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-rw-r--r--src/liballoc/arc.rs27
-rw-r--r--src/liballoc/rc.rs32
-rw-r--r--src/libcollections/vec.rs61
-rw-r--r--src/libcore/lib.rs1
-rw-r--r--src/libcore/nonzero.rs53
-rw-r--r--src/libcore/ptr.rs3
-rw-r--r--src/libcoretest/lib.rs1
-rw-r--r--src/libcoretest/nonzero.rs100
-rw-r--r--src/librustc/middle/lang_items.rs2
-rw-r--r--src/librustc_trans/trans/adt.rs199
-rw-r--r--src/librustc_trans/trans/common.rs1
-rw-r--r--src/librustc_trans/trans/debuginfo.rs14
-rw-r--r--src/test/run-pass/enum-null-pointer-opt.rs31
13 files changed, 370 insertions, 155 deletions
diff --git a/src/liballoc/arc.rs b/src/liballoc/arc.rs
index 8d8bbb42932..3e235caab18 100644
--- a/src/liballoc/arc.rs
+++ b/src/liballoc/arc.rs
@@ -76,11 +76,11 @@ use core::default::Default;
 use core::kinds::{Sync, Send};
 use core::mem::{min_align_of, size_of, drop};
 use core::mem;
+use core::nonzero::NonZero;
 use core::ops::{Drop, Deref};
 use core::option::Option;
 use core::option::Option::{Some, None};
-use core::ptr::RawPtr;
-use core::ptr;
+use core::ptr::{mod, RawPtr};
 use heap::deallocate;
 
 /// An atomically reference counted wrapper for shared state.
@@ -114,7 +114,7 @@ use heap::deallocate;
 pub struct Arc<T> {
     // FIXME #12808: strange name to try to avoid interfering with
     // field accesses of the contained type via Deref
-    _ptr: *mut ArcInner<T>,
+    _ptr: NonZero<*mut ArcInner<T>>,
 }
 
 unsafe impl<T: Sync + Send> Send for Arc<T> { }
@@ -130,7 +130,7 @@ unsafe impl<T: Sync + Send> Sync for Arc<T> { }
 pub struct Weak<T> {
     // FIXME #12808: strange name to try to avoid interfering with
     // field accesses of the contained type via Deref
-    _ptr: *mut ArcInner<T>,
+    _ptr: NonZero<*mut ArcInner<T>>,
 }
 
 unsafe impl<T: Sync + Send> Send for Weak<T> { }
@@ -165,7 +165,7 @@ impl<T> Arc<T> {
             weak: atomic::AtomicUint::new(1),
             data: data,
         };
-        Arc { _ptr: unsafe { mem::transmute(x) } }
+        Arc { _ptr: unsafe { NonZero::new(mem::transmute(x)) } }
     }
 
     /// Downgrades the `Arc<T>` to a `Weak<T>` reference.
@@ -194,7 +194,7 @@ impl<T> Arc<T> {
         // pointer is valid. Furthermore, we know that the `ArcInner` structure itself is `Sync`
         // because the inner data is `Sync` as well, so we're ok loaning out an immutable pointer
         // to these contents.
-        unsafe { &*self._ptr }
+        unsafe { &**self._ptr }
     }
 }
 
@@ -281,7 +281,7 @@ impl<T: Send + Sync + Clone> Arc<T> {
         // pointer that will ever be returned to T. Our reference count is guaranteed to be 1 at
         // this point, and we required the Arc itself to be `mut`, so we're returning the only
         // possible reference to the inner data.
-        let inner = unsafe { &mut *self._ptr };
+        let inner = unsafe { &mut **self._ptr };
         &mut inner.data
     }
 }
@@ -316,7 +316,8 @@ impl<T: Sync + Send> Drop for Arc<T> {
     fn drop(&mut self) {
         // This structure has #[unsafe_no_drop_flag], so this drop glue may run more than once (but
         // it is guaranteed to be zeroed after the first if it's run more than once)
-        if self._ptr.is_null() { return }
+        let ptr = *self._ptr;
+        if ptr.is_null() { 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 same logic applies to the below
@@ -346,7 +347,7 @@ impl<T: Sync + Send> Drop for Arc<T> {
 
         if self.inner().weak.fetch_sub(1, atomic::Release) == 1 {
             atomic::fence(atomic::Acquire);
-            unsafe { deallocate(self._ptr as *mut u8, size_of::<ArcInner<T>>(),
+            unsafe { deallocate(ptr as *mut u8, size_of::<ArcInner<T>>(),
                                 min_align_of::<ArcInner<T>>()) }
         }
     }
@@ -386,7 +387,7 @@ impl<T: Sync + Send> Weak<T> {
     #[inline]
     fn inner(&self) -> &ArcInner<T> {
         // See comments above for why this is "safe"
-        unsafe { &*self._ptr }
+        unsafe { &**self._ptr }
     }
 }
 
@@ -442,14 +443,16 @@ impl<T: Sync + Send> Drop for Weak<T> {
     /// } // implicit drop
     /// ```
     fn drop(&mut self) {
+        let ptr = *self._ptr;
+
         // see comments above for why this check is here
-        if self._ptr.is_null() { return }
+        if ptr.is_null() { 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 the memory orderings
         if self.inner().weak.fetch_sub(1, atomic::Release) == 1 {
             atomic::fence(atomic::Acquire);
-            unsafe { deallocate(self._ptr as *mut u8, size_of::<ArcInner<T>>(),
+            unsafe { deallocate(ptr as *mut u8, size_of::<ArcInner<T>>(),
                                 min_align_of::<ArcInner<T>>()) }
         }
     }
diff --git a/src/liballoc/rc.rs b/src/liballoc/rc.rs
index dfa55848c90..13dc4474c1a 100644
--- a/src/liballoc/rc.rs
+++ b/src/liballoc/rc.rs
@@ -150,11 +150,11 @@ use core::fmt;
 use core::hash::{mod, Hash};
 use core::kinds::marker;
 use core::mem::{transmute, min_align_of, size_of, forget};
+use core::nonzero::NonZero;
 use core::ops::{Deref, Drop};
 use core::option::Option;
 use core::option::Option::{Some, None};
-use core::ptr;
-use core::ptr::RawPtr;
+use core::ptr::{mod, RawPtr};
 use core::result::Result;
 use core::result::Result::{Ok, Err};
 
