diff --git a/src/etc/gdb_rust_pretty_printing.py b/src/etc/gdb_rust_pretty_printing.py index 216915dba5fe7c03116d1cf2906afd7bbafe392f..b1252f386df364dcd18708dc5bc6139fe465e0dd 100755 --- a/src/etc/gdb_rust_pretty_printing.py +++ b/src/etc/gdb_rust_pretty_printing.py @@ -322,8 +322,11 @@ class RustStdBTreeSetPrinter(object): def children(self): (length, data_ptr) = \ rustpp.extract_length_and_ptr_from_std_btreeset(self.__val) - val = GdbValue(data_ptr.get_wrapped_value().dereference()).get_child_at_index(3) - gdb_ptr = val.get_wrapped_value() + leaf_node = GdbValue(data_ptr.get_wrapped_value().dereference()) + maybe_uninit_keys = leaf_node.get_child_at_index(3) + manually_drop_keys = maybe_uninit_keys.get_child_at_index(1) + keys = manually_drop_keys.get_child_at_index(0) + gdb_ptr = keys.get_wrapped_value() for index in xrange(length): yield (str(index), gdb_ptr[index]) @@ -345,9 +348,14 @@ class RustStdBTreeMapPrinter(object): def children(self): (length, data_ptr) = \ rustpp.extract_length_and_ptr_from_std_btreemap(self.__val) - keys = GdbValue(data_ptr.get_wrapped_value().dereference()).get_child_at_index(3) + leaf_node = GdbValue(data_ptr.get_wrapped_value().dereference()) + maybe_uninit_keys = leaf_node.get_child_at_index(3) + manually_drop_keys = maybe_uninit_keys.get_child_at_index(1) + keys = manually_drop_keys.get_child_at_index(0) keys_ptr = keys.get_wrapped_value() - vals = GdbValue(data_ptr.get_wrapped_value().dereference()).get_child_at_index(4) + maybe_uninit_vals = leaf_node.get_child_at_index(4) + manually_drop_vals = maybe_uninit_vals.get_child_at_index(1) + vals = manually_drop_vals.get_child_at_index(0) vals_ptr = vals.get_wrapped_value() for index in xrange(length): yield (str(index), keys_ptr[index]) diff --git a/src/liballoc/collections/btree/node.rs b/src/liballoc/collections/btree/node.rs index 0315545262b6bc0a295953f22b4328070223356b..c86278fc5ddaacc10ecd0175d52860a3c75d20de 100644 --- a/src/liballoc/collections/btree/node.rs +++ b/src/liballoc/collections/btree/node.rs @@ -42,7 +42,7 @@ // This implies that even an empty internal node has at least one edge. use core::marker::PhantomData; -use core::mem; +use core::mem::{self, MaybeUninit}; use core::ptr::{self, Unique, NonNull}; use core::slice; @@ -73,7 +73,7 @@ struct LeafNode { /// This node's index into the parent node's `edges` array. /// `*node.parent.edges[node.parent_idx]` should be the same thing as `node`. /// This is only guaranteed to be initialized when `parent` is nonnull. - parent_idx: u16, + parent_idx: MaybeUninit, /// The number of keys and values this node stores. /// @@ -83,8 +83,8 @@ struct LeafNode { /// The arrays storing the actual data of the node. Only the first `len` elements of each /// array are initialized and valid. - keys: [K; CAPACITY], - vals: [V; CAPACITY], + keys: MaybeUninit<[K; CAPACITY]>, + vals: MaybeUninit<[V; CAPACITY]>, } impl LeafNode { @@ -94,10 +94,10 @@ unsafe fn new() -> Self { LeafNode { // As a general policy, we leave fields uninitialized if they can be, as this should // be both slightly faster and easier to track in Valgrind. - keys: mem::uninitialized(), - vals: mem::uninitialized(), + keys: MaybeUninit::uninitialized(), + vals: MaybeUninit::uninitialized(), parent: ptr::null(), - parent_idx: mem::uninitialized(), + parent_idx: MaybeUninit::uninitialized(), len: 0 } } @@ -115,10 +115,10 @@ unsafe impl Sync for LeafNode<(), ()> {} // ever take a pointer past the first key. static EMPTY_ROOT_NODE: LeafNode<(), ()> = LeafNode { parent: ptr::null(), - parent_idx: 0, + parent_idx: MaybeUninit::uninitialized(), len: 0, - keys: [(); CAPACITY], - vals: [(); CAPACITY], + keys: MaybeUninit::uninitialized(), + vals: MaybeUninit::uninitialized(), }; /// The underlying representation of internal nodes. As with `LeafNode`s, these should be hidden @@ -430,7 +430,7 @@ pub fn ascend(self) -> Result< root: self.root, _marker: PhantomData }, - idx: self.as_leaf().parent_idx as usize, + idx: unsafe { usize::from(*self.as_leaf().parent_idx.get_ref()) }, _marker: PhantomData }) } else { @@ -567,7 +567,7 @@ fn into_key_slice(self) -> &'a [K] { // the node, which is allowed by LLVM. unsafe { slice::from_raw_parts( - self.as_leaf().keys.as_ptr(), + self.as_leaf().keys.as_ptr() as *const K, self.len() ) } @@ -578,7 +578,7 @@ fn into_val_slice(self) -> &'a [V] { debug_assert!