Auto merge of #1012 - pepyakin:derive-partialeq-manually, r=fitzgen

Derive partialeq "manually" when possible

Fixes #879

r? @fitzgen

Author: bors-servo

src/codegen/impl_partialeq.rs

@@ -0,0 +1,122 @@
+
+use ir::comp::{CompInfo, CompKind, Field, FieldMethods};
+use ir::context::BindgenContext;
+use ir::item::{IsOpaque, Item};
+use ir::ty::{TypeKind, RUST_DERIVE_IN_ARRAY_LIMIT};
+use quote;
+
+/// Generate a manual implementation of `PartialEq` trait for the
+/// specified compound type.
+pub fn gen_partialeq_impl(
+    ctx: &BindgenContext,
+    comp_info: &CompInfo,
+    item: &Item,
+    ty_for_impl: &quote::Tokens,
+) -> Option<quote::Tokens> {
+    let mut tokens = vec![];
+
+    if item.is_opaque(ctx, &()) {
+        tokens.push(quote! {
+            &self._bindgen_opaque_blob[..] == &other._bindgen_opaque_blob[..]
+        });
+    } else if comp_info.kind() == CompKind::Union {
+        assert!(!ctx.options().rust_features().untagged_union());
+        tokens.push(quote! {
+            &self.bindgen_union_field[..] == &other.bindgen_union_field[..]
+        });
+    } else {
+        for base in comp_info.base_members().iter() {
+            if !base.requires_storage(ctx) {
+                continue;
+            }
+
+            let ty_item = ctx.resolve_item(base.ty);
+            let field_name = &base.field_name;
+
+            if ty_item.is_opaque(ctx, &()) {
+                let field_name = ctx.rust_ident(field_name);
+                tokens.push(quote! {
+                    &self. #field_name [..] == &other. #field_name [..]
+                });
+            } else {
+                tokens.push(gen_field(ctx, ty_item, field_name));
+            }
+        }
+
+        for field in comp_info.fields() {
+            match *field {
+                Field::DataMember(ref fd) => {
+                    let ty_item = ctx.resolve_item(fd.ty());
+                    let name = fd.name().unwrap();
+                    tokens.push(gen_field(ctx, ty_item, name));
+                }
+                Field::Bitfields(ref bu) => for bitfield in bu.bitfields() {
+                    let name_ident = ctx.rust_ident_raw(bitfield.name());
+                    tokens.push(quote! {
+                        self.#name_ident () == other.#name_ident ()
+                    });
+                },
+            }
+        }
+    }
+
+    Some(quote! {
+        fn eq(&self, other: & #ty_for_impl) -> bool {
+            #( #tokens )&&*
+        }
+    })
+}
+
+fn gen_field(ctx: &BindgenContext, ty_item: &Item, name: &str) -> quote::Tokens {
+    fn quote_equals(name_ident: quote::Ident) -> quote::Tokens {
+        quote! { self.#name_ident == other.#name_ident }
+    }
+
+    let name_ident = ctx.rust_ident(name);
+    let ty = ty_item.expect_type();
+
+    match *ty.kind() {
+        TypeKind::Void |
+        TypeKind::NullPtr |
+        TypeKind::Int(..) |
+        TypeKind::Complex(..) |
+        TypeKind::Float(..) |
+        TypeKind::Enum(..) |
+        TypeKind::TypeParam |
+        TypeKind::UnresolvedTypeRef(..) |
+        TypeKind::BlockPointer |
+        TypeKind::Reference(..) |
+        TypeKind::ObjCInterface(..) |
+        TypeKind::ObjCId |
+        TypeKind::ObjCSel |
+        TypeKind::Comp(..) |
+        TypeKind::Pointer(_) |
+        TypeKind::Function(..) |
+        TypeKind::Opaque => quote_equals(name_ident),
+
+        TypeKind::TemplateInstantiation(ref inst) => {
+            if inst.is_opaque(ctx, &ty_item) {
+                quote! {
+                    &self. #name_ident [..] == &other. #name_ident [..]
+                }
+            } else {
+                quote_equals(name_ident)
+            }
+        }
+
+        TypeKind::Array(_, len) => if len <= RUST_DERIVE_IN_ARRAY_LIMIT {
+            quote_equals(name_ident)
+        } else {
+            quote! {
+                &self. #name_ident [..] == &other. #name_ident [..]
+            }
+        },
+
+        TypeKind::ResolvedTypeRef(t) |
+        TypeKind::TemplateAlias(t, _) |
+        TypeKind::Alias(t) => {
+            let inner_item = ctx.resolve_item(t);
+            gen_field(ctx, inner_item, name)
+        }
+    }
+}

