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Auto merge of #35764 - eddyb:byegone, r=nikomatsakis
Remove the old AST-based backend from rustc_trans. Starting with Rust 1.13, `--disable-orbit` , `-Z orbit=off` and `#[rustc_no_mir]` have been removed. Only the new MIR backend is left in the compiler, and only early const_eval uses ASTs from other crates. Filling drop (previously "zeroing drop"), `#[unsafe_no_drop_flag]` and associated unstable APIs are gone. Implementing `Drop` doesn't add a flag anymore to the type, all of the dynamic drop is function local. This is a [breaking-change], please use `Option::None` and/or `mem::forget` if you are unsure about your ability to prevent/control the drop of a value. In the future, `union` will be usable in some such cases. **NOTE**: DO NOT MERGE before we get the new beta as the stage0, there's some cruft to remove. All of this will massively simplify any efforts to implement (and as such it blocks) features such as `union`s, safe use of `#[packed]` or new type layout optimizations, not to mention many other experiments.
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‎configure

-2
Original file line numberDiff line numberDiff line change
@@ -733,8 +733,6 @@ if [ -n "$CFG_ENABLE_DEBUG_ASSERTIONS" ]; then putvar CFG_ENABLE_DEBUG_ASSERTION
733733
if [ -n "$CFG_ENABLE_DEBUGINFO" ]; then putvar CFG_ENABLE_DEBUGINFO; fi
734734
if [ -n "$CFG_ENABLE_DEBUG_JEMALLOC" ]; then putvar CFG_ENABLE_DEBUG_JEMALLOC; fi
735735

736-
if [ -n "$CFG_DISABLE_ORBIT" ]; then putvar CFG_DISABLE_ORBIT; fi
737-
738736
step_msg "looking for build programs"
739737

740738
probe_need CFG_CURL curl

‎mk/main.mk

-6
Original file line numberDiff line numberDiff line change
@@ -162,12 +162,6 @@ ifdef CFG_ENABLE_DEBUGINFO
162162
CFG_RUSTC_FLAGS += -g
163163
endif
164164

165-
ifdef CFG_DISABLE_ORBIT
166-
$(info cfg: HOLD HOLD HOLD (CFG_DISABLE_ORBIT))
167-
RUSTFLAGS_STAGE1 += -Z orbit=off
168-
RUSTFLAGS_STAGE2 += -Z orbit=off
169-
endif
170-
171165
ifdef SAVE_TEMPS
172166
CFG_RUSTC_FLAGS += -C save-temps
173167
endif

‎src/liballoc/arc.rs

+2-17
Original file line numberDiff line numberDiff line change
@@ -121,7 +121,7 @@ const MAX_REFCOUNT: usize = (isize::MAX) as usize;
121121
/// }
122122
/// ```
123123
124-
#[unsafe_no_drop_flag]
124+
#[cfg_attr(stage0, unsafe_no_drop_flag)]
125125
#[stable(feature = "rust1", since = "1.0.0")]
126126
pub struct Arc<T: ?Sized> {
127127
ptr: Shared<ArcInner<T>>,
@@ -147,7 +147,7 @@ impl<T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<Arc<U>> for Arc<T> {}
147147
/// nodes behind strong `Arc<T>` pointers, and then storing the parent pointers
148148
/// as `Weak<T>` pointers.
149149
150-
#[unsafe_no_drop_flag]
150+
#[cfg_attr(stage0, unsafe_no_drop_flag)]
151151
#[stable(feature = "arc_weak", since = "1.4.0")]
152152
pub struct Weak<T: ?Sized> {
153153
ptr: Shared<ArcInner<T>>,
@@ -559,15 +559,6 @@ impl<T: ?Sized> Drop for Arc<T> {
559559
#[unsafe_destructor_blind_to_params]
560560
#[inline]
561561
fn drop(&mut self) {
562-
// This structure has #[unsafe_no_drop_flag], so this drop glue may run
563-
// more than once (but it is guaranteed to be zeroed after the first if
564-
// it's run more than once)
565-
let thin = *self.ptr as *const ();
566-
567-
if thin as usize == mem::POST_DROP_USIZE {
568-
return;
569-
}
570-
571562
// Because `fetch_sub` is already atomic, we do not need to synchronize
572563
// with other threads unless we are going to delete the object. This
573564
// same logic applies to the below `fetch_sub` to the `weak` count.
@@ -755,12 +746,6 @@ impl<T: ?Sized> Drop for Weak<T> {
755746
/// ```
756747
fn drop(&mut self) {
757748
let ptr = *self.ptr;
758-
let thin = ptr as *const ();
759-
760-
// see comments above for why this check is here
761-
if thin as usize == mem::POST_DROP_USIZE {
762-
return;
763-
}
764749

