---

yaml
---
r: 194505
b: refs/heads/tmp
c: 3902190
h: refs/heads/master
i:
  194503: e5eda09
v: v3

Author: pnkfelix

[refs]

@@ -34,7 +34,7 @@ refs/heads/building: 126db549b038c84269a1e4fe46f051b2c15d6970
 refs/heads/beta: a3b13610c5b93d9ada072471a001a5613df6a960
 refs/heads/windistfix: 7608dbad651f02e837ed05eef3d74a6662a6e928
 refs/tags/1.0.0-alpha: e42bd6d93a1d3433c486200587f8f9e12590a4d7
-refs/heads/tmp: 242ed0b7c0f6a21096f2cc3e1ad1bdb176d02545
+refs/heads/tmp: 3902190ac4d64962b2c1ac9a6ae88777b7112f82
 refs/tags/1.0.0-alpha.2: 4c705f6bc559886632d3871b04f58aab093bfa2f
 refs/tags/homu-tmp: 123a754cb8356d0e78837dd4e58103ad801309ff
 refs/heads/gate: 97c84447b65164731087ea82685580cc81424412

branches/tmp/src/liballoc/arc.rs

@@ -354,7 +354,8 @@ impl<T> Drop for Arc<T> {
         // more than once (but it is guaranteed to be zeroed after the first if
         // it's run more than once)
         let ptr = *self._ptr;
-        if ptr.is_null() { return }
+        // if ptr.is_null() { return }
+        if ptr.is_null() || ptr as usize == mem::POST_DROP_USIZE { return }
 
         // Because `fetch_sub` is already atomic, we do not need to synchronize
         // with other threads unless we are going to delete the object. This
@@ -485,7 +486,7 @@ impl<T> Drop for Weak<T> {
         let ptr = *self._ptr;
 
         // see comments above for why this check is here
-        if ptr.is_null() { return }
+        if ptr.is_null() || ptr as usize == mem::POST_DROP_USIZE { return }
 
         // If we find out that we were the last weak pointer, then its time to
         // deallocate the data entirely. See the discussion in Arc::drop() about

branches/tmp/src/liballoc/rc.rs

@@ -160,7 +160,7 @@ use core::default::Default;
 use core::fmt;
 use core::hash::{Hasher, Hash};
 use core::marker;
-use core::mem::{min_align_of, size_of, forget};
+use core::mem::{self, min_align_of, size_of, forget};
 use core::nonzero::NonZero;
 use core::ops::{Deref, Drop};
 use core::option::Option;
@@ -407,7 +407,7 @@ impl<T> Drop for Rc<T> {
     fn drop(&mut self) {
         unsafe {
             let ptr = *self._ptr;
-            if !ptr.is_null() {
+            if !ptr.is_null() && ptr as usize != mem::POST_DROP_USIZE {
                 self.dec_strong();
                 if self.strong() == 0 {
                     ptr::read(&**self); // destroy the contained object
@@ -718,7 +718,7 @@ impl<T> Drop for Weak<T> {
     fn drop(&mut self) {
         unsafe {
             let ptr = *self._ptr;
-            if !ptr.is_null() {
+            if !ptr.is_null() && ptr as usize != mem::POST_DROP_USIZE {
                 self.dec_weak();
                 // the weak count starts at 1, and will only go to zero if all
                 // the strong pointers have disappeared.

branches/tmp/src/libcollections/btree/map.rs

@@ -1143,39 +1143,15 @@ impl<'a, K, V> DoubleEndedIterator for RangeMut<'a, K, V> {
 }
 
 impl<'a, K: Ord, V> Entry<'a, K, V> {
+    /// Returns a mutable reference to the entry if occupied, or the VacantEntry if vacant
     #[unstable(feature = "std_misc",
                reason = "will soon be replaced by or_insert")]
-    #[deprecated(since = "1.0",
-                reason = "replaced with more ergonomic `or_insert` and `or_insert_with`")]
-    /// Returns a mutable reference to the entry if occupied, or the VacantEntry if vacant
     pub fn get(self) -> Result<&'a mut V, VacantEntry<'a, K, V>> {
         match self {
             Occupied(entry) => Ok(entry.into_mut()),
             Vacant(entry) => Err(entry),
         }
     }
-
-    #[unstable(feature = "collections",
-               reason = "matches entry v3 specification, waiting for dust to settle")]
-    /// Ensures a value is in the entry by inserting the default if empty, and returns
-    /// a mutable reference to the value in the entry.
-    pub fn or_insert(self, default: V) -> &'a mut V {
-        match self {
-            Occupied(entry) => entry.into_mut(),
-            Vacant(entry) => entry.insert(default),
-        }
-    }
-
-    #[unstable(feature = "collections",
-               reason = "matches entry v3 specification, waiting for dust to settle")]
-    /// Ensures a value is in the entry by inserting the result of the default function if empty,
-    /// and returns a mutable reference to the value in the entry.
-    pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V {
-        match self {
-            Occupied(entry) => entry.into_mut(),
-            Vacant(entry) => entry.insert(default()),
-        }
-    }
 }
 