@@ -174,7 +174,7 @@ struct RcBox<T> {
 pub struct Rc<T> {
     // FIXME #12808: strange names to try to avoid interfering with field accesses of the contained
     // type via Deref
-    _ptr: *mut RcBox<T>,
+    _ptr: NonZero<*mut RcBox<T>>,
     _nosend: marker::NoSend,
     _noshare: marker::NoSync
 }
@@ -196,11 +196,11 @@ impl<T> Rc<T> {
                 // there is an implicit weak pointer owned by all the strong pointers, which
                 // ensures that the weak destructor never frees the allocation while the strong
                 // destructor is running, even if the weak pointer is stored inside the strong one.
-                _ptr: transmute(box RcBox {
+                _ptr: NonZero::new(transmute(box RcBox {
                     value: value,
                     strong: Cell::new(1),
                     weak: Cell::new(1)
-                }),
+                })),
                 _nosend: marker::NoSend,
                 _noshare: marker::NoSync
             }
@@ -281,7 +281,7 @@ pub fn try_unwrap<T>(rc: Rc<T>) -> Result<T, Rc<T>> {
             let val = ptr::read(&*rc); // copy the contained object
             // destruct the box and skip our Drop
             // we can ignore the refcounts because we know we're unique
-            deallocate(rc._ptr as *mut u8, size_of::<RcBox<T>>(),
+            deallocate(*rc._ptr as *mut u8, size_of::<RcBox<T>>(),
                         min_align_of::<RcBox<T>>());
             forget(rc);
             Ok(val)
@@ -311,7 +311,7 @@ pub fn try_unwrap<T>(rc: Rc<T>) -> Result<T, Rc<T>> {
 #[experimental]
 pub fn get_mut<'a, T>(rc: &'a mut Rc<T>) -> Option<&'a mut T> {
     if is_unique(rc) {
-        let inner = unsafe { &mut *rc._ptr };
+        let inner = unsafe { &mut **rc._ptr };
         Some(&mut inner.value)
     } else {
         None
@@ -343,7 +343,7 @@ impl<T: Clone> Rc<T> {
         // pointer that will ever be returned to T. Our reference count is guaranteed to be 1 at
         // this point, and we required the `Rc<T>` itself to be `mut`, so we're returning the only
         // possible reference to the inner value.
-        let inner = unsafe { &mut *self._ptr };
+        let inner = unsafe { &mut **self._ptr };
         &mut inner.value
     }
 }
@@ -391,7 +391,8 @@ impl<T> Drop for Rc<T> {
     /// ```
     fn drop(&mut self) {
         unsafe {
-            if !self._ptr.is_null() {
+            let ptr = *self._ptr;
+            if !ptr.is_null() {
                 self.dec_strong();
                 if self.strong() == 0 {
                     ptr::read(&**self); // destroy the contained object
@@ -401,7 +402,7 @@ impl<T> Drop for Rc<T> {
                     self.dec_weak();
 
                     if self.weak() == 0 {
-                        deallocate(self._ptr as *mut u8, size_of::<RcBox<T>>(),
+                        deallocate(ptr as *mut u8, size_of::<RcBox<T>>(),
                                    min_align_of::<RcBox<T>>())
                     }
                 }
@@ -618,7 +619,7 @@ impl<T: fmt::Show> fmt::Show for Rc<T> {
 pub struct Weak<T> {
     // FIXME #12808: strange names to try to avoid interfering with
     // field accesses of the contained type via Deref
-    _ptr: *mut RcBox<T>,
+    _ptr: NonZero<*mut RcBox<T>>,
     _nosend: marker::NoSend,
     _noshare: marker::NoSync
 }
@@ -682,12 +683,13 @@ impl<T> Drop for Weak<T> {
     /// ```
     fn drop(&mut self) {
         unsafe {
-            if !self._ptr.is_null() {
+            let ptr = *self._ptr;
+            if !ptr.is_null() {
                 self.dec_weak();
                 // the weak count starts at 1, and will only go to zero if all the strong pointers
                 // have disappeared.
                 if self.weak() == 0 {
-                    deallocate(self._ptr as *mut u8, size_of::<RcBox<T>>(),
+                    deallocate(ptr as *mut u8, size_of::<RcBox<T>>(),
                                min_align_of::<RcBox<T>>())
                 }
             }
@@ -742,12 +744,12 @@ trait RcBoxPtr<T> {
 
 impl<T> RcBoxPtr<T> for Rc<T> {
     #[inline(always)]
-    fn inner(&self) -> &RcBox<T> { unsafe { &(*self._ptr) } }
+    fn inner(&self) -> &RcBox<T> { unsafe { &(**self._ptr) } }
 }
 
 impl<T> RcBoxPtr<T> for Weak<T> {
     #[inline(always)]
-    fn inner(&self) -> &RcBox<T> { unsafe { &(*self._ptr) } }
+    fn inner(&self) -> &RcBox<T> { unsafe { &(**self._ptr) } }
 }
 
 #[cfg(test)]
diff --git a/src/libcollections/vec.rs b/src/libcollections/vec.rs
index d700b187e8a..bf69980b49c 100644
--- a/src/libcollections/vec.rs
+++ b/src/libcollections/vec.rs
@@ -56,9 +56,10 @@ use core::hash::{mod, Hash};
 use core::iter::repeat;
 use core::kinds::marker::{ContravariantLifetime, InvariantType};
 use core::mem;
+use core::nonzero::NonZero;
 use core::num::{Int, UnsignedInt};
 use core::ops;
-use core::ptr::{mod, Unique};
+use core::ptr;
 use core::raw::Slice as RawSlice;
 use core::uint;
 
