Remove a const-if-hack in RawVec
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c605199e89
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@ -1,6 +1,8 @@
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#![unstable(feature = "raw_vec_internals", reason = "implementation detail", issue = "0")]
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#![doc(hidden)]
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#![feature(const_if_match)]
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use core::cmp;
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use core::mem;
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use core::ops::Drop;
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@ -51,15 +53,24 @@ pub struct RawVec<T, A: Alloc = Global> {
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impl<T, A: Alloc> RawVec<T, A> {
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/// Like `new`, but parameterized over the choice of allocator for
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/// the returned `RawVec`.
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#[cfg(not(bootstrap))]
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pub const fn new_in(a: A) -> Self {
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// `!0` is `usize::MAX`. This branch should be stripped at compile time.
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// FIXME(mark-i-m): use this line when `if`s are allowed in `const`:
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//let cap = if mem::size_of::<T>() == 0 { !0 } else { 0 };
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let cap = if mem::size_of::<T>() == 0 { !0 } else { 0 };
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// `Unique::empty()` doubles as "unallocated" and "zero-sized allocation".
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RawVec {
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ptr: Unique::empty(),
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// FIXME(mark-i-m): use `cap` when ifs are allowed in const
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cap,
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a,
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}
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}
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/// Like `new`, but parameterized over the choice of allocator for
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/// the returned `RawVec`.
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#[cfg(bootstrap)]
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pub const fn new_in(a: A) -> Self {
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RawVec {
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ptr: Unique::empty(),
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cap: [0, !0][(mem::size_of::<T>() == 0) as usize],
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a,
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}
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@ -131,17 +142,30 @@ impl<T> RawVec<T, Global> {
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/// `RawVec` with capacity `0`. If `T` is zero-sized, then it makes a
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/// `RawVec` with capacity `usize::MAX`. Useful for implementing
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/// delayed allocation.
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#[cfg(not(bootstrap))]
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pub const fn new() -> Self {
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// FIXME(Centril): Reintegrate this with `fn new_in` when we can.
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// `!0` is `usize::MAX`. This branch should be stripped at compile time.
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// FIXME(mark-i-m): use this line when `if`s are allowed in `const`:
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//let cap = if mem::size_of::<T>() == 0 { !0 } else { 0 };
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let cap = if mem::size_of::<T>() == 0 { !0 } else { 0 };
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// `Unique::empty()` doubles as "unallocated" and "zero-sized allocation".
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RawVec {
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ptr: Unique::empty(),
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// FIXME(mark-i-m): use `cap` when ifs are allowed in const
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cap,
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a: Global,
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}
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}
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/// Creates the biggest possible `RawVec` (on the system heap)
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/// without allocating. If `T` has positive size, then this makes a
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/// `RawVec` with capacity `0`. If `T` is zero-sized, then it makes a
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/// `RawVec` with capacity `usize::MAX`. Useful for implementing
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/// delayed allocation.
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#[cfg(bootstrap)]
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pub const fn new() -> Self {
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// `Unique::empty()` doubles as "unallocated" and "zero-sized allocation".
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RawVec {
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ptr: Unique::empty(),
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cap: [0, !0][(mem::size_of::<T>() == 0) as usize],
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a: Global,
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}
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