(!self.is_shared_root()); unsafe { slice::from_raw_parts( - self.as_leaf().vals.as_ptr(), + self.as_leaf().vals.as_ptr() as *const V, self.len() ) } @@ -605,7 +605,7 @@ fn into_key_slice_mut(mut self) -> &'a mut [K] { } else { unsafe { slice::from_raw_parts_mut( - &mut self.as_leaf_mut().keys as *mut [K] as *mut K, + self.as_leaf_mut().keys.get_mut() as *mut [K] as *mut K, self.len() ) } @@ -616,7 +616,7 @@ fn into_val_slice_mut(mut self) -> &'a mut [V] { debug_assert!(!self.is_shared_root()); unsafe { slice::from_raw_parts_mut( - &mut self.as_leaf_mut().vals as *mut [V] as *mut V, + self.as_leaf_mut().vals.get_mut() as *mut [V] as *mut V, self.len() ) } @@ -1013,7 +1013,7 @@ fn correct_parent_link(mut self) { let ptr = self.node.as_internal_mut() as *mut _; let mut child = self.descend(); child.as_leaf_mut().parent = ptr; - child.as_leaf_mut().parent_idx = idx; + child.as_leaf_mut().parent_idx.set(idx); } /// Unsafely asserts to the compiler some static information about whether the underlying @@ -1152,12 +1152,12 @@ pub fn split(mut self) ptr::copy_nonoverlapping( self.node.keys().as_ptr().add(self.idx + 1), - new_node.keys.as_mut_ptr(), + new_node.keys.as_mut_ptr() as *mut K, new_len ); ptr::copy_nonoverlapping( self.node.vals().as_ptr().add(self.idx + 1), - new_node.vals.as_mut_ptr(), + new_node.vals.as_mut_ptr() as *mut V, new_len ); @@ -1210,12 +1210,12 @@ pub fn split(mut self) ptr::copy_nonoverlapping( self.node.keys().as_ptr().add(self.idx + 1), - new_node.data.keys.as_mut_ptr(), + new_node.data.keys.as_mut_ptr() as *mut K, new_len ); ptr::copy_nonoverlapping( self.node.vals().as_ptr().add(self.idx + 1), - new_node.data.vals.as_mut_ptr(), + new_node.data.vals.as_mut_ptr() as *mut V, new_len ); ptr::copy_nonoverlapping( diff --git a/src/liballoc/lib.rs b/src/liballoc/lib.rs index b2303a02cb2651bb4168a86bff7dbbdd1e8bacfb..089480c06d20da7beb417fb8eafa08c3fe8e38ae 100644 --- a/src/liballoc/lib.rs +++ b/src/liballoc/lib.rs @@ -119,6 +119,7 @@ #![feature(exact_chunks)] #![feature(rustc_const_unstable)] #![feature(const_vec_new)] +#![feature(maybe_uninit)] // Allow testing this library diff --git a/src/libcore/fmt/float.rs b/src/libcore/fmt/float.rs index 03e7a9a49d8a763da0c6772b678ab23cba06ceb6..d01cd012031db45cbb99f4d51c008d8eba174fc1 100644 --- a/src/libcore/fmt/float.rs +++ b/src/libcore/fmt/float.rs @@ -9,7 +9,7 @@ // except according to those terms. use fmt::{Formatter, Result, LowerExp, UpperExp, Display, Debug}; -use mem; +use mem::MaybeUninit; use num::flt2dec; // Don't inline this so callers don't use the stack space this function @@ -20,11 +20,11 @@ fn float_to_decimal_common_exact(fmt: &mut Formatter, num: &T, where T: flt2dec::DecodableFloat { unsafe { - let mut buf: [u8; 1024] = mem::uninitialized(); // enough for f32 and f64 - let mut parts: [flt2dec::Part; 4] = mem::uninitialized(); + let mut buf = MaybeUninit::<[u8; 1024]>::uninitialized(); // enough for f32 and f64 + let mut parts = MaybeUninit::<[flt2dec::Part; 4]>::uninitialized(); let formatted = flt2dec::to_exact_fixed_str(flt2dec::strategy::grisu::format_exact, *num, sign, precision, - false, &mut buf, &mut parts); + false, buf.get_mut(), parts.get_mut()); fmt.pad_formatted_parts(&formatted) } } @@ -38,10 +38,11 @@ fn float_to_decimal_common_shortest(fmt: &mut Formatter, num: &T, { unsafe { // enough for f32 and f64 - let mut buf: [u8; flt2dec::MAX_SIG_DIGITS] = mem::uninitialized(); - let mut parts: [flt2dec::Part; 4] = mem::uninitialized(); + let mut buf = MaybeUninit::<[u8; flt2dec::MAX_SIG_DIGITS]>::uninitialized(); + let mut parts = MaybeUninit::<[flt2dec::Part; 4]>::uninitialized(); let formatted = flt2dec::to_shortest_str(flt2dec::strategy::grisu::format_shortest, *num, - sign, precision, false, &mut buf, &mut