Revert changes to servo_arc, style_derive, and style_traits

This reverts the Rust edition updates to these three traits as well as
incorporates https://phabricator.services.mozilla.com/D117887. The
purpose of this change is to reduce the diff with upstream stylo.

Finally, formatting is disabled for these crates as well.

components/servo_arc/Cargo.toml

@@ -5,7 +5,6 @@ authors = ["The Servo Project Developers"]
 license = "MIT OR Apache-2.0"
 repository = "https://github.com/servo/servo"
 description = "A fork of std::sync::Arc with some extra functionality and without weak references"
-edition = "2018"
 
 [lib]
 name = "servo_arc"

components/servo_arc/lib.rs

@@ -25,23 +25,30 @@
 // duplicate those here.
 #![allow(missing_docs)]
 
+#[cfg(feature = "servo")]
+extern crate serde;
+extern crate stable_deref_trait;
+
+#[cfg(feature = "servo")]
+use serde::{Deserialize, Serialize};
+use stable_deref_trait::{CloneStableDeref, StableDeref};
 use std::alloc::{self, Layout};
+use std::borrow;
 use std::cmp::Ordering;
 use std::convert::From;
+use std::fmt;
 use std::hash::{Hash, Hasher};
 use std::iter::{ExactSizeIterator, Iterator};
 use std::marker::PhantomData;
 use std::mem::{self, align_of, size_of};
 use std::ops::{Deref, DerefMut};
 use std::os::raw::c_void;
+use std::process;
+use std::ptr;
+use std::slice;
 use std::sync::atomic;
 use std::sync::atomic::Ordering::{Acquire, Relaxed, Release};
-use std::{borrow, fmt, isize, process, ptr, slice, usize};
-
-use nodrop::NoDrop;
-#[cfg(feature = "servo")]
-use serde::{Deserialize, Serialize};
-use stable_deref_trait::{CloneStableDeref, StableDeref};
+use std::{isize, usize};
 
 /// A soft limit on the amount of references that may be made to an `Arc`.
 ///
@@ -811,6 +818,7 @@ impl<H, T> Arc<HeaderSlice<H, [T]>> {
 
     /// Creates an Arc for a HeaderSlice using the given header struct and
     /// iterator to generate the slice. The resulting Arc will be fat.
+    #[inline]
     pub fn from_header_and_iter<I>(header: H, items: I) -> Self
     where
         I: Iterator<Item = T> + ExactSizeIterator,
@@ -904,7 +912,7 @@ impl<H, T> ThinArc<H, T> {
     {
         // Synthesize transient Arc, which never touches the refcount of the ArcInner.
         let transient = unsafe {
-            NoDrop::new(Arc {
+            mem::ManuallyDrop::new(Arc {
                 p: ptr::NonNull::new_unchecked(thin_to_thick(self.ptr.as_ptr())),
                 phantom: PhantomData,
             })
@@ -913,11 +921,6 @@ impl<H, T> ThinArc<H, T> {
         // Expose the transient Arc to the callback, which may clone it if it wants.
         let result = f(&transient);
 
-        // Forget the transient Arc to leave the refcount untouched.
-        // XXXManishearth this can be removed when unions stabilize,
-        // since then NoDrop becomes zero overhead
-        mem::forget(transient);
-
         // Forward the result.
         result
     }
@@ -1129,7 +1132,7 @@ impl<'a, T> ArcBorrow<'a, T> {
     /// Compare two `ArcBorrow`s via pointer equality. Will only return
     /// true if they come from the same allocation
     pub fn ptr_eq(this: &Self, other: &Self) -> bool {
-        std::ptr::eq(this.0, other.0)
+        this.0 as *const T == other.0 as *const T
     }
 
     /// Temporarily converts |self| into a bonafide Arc and exposes it to the
@@ -1141,16 +1144,11 @@ impl<'a, T> ArcBorrow<'a, T> {
         T: 'static,
     {
         // Synthesize transient Arc, which never touches the refcount.
-        let transient = unsafe { NoDrop::new(Arc::from_raw(self.0)) };
+        let transient = unsafe { mem::ManuallyDrop::new(Arc::from_raw(self.0)) };
 
         // Expose the transient Arc to the callback, which may clone it if it wants.
         let result = f(&transient);
 