@@ -133,11 +134,14 @@ use slice::CloneSliceExt;
 #[unsafe_no_drop_flag]
 #[stable]
 pub struct Vec<T> {
-    ptr: Unique<T>,
+    ptr: NonZero<*mut T>,
     len: uint,
     cap: uint,
 }
 
+unsafe impl<T: Send> Send for Vec<T> { }
+unsafe impl<T: Sync> Sync for Vec<T> { }
+
 /// A clone-on-write vector
 pub type CowVec<'a, T> = Cow<'a, Vec<T>, [T]>;
 
@@ -176,7 +180,7 @@ impl<T> Vec<T> {
         // non-null value which is fine since we never call deallocate on the ptr
         // if cap is 0. The reason for this is because the pointer of a slice
         // being NULL would break the null pointer optimization for enums.
-        Vec { ptr: Unique(EMPTY as *mut T), len: 0, cap: 0 }
+        Vec { ptr: unsafe { NonZero::new(EMPTY as *mut T) }, len: 0, cap: 0 }
     }
 
     /// Constructs a new, empty `Vec<T>` with the specified capacity.
@@ -209,7 +213,7 @@ impl<T> Vec<T> {
     #[stable]
     pub fn with_capacity(capacity: uint) -> Vec<T> {
         if mem::size_of::<T>() == 0 {
-            Vec { ptr: Unique(EMPTY as *mut T), len: 0, cap: uint::MAX }
+            Vec { ptr: unsafe { NonZero::new(EMPTY as *mut T) }, len: 0, cap: uint::MAX }
         } else if capacity == 0 {
             Vec::new()
         } else {
@@ -217,7 +221,7 @@ impl<T> Vec<T> {
                                .expect("capacity overflow");
             let ptr = unsafe { allocate(size, mem::min_align_of::<T>()) };
             if ptr.is_null() { ::alloc::oom() }
-            Vec { ptr: Unique(ptr as *mut T), len: 0, cap: capacity }
+            Vec { ptr: unsafe { NonZero::new(ptr as *mut T) }, len: 0, cap: capacity }
         }
     }
 
@@ -284,7 +288,7 @@ impl<T> Vec<T> {
     #[unstable = "needs finalization"]
     pub unsafe fn from_raw_parts(ptr: *mut T, length: uint,
                                  capacity: uint) -> Vec<T> {
-        Vec { ptr: Unique(ptr), len: length, cap: capacity }
+        Vec { ptr: NonZero::new(ptr), len: length, cap: capacity }
     }
 
     /// Creates a vector by copying the elements from a raw pointer.
@@ -795,7 +799,7 @@ impl<T> Vec<T> {
         if self.len == 0 {
             if self.cap != 0 {
                 unsafe {
-                    dealloc(self.ptr.0, self.cap)
+                    dealloc(*self.ptr, self.cap)
                 }
                 self.cap = 0;
             }
@@ -803,11 +807,12 @@ impl<T> Vec<T> {
             unsafe {
                 // Overflow check is unnecessary as the vector is already at
                 // least this large.
-                self.ptr = Unique(reallocate(self.ptr.0 as *mut u8,
-                                               self.cap * mem::size_of::<T>(),
-                                               self.len * mem::size_of::<T>(),
-                                               mem::min_align_of::<T>()) as *mut T);
-                if self.ptr.0.is_null() { ::alloc::oom() }
+                let ptr = reallocate(*self.ptr as *mut u8,
+                                     self.cap * mem::size_of::<T>(),
+                                     self.len * mem::size_of::<T>(),
+                                     mem::min_align_of::<T>()) as *mut T;
+                if ptr.is_null() { ::alloc::oom() }
+                self.ptr = NonZero::new(ptr);
             }
             self.cap = self.len;
         }
@@ -867,7 +872,7 @@ impl<T> Vec<T> {
     pub fn as_mut_slice<'a>(&'a mut self) -> &'a mut [T] {
         unsafe {
             mem::transmute(RawSlice {
-                data: self.ptr.0 as *const T,
+                data: *self.ptr as *const T,
                 len: self.len,
             })
         }
@@ -890,9 +895,9 @@ impl<T> Vec<T> {
     #[unstable = "matches collection reform specification, waiting for dust to settle"]
     pub fn into_iter(self) -> IntoIter<T> {
         unsafe {
-            let ptr = self.ptr.0;
+            let ptr = *self.ptr;
             let cap = self.cap;
-            let begin = self.ptr.0 as *const T;
+            let begin = ptr as *const T;
             let end = if mem::size_of::<T>() == 0 {
                 (ptr as uint + self.len()) as *const T
             } else {
@@ -1110,14 +1115,15 @@ impl<T> Vec<T> {
             let size = max(old_size, 2 * mem::size_of::<T>()) * 2;
             if old_size > size { panic!("capacity overflow") }
             unsafe {
-                self.ptr = Unique(alloc_or_realloc(self.ptr.0, old_size, size));
-                if self.ptr.0.is_null() { ::alloc::oom() }
+                let ptr = alloc_or_realloc(*self.ptr, old_size, size);
+                if ptr.is_null() { ::alloc::oom() }
+                self.ptr = NonZero::new(ptr);
             }
             self.cap = max(self.cap, 2) * 2;
         }
 