parts); + sign, precision, false, buf.get_mut(), + parts.get_mut()); fmt.pad_formatted_parts(&formatted) } } @@ -75,11 +76,11 @@ fn float_to_exponential_common_exact(fmt: &mut Formatter, num: &T, where T: flt2dec::DecodableFloat { unsafe { - let mut buf: [u8; 1024] = mem::uninitialized(); // enough for f32 and f64 - let mut parts: [flt2dec::Part; 6] = mem::uninitialized(); + let mut buf = MaybeUninit::<[u8; 1024]>::uninitialized(); // enough for f32 and f64 + let mut parts = MaybeUninit::<[flt2dec::Part; 6]>::uninitialized(); let formatted = flt2dec::to_exact_exp_str(flt2dec::strategy::grisu::format_exact, *num, sign, precision, - upper, &mut buf, &mut parts); + upper, buf.get_mut(), parts.get_mut()); fmt.pad_formatted_parts(&formatted) } } @@ -94,11 +95,11 @@ fn float_to_exponential_common_shortest(fmt: &mut Formatter, { unsafe { // enough for f32 and f64 - let mut buf: [u8; flt2dec::MAX_SIG_DIGITS] = mem::uninitialized(); - let mut parts: [flt2dec::Part; 6] = mem::uninitialized(); + let mut buf = MaybeUninit::<[u8; flt2dec::MAX_SIG_DIGITS]>::uninitialized(); + let mut parts = MaybeUninit::<[flt2dec::Part; 6]>::uninitialized(); let formatted = flt2dec::to_shortest_exp_str(flt2dec::strategy::grisu::format_shortest, *num, sign, (0, 0), upper, - &mut buf, &mut parts); + buf.get_mut(), parts.get_mut()); fmt.pad_formatted_parts(&formatted) } } diff --git a/src/libcore/lib.rs b/src/libcore/lib.rs index 675e73e952cc2ca011c055a949d38c75e99b18e2..3b7646fa2686f600ee759b3b2798a964f8cf3932 100644 --- a/src/libcore/lib.rs +++ b/src/libcore/lib.rs @@ -246,6 +246,8 @@ #[allow(unused_macros)] macro_rules! vector_impl { ($([$f:ident, $($args:tt)*]),*) => { $($f!($($args)*);)* } } #[path = "../stdsimd/coresimd/mod.rs"] +// replacing uses of mem::{uninitialized,zeroed} with MaybeUninit needs to be in the stdsimd repo +#[allow(deprecated)] #[allow(missing_docs, missing_debug_implementations, dead_code, unused_imports)] #[unstable(feature = "stdsimd", issue = "48556")] #[cfg(not(stage0))] // allow changes to how stdsimd works in stage0 diff --git a/src/libcore/mem.rs b/src/libcore/mem.rs index 1803adee3c18e04de03142700875c3d38e544502..c99c9f96f12d67d712b0fef3a413440d57e67245 100644 --- a/src/libcore/mem.rs +++ b/src/libcore/mem.rs @@ -514,6 +514,7 @@ pub fn needs_drop() -> bool { /// assert_eq!(0, x); /// ``` #[inline] +#[rustc_deprecated(since = "2.0.0", reason = "use `mem::MaybeUninit::zeroed` instead")] #[stable(feature = "rust1", since = "1.0.0")] pub unsafe fn zeroed() -> T { intrinsics::init() @@ -608,6 +609,7 @@ pub unsafe fn zeroed() -> T { /// [copy_no]: ../intrinsics/fn.copy_nonoverlapping.html /// [`Drop`]: ../ops/trait.Drop.html #[inline] +#[rustc_deprecated(since = "2.0.0", reason = "use `mem::MaybeUninit::uninitialized` instead")] #[stable(feature = "rust1", since = "1.0.0")] pub unsafe fn uninitialized() -> T { intrinsics::uninit() @@ -1024,3 +1026,97 @@ fn deref_mut(&mut self) -> &mut Self::Target { &mut self.value } } + +/// A newtype to construct uninitialized instances of `T` +#[allow(missing_debug_implementations)] +#[unstable(feature = "maybe_uninit", issue = "53491")] +// NOTE after stabilizing `MaybeUninit` proceed to deprecate `mem::{uninitialized,zeroed}` +pub union MaybeUninit { + uninit: (), + value: ManuallyDrop, +} + +impl MaybeUninit { + /// Create a new `MaybeUninit` in an uninitialized state. + /// + /// Note that dropping a `MaybeUninit` will never call `T`'s drop code. + /// It is your responsibility to make sure `T` gets dropped if it got initialized. + #[unstable(feature = "maybe_uninit", issue = "53491")] + pub const fn uninitialized() -> MaybeUninit { + MaybeUninit { uninit: () } + } + + /// Create a new `MaybeUninit` in an uninitialized state, with the memory being + /// filled with `0` bytes. It depends on `T` whether that already makes for + /// proper initialization. For example, `MaybeUninit::zeroed()` is initialized, + /// but `MaybeUninit<&'static i32>::zeroed()` is not because references must not + /// be null. + /// + /// Note that dropping a `MaybeUninit` will never call `T`'s drop code. + /// It is your responsibility to make sure `T` gets dropped if it got initialized. + #[unstable(feature = "maybe_uninit", issue = "53491")] + pub fn zeroed() -> MaybeUninit { + let mut u = MaybeUninit::::uninitialized(); + unsafe { + u.as_mut_ptr().write_bytes(0u8, 1); + } + u + } + + /// Set the value of the `MaybeUninit`. This overwrites any previous value without dropping it. + #[unstable(feature = "maybe_uninit", issue = "53491")] + pub fn set(&mut self, val: T) { + unsafe { + self.value = ManuallyDrop::new(val); + } + } + + /// Extract the value from the `MaybeUninit` container. This is a great way + /// to ensure that the data will get dropped, because the resulting `T` is + /// subject to the usual drop handling. + /// + /// # Unsafety + /// + /// It is up to the caller to guarantee that the the `MaybeUninit` really is in an initialized + /// state, otherwise this will immediately cause undefined behavior. + #[unstable(feature = "maybe_uninit", issue = "53491")] + pub unsafe fn into_inner(self) -> T { + ManuallyDrop::into_inner(self.value) + } + + /// Get a reference to the contained value. + /// + /// # Unsafety + /// + /// It is up to the caller to guarantee that the the `MaybeUninit` really is in an initialized + /// state, otherwise this will immediately cause undefined behavior. + #[unstable(feature = "maybe_uninit", issue = "53491")] + pub unsafe fn get_ref(&self) -> &T { + &*self.value + } + + /// Get a mutable reference to the contained value. + /// + /// # Unsafety + /// + /// It is up to the caller to guarantee that the the `MaybeUninit` really is in an initialized + /// state, otherwise this will immediately cause undefined behavior. + #[unstable(feature = "maybe_uninit", issue = "53491")] + pub unsafe fn get_mut(&mut self) -> &mut T { + &mut *self.value + } + + /// Get a pointer to the contained value. Reading from this pointer will be undefined + /// behavior unless the `MaybeUninit` is initialized. + #[unstable(feature = "maybe_uninit", issue = "53491")] + pub fn as_ptr(&self) -> *const T { + unsafe { &*self.value as *const T } + } + + /// Get a mutable pointer to the contained value. Reading from this pointer will be undefined + /// behavior unless the `MaybeUninit` is initialized. + #[unstable(feature = "maybe_uninit", issue = "53491")] + pub fn as_mut_ptr(&mut self) -> *mut T { + unsafe { &mut *self.value as *mut T } + } +} diff --git a/src/libcore/ptr.rs b/src/libcore/ptr.rs index 57351822cc3cfe765ebd961dde0e12c61ff470e6..6312aa439d20f9075f9a5ca98b9fb01010ff75f9 100644 --- a/src/libcore/ptr.rs +++ b/src/libcore/ptr.rs @@ -22,7 +22,7 @@ use fmt; use hash; use marker::{PhantomData, Unsize}; -use mem; +use mem::{self, MaybeUninit}; use nonzero::NonZero; use cmp::Ordering::{self, Less, Equal, Greater}; @@ -142,16 +142,12 @@ pub const fn null_mut() -> *mut T { 0 as *mut T } #[stable(feature = "rust1", since = "1.0.0")] pub unsafe fn swap(x: *mut T, y: *mut T) { // Give ourselves some scratch space to work with - let mut tmp: T = mem::uninitialized(); + let mut tmp = MaybeUninit::::uninitialized(); // Perform the swap - copy_nonoverlapping(x, &mut tmp, 1); + copy_nonoverlapping(x, tmp.as_mut_ptr(), 1); copy(y, x, 1); // `x` and `y` may overlap - copy_nonoverlapping(&tmp, y, 1); - - // y and t now point to the same thing, but we need to completely forget `tmp` - // because it's no longer relevant. - mem::forget(tmp); + copy_nonoverlapping(tmp.get_ref(), y, 1); } /// Swaps a sequence of values at two mutable locations of the same type. @@ -224,8 +220,8 @@ unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) { while i + block_size <= len { // Create some uninitialized memory as scratch space // Declaring `t` here avoids aligning the stack when this loop is unused - let mut t: Block = mem::uninitialized(); - let t = &mut t as *mut _ as *mut u8; + let mut t = mem::MaybeUninit::::uninitialized(); + let t = t.as_mut_ptr() as *mut u8; let x = x.add(i); let y = y.add(i); @@ -239,10 +235,10 @@ unsafe fn swap_nonoverlapping_bytes(x: *mut u8, y: *mut u8, len: usize) { if i < len { // Swap any remaining bytes - let mut t: UnalignedBlock = mem::uninitialized(); + let mut t = mem::MaybeUninit::::uninitialized(); let rem = len - i; - let t = &mut t as *mut _ as *mut u8; + let t = t.as_mut_ptr() as *mut u8; let x = x.add(i); let y = y.add(i); @@ -296,9 +292,9 @@ pub unsafe fn replace(dest: *mut T, mut src: T) -> T { #[inline] #[stable(feature = "rust1", since = "1.0.0")] pub unsafe fn read(src: *const T) -> T { - let mut tmp: T = mem::uninitialized(); - copy_nonoverlapping(src, &mut tmp, 1); - tmp + let mut tmp = MaybeUninit::::uninitialized(); + copy_nonoverlapping(src, tmp.as_mut_ptr(), 1); + tmp.into_inner() } /// Reads the value from `src` without moving it. This leaves the @@ -330,11 +326,11 @@ pub unsafe fn read(src: *const T) -> T { #[inline] #[stable(feature = "ptr_unaligned", since = "1.17.0")] pub unsafe fn read_unaligned(src: *const T) -> T { - let mut tmp: T = mem::uninitialized(); + let mut tmp = MaybeUninit::::uninitialized(); copy_nonoverlapping(src as *const u8, - &mut tmp as *mut T as *mut u8, + tmp.as_mut_ptr() as *mut u8, mem::size_of::()); - tmp + tmp.into_inner() } /// Overwrites a memory location with the given value without reading or diff --git a/src/libcore/slice/rotate.rs b/src/libcore/slice/rotate.rs index 0d182b8497452e2bf7db6d6417b4b6e2092d3b34..07153735300b89ccc376e472aac7f0bcbfb51f80 100644 --- a/src/libcore/slice/rotate.rs +++ b/src/libcore/slice/rotate.rs @@ -9,7 +9,7 @@ // except according to those terms. use cmp; -use mem; +use mem::{self, MaybeUninit}; use ptr; /// Rotation is much faster if it has access to a little bit of memory. This @@ -26,12 +26,6 @@ union RawArray { } impl RawArray { - fn new() -> Self { - unsafe { mem::uninitialized() } - } - fn ptr(&self) -> *mut T { - unsafe { &self.typed as *const T as *mut T } - } fn cap() -> usize { if mem::size_of::() == 0 { usize::max_value() @@ -88,8 +82,8 @@ pub unsafe fn ptr_rotate(mut left: usize, mid: *mut T, mut right: usize) { } } - let rawarray = RawArray::new(); - let buf = rawarray.ptr(); + let mut rawarray = MaybeUninit::>::uninitialized(); + let buf = &mut (*rawarray.as_mut_ptr()).typed as *mut [T; 2] as *mut T; let dim = mid.sub(left).add(right); if left <= right { diff --git a/src/libcore/slice/sort.rs b/src/libcore/slice/sort.rs index e4c1fd03f9eb384b1197e5a6d3b82ed14f85d349..affe84fbef91f2e6908385556b1e3b8d0d90c2dd 100644 --- a/src/libcore/slice/sort.rs +++ b/src/libcore/slice/sort.rs @@ -17,7 +17,7 @@ //! stable sorting implementation. use cmp; -use mem; +use mem::{self, MaybeUninit}; use ptr; /// When dropped, copies from `src` into `dest`. @@ -226,14 +226,14 @@ fn partition_in_blocks(v: &mut [T], pivot: &T, is_less: &mut F) -> usize let mut block_l = BLOCK; let mut start_l = ptr::null_mut(); let mut end_l = ptr::null_mut(); - let mut offsets_l: [u8; BLOCK] = unsafe { mem::uninitialized() }; + let mut offsets_l = MaybeUninit::<[u8; BLOCK]>::uninitialized(); // The current block on the right side (from `r.sub(block_r)` to `r`). let mut r = unsafe { l.add(v.len()) }; let mut block_r = BLOCK; let mut start_r = ptr::null_mut(); let mut end_r = ptr::null_mut(); - let mut offsets_r: [u8; BLOCK] = unsafe { mem::uninitialized() }; + let mut offsets_r = MaybeUninit::<[u8; BLOCK]>::uninitialized(); // FIXME: When we get VLAs, try creating one array of length `min(v.len(), 2 * BLOCK)` rather // than two fixed-size arrays of length `BLOCK`. VLAs might be more cache-efficient. @@ -272,8 +272,8 @@ fn width(l: *mut T, r: *mut T) -> usize { if start_l == end_l { // Trace `block_l` elements from the left side. - start_l = offsets_l.as_mut_ptr(); - end_l = offsets_l.as_mut_ptr(); + start_l = offsets_l.as_mut_ptr() as *mut u8; + end_l = offsets_l.as_mut_ptr() as *mut u8; let mut elem = l; for i in 0..block_l { @@ -288,8 +288,8 @@ fn width(l: *mut T, r: *mut T) -> usize { if start_r == end_r { // Trace `block_r` elements from the right side. - start_r = offsets_r.as_mut_ptr(); - end_r = offsets_r.as_mut_ptr(); + start_r = offsets_r.as_mut_ptr() as *mut u8; + end_r = offsets_r.as_mut_ptr() as *mut u8; let mut elem = r; for i in 0..block_r { diff --git a/src/librustc/ty/layout.rs b/src/librustc/ty/layout.rs index 4e37a34a0c8a7f9af70d13a8f8d1cd8a790a3003..3d2088ea12e8efa69a0f4a8a058738901d5fd8ee 100644 --- a/src/librustc/ty/layout.rs +++ b/src/librustc/ty/layout.rs @@ -449,7 +449,7 @@ enum StructKind { } } - if sized && fields.iter().any(|f| f.abi == Abi::Uninhabited) { + if sized && fields.iter().any(|f| f.abi.is_uninhabited()) { abi = Abi::Uninhabited; } @@ -724,7 +724,7 @@ enum StructKind { // See issue #49298 for more details on the need to leave space // for non-ZST uninhabited data (mostly partial initialization). let absent = |fields: &[TyLayout]| { - let uninhabited = fields.iter().any(|f| f.abi == Abi::Uninhabited); + let uninhabited = fields.iter().any(|f| f.abi.is_uninhabited()); let is_zst = fields.iter().all(|f| f.is_zst()); uninhabited && is_zst }; @@ -872,7 +872,7 @@ enum StructKind { _ => Abi::Aggregate { sized: true }, }; - if st.iter().all(|v| v.abi == Abi::Uninhabited) { + if st.iter().all(|v| v.abi.is_uninhabited()) { abi = Abi::Uninhabited; } @@ -900,7 +900,7 @@ enum StructKind { let discr_type = def.repr.discr_type(); let bits = Integer::from_attr(tcx, discr_type).size().bits(); for (i, discr) in def.discriminants(tcx).enumerate() { - if variants[i].iter().any(|f| f.abi == Abi::Uninhabited) { + if variants[i].iter().any(|f| f.abi.is_uninhabited()) { continue; } let mut x = discr.val as i128; @@ -1096,7 +1096,7 @@ enum StructKind { } } - if layout_variants.iter().all(|v| v.abi == Abi::Uninhabited) { + if layout_variants.iter().all(|v| v.abi.is_uninhabited()) { abi = Abi::Uninhabited; } diff --git a/src/librustc_codegen_llvm/debuginfo/mod.rs b/src/librustc_codegen_llvm/debuginfo/mod.rs index 99919a940b40511dcd605cea460440d5a1a9e05a..7b0c413e857617b7ffbd5fd975285875ddf33579 100644 --- a/src/librustc_codegen_llvm/debuginfo/mod.rs +++ b/src/librustc_codegen_llvm/debuginfo/mod.rs @@ -279,7 +279,7 @@ pub fn create_function_debug_context( } None => {} }; - if cx.layout_of(sig.output()).abi == ty::layout::Abi::Uninhabited { + if cx.layout_of(sig.output()).abi.is_uninhabited() { flags = flags | DIFlags::FlagNoReturn; } diff --git a/src/librustc_codegen_llvm/declare.rs b/src/librustc_codegen_llvm/declare.rs index 5e743ac51bc616ffebbf47aa31851f9911a243a7..7141c9ece89d7180ea0c7f85f22e1fb29afbf8e1 100644 --- a/src/librustc_codegen_llvm/declare.rs +++ b/src/librustc_codegen_llvm/declare.rs @@ -23,7 +23,7 @@ use llvm; use llvm::AttributePlace::Function; use rustc::ty::{self, Ty}; -use rustc::ty::layout::{self, LayoutOf}; +use rustc::ty::layout::LayoutOf; use rustc::session::config::Sanitizer; use rustc_data_structures::small_c_str::SmallCStr; use rustc_target::spec::PanicStrategy; @@ -137,7 +137,7 @@ pub fn declare_fn( let fty = FnType::new(cx, sig, &[]); let llfn = declare_raw_fn(cx, name, fty.llvm_cconv(), fty.llvm_type(cx)); - if cx.layout_of(sig.output()).abi == layout::Abi::Uninhabited { + if cx.layout_of(sig.output()).abi.is_uninhabited() { llvm::Attribute::NoReturn.apply_llfn(Function, llfn); } diff --git a/src/librustc_codegen_llvm/mir/block.rs b/src/librustc_codegen_llvm/mir/block.rs index a534b4e478fb793e4f96496e4621287c25eb0a24..709fceb492509e9c88cddac93057e6d66d32c55c 100644 --- a/src/librustc_codegen_llvm/mir/block.rs +++ b/src/librustc_codegen_llvm/mir/block.rs @@ -482,6 +482,54 @@ fn codegen_terminator(&mut self, _ => FnType::new(bx.cx, sig, &extra_args) }; + // emit a panic instead of instantiating an uninhabited type + if (intrinsic == Some("init") || intrinsic == Some("uninit")) && + fn_ty.ret.layout.abi.is_uninhabited() + { + let loc = bx.sess().source_map().lookup_char_pos(span.lo()); + let filename = Symbol::intern(&loc.file.name.to_string()).as_str(); + let filename = C_str_slice(bx.cx, filename); + let line = C_u32(bx.cx, loc.line as u32); + let col = C_u32(bx.cx, loc.col.to_usize() as u32 + 1); + let align = tcx.data_layout.aggregate_align + .max(tcx.data_layout.i32_align) + .max(tcx.data_layout.pointer_align); + + let str = format!