765750
// If we find out that we were the last weak pointer, then its time to
766751
// deallocate the data entirely. See the discussion in Arc::drop() about

‎src/liballoc/lib.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -88,7 +88,7 @@
8888
#![feature(staged_api)]
8989
#![feature(unboxed_closures)]
9090
#![feature(unique)]
91-
#![feature(unsafe_no_drop_flag, filling_drop)]
91+
#![cfg_attr(stage0, feature(unsafe_no_drop_flag))]
9292
#![feature(unsize)]
9393

9494
#![cfg_attr(not(test), feature(fused, raw, fn_traits, placement_new_protocol))]

‎src/liballoc/raw_vec.rs

+2-9
Original file line numberDiff line numberDiff line change
@@ -44,7 +44,7 @@ use core::cmp;
4444
/// `shrink_to_fit`, and `from_box` will actually set RawVec's private capacity
4545
/// field. This allows zero-sized types to not be special-cased by consumers of
4646
/// this type.
47-
#[unsafe_no_drop_flag]
47+
#[cfg_attr(stage0, unsafe_no_drop_flag)]
4848
pub struct RawVec<T> {
4949
ptr: Unique<T>,
5050
cap: usize,
@@ -546,21 +546,14 @@ impl<T> RawVec<T> {
546546
mem::forget(self);
547547
output
548548
}
549-
550-
/// This is a stupid name in the hopes that someone will find this in the
551-
/// not too distant future and remove it with the rest of
552-
/// #[unsafe_no_drop_flag]
553-
pub fn unsafe_no_drop_flag_needs_drop(&self) -> bool {
554-
self.cap != mem::POST_DROP_USIZE
555-
}
556549
}
557550

558551
impl<T> Drop for RawVec<T> {
559552
#[unsafe_destructor_blind_to_params]
560553
/// Frees the memory owned by the RawVec *without* trying to Drop its contents.
561554
fn drop(&mut self) {
562555
let elem_size = mem::size_of::<T>();
563-
if elem_size != 0 && self.cap != 0 && self.unsafe_no_drop_flag_needs_drop() {
556+
if elem_size != 0 && self.cap != 0 {
564557
let align = mem::align_of::<T>();
565558

566559
let num_bytes = elem_size * self.cap;

‎src/liballoc/rc.rs

+16-22
Original file line numberDiff line numberDiff line change
@@ -182,7 +182,7 @@ struct RcBox<T: ?Sized> {
182182
/// A reference-counted pointer type over an immutable value.
183183
///
184184
/// See the [module level documentation](./index.html) for more details.
185-
#[unsafe_no_drop_flag]
185+
#[cfg_attr(stage0, unsafe_no_drop_flag)]
186186
#[stable(feature = "rust1", since = "1.0.0")]
187187
pub struct Rc<T: ?Sized> {
188188
ptr: Shared<RcBox<T>>,
@@ -466,21 +466,18 @@ impl<T: ?Sized> Drop for Rc<T> {
466466
fn drop(&mut self) {
467467
unsafe {
468468
let ptr = *self.ptr;
469-
let thin = ptr as *const ();
470469

471-
if thin as usize != mem::POST_DROP_USIZE {
472-
self.dec_strong();
473-
if self.strong() == 0 {
474-
// destroy the contained object
475-
ptr::drop_in_place(&mut (*ptr).value);
470+
self.dec_strong();
471+
if self.strong() == 0 {
472+
// destroy the contained object
473+
ptr::drop_in_place(&mut (*ptr).value);
476474

477-
// remove the implicit "strong weak" pointer now that we've
478-
// destroyed the contents.
479-
self.dec_weak();
475+
// remove the implicit "strong weak" pointer now that we've
476+
// destroyed the contents.
477+
self.dec_weak();
480478

