Auto merge of #20017 - servo:derive-all-the-things, r=emilio

Optimise more AnimationValue methods 🐉🐲

```
__TEXT	__DATA	__OBJC	others	dec	hex
87101440	5226496	0	64122880	156450816	9534000	XUL.old
87072768	5226496	0	64122880	156422144	952d000	XUL.new
```

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---
This change is [<img src="https://reviewable.io/review_button.svg" height="34" align="absmiddle" alt="Reviewable"/>](https://reviewable.io/reviews/servo/servo/20017)
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components/style/properties/helpers/animated_properties.mako.rs

@@ -24,11 +24,11 @@ use properties::longhands::visibility::computed_value::T as Visibility;
 #[cfg(feature = "gecko")]
 use properties::PropertyId;
 use properties::{LonghandId, ShorthandId};
-use selectors::parser::SelectorParseErrorKind;
 use servo_arc::Arc;
 use smallvec::SmallVec;
-use std::{cmp, mem, ptr};
+use std::{cmp, ptr};
 use std::fmt::{self, Write};
+use std::mem::{self, ManuallyDrop};
 #[cfg(feature = "gecko")] use hash::FnvHashMap;
 use style_traits::{CssWriter, ParseError, ToCss};
 use super::ComputedValues;
@@ -141,21 +141,42 @@ impl TransitionProperty {
 
     /// Parse a transition-property value.
     pub fn parse<'i, 't>(input: &mut Parser<'i, 't>) -> Result<Self, ParseError<'i>> {
+        // FIXME(https://github.com/rust-lang/rust/issues/33156): remove this
+        // enum and use PropertyId when stable Rust allows destructors in
+        // statics.
+        //
+        // FIXME: This should handle aliases too.
+        pub enum StaticId {
+            All,
+            Longhand(LonghandId),
+            Shorthand(ShorthandId),
+        }
+        ascii_case_insensitive_phf_map! {
+            static_id -> StaticId = {
+                "all" => StaticId::All,
+                % for prop in data.shorthands_except_all():
+                "${prop.name}" => StaticId::Shorthand(ShorthandId::${prop.camel_case}),
+                % endfor
+                % for prop in data.longhands:
+                "${prop.name}" => StaticId::Longhand(LonghandId::${prop.camel_case}),
+                % endfor
+            }
+        }
+
         let location = input.current_source_location();
         let ident = input.expect_ident()?;
-        match_ignore_ascii_case! { &ident,
-            "all" => Ok(TransitionProperty::All),
-            % for prop in data.shorthands_except_all():
-                "${prop.name}" => Ok(TransitionProperty::Shorthand(ShorthandId::${prop.camel_case})),
-            % endfor
-            % for prop in data.longhands:
-                "${prop.name}" => Ok(TransitionProperty::Longhand(LonghandId::${prop.camel_case})),
-            % endfor
-            "none" => Err(location.new_custom_error(SelectorParseErrorKind::UnexpectedIdent(ident.clone()))),
-            _ => CustomIdent::from_ident(location, ident, &[]).map(TransitionProperty::Unsupported),
-        }
-    }
 
+        Ok(match static_id(&ident) {
+            Some(&StaticId::All) => TransitionProperty::All,
+            Some(&StaticId::Longhand(id)) => TransitionProperty::Longhand(id),
+            Some(&StaticId::Shorthand(id)) => TransitionProperty::Shorthand(id),
+            None => {
+                TransitionProperty::Unsupported(
+                    CustomIdent::from_ident(location, ident, &["none"])?,
+                )
+            },
+        })
+    }
 
     /// Convert TransitionProperty to nsCSSPropertyID.
     #[cfg(feature = "gecko")]
@@ -345,8 +366,8 @@ unsafe impl HasSimpleFFI for AnimationValueMap {}
 ///
 /// FIXME: We need to add a path for custom properties, but that's trivial after
 /// this (is a similar path to that of PropertyDeclaration).
-#[derive(Clone, Debug, PartialEq)]
 #[cfg_attr(feature = "servo", derive(MallocSizeOf))]
+#[derive(Debug)]
 #[repr(u16)]
 pub enum AnimationValue {
     % for prop in data.longhands:
@@ -370,6 +391,95 @@ pub enum AnimationValue {
             unanimated.append(prop)
 %>
 