-        // Forget the transient Arc to leave the refcount untouched.
-        // XXXManishearth this can be removed when unions stabilize,
-        // since then NoDrop becomes zero overhead
-        mem::forget(transient);
-
         // Forward the result.
         result
     }
@@ -1309,13 +1307,12 @@ impl<A: fmt::Debug, B: fmt::Debug> fmt::Debug for ArcUnion<A, B> {
 
 #[cfg(test)]
 mod tests {
+    use super::{Arc, HeaderWithLength, ThinArc};
     use std::clone::Clone;
     use std::ops::Drop;
     use std::sync::atomic;
     use std::sync::atomic::Ordering::{Acquire, SeqCst};
 
-    use super::{Arc, HeaderWithLength, ThinArc};
-
     #[derive(PartialEq)]
     struct Canary(*mut atomic::AtomicUsize);
 

components/style_derive/Cargo.toml

@@ -3,7 +3,6 @@ name = "style_derive"
 version = "0.0.1"
 authors = ["The Servo Project Developers"]
 license = "MPL-2.0"
-edition = "2018"
 publish = false
 
 [lib]

components/style_derive/animate.rs

@@ -3,14 +3,10 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use darling::util::PathList;
-use darling::FromDeriveInput;
-use darling::FromField;
-use darling::FromVariant;
 use derive_common::cg;
 use proc_macro2::TokenStream;
-use quote::quote;
 use quote::TokenStreamExt;
-use syn::{parse_quote, DeriveInput, WhereClause};
+use syn::{DeriveInput, WhereClause};
 use synstructure::{Structure, VariantInfo};
 
 pub fn derive(mut input: DeriveInput) -> TokenStream {

components/style_derive/compute_squared_distance.rs

@@ -3,12 +3,10 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use crate::animate::{AnimationFieldAttrs, AnimationInputAttrs, AnimationVariantAttrs};
-use darling::FromField;
 use derive_common::cg;
 use proc_macro2::TokenStream;
-use quote::quote;
 use quote::TokenStreamExt;
-use syn::{parse_quote, DeriveInput, WhereClause};
+use syn::{DeriveInput, WhereClause};
 use synstructure;
 
 pub fn derive(mut input: DeriveInput) -> TokenStream {

components/style_derive/lib.rs

@@ -4,6 +4,17 @@
 
 #![recursion_limit = "128"]
 
+#[macro_use]
+extern crate darling;
+extern crate derive_common;
+extern crate proc_macro;
+extern crate proc_macro2;
+#[macro_use]
+extern crate quote;
+#[macro_use]
+extern crate syn;
+extern crate synstructure;
+
 use proc_macro::TokenStream;
 
 mod animate;

components/style_derive/parse.rs

@@ -3,12 +3,9 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use crate::to_css::{CssBitflagAttrs, CssVariantAttrs};
-use darling::FromField;
-use darling::FromVariant;
 use derive_common::cg;
 use proc_macro2::{Span, TokenStream};
-use quote::{quote, TokenStreamExt};
-use syn::parse_quote;
+use quote::TokenStreamExt;
 use syn::{self, DeriveInput, Ident, Path};
 use synstructure::{Structure, VariantInfo};
 
@@ -132,7 +129,7 @@ fn parse_non_keyword_variant(
         }
     } else {
         quote! {
-            if let Ok(v) = input.r#try(|i| <#ty as crate::parser::Parse>::parse(context, i)) {
+            if let Ok(v) = input.try(|i| <#ty as crate::parser::Parse>::parse(context, i)) {
                 return Ok(#name::#variant_name(v));
             }
         }

components/style_derive/specified_value_info.rs

@@ -4,14 +4,10 @@
 
 use crate::parse::ParseVariantAttrs;
 use crate::to_css::{CssFieldAttrs, CssInputAttrs, CssVariantAttrs};
-use darling::FromDeriveInput;
-use darling::FromField;
-use darling::FromVariant;
 use derive_common::cg;
 use proc_macro2::TokenStream;
-use quote::quote;
 use quote::TokenStreamExt;
-use syn::{parse_quote, Data, DeriveInput, Fields, Ident, Type};
+use syn::{Data, DeriveInput, Fields, Ident, Type};
 
 pub fn derive(mut input: DeriveInput) -> TokenStream {
     let css_attrs = cg::parse_input_attrs::<CssInputAttrs>(&input);

components/style_derive/to_animated_value.rs

@@ -2,11 +2,10 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use crate::to_computed_value;
 use proc_macro2::TokenStream;
-use quote::quote;
-use syn::{parse_quote, DeriveInput};
+use syn::DeriveInput;
 use synstructure::BindStyle;
+use to_computed_value;
 