         unsafe {
-            let end = self.ptr.0.offset(self.len as int);
+            let end = (*self.ptr).offset(self.len as int);
             ptr::write(&mut *end, value);
             self.len += 1;
         }
@@ -1162,11 +1168,11 @@ impl<T> Vec<T> {
     #[unstable = "matches collection reform specification, waiting for dust to settle"]
     pub fn drain<'a>(&'a mut self) -> Drain<'a, T> {
         unsafe {
-            let begin = self.ptr.0 as *const T;
+            let begin = *self.ptr as *const T;
             let end = if mem::size_of::<T>() == 0 {
-                (self.ptr.0 as uint + self.len()) as *const T
+                (*self.ptr as uint + self.len()) as *const T
             } else {
-                self.ptr.0.offset(self.len() as int) as *const T
+                (*self.ptr).offset(self.len() as int) as *const T
             };
             self.set_len(0);
             Drain {
@@ -1231,10 +1237,9 @@ impl<T> Vec<T> {
             let size = capacity.checked_mul(mem::size_of::<T>())
                                .expect("capacity overflow");
             unsafe {
-                self.ptr = Unique(alloc_or_realloc(self.ptr.0,
-                                                     self.cap * mem::size_of::<T>(),
-                                                     size));
-                if self.ptr.0.is_null() { ::alloc::oom() }
+                let ptr = alloc_or_realloc(*self.ptr, self.cap * mem::size_of::<T>(), size);
+                if ptr.is_null() { ::alloc::oom() }
+                self.ptr = NonZero::new(ptr);
             }
             self.cap = capacity;
         }
@@ -1357,7 +1362,7 @@ impl<T> AsSlice<T> for Vec<T> {
     fn as_slice<'a>(&'a self) -> &'a [T] {
         unsafe {
             mem::transmute(RawSlice {
-                data: self.ptr.0 as *const T,
+                data: *self.ptr as *const T,
                 len: self.len
             })
         }
@@ -1382,7 +1387,7 @@ impl<T> Drop for Vec<T> {
                 for x in self.iter() {
                     ptr::read(x);
                 }
-                dealloc(self.ptr.0, self.cap)
+                dealloc(*self.ptr, self.cap)
             }
         }
     }
@@ -1420,7 +1425,7 @@ impl<T> IntoIter<T> {
             for _x in self { }
             let IntoIter { allocation, cap, ptr: _ptr, end: _end } = self;
             mem::forget(self);
-            Vec { ptr: Unique(allocation), cap: cap, len: 0 }
+            Vec { ptr: NonZero::new(allocation), cap: cap, len: 0 }
         }
     }
 
diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs
index 6d0d6e0817a..d646245510d 100644
--- a/src/libcore/lib.rs
+++ b/src/libcore/lib.rs
@@ -93,6 +93,7 @@ pub mod prelude;
 
 pub mod intrinsics;
 pub mod mem;
+pub mod nonzero;
 pub mod ptr;
 
 /* Core language traits */
diff --git a/src/libcore/nonzero.rs b/src/libcore/nonzero.rs
new file mode 100644
index 00000000000..c429e4b8212
--- /dev/null
+++ b/src/libcore/nonzero.rs
@@ -0,0 +1,53 @@
+// Copyright 2012-2014 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.
+
+//! Exposes the NonZero lang item which provides optimization hints.
+
+use ops::Deref;
+
+/// Unsafe trait to indicate what types are usable with the NonZero struct
+pub unsafe trait Zeroable {}
+
+unsafe impl<T> Zeroable for *const T {}
+unsafe impl<T> Zeroable for *mut T {}
+unsafe impl Zeroable for int {}
+unsafe impl Zeroable for uint {}
+unsafe impl Zeroable for i8 {}
+unsafe impl Zeroable for u8 {}
+unsafe impl Zeroable for i16 {}
+unsafe impl Zeroable for u16 {}
+unsafe impl Zeroable for i32 {}
+unsafe impl Zeroable for u32 {}
+unsafe impl Zeroable for i64 {}
+unsafe impl Zeroable for u64 {}
+
+/// A wrapper type for raw pointers and integers that will never be
+/// NULL or 0 that might allow certain optimizations.
+#[lang="non_zero"]
+#[deriving(Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Show)]
+#[experimental]
+pub struct NonZero<T: Zeroable>(T);
+
+impl<T: Zeroable> NonZero<T> {
+    /// Create an instance of NonZero with the provided value.
+    /// You must indeed ensure that the value is actually "non-zero".
+    #[inline(always)]
+    pub unsafe fn new(inner: T) -> NonZero<T> {
+        NonZero(inner)
+    }
+}
+
+impl<T: Zeroable> Deref<T> for NonZero<T> {
+    #[inline]
+    fn deref<'a>(&'a self) -> &'a T {
+        let NonZero(ref inner) = *self;
+        inner
+    }
+}
diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs
index 8c9d77a0e9c..8c724b4d852 100644
--- a/src/libcore/ptr.rs
+++ b/src/libcore/ptr.rs
@@ -90,9 +90,9 @@
 use mem;
 use clone::Clone;
 use intrinsics;
+use kinds::{Send, Sync};
 use option::Option;
 use option::Option::{Some, None};
-use kinds::{Send, Sync};
 
 use cmp::{PartialEq, Eq, Ord, PartialOrd, Equiv};
 use cmp::Ordering;
@@ -109,6 +109,7 @@ pub use intrinsics::copy_memory;
 #[experimental = "uncertain about naming and semantics"]
 pub use intrinsics::set_memory;
 
