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Replace inheritance_integrity by trait shenanigans

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For each derived DomObject impl, we also generate a dummy trait
ShouldNotImplDomObject that is implemented for all T: DomObject.
We then try to implement it for each field type except the first one.
If compilation succeed, this means that field type doesn't implement
DomObject itself otherwise it would break coherence rules.

error[E0119]: conflicting implementations of trait `dom::xmlhttprequest::_IMPL_DOMOBJECT_FOR_XMLHttpRequest::ShouldNotImplDomObject` for type `((), SomeFieldTypeThatShouldNotImplementDomObject)`:
   --> /Users/nox/src/servo/components/script/dom/xmlhttprequest.rs:120:1
    |
120 | #[dom_struct]
    | ^^^^^^^^^^^^^
    | |
    | first implementation here
    | conflicting implementation for `((), SomeFieldTypeThatShouldNotImplementDomObject)`
This commit is contained in:
Anthony Ramine 2017-02-15 17:48:36 +01:00
parent 37dab8f9f2
commit a6d59d8714
7 changed files with 56 additions and 139 deletions
Download patch file Download diff file Expand all files Collapse all files

59
components/domobject_derive/lib.rs
View file

@ -14,17 +14,27 @@ pub fn expand_token_stream(input: proc_macro::TokenStream) -> proc_macro::TokenS
fn expand_string(input: &str) -> String {
let type_ = syn::parse_macro_input(input).unwrap();
let first_field_name = if let syn::Body::Struct(syn::VariantData::Struct(ref fields)) = type_.body {
let first_field = fields.first().expect("#[derive(DomObject)] should not be applied on empty structs");
first_field.ident.as_ref().unwrap()
let fields = if let syn::Body::Struct(syn::VariantData::Struct(ref fields)) = type_.body {
fields
} else {
panic!("#[derive(DomObject)] should only be applied on proper structs")
};
let (first_field, fields) = fields
.split_first()
.expect("#[derive(DomObject)] should not be applied on empty structs");
let first_field_name = first_field.ident.as_ref().unwrap();
let mut field_types = vec![];
for field in fields {
if !field_types.contains(&&field.ty) {
field_types.push(&field.ty);
}
}
let name = &type_.ident;
let (impl_generics, ty_generics, where_clause) = type_.generics.split_for_impl();
let tokens = quote! {
let mut items = quote! {
impl #impl_generics ::js::conversions::ToJSValConvertible for #name #ty_generics #where_clause {
#[allow(unsafe_code)]
unsafe fn to_jsval(&self,
@ -49,5 +59,46 @@ fn expand_string(input: &str) -> String {
}
};
let mut params = quote::Tokens::new();
params.append_separated(type_.generics.ty_params.iter().map(|param| &param.ident), ", ");
// For each field in the struct, we implement ShouldNotImplDomObject for a
// pair of all the type parameters of the DomObject and and the field type.
// This allows us to support parameterized DOM objects
// such as IteratorIterable<T>.
items.append_all(field_types.iter().map(|ty| {
quote! {
impl #impl_generics ShouldNotImplDomObject for ((#params), #ty) #where_clause {}
}
}));
let bound = syn::TyParamBound::Trait(
syn::PolyTraitRef {
bound_lifetimes: vec![],
trait_ref: syn::parse_path("::dom::bindings::reflector::DomObject").unwrap(),
},
syn::TraitBoundModifier::None
);
let mut generics = type_.generics.clone();
generics.ty_params.push(syn::TyParam {
attrs: vec![],
ident: "__T".into(),
bounds: vec![bound],
default: None,
});
let (impl_generics, _, where_clause) = generics.split_for_impl();
items.append(quote! {
trait ShouldNotImplDomObject {}
impl #impl_generics ShouldNotImplDomObject for ((#params), __T) #where_clause {}
}.as_str());
let dummy_const = syn::Ident::new(format!("_IMPL_DOMOBJECT_FOR_{}", name));
let tokens = quote! {
#[allow(non_upper_case_globals)]
const #dummy_const: () = { #items };
};
tokens.to_string()
}