 impl<'a, K: Ord, V> VacantEntry<'a, K, V> {
@@ -1587,12 +1563,21 @@ impl<K: Ord, V> BTreeMap<K, V> {
     /// ```
     /// # #![feature(collections)]
     /// use std::collections::BTreeMap;
+    /// use std::collections::btree_map::Entry;
     ///
     /// let mut count: BTreeMap<&str, usize> = BTreeMap::new();
     ///
     /// // count the number of occurrences of letters in the vec
-    /// for x in vec!["a","b","a","c","a","b"] {
-    ///     *count.entry(x).or_insert(0) += 1;
+    /// for x in vec!["a","b","a","c","a","b"].iter() {
+    ///     match count.entry(*x) {
+    ///         Entry::Vacant(view) => {
+    ///             view.insert(1);
+    ///         },
+    ///         Entry::Occupied(mut view) => {
+    ///             let v = view.get_mut();
+    ///             *v += 1;
+    ///         },
+    ///     }
     /// }
     ///
     /// assert_eq!(count["a"], 3);

branches/tmp/src/libcollections/btree/node.rs

@@ -280,9 +280,11 @@ impl<T> Drop for RawItems<T> {
 #[unsafe_destructor]
 impl<K, V> Drop for Node<K, V> {
     fn drop(&mut self) {
-        if self.keys.is_null() {
+        if self.keys.is_null() ||
+            (unsafe { self.keys.get() as *const K as usize == mem::POST_DROP_USIZE })
+        {
             // Since we have #[unsafe_no_drop_flag], we have to watch
-            // out for a null value being stored in self.keys. (Using
+            // out for the sentinel value being stored in self.keys. (Using
             // null is technically a violation of the `Unique`
             // requirements, though.)
             return;

branches/tmp/src/libcollections/vec.rs

@@ -1694,7 +1694,7 @@ impl<T> Drop for Vec<T> {
     fn drop(&mut self) {
         // This is (and should always remain) a no-op if the fields are
         // zeroed (when moving out, because of #[unsafe_no_drop_flag]).
-        if self.cap != 0 {
+        if self.cap != 0 && self.cap != mem::POST_DROP_USIZE {
             unsafe {
                 for x in &*self {
                     ptr::read(x);
@@ -1977,7 +1977,7 @@ impl<'a, T> ExactSizeIterator for Drain<'a, T> {}
 #[stable(feature = "rust1", since = "1.0.0")]
 impl<'a, T> Drop for Drain<'a, T> {
     fn drop(&mut self) {
-        // self.ptr == self.end == null if drop has already been called,
+        // self.ptr == self.end == mem::POST_DROP_USIZE if drop has already been called,
         // so we can use #[unsafe_no_drop_flag].
 