+
 /// Creates a null raw pointer.
 ///
 /// # Examples
diff --git a/src/libcoretest/lib.rs b/src/libcoretest/lib.rs
index 44029ebb7fa..e6608eee3dd 100644
--- a/src/libcoretest/lib.rs
+++ b/src/libcoretest/lib.rs
@@ -25,6 +25,7 @@ mod fmt;
 mod hash;
 mod iter;
 mod mem;
+mod nonzero;
 mod num;
 mod ops;
 mod option;
diff --git a/src/libcoretest/nonzero.rs b/src/libcoretest/nonzero.rs
new file mode 100644
index 00000000000..ed66be3d890
--- /dev/null
+++ b/src/libcoretest/nonzero.rs
@@ -0,0 +1,100 @@
+// Copyright 2012-2014 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.
+
+use core::nonzero::NonZero;
+use core::option::Option;
+use core::option::Option::{Some, None};
+use std::mem::size_of;
+
+#[test]
+fn test_create_nonzero_instance() {
+    let _a = unsafe {
+        NonZero::new(21i)
+    };
+}
+
+#[test]
+fn test_size_nonzero_in_option() {
+    assert_eq!(size_of::<NonZero<u32>>(), size_of::<Option<NonZero<u32>>>());
+}
+
+#[test]
+fn test_match_on_nonzero_option() {
+    let a = Some(unsafe {
+        NonZero::new(42i)
+    });
+    match a {
+        Some(val) => assert_eq!(*val, 42),
+        None => panic!("unexpected None while matching on Some(NonZero(_))")
+    }
+
+    match unsafe { Some(NonZero::new(43i)) } {
+        Some(val) => assert_eq!(*val, 43),
+        None => panic!("unexpected None while matching on Some(NonZero(_))")
+    }
+}
+
+#[test]
+fn test_match_option_empty_vec() {
+    let a: Option<Vec<int>> = Some(vec![]);
+    match a {
+        None => panic!("unexpected None while matching on Some(vec![])"),
+        _ => {}
+    }
+}
+
+#[test]
+fn test_match_option_vec() {
+    let a = Some(vec![1i, 2, 3, 4]);
+    match a {
+        Some(v) => assert_eq!(v, vec![1i, 2, 3, 4]),
+        None => panic!("unexpected None while matching on Some(vec![1, 2, 3, 4])")
+    }
+}
+
+#[test]
+fn test_match_option_rc() {
+    use std::rc::Rc;
+
+    let five = Rc::new(5i);
+    match Some(five) {
+        Some(r) => assert_eq!(*r, 5i),
+        None => panic!("unexpected None while matching on Some(Rc::new(5))")
+    }
+}
+
+#[test]
+fn test_match_option_arc() {
+    use std::sync::Arc;
+
+    let five = Arc::new(5i);
+    match Some(five) {
+        Some(a) => assert_eq!(*a, 5i),
+        None => panic!("unexpected None while matching on Some(Arc::new(5))")
+    }
+}
+
+#[test]
+fn test_match_option_empty_string() {
+    let a = Some(String::new());
+    match a {
+        None => panic!("unexpected None while matching on Some(String::new())"),
+        _ => {}
+    }
+}
+
+#[test]
+fn test_match_option_string() {
+    let five = "Five".into_string();
+    match Some(five) {
+        Some(s) => assert_eq!(s, "Five"),
+        None => panic!("unexpected None while matching on Some(String { ... })")
+    }
+}
diff --git a/src/librustc/middle/lang_items.rs b/src/librustc/middle/lang_items.rs
index ca3087f08c4..90e3e2bb34a 100644
--- a/src/librustc/middle/lang_items.rs
+++ b/src/librustc/middle/lang_items.rs
@@ -327,6 +327,8 @@ lets_do_this! {
     NoSyncItem,                      "no_sync_bound",           no_sync_bound;
     ManagedItem,                     "managed_bound",           managed_bound;
 
+    NonZeroItem,                     "non_zero",                non_zero;
+
     IteratorItem,                    "iterator",                iterator;
 
     StackExhaustedLangItem,          "stack_exhausted",         stack_exhausted;
diff --git a/src/librustc_trans/trans/adt.rs b/src/librustc_trans/trans/adt.rs
index 0d2876bdf81..cd788945d3b 100644
--- a/src/librustc_trans/trans/adt.rs
+++ b/src/librustc_trans/trans/adt.rs
@@ -43,14 +43,13 @@
 
 #![allow(unsigned_negation)]
 
-pub use self::PointerField::*;
 pub use self::Repr::*;
 
 use std::num::Int;
 use std::rc::Rc;
 
 use llvm::{ValueRef, True, IntEQ, IntNE};
-use back::abi;
+use back::abi::FAT_PTR_ADDR;
 use middle::subst;
 use middle::subst::Subst;
 use trans::_match;
@@ -71,7 +70,6 @@ use util::ppaux::ty_to_string;
 
 type Hint = attr::ReprAttr;
 
-
 /// Representations.
 #[deriving(Eq, PartialEq, Show)]
 pub enum Repr<'tcx> {
@@ -101,7 +99,7 @@ pub enum Repr<'tcx> {
         nullfields: Vec<Ty<'tcx>>
     },
     /// Two cases distinguished by a nullable pointer: the case with discriminant
-    /// `nndiscr` is represented by the struct `nonnull`, where the `ptrfield`th
+    /// `nndiscr` is represented by the struct `nonnull`, where the `discrfield`th
     /// field is known to be nonnull due to its type; if that field is null, then
     /// it represents the other case, which is inhabited by at most one value
     /// (and all other fields are undefined/unused).
@@ -112,7 +110,7 @@ pub enum Repr<'tcx> {
     StructWrappedNullablePointer {
         nonnull: Struct<'tcx>,
         nndiscr: Disr,
-        ptrfield: PointerField,
+        discrfield: DiscrField,
         nullfields: Vec<Ty<'tcx>>,
     }
 }
@@ -230,22 +228,24 @@ fn represent_type_uncached<'a, 'tcx>(cx: &CrateContext<'a, 'tcx>,
                         let st = mk_struct(cx, cases[discr].tys[],
                                            false, t);
                         match cases[discr].find_ptr(cx) {
-                            Some(ThinPointer(_)) if st.fields.len() == 1 => {
+                            Some(ref df) if df.len() == 1 && st.fields.len() == 1 => {
                                 return RawNullablePointer {
                                     nndiscr: discr as Disr,
                                     nnty: st.fields[0],
                                     nullfields: cases[1 - discr].tys.clone()
                                 };
                             }
-                            Some(ptrfield) => {
+                            Some(mut discrfield) => {
+                                discrfield.push(0);
+                                discrfield.reverse();
                                 return StructWrappedNullablePointer {
                                     nndiscr: discr as Disr,
                                     nonnull: st,
-                                    ptrfield: ptrfield,
+                                    discrfield: discrfield,
                                     nullfields: cases[1 - discr].tys.clone()
                                 };
                             }
-                            None => { }
+                            None => {}
                         }
                     }
                     discr += 1;
@@ -335,49 +335,98 @@ struct Case<'tcx> {
     tys: Vec<Ty<'tcx>>
 }
 
