use rustc::lint::*;
use rustc::ty::{self, Ty};
use rustc::hir::*;
use syntax::codemap::Span;
use utils::paths;
use utils::{is_automatically_derived, is_copy, match_path, span_lint_and_then};
declare_lint! {
pub DERIVE_HASH_XOR_EQ,
Warn,
"deriving `Hash` but implementing `PartialEq` explicitly"
}
declare_lint! {
pub EXPL_IMPL_CLONE_ON_COPY,
Warn,
"implementing `Clone` explicitly on `Copy` types"
}
pub struct Derive;
impl LintPass for Derive {
fn get_lints(&self) -> LintArray {
lint_array!(EXPL_IMPL_CLONE_ON_COPY, DERIVE_HASH_XOR_EQ)
}
}
impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Derive {
fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
if let ItemImpl(_, _, _, _, Some(ref trait_ref), _, _) = item.node {
let ty = cx.tcx.type_of(cx.tcx.hir.local_def_id(item.id));
let is_automatically_derived = is_automatically_derived(&*item.attrs);
check_hash_peq(cx, item.span, trait_ref, ty, is_automatically_derived);
if !is_automatically_derived {
check_copy_clone(cx, item, trait_ref, ty);
}
}
}
}
fn check_hash_peq<'a, 'tcx>(
cx: &LateContext<'a, 'tcx>,
span: Span,
trait_ref: &TraitRef,
ty: Ty<'tcx>,
hash_is_automatically_derived: bool,
) {
if_chain! {
if match_path(&trait_ref.path, &paths::HASH);
if let Some(peq_trait_def_id) = cx.tcx.lang_items().eq_trait();
then {
cx.tcx.for_each_relevant_impl(peq_trait_def_id, ty, |impl_id| {
let peq_is_automatically_derived = is_automatically_derived(&cx.tcx.get_attrs(impl_id));
if peq_is_automatically_derived == hash_is_automatically_derived {
return;
}
let trait_ref = cx.tcx.impl_trait_ref(impl_id).expect("must be a trait implementation");
if trait_ref.substs.type_at(1) == ty {
let mess = if peq_is_automatically_derived {
"you are implementing `Hash` explicitly but have derived `PartialEq`"
} else {
"you are deriving `Hash` but have implemented `PartialEq` explicitly"
};
span_lint_and_then(
cx, DERIVE_HASH_XOR_EQ, span,
mess,
|db| {
if let Some(node_id) = cx.tcx.hir.as_local_node_id(impl_id) {
db.span_note(
cx.tcx.hir.span(node_id),
"`PartialEq` implemented here"
);
}
});
}
});
}
}
}
fn check_copy_clone<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, item: &Item, trait_ref: &TraitRef, ty: Ty<'tcx>) {
if match_path(&trait_ref.path, &paths::CLONE_TRAIT) {
if !is_copy(cx, ty) {
return;
}
match ty.sty {
ty::TyAdt(def, _) if def.is_union() => return,
ty::TyAdt(def, substs) => for variant in &def.variants {
for field in &variant.fields {
if let ty::TyFnDef(..) = field.ty(cx.tcx, substs).sty {
return;
}
}
for subst in substs {
if let ty::subst::UnpackedKind::Type(subst) = subst.unpack() {
if let ty::TyParam(_) = subst.sty {
return;
}
}
}
},
_ => (),
}
span_lint_and_then(
cx,
EXPL_IMPL_CLONE_ON_COPY,
item.span,
"you are implementing `Clone` explicitly on a `Copy` type",
|db| {
db.span_note(item.span, "consider deriving `Clone` or removing `Copy`");
},
);
}
}