         // destroy the remaining elements

branches/tmp/src/libcollections/vec_map.rs

@@ -632,12 +632,21 @@ impl<V> VecMap<V> {
     /// ```
     /// # #![feature(collections)]
     /// use std::collections::VecMap;
+    /// use std::collections::vec_map::Entry;
     ///
     /// let mut count: VecMap<u32> = VecMap::new();
     ///
     /// // count the number of occurrences of numbers in the vec
-    /// for x in vec![1, 2, 1, 2, 3, 4, 1, 2, 4] {
-    ///     *count.entry(x).or_insert(0) += 1;
+    /// for x in vec![1, 2, 1, 2, 3, 4, 1, 2, 4].iter() {
+    ///     match count.entry(*x) {
+    ///         Entry::Vacant(view) => {
+    ///             view.insert(1);
+    ///         },
+    ///         Entry::Occupied(mut view) => {
+    ///             let v = view.get_mut();
+    ///             *v += 1;
+    ///         },
+    ///     }
     /// }
     ///
     /// assert_eq!(count[1], 3);
@@ -666,37 +675,13 @@ impl<V> VecMap<V> {
 impl<'a, V> Entry<'a, V> {
     #[unstable(feature = "collections",
                reason = "will soon be replaced by or_insert")]
-    #[deprecated(since = "1.0",
-                reason = "replaced with more ergonomic `or_insert` and `or_insert_with`")]
     /// Returns a mutable reference to the entry if occupied, or the VacantEntry if vacant
     pub fn get(self) -> Result<&'a mut V, VacantEntry<'a, V>> {
         match self {
             Occupied(entry) => Ok(entry.into_mut()),
             Vacant(entry) => Err(entry),
         }
     }
-
-    #[unstable(feature = "collections",
-               reason = "matches entry v3 specification, waiting for dust to settle")]
-    /// Ensures a value is in the entry by inserting the default if empty, and returns
-    /// a mutable reference to the value in the entry.
-    pub fn or_insert(self, default: V) -> &'a mut V {
-        match self {
-            Occupied(entry) => entry.into_mut(),
-            Vacant(entry) => entry.insert(default),
-        }
-    }
-
-    #[unstable(feature = "collections",
-               reason = "matches entry v3 specification, waiting for dust to settle")]
-    /// Ensures a value is in the entry by inserting the result of the default function if empty,
-    /// and returns a mutable reference to the value in the entry.
-    pub fn or_insert_with<F: FnOnce() -> V>(self, default: F) -> &'a mut V {
-        match self {
-            Occupied(entry) => entry.into_mut(),
-            Vacant(entry) => entry.insert(default()),
-        }
-    }
 }
 
 impl<'a, V> VacantEntry<'a, V> {

branches/tmp/src/libcore/intrinsics.rs

@@ -191,13 +191,35 @@ extern "rust-intrinsic" {
     /// crate it is invoked in.
     pub fn type_id<T: ?Sized + 'static>() -> u64;
 
+    /// Create a value initialized to so that its drop flag,
+    /// if any, says that it has been dropped.
+    ///
+    /// `init_dropped` is unsafe because it returns a datum with all
+    /// of its bytes set to the drop flag, which generally does not
+    /// correspond to a valid value.
+    ///
+    /// This intrinsic is likely to be deprecated in the future when
+    /// Rust moves to non-zeroing dynamic drop (and thus removes the
+    /// embedded drop flags that are being established by this
+    /// intrinsic).
+    #[cfg(not(stage0))]
+    pub fn init_dropped<T>() -> T;
+
     /// Create a value initialized to zero.
     ///
     /// `init` is unsafe because it returns a zeroed-out datum,
-    /// which is unsafe unless T is Copy.
+    /// which is unsafe unless T is `Copy`.  Also, even if T is
+    /// `Copy`, an all-zero value may not correspond to any legitimate
+    /// state for the type in question.
     pub fn init<T>() -> T;
 
     /// Create an uninitialized value.
+    ///
+    /// `uninit` is unsafe because there is no guarantee of what its
+    /// contents are. In particular its drop-flag may be set to any
+    /// state, which means it may claim either dropped or
+    /// undropped. In the general case one must use `ptr::write` to
+    /// initialize memory previous set to the result of `uninit`.
     pub fn uninit<T>() -> T;
 
     /// Move a value out of scope without running drop glue.

branches/tmp/src/libcore/mem.rs

@@ -158,6 +158,29 @@ pub unsafe fn zeroed<T>() -> T {
     intrinsics::init()
 }
 
+/// Create a value initialized to an unspecified series of bytes.
+///
+/// The byte sequence usually indicates that the value at the memory
+/// in question has been dropped. Thus, *if* T carries a drop flag,
+/// any associated destructor will not be run when the value falls out
+/// of scope.
+///
+/// Some code at one time used the `zeroed` function above to
+/// accomplish this goal.
+///
+/// This function is expected to be deprecated with the transition
+/// to non-zeroing drop.
+#[inline]
+#[unstable(feature = "filling_drop")]
+pub unsafe fn dropped<T>() -> T {
+    let mut x: T = uninitialized();
+    let p: *mut u8 = transmute(&mut x as *mut T);
+    for i in 0..size_of::<T>() {
+        *p.offset(i as isize) = POST_DROP_U8;
+    }
+    x
+}
+
 /// Create an uninitialized value.
 ///
 /// Care must be taken when using this function, if the type `T` has a destructor and the value
@@ -291,6 +314,40 @@ pub fn replace<T>(dest: &mut T, mut src: T) -> T {
 #[stable(feature = "rust1", since = "1.0.0")]
 pub fn drop<T>(_x: T) { }
 