+/// This represents the (GEP) indices to follow to get to the discriminant field
+pub type DiscrField = Vec<uint>;
+
+fn find_discr_field_candidate<'tcx>(tcx: &ty::ctxt<'tcx>,
+                                    ty: Ty<'tcx>,
+                                    mut path: DiscrField) -> Option<DiscrField> {
+    match ty.sty {
+        // Fat &T/&mut T/Box<T> i.e. T is [T], str, or Trait
+        ty::ty_rptr(_, ty::mt { ty, .. }) | ty::ty_uniq(ty) if !ty::type_is_sized(tcx, ty) => {
+            path.push(FAT_PTR_ADDR);
+            Some(path)
+        },
 
-#[deriving(Copy, Eq, PartialEq, Show)]
-pub enum PointerField {
-    ThinPointer(uint),
-    FatPointer(uint)
-}
+        // Regular thin pointer: &T/&mut T/Box<T>
+        ty::ty_rptr(..) | ty::ty_uniq(..) => Some(path),
 
-impl<'tcx> Case<'tcx> {
-    fn is_zerolen<'a>(&self, cx: &CrateContext<'a, 'tcx>, scapegoat: Ty<'tcx>)
-                      -> bool {
-        mk_struct(cx, self.tys[], false, scapegoat).size == 0
-    }
+        // Functions are just pointers
+        ty::ty_bare_fn(..) => Some(path),
 
-    fn find_ptr<'a>(&self, cx: &CrateContext<'a, 'tcx>) -> Option<PointerField> {
-        for (i, &ty) in self.tys.iter().enumerate() {
-            match ty.sty {
-                // &T/&mut T/Box<T> could either be a thin or fat pointer depending on T
-                ty::ty_rptr(_, ty::mt { ty, .. }) | ty::ty_uniq(ty) => match ty.sty {
-                    // &[T] and &str are a pointer and length pair
-                    ty::ty_vec(_, None) | ty::ty_str => return Some(FatPointer(i)),
+        // Closures are a pair of pointers: the code and environment
+        ty::ty_closure(..) => {
+            path.push(FAT_PTR_ADDR);
+            Some(path)
+        },
 
-                    // &Trait is a pair of pointers: the actual object and a vtable
-                    ty::ty_trait(..) => return Some(FatPointer(i)),
+        // Is this the NonZero lang item wrapping a pointer or integer type?
+        ty::ty_struct(did, ref substs) if Some(did) == tcx.lang_items.non_zero() => {
+            let nonzero_fields = ty::lookup_struct_fields(tcx, did);
+            assert_eq!(nonzero_fields.len(), 1);
+            let nonzero_field = ty::lookup_field_type(tcx, did, nonzero_fields[0].id, substs);
+            match nonzero_field.sty {
+                ty::ty_ptr(..) | ty::ty_int(..) | ty::ty_uint(..) => {
+                    path.push(0);
+                    Some(path)
+                },
+                _ => None
+            }
+        },
 
-                    ty::ty_struct(..) if !ty::type_is_sized(cx.tcx(), ty) => {
-                        return Some(FatPointer(i))
-                    }
+        // Perhaps one of the fields of this struct is non-zero
+        // let's recurse and find out
+        ty::ty_struct(def_id, ref substs) => {
+            let fields = ty::lookup_struct_fields(tcx, def_id);
+            for (j, field) in fields.iter().enumerate() {
+                let field_ty = ty::lookup_field_type(tcx, def_id, field.id, substs);
+                if let Some(mut fpath) = find_discr_field_candidate(tcx, field_ty, path.clone()) {
+                    fpath.push(j);
+                    return Some(fpath);
+                }
+            }
+            None
+        },
 
-                    // Any other &T is just a pointer
-                    _ => return Some(ThinPointer(i))
-                },
+        // Can we use one of the fields in this tuple?
+        ty::ty_tup(ref tys) => {
+            for (j, &ty) in tys.iter().enumerate() {
+                if let Some(mut fpath) = find_discr_field_candidate(tcx, ty, path.clone()) {
+                    fpath.push(j);
+                    return Some(fpath);
+                }
+            }
+            None
+        },
 
-                // Functions are just pointers
-                ty::ty_bare_fn(..) => return Some(ThinPointer(i)),
+        // Is this a fixed-size array of something non-zero
+        // with at least one element?
+        ty::ty_vec(ety, Some(d)) if d > 0 => {
+            if let Some(mut vpath) = find_discr_field_candidate(tcx, ety, path) {
+                vpath.push(0);
+                Some(vpath)
+            } else {
+                None
+            }
+        },
 
-                // Closures are a pair of pointers: the code and environment
-                ty::ty_closure(..) => return Some(FatPointer(i)),
+        // Anything else is not a pointer
+        _ => None
+    }
+}
+
+impl<'tcx> Case<'tcx> {
+    fn is_zerolen<'a>(&self, cx: &CrateContext<'a, 'tcx>, scapegoat: Ty<'tcx>) -> bool {
+        mk_struct(cx, self.tys[], false, scapegoat).size == 0
+    }
 
-                // Anything else is not a pointer
-                _ => continue
+    fn find_ptr<'a>(&self, cx: &CrateContext<'a, 'tcx>) -> Option<DiscrField> {
+        for (i, &ty) in self.tys.iter().enumerate() {
+            if let Some(mut path) = find_discr_field_candidate(cx.tcx(), ty, vec![]) {
+                path.push(i);
+                return Some(path);
             }
         }
-
         None
     }
 }
@@ -709,8 +758,8 @@ pub fn trans_get_discr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, r: &Repr<'tcx>,
             val = ICmp(bcx, cmp, Load(bcx, scrutinee), C_null(llptrty));
             signed = false;
         }
-        StructWrappedNullablePointer { nndiscr, ptrfield, .. } => {
-            val = struct_wrapped_nullable_bitdiscr(bcx, nndiscr, ptrfield, scrutinee);
+        StructWrappedNullablePointer { nndiscr, ref discrfield, .. } => {
+            val = struct_wrapped_nullable_bitdiscr(bcx, nndiscr, discrfield, scrutinee);
             signed = false;
         }
     }
@@ -720,12 +769,9 @@ pub fn trans_get_discr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, r: &Repr<'tcx>,
     }
 }
 