( + "Attempted to instantiate uninhabited type {} using mem::{}", + sig.output(), + if intrinsic == Some("init") { "zeroed" } else { "uninitialized" } + ); + let msg_str = Symbol::intern(&str).as_str(); + let msg_str = C_str_slice(bx.cx, msg_str); + let msg_file_line_col = C_struct(bx.cx, + &[msg_str, filename, line, col], + false); + let msg_file_line_col = consts::addr_of(bx.cx, + msg_file_line_col, + align, + Some("panic_loc")); + + // Obtain the panic entry point. + let def_id = + common::langcall(bx.tcx(), Some(span), "", lang_items::PanicFnLangItem); + let instance = ty::Instance::mono(bx.tcx(), def_id); + let fn_ty = FnType::of_instance(bx.cx, &instance); + let llfn = callee::get_fn(bx.cx, instance); + + // Codegen the actual panic invoke/call. + do_call( + self, + bx, + fn_ty, + llfn, + &[msg_file_line_col], + destination.as_ref().map(|(_, bb)| (ReturnDest::Nothing, *bb)), + cleanup, + ); + return; + } + // The arguments we'll be passing. Plus one to account for outptr, if used. let arg_count = fn_ty.args.len() + fn_ty.ret.is_indirect() as usize; let mut llargs = Vec::with_capacity(arg_count); diff --git a/src/librustc_codegen_llvm/mir/place.rs b/src/librustc_codegen_llvm/mir/place.rs index 70ace15e5236f06b3cce9ab36b89d82194f11b94..bc6ebd360e8315db992b5867e7da985187f1b428 100644 --- a/src/librustc_codegen_llvm/mir/place.rs +++ b/src/librustc_codegen_llvm/mir/place.rs @@ -278,7 +278,7 @@ pub fn project_field(self, bx: &Builder<'a, 'll, 'tcx>, ix: usize) -> PlaceRef<' /// Obtain the actual discriminant of a value. pub fn codegen_get_discr(self, bx: &Builder<'a, 'll, 'tcx>, cast_to: Ty<'tcx>) -> &'ll Value { let cast_to = bx.cx.layout_of(cast_to).immediate_llvm_type(bx.cx); - if self.layout.abi == layout::Abi::Uninhabited { + if self.layout.abi.is_uninhabited() { return C_undef(cast_to); } match self.layout.variants { @@ -341,7 +341,7 @@ pub fn codegen_get_discr(self, bx: &Builder<'a, 'll, 'tcx>, cast_to: Ty<'tcx>) - /// Set the discriminant for a new value of the given case of the given /// representation. pub fn codegen_set_discr(&self, bx: &Builder<'a, 'll, 'tcx>, variant_index: usize) { - if self.layout.for_variant(bx.cx, variant_index).abi == layout::Abi::Uninhabited { + if self.layout.for_variant(bx.cx, variant_index).abi.is_uninhabited() { return; } match self.layout.variants { diff --git a/src/librustc_codegen_llvm/mir/rvalue.rs b/src/librustc_codegen_llvm/mir/rvalue.rs index c3ec347f60876c03dc846bbec04f75f546b8d75d..fa22bdff94dddbeb29fda3c9a0295e6c2100ea8b 100644 --- a/src/librustc_codegen_llvm/mir/rvalue.rs +++ b/src/librustc_codegen_llvm/mir/rvalue.rs @@ -290,7 +290,7 @@ pub fn codegen_rvalue_operand(&mut self, mir::CastKind::Misc => { assert!(cast.is_llvm_immediate()); let ll_t_out = cast.immediate_llvm_type(bx.cx); - if operand.layout.abi == layout::Abi::Uninhabited { + if operand.layout.abi.is_uninhabited() { return (bx, OperandRef { val: OperandValue::Immediate(C_undef(ll_t_out)), layout: cast, diff --git a/src/librustc_mir/interpret/operand.rs b/src/librustc_mir/interpret/operand.rs index c7f84f768395351c35405e9fa0c7a39ea4e334fc..c966750f3aa07d8b28c7f00fca94254e819189c0 100644 --- a/src/librustc_mir/interpret/operand.rs +++ b/src/librustc_mir/interpret/operand.rs @@ -524,7 +524,7 @@ pub fn read_discriminant( rval: OpTy<'tcx>, ) -> EvalResult<'tcx, (u128, usize)> { trace!("read_discriminant_value {:#?}", rval.layout); - if rval.layout.abi == layout::Abi::Uninhabited { + if rval.layout.abi.is_uninhabited() { return err!