зеркало из https://github.com/mozilla/gecko-dev.git
Bug 1716535 - Remove nodrop dependency. r=glandium
ManuallyDrop is just fine. Differential Revision: https://phabricator.services.mozilla.com/D117887
This commit is contained in:
Emilio Cobos Álvarez
Родитель
680ed2d221
Коммит
a22ca7007a
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@ -3430,12 +3430,6 @@ dependencies = [
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"void",
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]
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[[package]]
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name = "nodrop"
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version = "0.1.14"
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source = "registry+https://github.com/rust-lang/crates.io-index"
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checksum = "72ef4a56884ca558e5ddb05a1d1e7e1bfd9a68d9ed024c21704cc98872dae1bb"
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[[package]]
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name = "nom"
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version = "5.1.2"
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@ -4600,7 +4594,6 @@ dependencies = [
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name = "servo_arc"
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version = "0.1.1"
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dependencies = [
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"nodrop",
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"stable_deref_trait",
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]
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@ -15,6 +15,5 @@ gecko_refcount_logging = []
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servo = ["serde"]
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[dependencies]
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nodrop = { version = "0.1.8" }
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serde = { version = "1.0", optional = true }
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stable_deref_trait = "1.0.0"
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@ -25,12 +25,10 @@
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// duplicate those here.
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#![allow(missing_docs)]
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extern crate nodrop;
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#[cfg(feature = "servo")]
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extern crate serde;
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extern crate stable_deref_trait;
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use nodrop::NoDrop;
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#[cfg(feature = "servo")]
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use serde::{Deserialize, Serialize};
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use stable_deref_trait::{CloneStableDeref, StableDeref};
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@ -305,7 +303,7 @@ impl<T> Arc<T> {
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F: FnOnce(&RawOffsetArc<T>) -> U,
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{
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// Synthesize transient Arc, which never touches the refcount of the ArcInner.
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let transient = unsafe { NoDrop::new(Arc::into_raw_offset(ptr::read(self))) };
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let transient = unsafe { mem::ManuallyDrop::new(Arc::into_raw_offset(ptr::read(self))) };
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// Expose the transient Arc to the callback, which may clone it if it wants.
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let result = f(&transient);
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@ -926,7 +924,7 @@ impl<H, T> ThinArc<H, T> {
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{
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// Synthesize transient Arc, which never touches the refcount of the ArcInner.
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let transient = unsafe {
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NoDrop::new(Arc {
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mem::ManuallyDrop::new(Arc {
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p: ptr::NonNull::new_unchecked(thin_to_thick(self.ptr.as_ptr())),
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phantom: PhantomData,
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})
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@ -935,11 +933,6 @@ impl<H, T> ThinArc<H, T> {
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// Expose the transient Arc to the callback, which may clone it if it wants.
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let result = f(&transient);
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// Forget the transient Arc to leave the refcount untouched.
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// XXXManishearth this can be removed when unions stabilize,
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// since then NoDrop becomes zero overhead
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mem::forget(transient);
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// Forward the result.
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result
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}
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@ -1140,16 +1133,11 @@ impl<T> RawOffsetArc<T> {
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F: FnOnce(&Arc<T>) -> U,
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{
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// Synthesize transient Arc, which never touches the refcount of the ArcInner.
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let transient = unsafe { NoDrop::new(Arc::from_raw(self.ptr.as_ptr())) };
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let transient = unsafe { mem::ManuallyDrop::new(Arc::from_raw(self.ptr.as_ptr())) };
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// Expose the transient Arc to the callback, which may clone it if it wants.
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let result = f(&transient);
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// Forget the transient Arc to leave the refcount untouched.
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// XXXManishearth this can be removed when unions stabilize,
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// since then NoDrop becomes zero overhead
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mem::forget(transient);
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// Forward the result.
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result
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}
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@ -1272,16 +1260,11 @@ impl<'a, T> ArcBorrow<'a, T> {
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T: 'static,
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{
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// Synthesize transient Arc, which never touches the refcount.
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let transient = unsafe { NoDrop::new(Arc::from_raw(self.0)) };
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let transient = unsafe { mem::ManuallyDrop::new(Arc::from_raw(self.0)) };
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// Expose the transient Arc to the callback, which may clone it if it wants.
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let result = f(&transient);
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// Forget the transient Arc to leave the refcount untouched.
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// XXXManishearth this can be removed when unions stabilize,
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// since then NoDrop becomes zero overhead
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mem::forget(transient);
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// Forward the result.
