Replace inheritance_integrity by trait shenanigans

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)`

1 files changed, 0 insertions, 96 deletions

diff --git a/components/plugins/lints/inheritance_integrity.rs b/components/plugins/lints/inheritance_integrity.rs
deleted file mode 100644
index 28dea9aeb41..00000000000
--- a/components/plugins/lints/inheritance_integrity.rs
+++ /dev/null
@@ -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");
-            }
-        }
-    }
-}