481-
if self.weak() == 0 {
482-
deallocate(ptr as *mut u8, size_of_val(&*ptr), align_of_val(&*ptr))
483-
}
479+
if self.weak() == 0 {
480+
deallocate(ptr as *mut u8, size_of_val(&*ptr), align_of_val(&*ptr))
484481
}
485482
}
486483
}
@@ -724,7 +721,7 @@ impl<T> From<T> for Rc<T> {
724721
/// dropped.
725722
///
726723
/// See the [module level documentation](./index.html) for more.
727-
#[unsafe_no_drop_flag]
724+
#[cfg_attr(stage0, unsafe_no_drop_flag)]
728725
#[stable(feature = "rc_weak", since = "1.4.0")]
729726
pub struct Weak<T: ?Sized> {
730727
ptr: Shared<RcBox<T>>,
@@ -825,15 +822,12 @@ impl<T: ?Sized> Drop for Weak<T> {
825822
fn drop(&mut self) {
826823
unsafe {
827824
let ptr = *self.ptr;
828-
let thin = ptr as *const ();
829825

830-
if thin as usize != mem::POST_DROP_USIZE {
831-
self.dec_weak();
832-
// the weak count starts at 1, and will only go to zero if all
833-
// the strong pointers have disappeared.
834-
if self.weak() == 0 {
835-
deallocate(ptr as *mut u8, size_of_val(&*ptr), align_of_val(&*ptr))
836-
}
826+
self.dec_weak();
827+
// the weak count starts at 1, and will only go to zero if all
828+
// the strong pointers have disappeared.
829+
if self.weak() == 0 {
830+
deallocate(ptr as *mut u8, size_of_val(&*ptr), align_of_val(&*ptr))
837831
}
838832
}
839833
}

‎src/libcollections/lib.rs

+1-1
Original file line numberDiff line numberDiff line change
@@ -52,7 +52,7 @@
5252
#![feature(step_by)]
5353
#![feature(unicode)]
5454
#![feature(unique)]
55-
#![feature(unsafe_no_drop_flag)]
55+
#![cfg_attr(stage0, feature(unsafe_no_drop_flag))]
5656
#![cfg_attr(test, feature(rand, test))]
5757

5858
#![no_std]

‎src/libcollections/vec.rs

+4-6
Original file line numberDiff line numberDiff line change
@@ -268,7 +268,7 @@ use super::range::RangeArgument;
268268
/// Vec does not currently guarantee the order in which elements are dropped
269269
/// (the order has changed in the past, and may change again).
270270
///
271-
#[unsafe_no_drop_flag]
271+
#[cfg_attr(stage0, unsafe_no_drop_flag)]
272272
#[stable(feature = "rust1", since = "1.0.0")]
273273
pub struct Vec<T> {
274274
buf: RawVec<T>,
@@ -1600,11 +1600,9 @@ impl<T: Ord> Ord for Vec<T> {
16001600
impl<T> Drop for Vec<T> {
16011601
#[unsafe_destructor_blind_to_params]
16021602
fn drop(&mut self) {
1603-
if self.buf.unsafe_no_drop_flag_needs_drop() {
1604-
unsafe {
1605-
// use drop for [T]
1606-
ptr::drop_in_place(&mut self[..]);
1607-
}
1603+
unsafe {
1604+
// use drop for [T]
1605+
ptr::drop_in_place(&mut self[..]);
16081606
}
16091607
// RawVec handles deallocation
16101608
}

‎src/libcore/intrinsics.rs

-13
Original file line numberDiff line numberDiff line change
@@ -244,19 +244,6 @@ extern "rust-intrinsic" {
244244
/// crate it is invoked in.
245245
pub fn type_id<T: ?Sized + 'static>() -> u64;
246246

247-
/// Creates a value initialized to so that its drop flag,
248-
/// if any, says that it has been dropped.
249-
///
250-
/// `init_dropped` is unsafe because it returns a datum with all
251-
/// of its bytes set to the drop flag, which generally does not
252-
/// correspond to a valid value.
253-
///
254-
/// This intrinsic is likely to be deprecated in the future when
255-
/// Rust moves to non-zeroing dynamic drop (and thus removes the
256-
/// embedded drop flags that are being established by this
257-
/// intrinsic).
258-
pub fn init_dropped<T>() -> T;
259-
260247
/// Creates a value initialized to zero.
261248
///
262249
/// `init` is unsafe because it returns a zeroed-out datum,

