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/* 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::lint::{Context, LintPass, LintArray, Level};
use rustc::middle::def;
use rustc::middle::def_id::DefId;
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)
}
fn check_struct_def(&mut self, cx: &Context, def: &ast::StructDef, _i: ast::Ident,
_gen: &ast::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(DefId::local(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.node.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 ast::TyPath(..) = f.node.ty.node {
if let Some(&def::PathResolution { base_def: def::DefTy(def_id, _), .. }) =
cx.tcx.def_map.borrow().get(&f.node.ty.id) {
if cx.tcx.has_attr(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 {
cx.span_lint(INHERITANCE_INTEGRITY, cx.tcx.map.expect_item(id).span,
"This DOM struct has both Reflector and bare DOM struct members");
if cx.current_level(INHERITANCE_INTEGRITY) != Level::Allow {
let sess = cx.sess();
sess.span_note(sp, "Reflector found here");
for span in &dom_spans {
sess.span_note(*span, "Bare DOM struct found here");
}
}
}
// Nor should we have more than one dom struct field
} else if dom_spans.len() > 1 {
cx.span_lint(INHERITANCE_INTEGRITY, cx.tcx.map.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 {
cx.sess().span_note(*span, "Bare DOM struct found here");
}
}
} else if dom_spans.is_empty() {
cx.span_lint(INHERITANCE_INTEGRITY, cx.tcx.map.expect_item(id).span,
"This DOM struct has no reflector or parent DOM struct");
}
}
}
}
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