+#[repr(C)]
+struct AnimationValueVariantRepr<T> {
+    tag: u16,
+    value: T
+}
+
+impl Clone for AnimationValue {
+    #[inline]
+    fn clone(&self) -> Self {
+        use self::AnimationValue::*;
+
+        <%
+            [copy, others] = [list(g) for _, g in groupby(animated, key=lambda x: not x.specified_is_copy())]
+        %>
+
+        let self_tag = unsafe { *(self as *const _ as *const u16) };
+        if self_tag <= LonghandId::${copy[-1].camel_case} as u16 {
+            #[derive(Clone, Copy)]
+            #[repr(u16)]
+            enum CopyVariants {
+                % for prop in copy:
+                _${prop.camel_case}(${prop.animated_type()}),
+                % endfor
+            }
+
+            unsafe {
+                let mut out = mem::uninitialized();
+                ptr::write(
+                    &mut out as *mut _ as *mut CopyVariants,
+                    *(self as *const _ as *const CopyVariants),
+                );
+                return out;
+            }
+        }
+
+        match *self {
+            % for ty, props in groupby(others, key=lambda x: x.animated_type()):
+            <% props = list(props) %>
+            ${" |\n".join("{}(ref value)".format(prop.camel_case) for prop in props)} => {
+                % if len(props) == 1:
+                ${props[0].camel_case}(value.clone())
+                % else:
+                unsafe {
+                    let mut out = ManuallyDrop::new(mem::uninitialized());
+                    ptr::write(
+                        &mut out as *mut _ as *mut AnimationValueVariantRepr<${ty}>,
+                        AnimationValueVariantRepr {
+                            tag: *(self as *const _ as *const u16),
+                            value: value.clone(),
+                        },
+                    );
+                    ManuallyDrop::into_inner(out)
+                }
+                % endif
+            }
+            % endfor
+            _ => unsafe { debug_unreachable!() }
+        }
+    }
+}
+
+impl PartialEq for AnimationValue {
+    #[inline]
+    fn eq(&self, other: &Self) -> bool {
+        use self::AnimationValue::*;
+
+        unsafe {
+            let this_tag = *(self as *const _ as *const u16);
+            let other_tag = *(other as *const _ as *const u16);
+            if this_tag != other_tag {
+                return false;
+            }
+
+            match *self {
+                % for ty, props in groupby(animated, key=lambda x: x.animated_type()):
+                ${" |\n".join("{}(ref this)".format(prop.camel_case) for prop in props)} => {
+                    let other_repr =
+                        &*(other as *const _ as *const AnimationValueVariantRepr<${ty}>);
+                    *this == other_repr.value
+                }
+                % endfor
+                ${" |\n".join("{}(void)".format(prop.camel_case) for prop in unanimated)} => {
+                    void::unreachable(void)
+                }
+            }
+        }
+    }
+}
+
 impl AnimationValue {
     /// Returns the longhand id this animated value corresponds to.
     #[inline]
@@ -564,12 +674,6 @@ fn animate_discrete<T: Clone>(this: &T, other: &T, procedure: Procedure) -> Resu
     }
 }
 
-#[repr(C)]
-struct AnimationValueVariantRepr<T> {
-    tag: u16,
-    value: T
-}
-
 impl Animate for AnimationValue {
     fn animate(&self, other: &Self, procedure: Procedure) -> Result<Self, ()> {
         Ok(unsafe {

components/style/values/computed/border.rs

@@ -88,7 +88,7 @@ impl ToAnimatedZero for BorderCornerRadius {
 /// The computed value of the `border-image-repeat` property:
 ///
 /// https://drafts.csswg.org/css-backgrounds/#the-border-image-repeat
-#[derive(Clone, Debug, MallocSizeOf, PartialEq)]
+#[derive(Clone, Copy, Debug, MallocSizeOf, PartialEq)]
 pub struct BorderImageRepeat(pub BorderImageRepeatKeyword, pub BorderImageRepeatKeyword);
 
 impl BorderImageRepeat {