 pub fn derive(input: DeriveInput) -> TokenStream {
     let trait_impl = |from_body, to_body| {

components/style_derive/to_animated_zero.rs

@@ -5,9 +5,8 @@
 use crate::animate::{AnimationFieldAttrs, AnimationInputAttrs, AnimationVariantAttrs};
 use derive_common::cg;
 use proc_macro2::TokenStream;
-use quote::quote;
 use quote::TokenStreamExt;
-use syn::{self, parse_quote};
+use syn;
 use synstructure;
 
 pub fn derive(mut input: syn::DeriveInput) -> TokenStream {

components/style_derive/to_computed_value.rs

@@ -2,11 +2,8 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use darling::FromField;
 use derive_common::cg;
 use proc_macro2::TokenStream;
-use quote::quote;
-use syn::parse_quote;
 use syn::{DeriveInput, Ident, Path};
 use synstructure::{BindStyle, BindingInfo};
 

components/style_derive/to_css.rs

@@ -3,15 +3,9 @@
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
 use darling::util::Override;
-use darling::FromDeriveInput;
-use darling::FromField;
-use darling::FromMeta;
-use darling::FromVariant;
 use derive_common::cg;
 use proc_macro2::{Span, TokenStream};
-use quote::quote;
 use quote::{ToTokens, TokenStreamExt};
-use syn::parse_quote;
 use syn::{self, Data, Ident, Path, WhereClause};
 use synstructure::{BindingInfo, Structure, VariantInfo};
 
@@ -209,7 +203,7 @@ fn derive_variant_fields_expr(
     let mut iter = bindings
         .iter()
         .filter_map(|binding| {
-            let attrs = cg::parse_field_attrs::<CssFieldAttrs>(binding.ast());
+            let attrs = cg::parse_field_attrs::<CssFieldAttrs>(&binding.ast());
             if attrs.skip {
                 return None;
             }

components/style_derive/to_resolved_value.rs

@@ -2,13 +2,11 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
 
-use crate::to_computed_value;
-use darling::FromField;
 use derive_common::cg;
 use proc_macro2::TokenStream;
-use quote::quote;
-use syn::{parse_quote, DeriveInput};
+use syn::DeriveInput;
 use synstructure::BindStyle;
+use to_computed_value;
 
 pub fn derive(input: DeriveInput) -> TokenStream {
     let trait_impl = |from_body, to_body| {

components/style_traits/Cargo.toml

@@ -3,7 +3,6 @@ name = "style_traits"
 version = "0.0.1"
 authors = ["The Servo Project Developers"]
 license = "MPL-2.0"
-edition = "2018"
 publish = false
 
 [lib]
@@ -22,7 +21,7 @@ euclid = "0.22"
 lazy_static = "1"
 malloc_size_of = { path = "../malloc_size_of" }
 malloc_size_of_derive = "0.1"
-selectors = { path = "../selectors", features = ["shmem"] }
+selectors = { path = "../selectors" }
 serde = "1.0"
 servo_arc = { path = "../servo_arc" }
 servo_atoms = { path = "../atoms", optional = true }

components/style_traits/arc_slice.rs

@@ -4,16 +4,14 @@
 
 //! A thin atomically-reference-counted slice.
 
+use serde::de::{Deserialize, Deserializer};
+use serde::ser::{Serialize, Serializer};
+use servo_arc::ThinArc;
 use std::ops::Deref;
 use std::ptr::NonNull;
 use std::{iter, mem};
 
-use lazy_static::lazy_static;
 use malloc_size_of::{MallocSizeOf, MallocSizeOfOps, MallocUnconditionalSizeOf};
-use serde::de::{Deserialize, Deserializer};
-use serde::ser::{Serialize, Serializer};
-use servo_arc::ThinArc;
-use to_shmem_derive::ToShmem;
 
 /// A canary that we stash in ArcSlices.
 ///

components/style_traits/dom.rs

@@ -4,10 +4,7 @@
 
 //! Types used to access the DOM from style calculation.
 
-use bitflags::bitflags;
 use malloc_size_of::malloc_size_of_is_0;
-use malloc_size_of_derive::MallocSizeOf;
-use serde::{Deserialize, Serialize};
 
 /// An opaque handle to a node, which, unlike UnsafeNode, cannot be transformed
 /// back into a non-opaque representation. The only safe operation that can be