+macro_rules! repeat_u8_as_u32 {
+    ($name:expr) => { (($name as u32) << 24 |
+                       ($name as u32) << 16 |
+                       ($name as u32) <<  8 |
+                       ($name as u32)) }
+}
+macro_rules! repeat_u8_as_u64 {
+    ($name:expr) => { ((repeat_u8_as_u32!($name) as u64) << 32 |
+                       (repeat_u8_as_u32!($name) as u64)) }
+}
+
+// NOTE: Keep synchronized with values used in librustc_trans::trans::adt.
+//
+// In particular, the POST_DROP_U8 marker must never equal the
+// DTOR_NEEDED_U8 marker.
+//
+// For a while pnkfelix was using 0xc1 here.
+// But having the sign bit set is a pain, so 0x1d is probably better.
+//
+// And of course, 0x00 brings back the old world of zero'ing on drop.
+#[cfg(not(stage0))] pub const POST_DROP_U8: u8 = 0x0;
+#[cfg(not(stage0))] pub const POST_DROP_U32: u32 = repeat_u8_as_u32!(POST_DROP_U8);
+#[cfg(not(stage0))] pub const POST_DROP_U64: u64 = repeat_u8_as_u64!(POST_DROP_U8);
+
+#[cfg(target_pointer_width = "32")]
+#[cfg(not(stage0))] pub const POST_DROP_USIZE: usize = POST_DROP_U32 as usize;
+#[cfg(target_pointer_width = "64")]
+#[cfg(not(stage0))] pub const POST_DROP_USIZE: usize = POST_DROP_U64 as usize;
+
+#[cfg(stage0)] pub const POST_DROP_U8: u8 = 0;
+#[cfg(stage0)] pub const POST_DROP_U32: u32 = 0;
+#[cfg(stage0)] pub const POST_DROP_U64: u64 = 0;
+#[cfg(stage0)] pub const POST_DROP_USIZE: usize = 0;
+
 /// Interprets `src` as `&U`, and then reads `src` without moving the contained value.
 ///
 /// This function will unsafely assume the pointer `src` is valid for `sizeof(U)` bytes by

branches/tmp/src/libcore/ptr.rs

@@ -230,6 +230,21 @@ pub unsafe fn read_and_zero<T>(dest: *mut T) -> T {
     tmp
 }
 
+/// Variant of read_and_zero that writes the specific drop-flag byte
+/// (which may be more apropriate than zero).
+#[inline(always)]
+#[unstable(feature = "core",
+           reason = "may play a larger role in std::ptr future extensions")]
+pub unsafe fn read_and_drop<T>(dest: *mut T) -> T {
+    // Copy the data out from `dest`:
+    let tmp = read(&*dest);
+
+    // Now mark `dest` as dropped:
+    write_bytes(dest, mem::POST_DROP_U8, 1);
+
+    tmp
+}
+
 /// Overwrites a memory location with the given value without reading or
 /// dropping the old value.
 ///

branches/tmp/src/librustc/metadata/loader.rs

@@ -426,8 +426,8 @@ impl<'a> Context<'a> {
             info!("lib candidate: {}", path.display());
 
             let hash_str = hash.to_string();
-            let slot = candidates.entry(hash_str)
-                                 .or_insert_with(|| (HashMap::new(), HashMap::new()));
+            let slot = candidates.entry(hash_str).get().unwrap_or_else(
+                |vacant_entry| vacant_entry.insert((HashMap::new(), HashMap::new())));
             let (ref mut rlibs, ref mut dylibs) = *slot;
             if rlib {
                 rlibs.insert(fs::realpath(path).unwrap(), kind);

branches/tmp/src/librustc/middle/dataflow.rs

@@ -160,7 +160,12 @@ fn build_nodeid_to_index(decl: Option<&ast::FnDecl>,
 
     cfg.graph.each_node(|node_idx, node| {
         if let cfg::CFGNodeData::AST(id) = node.data {
-            index.entry(id).or_insert(vec![]).push(node_idx);
+            match index.entry(id).get() {
+                Ok(v) => v.push(node_idx),
+                Err(e) => {
+                    e.insert(vec![node_idx]);
+                }
+            }
         }
         true
     });
@@ -180,7 +185,12 @@ fn build_nodeid_to_index(decl: Option<&ast::FnDecl>,
         visit::walk_fn_decl(&mut formals, decl);
         impl<'a, 'v> visit::Visitor<'v> for Formals<'a> {
             fn visit_pat(&mut self, p: &ast::Pat) {
-                self.index.entry(p.id).or_insert(vec![]).push(self.entry);
+                match self.index.entry(p.id).get() {
+                    Ok(v) => v.push(self.entry),
+                    Err(e) => {
+                        e.insert(vec![self.entry]);
+                    }
+                }
                 visit::walk_pat(self, p)
             }
         }