3
components/plugins/jstraceable.rs
View file

@ -16,9 +16,6 @@ pub fn expand_dom_struct(cx: &mut ExtCtxt, sp: Span, _: &MetaItem, anno: Annotat
item2.attrs.push(quote_attr!(cx, #[derive(HeapSizeOf)]));
item2.attrs.push(quote_attr!(cx, #[derive(DenyPublicFields)]));
item2.attrs.push(quote_attr!(cx, #[derive(DomObject)]));
// #[dom_struct] gets consumed, so this lets us keep around a residue
// Do NOT register a modifier/decorator on this attribute
item2.attrs.push(quote_attr!(cx, #[_dom_struct_marker]));
Annotatable::Item(P(item2))
} else {
cx.span_err(sp, "#[dom_struct] applied to something other than a struct");

3
components/plugins/lib.rs
View file

@ -44,12 +44,9 @@ pub fn plugin_registrar(reg: &mut Registry) {
MultiModifier(box jstraceable::expand_dom_struct));
reg.register_late_lint_pass(box lints::unrooted_must_root::UnrootedPass::new());
reg.register_late_lint_pass(box lints::inheritance_integrity::InheritancePass);
reg.register_early_lint_pass(box lints::ban::BanPass);
reg.register_attribute("_dom_struct_marker".to_string(), Whitelisted);
reg.register_attribute("allow_unrooted_interior".to_string(), Whitelisted);
reg.register_attribute("must_root".to_string(), Whitelisted);
reg.register_attribute("servo_lang".to_string(), Whitelisted);
register_clippy(reg);
}

96
components/plugins/lints/inheritance_integrity.rs
View file

@ -1,96 +0,0 @@
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use rustc::hir::{self, def};
use rustc::lint::{LateContext, LintPass, LintArray, Level, LateLintPass, LintContext};
use syntax::ast;
use utils::match_lang_ty;
declare_lint!(INHERITANCE_INTEGRITY, Deny,
"Ensures that struct fields are properly laid out for inheritance to work");
/// Lint for ensuring proper layout of DOM structs
///
/// A DOM struct must have one Reflector field or one field
/// which itself is a DOM struct (in which case it must be the first field).
pub struct InheritancePass;
impl LintPass for InheritancePass {
fn get_lints(&self) -> LintArray {
lint_array!(INHERITANCE_INTEGRITY)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InheritancePass {
fn check_struct_def(&mut self, cx: &LateContext, def: &hir::VariantData, _n: ast::Name,
_gen: &hir::Generics, id: ast::NodeId) {
// Lints are run post expansion, so it's fine to use
// #[_dom_struct_marker] here without also checking for #[dom_struct]
if cx.tcx.has_attr(cx.tcx.hir.local_def_id(id), "_dom_struct_marker") {
// Find the reflector, if any
let reflector_span = def.fields().iter().enumerate()
.find(|&(ctr, f)| {
if match_lang_ty(cx, &*f.ty, "reflector") {
if ctr > 0 {
cx.span_lint(INHERITANCE_INTEGRITY, f.span,
"The Reflector should be the first field of the DOM \
struct");
}
return true;
}
false
})
.map(|(_, f)| f.span);
// Find all #[dom_struct] fields
let dom_spans: Vec<_> = def.fields().iter().enumerate().filter_map(|(ctr, f)| {
if let hir::TyPath(hir::QPath::Resolved(_, ref path)) = f.ty.node {
if let def::Def::PrimTy(_) = path.def {
return None;
}
if cx.tcx.has_attr(path.def.def_id(), "_dom_struct_marker") {
// If the field is not the first, it's probably
// being misused (a)
if ctr > 0 {
cx.span_lint(INHERITANCE_INTEGRITY, f.span,
"Bare DOM structs should only be used as the first field of a \
DOM struct. Consider using JS<T> instead.");
}
return Some(f.span)
}
}
None
}).collect();
// We should not have both a reflector and a dom struct field
if let Some(sp) = reflector_span {
if dom_spans.len() > 0 {
let mut db = cx.struct_span_lint(INHERITANCE_INTEGRITY,
cx.tcx.hir.expect_item(id).span,
"This DOM struct has both Reflector \
and bare DOM struct members");
if cx.current_level(INHERITANCE_INTEGRITY) != Level::Allow {
db.span_note(sp, "Reflector found here");
for span in &dom_spans {
db.span_note(*span, "Bare DOM struct found here");
}
}
}
// Nor should we have more than one dom struct field
} else if dom_spans.len() > 1 {
let mut db = cx.struct_span_lint(INHERITANCE_INTEGRITY,
cx.tcx.hir.expect_item(id).span,
"This DOM struct has multiple \
DOM struct members, only one is allowed");
if cx.current_level(INHERITANCE_INTEGRITY) != Level::Allow {
for span in &dom_spans {
db.span_note(*span, "Bare DOM struct found here");
}
}
} else if dom_spans.is_empty() {
cx.span_lint(INHERITANCE_INTEGRITY, cx.tcx.hir.expect_item(id).span,
"This DOM struct has no reflector or parent DOM struct");
}
}
}
}