‎src/libcore/mem.rs

-71
Original file line numberDiff line numberDiff line change
@@ -241,27 +241,6 @@ pub unsafe fn zeroed<T>() -> T {
241241
intrinsics::init()
242242
}
243243

244-
/// Creates a value initialized to an unspecified series of bytes.
245-
///
246-
/// The byte sequence usually indicates that the value at the memory
247-
/// in question has been dropped. Thus, *if* T carries a drop flag,
248-
/// any associated destructor will not be run when the value falls out
249-
/// of scope.
250-
///
251-
/// Some code at one time used the `zeroed` function above to
252-
/// accomplish this goal.
253-
///
254-
/// This function is expected to be deprecated with the transition
255-
/// to non-zeroing drop.
256-
#[inline]
257-
#[unstable(feature = "filling_drop", issue = "5016")]
258-
pub unsafe fn dropped<T>() -> T {
259-
#[inline(always)]
260-
unsafe fn dropped_impl<T>() -> T { intrinsics::init_dropped() }
261-
262-
dropped_impl()
263-
}
264-
265244
/// Bypasses Rust's normal memory-initialization checks by pretending to
266245
/// produce a value of type T, while doing nothing at all.
267246
///
@@ -518,56 +497,6 @@ pub fn replace<T>(dest: &mut T, mut src: T) -> T {
518497
#[stable(feature = "rust1", since = "1.0.0")]
519498
pub fn drop<T>(_x: T) { }
520499

521-
macro_rules! repeat_u8_as_u16 {
522-
($name:expr) => { (($name as u16) << 8 |
523-
($name as u16)) }
524-
}
525-
macro_rules! repeat_u8_as_u32 {
526-
($name:expr) => { (($name as u32) << 24 |
527-
($name as u32) << 16 |
528-
($name as u32) << 8 |
529-
($name as u32)) }
530-
}
531-
macro_rules! repeat_u8_as_u64 {
532-
($name:expr) => { ((repeat_u8_as_u32!($name) as u64) << 32 |
533-
(repeat_u8_as_u32!($name) as u64)) }
534-
}
535-
536-
// NOTE: Keep synchronized with values used in librustc_trans::trans::adt.
537-
//
538-
// In particular, the POST_DROP_U8 marker must never equal the
539-
// DTOR_NEEDED_U8 marker.
540-
//
541-
// For a while pnkfelix was using 0xc1 here.
542-
// But having the sign bit set is a pain, so 0x1d is probably better.
543-
//
544-
// And of course, 0x00 brings back the old world of zero'ing on drop.
545-
#[unstable(feature = "filling_drop", issue = "5016")]
546-
#[allow(missing_docs)]
547-
pub const POST_DROP_U8: u8 = 0x1d;
548-
#[unstable(feature = "filling_drop", issue = "5016")]
549-
#[allow(missing_docs)]
550-
pub const POST_DROP_U16: u16 = repeat_u8_as_u16!(POST_DROP_U8);
551-
#[unstable(feature = "filling_drop", issue = "5016")]
552-
#[allow(missing_docs)]
553-
pub const POST_DROP_U32: u32 = repeat_u8_as_u32!(POST_DROP_U8);
554-
#[unstable(feature = "filling_drop", issue = "5016")]
555-
#[allow(missing_docs)]
556-
pub const POST_DROP_U64: u64 = repeat_u8_as_u64!(POST_DROP_U8);
557-
558-
#[cfg(target_pointer_width = "16")]
559-
#[unstable(feature = "filling_drop", issue = "5016")]
560-
#[allow(missing_docs)]
561-
pub const POST_DROP_USIZE: usize = POST_DROP_U16 as usize;
562-
#[cfg(target_pointer_width = "32")]
563-
#[unstable(feature = "filling_drop", issue = "5016")]
564-
#[allow(missing_docs)]
565-
pub const POST_DROP_USIZE: usize = POST_DROP_U32 as usize;
566-
#[cfg(target_pointer_width = "64")]
567-
#[unstable(feature = "filling_drop", issue = "5016")]
568-
#[allow(missing_docs)]
569-
pub const POST_DROP_USIZE: usize = POST_DROP_U64 as usize;
570-
571500
/// Interprets `src` as `&U`, and then reads `src` without moving the contained
572501
/// value.
573502
///