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result
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}
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@ -1 +0,0 @@
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{"files":{"Cargo.toml":"e43d9892df1d8d932b5f5d27f303f1a302b550b5a37b9b8fb1b107aa5273b8af","LICENSE-APACHE":"a60eea817514531668d7e00765731449fe14d059d3249e0bc93b36de45f759f2","LICENSE-MIT":"0245ee104228a100ce5fceecf43e25faae450494d9173f43fd94c27d69fdac13","README.rst":"3a12c4caf645c40c7b9608c150c7e2bee50eafd114b802329f508a489d9e175b","src/lib.rs":"3e00173987c5fc462956c36f492426cbf0d900a2634c6b4e47580d6b142273ee"},"package":"72ef4a56884ca558e5ddb05a1d1e7e1bfd9a68d9ed024c21704cc98872dae1bb"}
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@ -1,36 +0,0 @@
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# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO
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#
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# When uploading crates to the registry Cargo will automatically
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# "normalize" Cargo.toml files for maximal compatibility
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# with all versions of Cargo and also rewrite `path` dependencies
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# to registry (e.g., crates.io) dependencies
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#
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# If you believe there's an error in this file please file an
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# issue against the rust-lang/cargo repository. If you're
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# editing this file be aware that the upstream Cargo.toml
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# will likely look very different (and much more reasonable)
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[package]
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name = "nodrop"
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version = "0.1.14"
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authors = ["bluss"]
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description = "A wrapper type to inhibit drop (destructor).\n\n***Deprecated: Use ManuallyDrop or MaybeUninit instead!***\n"
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documentation = "https://docs.rs/nodrop/"
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keywords = []
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categories = ["rust-patterns"]
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license = "MIT/Apache-2.0"
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repository = "https://github.com/bluss/arrayvec"
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[package.metadata.release]
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no-dev-version = true
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tag-name = "nodrop-{{version}}"
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[dependencies.nodrop-union]
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version = "0.1.8"
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optional = true
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[features]
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default = ["std"]
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std = []
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use_needs_drop = []
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use_union = ["nodrop-union"]
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[badges.maintenance]
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status = "deprecated"
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@ -1,71 +0,0 @@
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nodrop
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======
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Recent Changes (nodrop)
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-----------------------
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- 0.1.14
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- Mark nodrop deprecated
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With the release of arrayvec 0.5, nodrop is unused.
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With the release of Rust 1.36 and MaybeUninit, nodrop has no
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purpose (but for older Rust releases).
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- 0.1.13
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- Update to include license files in the crate by @ignatenkobrain
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- 0.1.12
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- Remove dependency on crate odds.
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- 0.1.11
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- Remove erronous assertion in test (#77)
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- 0.1.10
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- Update for stable ``needs_drop`` (Rust 1.21, was nightly only)
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- 0.1.9
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- Fix issue in recent nightly where ``repr(u8)`` did not work. Use
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a better way to get rid of the enum layout optimization.
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- 0.1.8
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- Add crate feature ``use_union`` that uses untagged unions to implement NoDrop.
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Finally we have an implementation without hacks, without a runtime flag,
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and without an actual ``Drop`` impl (which was needed to suppress drop).
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The crate feature requires nightly and is unstable.
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- 0.1.7
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- Remove crate feature ``no_drop_flag``, because it doesn't compile on nightly
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anymore. Drop flags are gone anyway!
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- 0.1.6
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- Add feature std, which you can opt out of to use ``no_std``.
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- 0.1.5
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- Added crate feature ``use_needs_drop`` which is a nightly-only
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optimization, which skips overwriting if the inner value does not need
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drop.
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License
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=======
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Dual-licensed to be compatible with the Rust project.
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Licensed under the Apache License, Version 2.0
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http://www.apache.org/licenses/LICENSE-2.0 or the MIT license
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http://opensource.org/licenses/MIT, at your
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option. This file may not be copied, modified, or distributed
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except according to those terms.
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@ -1,189 +0,0 @@
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//! A wrapper type to inhibit drop (destructor).
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//!
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//! ***Deprecated: Use ManuallyDrop or MaybeUninit instead!***
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//!
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//! The **nodrop** crate has the following cargo feature flags:
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//!
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//! - `std`
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//! - Optional, enabled by default
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//! - Use libstd
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//! - `use_needs_drop`
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//! - Optional
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//! - Requires Rust 1.21
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//! - Use `needs_drop` to skip overwriting if not necessary
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//! - `use_union`
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//! - Optional
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//! - Requires nightly channel
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//! - Using untagged union, finally we have an implementation of `NoDrop` without hacks,
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//! for example the fact that `NoDrop<T>` never has a destructor anymore.