(Unreachable); } diff --git a/src/librustc_target/abi/mod.rs b/src/librustc_target/abi/mod.rs index 5c4cd849f89bcd681e323d5db483f2d6764a874e..96eb69163220e7b33c57287bd9ac35596ab6b589 100644 --- a/src/librustc_target/abi/mod.rs +++ b/src/librustc_target/abi/mod.rs @@ -802,6 +802,14 @@ pub fn is_signed(&self) -> bool { _ => false, } } + + /// Returns true if this is an uninhabited type + pub fn is_uninhabited(&self) -> bool { + match *self { + Abi::Uninhabited => true, + _ => false, + } + } } #[derive(PartialEq, Eq, Hash, Debug)] diff --git a/src/test/codegen/box-maybe-uninit.rs b/src/test/codegen/box-maybe-uninit.rs new file mode 100644 index 0000000000000000000000000000000000000000..168e1a3eba0c56f9a22c0d9581fe50d95e89759f --- /dev/null +++ b/src/test/codegen/box-maybe-uninit.rs @@ -0,0 +1,23 @@ +// 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 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// compile-flags: -O +#![crate_type="lib"] +#![feature(maybe_uninit)] + +use std::mem::MaybeUninit; + +// Boxing a `MaybeUninit` value should not copy junk from the stack +#[no_mangle] +pub fn box_uninitialized() -> Box> { + // CHECK-LABEL: @box_uninitialized + // CHECK-NOT: store + Box::new(MaybeUninit::uninitialized()) +} diff --git a/src/test/debuginfo/nil-enum.rs b/src/test/debuginfo/nil-enum.rs index 94377421c0b0c9927a039b26970371581d959315..ab9c7e2dd2758a5d4dec1827be9c915f7fef0848 100644 --- a/src/test/debuginfo/nil-enum.rs +++ b/src/test/debuginfo/nil-enum.rs @@ -8,6 +8,8 @@ // option. This file may not be copied, modified, or distributed // except according to those terms. +// NOTE Instantiating an empty enum is UB. This test may break in the future. + // LLDB can't handle zero-sized values // ignore-lldb @@ -25,8 +27,11 @@ #![allow(unused_variables)] #![feature(omit_gdb_pretty_printer_section)] +#![feature(maybe_uninit)] #![omit_gdb_pretty_printer_section] +use std::mem::MaybeUninit; + enum ANilEnum {} enum AnotherNilEnum {} @@ -35,8 +40,8 @@ enum AnotherNilEnum {} // The error from gdbr is expected since nil enums are not supposed to exist. fn main() { unsafe { - let first: ANilEnum = ::std::mem::zeroed(); - let second: AnotherNilEnum = ::std::mem::zeroed(); + let first: ANilEnum = MaybeUninit::uninitialized().into_inner(); + let second: AnotherNilEnum = MaybeUninit::uninitialized().into_inner(); zzz(); // #break } diff --git a/src/test/run-pass/panic-uninitialized-zeroed.rs b/src/test/run-pass/panic-uninitialized-zeroed.rs new file mode 100644 index 0000000000000000000000000000000000000000..2972f6efa32e05f3eab76c0229b61767a978ad44 --- /dev/null +++ b/src/test/run-pass/panic-uninitialized-zeroed.rs @@ -0,0 +1,83 @@ +// Copyright 2018 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 or the MIT license +// , at your +// option. This file may not be copied, modified, or distributed +// except according to those terms. + +// ignore-wasm32-bare always compiled as panic=abort right now and this requires unwinding +// This test checks that instantiating an uninhabited type via `mem::{uninitialized,zeroed}` results +// in a runtime panic. + +#![feature(never_type)] + +use std::{mem, panic}; + +#[allow(dead_code)] +struct Foo { + x: u8, + y: !, +} + +enum Bar {} + +fn main() { + unsafe { + assert_eq!( + panic::catch_unwind(|| { + mem::uninitialized::() + }).err().and_then(|a| a.downcast_ref::().map(|s| { + s == "Attempted to instantiate uninhabited type ! using mem::uninitialized" + })), + Some(true) + ); + + assert_eq!( + panic::catch_unwind(|| { + mem::zeroed::() + }).err().and_then(|a| a.downcast_ref::().map(|s| { + s == "Attempted to instantiate uninhabited type ! using mem::zeroed" + })), + Some(true) + ); + + assert_eq!( + panic::catch_unwind(|| { + mem::uninitialized::() + }).err().and_then(|a| a.downcast_ref::().map(|s| { + s == "Attempted to instantiate uninhabited type Foo using mem::uninitialized" + })), + Some(true) + ); + + assert_eq!( + panic::catch_unwind(|| { + mem::zeroed::() + }).err().and_then(|a| a.downcast_ref::().map(|s| { + s == "Attempted to instantiate uninhabited type Foo using mem::zeroed" + })), + Some(true) + ); + + assert_eq!( + panic::catch_unwind(|| { + mem::uninitialized::() + }).err().and_then(|a| a.downcast_ref::().map(|s| { + s == "Attempted to instantiate uninhabited type Bar using mem::uninitialized" + })), + Some(true) + ); + + assert_eq!( + panic::catch_unwind(|| { + mem::zeroed::() + }).err().and_then(|a| a.downcast_ref::().map(|s| { + s == "Attempted to instantiate uninhabited type Bar using mem::zeroed" + })), + Some(true) + ); + } +}