-fn struct_wrapped_nullable_bitdiscr(bcx: Block, nndiscr: Disr, ptrfield: PointerField,
+fn struct_wrapped_nullable_bitdiscr(bcx: Block, nndiscr: Disr, discrfield: &DiscrField,
                                     scrutinee: ValueRef) -> ValueRef {
-    let llptrptr = match ptrfield {
-        ThinPointer(field) => GEPi(bcx, scrutinee, &[0, field]),
-        FatPointer(field) => GEPi(bcx, scrutinee, &[0, field, abi::FAT_PTR_ADDR])
-    };
+    let llptrptr = GEPi(bcx, scrutinee, discrfield[]);
     let llptr = Load(bcx, llptrptr);
     let cmp = if nndiscr == 0 { IntEQ } else { IntNE };
     ICmp(bcx, cmp, llptr, C_null(val_ty(llptr)))
@@ -811,17 +857,10 @@ pub fn trans_set_discr<'blk, 'tcx>(bcx: Block<'blk, 'tcx>, r: &Repr<'tcx>,
                 Store(bcx, C_null(llptrty), val)
             }
         }
-        StructWrappedNullablePointer { ref nonnull, nndiscr, ptrfield, .. } => {
+        StructWrappedNullablePointer { nndiscr, ref discrfield, .. } => {
             if discr != nndiscr {
-                let (llptrptr, llptrty) = match ptrfield {
-                    ThinPointer(field) =>
-                        (GEPi(bcx, val, &[0, field]),
-                         type_of::type_of(bcx.ccx(), nonnull.fields[field])),
-                    FatPointer(field) => {
-                        let v = GEPi(bcx, val, &[0, field, abi::FAT_PTR_ADDR]);
-                        (v, val_ty(v).element_type())
-                    }
-                };
+                let llptrptr = GEPi(bcx, val, discrfield[]);
+                let llptrty = val_ty(llptrptr).element_type();
                 Store(bcx, C_null(llptrty), llptrptr)
             }
         }
@@ -1041,7 +1080,7 @@ pub fn trans_const<'a, 'tcx>(ccx: &CrateContext<'a, 'tcx>, r: &Repr<'tcx>, discr
                          false)
             } else {
                 let vals = nonnull.fields.iter().map(|&ty| {
-                    // Always use null even if it's not the `ptrfield`th
+                    // Always use null even if it's not the `discrfield`th
                     // field; see #8506.
                     C_null(type_of::sizing_type_of(ccx, ty))
                 }).collect::<Vec<ValueRef>>();
@@ -1121,9 +1160,8 @@ fn padding(ccx: &CrateContext, size: u64) -> ValueRef {
 #[inline]
 fn roundup(x: u64, a: u32) -> u64 { let a = a as u64; ((x + (a - 1)) / a) * a }
 
-/// Get the discriminant of a constant value.  (Not currently used.)
-pub fn const_get_discrim(ccx: &CrateContext, r: &Repr, val: ValueRef)
-    -> Disr {
+/// Get the discriminant of a constant value.
+pub fn const_get_discrim(ccx: &CrateContext, r: &Repr, val: ValueRef) -> Disr {
     match *r {
         CEnum(ity, _, _) => {
             match ity {
@@ -1138,25 +1176,8 @@ pub fn const_get_discrim(ccx: &CrateContext, r: &Repr, val: ValueRef)
             }
         }
         Univariant(..) => 0,
-        RawNullablePointer { nndiscr, .. } => {
-            if is_null(val) {
-                /* subtraction as uint is ok because nndiscr is either 0 or 1 */
-                (1 - nndiscr) as Disr
-            } else {
-                nndiscr
-            }
-        }
-        StructWrappedNullablePointer { nndiscr, ptrfield, .. } => {
-            let (idx, sub_idx) = match ptrfield {
-                ThinPointer(field) => (field, None),
-                FatPointer(field) => (field, Some(abi::FAT_PTR_ADDR))
-            };
-            if is_null(const_struct_field(ccx, val, idx, sub_idx)) {
-                /* subtraction as uint is ok because nndiscr is either 0 or 1 */
-                (1 - nndiscr) as Disr
-            } else {
-                nndiscr
-            }
+        RawNullablePointer { .. } | StructWrappedNullablePointer { .. } => {
+            ccx.sess().bug("const discrim access of non c-like enum")
         }
     }
 }
@@ -1170,29 +1191,25 @@ pub fn const_get_field(ccx: &CrateContext, r: &Repr, val: ValueRef,
                        _discr: Disr, ix: uint) -> ValueRef {
     match *r {
         CEnum(..) => ccx.sess().bug("element access in C-like enum const"),
-        Univariant(..) => const_struct_field(ccx, val, ix, None),
-        General(..) => const_struct_field(ccx, val, ix + 1, None),
+        Univariant(..) => const_struct_field(ccx, val, ix),
+        General(..) => const_struct_field(ccx, val, ix + 1),
         RawNullablePointer { .. } => {
             assert_eq!(ix, 0);
             val
-        }
-        StructWrappedNullablePointer{ .. } => const_struct_field(ccx, val, ix, None)
+        },
+        StructWrappedNullablePointer{ .. } => const_struct_field(ccx, val, ix)
     }
 }
 