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//!
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#![cfg_attr(not(any(test, feature="std")), no_std)]
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#[cfg(not(any(test, feature="std")))]
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extern crate core as std;
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#[cfg(feature = "use_union")]
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extern crate nodrop_union as imp;
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pub use imp::NoDrop;
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#[cfg(not(feature = "use_union"))]
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mod imp {
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use std::ptr;
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use std::mem;
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use std::ops::{Deref, DerefMut};
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/// repr(u8) - Make sure the non-nullable pointer optimization does not occur!
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#[repr(u8)]
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enum Flag<T> {
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Alive(T),
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// Dummy u8 field below, again to beat the enum layout opt
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Dropped(u8),
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}
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/// A type holding **T** that will not call its destructor on drop
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pub struct NoDrop<T>(Flag<T>);
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impl<T> NoDrop<T> {
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/// Create a new **NoDrop**.
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#[inline]
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pub fn new(value: T) -> NoDrop<T> {
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NoDrop(Flag::Alive(value))
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}
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/// Extract the inner value.
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///
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/// Once extracted, the value can of course drop again.
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#[inline]
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pub fn into_inner(mut self) -> T {
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let inner = unsafe {
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ptr::read(&mut *self)
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};
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// skip Drop, so we don't even have to overwrite
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mem::forget(self);
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inner
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}
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}
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#[cfg(not(feature = "use_needs_drop"))]
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#[inline]
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fn needs_drop<T>() -> bool {
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true
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}
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#[cfg(feature = "use_needs_drop")]
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#[inline]
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fn needs_drop<T>() -> bool {
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unsafe {
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::std::mem::needs_drop::<T>()
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}
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}
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impl<T> Drop for NoDrop<T> {
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fn drop(&mut self) {
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if needs_drop::<T>() {
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// inhibit drop
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unsafe {
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ptr::write(&mut self.0, Flag::Dropped(0));
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}
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}
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}
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}
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impl<T> Deref for NoDrop<T> {
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type Target = T;
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// Use type invariant, always Flag::Alive.
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#[inline]
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fn deref(&self) -> &T {
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match self.0 {
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Flag::Alive(ref inner) => inner,
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_ => unsafe { debug_assert_unreachable() }
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}
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}
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}
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impl<T> DerefMut for NoDrop<T> {
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// Use type invariant, always Flag::Alive.
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#[inline]
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fn deref_mut(&mut self) -> &mut T {
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match self.0 {
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Flag::Alive(ref mut inner) => inner,
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_ => unsafe { debug_assert_unreachable() }
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}
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}
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}
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#[cfg(test)]
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#[test]
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fn test_no_nonnullable_opt() {
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// Make sure `Flag` does not apply the non-nullable pointer optimization
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// as Option would do.
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assert!(mem::size_of::<Flag<&i32>>() > mem::size_of::<&i32>());
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assert!(mem::size_of::<Flag<Vec<i32>>>() > mem::size_of::<Vec<i32>>());
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}
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// copying this code saves us microcrate deps
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#[inline]
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unsafe fn debug_assert_unreachable() -> ! {
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debug_assert!(false, "Reached unreachable section: this is a bug!");
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enum Void { }
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match *(1 as *const Void) { }
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}
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}
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#[cfg(test)]
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mod tests {
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use super::NoDrop;
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#[test]
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fn test_drop() {
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use std::cell::Cell;
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let flag = &Cell::new(0);
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struct Bump<'a>(&'a Cell<i32>);
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impl<'a> Drop for Bump<'a> {
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fn drop(&mut self) {
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let n = self.0.get();
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self.0.set(n + 1);
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}
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}
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{
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let _ = NoDrop::new([Bump(flag), Bump(flag)]);
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}
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assert_eq!(flag.get(), 0);
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// test something with the nullable pointer optimization
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flag.set(0);
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{
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let mut array = NoDrop::new(Vec::new());
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array.push(vec![Bump(flag)]);
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array.push(vec![Bump(flag), Bump(flag)]);
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array.push(vec![]);
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array.push(vec![Bump(flag)]);
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drop(array.pop());
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assert_eq!(flag.get(), 1);
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drop(array.pop());
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assert_eq!(flag.get(), 1);
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drop(array.pop());
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assert_eq!(flag.get(), 3);
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}
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// last one didn't drop.
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assert_eq!(flag.get(), 3);
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flag.set(0);
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{
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let array = NoDrop::new(Bump(flag));
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array.into_inner();
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assert_eq!(flag.get(), 1);
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}
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assert_eq!(flag.get(), 1);
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}
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}
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