Auto merge of #42609 - brson:beta-next, r=alexcrichton

Beta next

- #42521
- #42512
- #42482
- #42481
- #42480

r? @nikomatsakis remember to untag 'beta-nominated' on linked issues

Author: bors

src/Cargo.lock

@@ -28,7 +28,7 @@ pub const CFG_RELEASE_NUM: &'static str = "1.19.0";
 // An optional number to put after the label, e.g. '.2' -> '-beta.2'
 // Be sure to make this starts with a dot to conform to semver pre-release
 // versions (section 9)
-pub const CFG_PRERELEASE_VERSION: &'static str = ".1";
+pub const CFG_PRERELEASE_VERSION: &'static str = ".2";
 
 pub struct GitInfo {
     inner: Option<Info>,

src/bootstrap/channel.rs

@@ -1200,6 +1200,13 @@ impl<'a, 'gcx, 'tcx> RegionVarBindings<'a, 'gcx, 'tcx> {
         for verify in self.verifys.borrow().iter() {
             debug!("collect_errors: verify={:?}", verify);
             let sub = normalize(self.tcx, var_data, verify.region);
+
+            // This was an inference variable which didn't get
+            // constrained, therefore it can be assume to hold.
+            if let ty::ReEmpty = *sub {
+                continue;
+            }
+
             if verify.bound.is_met(region_rels, var_data, sub) {
                 continue;
             }

src/librustc/infer/region_inference/mod.rs

@@ -446,9 +446,13 @@ impl<'a, 'gcx, 'tcx> ConfirmContext<'a, 'gcx, 'tcx> {
             // overloaded lvalue ops, and will be fixed by them in order to get
             // the correct region.
             let mut source = self.node_ty(expr.id);
-            if let Some(adjustments) = self.tables.borrow_mut().adjustments.get_mut(&expr.id) {
+            // Do not mutate adjustments in place, but rather take them,
+            // and replace them after mutating them, to avoid having the
+            // tables borrowed during (`deref_mut`) method resolution.
+            let previous_adjustments = self.tables.borrow_mut().adjustments.remove(&expr.id);
+            if let Some(mut adjustments) = previous_adjustments {
                 let pref = LvaluePreference::PreferMutLvalue;
-                for adjustment in adjustments {
+                for adjustment in &mut adjustments {
                     if let Adjust::Deref(Some(ref mut deref)) = adjustment.kind {
                         if let Some(ok) = self.try_overloaded_deref(expr.span, source, pref) {
                             let method = self.register_infer_ok_obligations(ok);
@@ -462,6 +466,7 @@ impl<'a, 'gcx, 'tcx> ConfirmContext<'a, 'gcx, 'tcx> {
                     }
                     source = adjustment.target;
                 }
+                self.tables.borrow_mut().adjustments.insert(expr.id, adjustments);
             }
 
             match expr.node {

src/librustc_typeck/check/method/confirm.rs

@@ -11,8 +11,9 @@
 use io;
 use libc::{self, c_int};
 use mem;
-use sys::{cvt, cvt_r};
+use sync::atomic::{AtomicBool, ATOMIC_BOOL_INIT, Ordering};
 use sys::fd::FileDesc;
+use sys::{cvt, cvt_r};
 
 ////////////////////////////////////////////////////////////////////////////////
 // Anonymous pipes
@@ -21,6 +22,9 @@ use sys::fd::FileDesc;
 pub struct AnonPipe(FileDesc);
 
 pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> {
+    weak! { fn pipe2(*mut c_int, c_int) -> c_int }
+    static INVALID: AtomicBool = ATOMIC_BOOL_INIT;
+
     let mut fds = [0; 2];
 
     // Unfortunately the only known way right now to create atomically set the
@@ -31,13 +35,26 @@ pub fn anon_pipe() -> io::Result<(AnonPipe, AnonPipe)> {
                 target_os = "freebsd",
                 target_os = "linux",
                 target_os = "netbsd",
-                target_os = "openbsd"))
+                target_os = "openbsd")) &&
+       !INVALID.load(Ordering::SeqCst)
     {
-        weak! { fn pipe2(*mut c_int, c_int) -> c_int }
+
         if let Some(pipe) = pipe2.get() {
-            cvt(unsafe { pipe(fds.as_mut_ptr(), libc::O_CLOEXEC) })?;
-            return Ok((AnonPipe(FileDesc::new(fds[0])),
-                       AnonPipe(FileDesc::new(fds[1]))));
+            // Note that despite calling a glibc function here we may still
+            // get ENOSYS. Glibc has `pipe2` since 2.9 and doesn't try to
+            // emulate on older kernels, so if you happen to be running on
+            // an older kernel you may see `pipe2` as a symbol but still not
+            // see the syscall.
+            match cvt(unsafe { pipe(fds.as_mut_ptr(), libc::O_CLOEXEC) }) {
+                Ok(_) => {
+                    return Ok((AnonPipe(FileDesc::new(fds[0])),
+                               AnonPipe(FileDesc::new(fds[1]))));
+                }
+                Err(ref e) if e.raw_os_error() == Some(libc::ENOSYS) => {
+                    INVALID.store(true, Ordering::SeqCst);
+                }
+                Err(e) => return Err(e),
+            }
         }
     }
     cvt(unsafe { libc::pipe(fds.as_mut_ptr()) })?;

src/libstd/sys/unix/pipe.rs

@@ -0,0 +1,41 @@
+// 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 std::ops::{Deref, DerefMut};
+
+struct CheckedDeref<T, F> {
+    value: T,
+    check: F
+}
+
+impl<F: Fn(&T) -> bool, T> Deref for CheckedDeref<T, F> {
+    type Target = T;
+    fn deref(&self) -> &T {
+        assert!((self.check)(&self.value));
+        &self.value
+    }
+}
+
+impl<F: Fn(&T) -> bool, T> DerefMut for CheckedDeref<T, F> {
+    fn deref_mut(&mut self) -> &mut T {
+        assert!((self.check)(&self.value));
+        &mut self.value
+    }
+}
+
+
+fn main() {
+    let mut v = CheckedDeref {
+        value: vec![0],
+        check: |v: &Vec<_>| !v.is_empty()
+    };
+    v.push(1);
+    assert_eq!(*v, vec![0, 1]);
+}

src/test/run-pass/issue-42463.rs

@@ -0,0 +1,32 @@
+// 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.
+
+struct Foo<T>(T);
+
+struct IntoIter<T>(T);
+
+impl<'a, T: 'a> Iterator for IntoIter<T> {
+    type Item = ();
+
+    fn next(&mut self) -> Option<()> {
+        None
+    }
+}
+
+impl<T> IntoIterator for Foo<T> {
+    type Item = ();
+    type IntoIter = IntoIter<T>;
+
+    fn into_iter(self) -> IntoIter<T> {
+        IntoIter(self.0)
+    }
+}
+
+fn main() {}