 /// Extract field of struct-like const, skipping our alignment padding.
-fn const_struct_field(ccx: &CrateContext, val: ValueRef, ix: uint, sub_idx: Option<uint>)
-    -> ValueRef {
+fn const_struct_field(ccx: &CrateContext, val: ValueRef, ix: uint) -> ValueRef {
     // Get the ix-th non-undef element of the struct.
     let mut real_ix = 0; // actual position in the struct
     let mut ix = ix; // logical index relative to real_ix
     let mut field;
     loop {
         loop {
-            field = match sub_idx {
-                Some(si) => const_get_elt(ccx, val, &[real_ix, si as u32]),
-                None => const_get_elt(ccx, val, &[real_ix])
-            };
+            field = const_get_elt(ccx, val, &[real_ix]);
             if !is_undef(field) {
                 break;
             }
diff --git a/src/librustc_trans/trans/common.rs b/src/librustc_trans/trans/common.rs
index ea2a4ef6b28..d080cda4b81 100644
--- a/src/librustc_trans/trans/common.rs
+++ b/src/librustc_trans/trans/common.rs
@@ -750,6 +750,7 @@ pub fn is_undef(val: ValueRef) -> bool {
     }
 }
 
+#[allow(dead_code)] // potentially useful
 pub fn is_null(val: ValueRef) -> bool {
     unsafe {
         llvm::LLVMIsNull(val) != False
diff --git a/src/librustc_trans/trans/debuginfo.rs b/src/librustc_trans/trans/debuginfo.rs
index 640e83469b2..b8c4a23b87a 100644
--- a/src/librustc_trans/trans/debuginfo.rs
+++ b/src/librustc_trans/trans/debuginfo.rs
@@ -2292,14 +2292,14 @@ impl<'tcx> EnumMemberDescriptionFactory<'tcx> {
             },
             adt::StructWrappedNullablePointer { nonnull: ref struct_def,
                                                 nndiscr,
-                                                ptrfield, ..} => {
+                                                ref discrfield, ..} => {
                 // Create a description of the non-null variant
                 let (variant_type_metadata, variant_llvm_type, member_description_factory) =
                     describe_enum_variant(cx,
                                           self.enum_type,
                                           struct_def,
                                           &*(*self.variants)[nndiscr as uint],
-                                          OptimizedDiscriminant(ptrfield),
+                                          OptimizedDiscriminant,
                                           self.containing_scope,
                                           self.span);
 
@@ -2315,10 +2315,10 @@ impl<'tcx> EnumMemberDescriptionFactory<'tcx> {
                 // member's name.
                 let null_variant_index = (1 - nndiscr) as uint;
                 let null_variant_name = token::get_name((*self.variants)[null_variant_index].name);
-                let discrfield = match ptrfield {
-                    adt::ThinPointer(field) => format!("{}", field),
-                    adt::FatPointer(field) => format!("{}", field)
-                };
+                let discrfield = discrfield.iter()
+                                           .skip(1)
+                                           .map(|x| x.to_string())
+                                           .collect::<Vec<_>>().connect("$");
                 let union_member_name = format!("RUST$ENCODED$ENUM${}${}",
                                                 discrfield,
                                                 null_variant_name);
@@ -2367,7 +2367,7 @@ impl<'tcx> VariantMemberDescriptionFactory<'tcx> {
 #[deriving(Copy)]
 enum EnumDiscriminantInfo {
     RegularDiscriminant(DIType),
-    OptimizedDiscriminant(adt::PointerField),
+    OptimizedDiscriminant,
     NoDiscriminant
 }
 
diff --git a/src/test/run-pass/enum-null-pointer-opt.rs b/src/test/run-pass/enum-null-pointer-opt.rs
index 2d4819231fa..d8d74c8bb45 100644
--- a/src/test/run-pass/enum-null-pointer-opt.rs
+++ b/src/test/run-pass/enum-null-pointer-opt.rs
@@ -9,7 +9,12 @@
 // except according to those terms.
 
 
+extern crate core;
+
+use core::nonzero::NonZero;
 use std::mem::size_of;
+use std::rc::Rc;
+use std::sync::Arc;
 
 trait Trait {}
 
@@ -34,9 +39,33 @@ fn main() {
     // Pointers - Box<T>
     assert_eq!(size_of::<Box<int>>(), size_of::<Option<Box<int>>>());
 
-
     // The optimization can't apply to raw pointers
     assert!(size_of::<Option<*const int>>() != size_of::<*const int>());
     assert!(Some(0 as *const int).is_some()); // Can't collapse None to null
 
+    struct Foo {
+        _a: Box<int>
+    }
+    struct Bar(Box<int>);
+
+    // Should apply through structs
+    assert_eq!(size_of::<Foo>(), size_of::<Option<Foo>>());
+    assert_eq!(size_of::<Bar>(), size_of::<Option<Bar>>());
+    // and tuples
+    assert_eq!(size_of::<(u8, Box<int>)>(), size_of::<Option<(u8, Box<int>)>>());
+    // and fixed-size arrays
+    assert_eq!(size_of::<[Box<int>, ..1]>(), size_of::<Option<[Box<int>, ..1]>>());
+
+    // Should apply to NonZero
+    assert_eq!(size_of::<NonZero<uint>>(), size_of::<Option<NonZero<uint>>>());
+    assert_eq!(size_of::<NonZero<*mut i8>>(), size_of::<Option<NonZero<*mut i8>>>());
+
+    // Should apply to types that use NonZero internally
+    assert_eq!(size_of::<Vec<int>>(), size_of::<Option<Vec<int>>>());
+    assert_eq!(size_of::<Arc<int>>(), size_of::<Option<Arc<int>>>());
+    assert_eq!(size_of::<Rc<int>>(), size_of::<Option<Rc<int>>>());
+
+    // Should apply to types that have NonZero transitively
+    assert_eq!(size_of::<String>(), size_of::<Option<String>>());
+
 }
generated by cgit-pink 1.4.1-3-g733a5 (git 2.37.1) at 2026-04-27 19:36:46 +0000