b/src/test/compile-fail/region-bound-on-closure-outlives-call.rs
@@ -0,0 +1,16 @@
+// Copyright 2014 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.
+
+fn call_rec(f: |uint| -> uint) -> uint {
+ (|x| f(x))(call_rec(f)) //~ ERROR cannot move out of `f`
+}
+
+fn main() {}
+