src/codegen/mod.rs

@@ -1,4 +1,5 @@
 mod impl_debug;
+mod impl_partialeq;
 mod error;
 mod helpers;
 pub mod struct_layout;
@@ -14,7 +15,7 @@ use ir::comp::{Base, Bitfield, BitfieldUnit, CompInfo, CompKind, Field,
 use ir::context::{BindgenContext, ItemId};
 use ir::derive::{CanDeriveCopy, CanDeriveDebug, CanDeriveDefault,
                  CanDeriveHash, CanDerivePartialOrd, CanDeriveOrd,
-                 CanDerivePartialEq, CanDeriveEq};
+                 CanDerivePartialEq, CanDeriveEq, CannotDeriveReason};
 use ir::dot;
 use ir::enum_ty::{Enum, EnumVariant, EnumVariantValue};
 use ir::function::{Abi, Function, FunctionSig};
@@ -1420,6 +1421,7 @@ impl CodeGenerator for CompInfo {
         let mut needs_clone_impl = false;
         let mut needs_default_impl = false;
         let mut needs_debug_impl = false;
+        let mut needs_partialeq_impl = false;
         if let Some(comment) = item.comment(ctx) {
             attributes.push(attributes::doc(comment));
         }
@@ -1475,6 +1477,14 @@ impl CodeGenerator for CompInfo {
 
         if item.can_derive_partialeq(ctx) {
             derives.push("PartialEq");
+        } else {
+            needs_partialeq_impl = 
+                ctx.options().derive_partialeq && 
+                ctx.options().impl_partialeq &&
+                ctx.lookup_can_derive_partialeq_or_partialord(item.id())
+                    .map_or(true, |x| {
+                        x == CannotDeriveReason::ArrayTooLarge
+                    });
         }
 
         if item.can_derive_eq(ctx) {
@@ -1535,25 +1545,14 @@ impl CodeGenerator for CompInfo {
             }
 
             for base in self.base_members() {
-                // Virtual bases are already taken into account by the vtable
-                // pointer.
-                //
-                // FIXME(emilio): Is this always right?
-                if base.is_virtual() {
-                    continue;
-                }
-
-                let base_ty = ctx.resolve_type(base.ty);
-                // NB: We won't include unsized types in our base chain because they
-                // would contribute to our size given the dummy field we insert for
-                // unsized types.
-                if base_ty.is_unsized(ctx, base.ty) {
+                if !base.requires_storage(ctx) {
                     continue;
                 }
 
                 let inner = base.ty.to_rust_ty_or_opaque(ctx, &());
                 let field_name = ctx.rust_ident(&base.field_name);
 
+                let base_ty = ctx.resolve_type(base.ty);
                 struct_layout.saw_base(base_ty);
 
                 fields.push(quote! {
@@ -1667,33 +1666,34 @@ impl CodeGenerator for CompInfo {
             }
         }
 
-        let mut generics = quote! {};
+        let mut generic_param_names = vec![];
 
         if let Some(ref params) = used_template_params {
-            if !params.is_empty() {
-                let mut param_names = vec![];
+            for (idx, ty) in params.iter().enumerate() {
+                let param = ctx.resolve_type(*ty);
+                let name = param.name().unwrap();
+                let ident = ctx.rust_ident(name);
+                generic_param_names.push(ident.clone());
 
-                for (idx, ty) in params.iter().enumerate() {
-                    let param = ctx.resolve_type(*ty);
-                    let name = param.name().unwrap();
-                    let ident = ctx.rust_ident(name);
-                    param_names.push(ident.clone());
-
-                    let prefix = ctx.trait_prefix();
-                    let field_name = ctx.rust_ident(format!("_phantom_{}", idx));
-                    fields.push(quote! {
-                        pub #field_name : ::#prefix::marker::PhantomData<
-                            ::#prefix::cell::UnsafeCell<#ident>
-                        > ,
-                    });
-                }
-
-                generics = quote! {
-                    < #( #param_names ),* >
-                };
+                let prefix = ctx.trait_prefix();
+                let field_name = ctx.rust_ident(format!("_phantom_{}", idx));
+                fields.push(quote! {
+                    pub #field_name : ::#prefix::marker::PhantomData<
+                        ::#prefix::cell::UnsafeCell<#ident>
+                    > ,
+                });
             }
         }
 
+        let generics = if !generic_param_names.is_empty() {
+            let generic_param_names = generic_param_names.clone();
+            quote! {
+                < #( #generic_param_names ),* >
+            }
+        } else {
+            quote! { }
+        };
+
         tokens.append(quote! {
             #generics {
                 #( #fields )*
@@ -1896,6 +1896,27 @@ impl CodeGenerator for CompInfo {
             });
         }
 
+        if needs_partialeq_impl {
+            if let Some(impl_) = impl_partialeq::gen_partialeq_impl(ctx, self, item, &ty_for_impl) {
+                
+                let partialeq_bounds = if !generic_param_names.is_empty() {
+                    let bounds = generic_param_names.iter().map(|t| {
+                        quote! { #t: PartialEq }
+                    });
+                    quote! { where #( #bounds ),* }
+                } else {
+                    quote! { }
+                };
+
+                let prefix = ctx.trait_prefix();
+                result.push(quote! {
+                    impl #generics ::#prefix::cmp::PartialEq for #ty_for_impl #partialeq_bounds {
+                        #impl_
+                    }
+                });
+            }
+        }
+
         if !methods.is_empty() {
             result.push(quote! {
                 impl #generics #ty_for_impl {