1
components/plugins/lints/mod.rs
View file

@ -3,5 +3,4 @@
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
pub mod ban;
pub mod inheritance_integrity;
pub mod unrooted_must_root;

30
components/plugins/utils.rs
View file

@ -2,18 +2,13 @@
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
use rustc::hir::{self, def};
use rustc::hir::def_id::DefId;
use rustc::lint::{LateContext, LintContext};
use syntax::ast;
use syntax::attr::mark_used;
use syntax::codemap::{ExpnFormat, Span};
use syntax::ptr::P;
/// Matches a type with a provided string, and returns its type parameters if successful
///
/// Try not to use this for types defined in crates you own, use match_lang_ty instead (for lint passes)
pub fn match_ty_unwrap<'a>(ty: &'a ast::Ty, segments: &[&str]) -> Option<&'a [P<ast::Ty>]> {
match ty.node {
ast::TyKind::Path(_, ast::Path { segments: ref seg, .. }) => {
@ -42,31 +37,6 @@ pub fn match_ty_unwrap<'a>(ty: &'a ast::Ty, segments: &[&str]) -> Option<&'a [P<
}
}
/// Checks if a type has a #[servo_lang = "str"] attribute
pub fn match_lang_ty(cx: &LateContext, ty: &hir::Ty, value: &str) -> bool {
let def = match ty.node {
hir::TyPath(hir::QPath::Resolved(_, ref path)) => path.def,
_ => return false,
};
if let def::Def::PrimTy(_) = def {
return false;
}
match_lang_did(cx, def.def_id(), value)
}
pub fn match_lang_did(cx: &LateContext, did: DefId, value: &str) -> bool {
cx.tcx.get_attrs(did).iter().any(|attr| {
if attr.check_name("servo_lang") && attr.value_str().map_or(false, |v| v == value) {
mark_used(attr);
true
} else {
false
}
})
}
/// check if a DefId's path matches the given absolute type path
/// usage e.g. with
/// `match_def_path(cx, id, &["core", "option", "Option"])`

3
components/script/dom/bindings/reflector.rs
View file

@ -27,9 +27,8 @@ pub fn reflect_dom_object<T, U>(
/// A struct to store a reference to the reflector of a DOM object.
#[allow(unrooted_must_root)]
#[must_root]
#[servo_lang = "reflector"]
#[derive(HeapSizeOf)]
#[must_root]
// If you're renaming or moving this field, update the path in plugins::reflector as well
pub struct Reflector {
#[ignore_heap_size_of = "defined and measured in rust-mozjs"]