‎src/libcore/ptr.rs

-15
Original file line numberDiff line numberDiff line change
@@ -140,21 +140,6 @@ pub unsafe fn read<T>(src: *const T) -> T {
140140
tmp
141141
}
142142

143-
#[allow(missing_docs)]
144-
#[inline(always)]
145-
#[unstable(feature = "filling_drop",
146-
reason = "may play a larger role in std::ptr future extensions",
147-
issue = "5016")]
148-
pub unsafe fn read_and_drop<T>(dest: *mut T) -> T {
149-
// Copy the data out from `dest`:
150-
let tmp = read(&*dest);
151-
152-
// Now mark `dest` as dropped:
153-
write_bytes(dest, mem::POST_DROP_U8, 1);
154-
155-
tmp
156-
}
157-
158143
/// Overwrites a memory location with the given value without reading or
159144
/// dropping the old value.
160145
///

‎src/librustc/hir/map/mod.rs

+1-4
Original file line numberDiff line numberDiff line change
@@ -315,8 +315,7 @@ impl<'ast> Map<'ast> {
315315
RootInlinedParent(parent) => match *parent {
316316
InlinedItem::Item(def_id, _) |
317317
InlinedItem::TraitItem(def_id, _) |
318-
InlinedItem::ImplItem(def_id, _) |
319-
InlinedItem::Foreign(def_id, _) =>
318+
InlinedItem::ImplItem(def_id, _) =>
320319
return DepNode::MetaData(def_id)
321320
},
322321

@@ -940,8 +939,6 @@ pub fn map_decoded_item<'ast, F: FoldOps>(map: &Map<'ast>,
940939
II::ImplItem(fld.fold_ops.new_def_id(d),
941940
ii.map(|ii| fld.fold_impl_item(ii)))
942941
}
943-
II::Foreign(d, i) => II::Foreign(fld.fold_ops.new_def_id(d),
944-
i.map(|i| fld.fold_foreign_item(i)))
945942
};
946943

947944
let ii = map.forest.inlined_items.alloc(ii);

‎src/librustc/middle/cstore.rs

+2-5
Original file line numberDiff line numberDiff line change
@@ -96,17 +96,15 @@ pub enum DefLike {
9696
pub enum InlinedItem {
9797
Item(DefId /* def-id in source crate */, P<hir::Item>),
9898
TraitItem(DefId /* impl id */, P<hir::TraitItem>),
99-
ImplItem(DefId /* impl id */, P<hir::ImplItem>),
100-
Foreign(DefId /* extern item */, P<hir::ForeignItem>),
99+
ImplItem(DefId /* impl id */, P<hir::ImplItem>)
101100
}
102101

103102
/// A borrowed version of `hir::InlinedItem`.
104103
#[derive(Clone, Copy, PartialEq, Eq, Hash, Debug)]
105104
pub enum InlinedItemRef<'a> {
106105
Item(DefId, &'a hir::Item),
107106
TraitItem(DefId, &'a hir::TraitItem),
108-
ImplItem(DefId, &'a hir::ImplItem),
109-
Foreign(DefId, &'a hir::ForeignItem)
107+
ImplItem(DefId, &'a hir::ImplItem)
110108
}
111109

112110
/// Item definitions in the currently-compiled crate would have the CrateNum
@@ -286,7 +284,6 @@ impl InlinedItem {
286284
{
287285
match *self {
288286
InlinedItem::Item(_, ref i) => visitor.visit_item(&i),
289-
InlinedItem::Foreign(_, ref i) => visitor.visit_foreign_item(&i),
290287
InlinedItem::TraitItem(_, ref ti) => visitor.visit_trait_item(ti),
291288
InlinedItem::ImplItem(_, ref ii) => visitor.visit_impl_item(ii),
292289
}

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