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Manually check trait implementations

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This commit is contained in:
Florian Hahn 2015-12-17 23:58:56 +01:00
parent 6093ea8039
commit ba24fbd404
1 changed files with 31 additions and 12 deletions
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43
src/librustc/middle/traits/error_reporting.rs
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@ -27,6 +27,7 @@ use fmt_macros::{Parser, Piece, Position};
use middle::def_id::DefId;
use middle::infer::InferCtxt;
use middle::ty::{self, ToPredicate, HasTypeFlags, ToPolyTraitRef, TraitRef, Ty};
use middle::ty::fast_reject;
use middle::ty::fold::TypeFoldable;
use util::nodemap::{FnvHashMap, FnvHashSet};
@ -233,20 +234,38 @@ pub fn report_selection_error<'a, 'tcx>(infcx: &InferCtxt<'a, 'tcx>,
if let Some(s) = custom_note {
err.fileline_note(obligation.cause.span, &s);
} else {
let mut impl_candidates = Vec::new();
infcx.tcx.lookup_trait_def(trait_ref.def_id())
.for_each_relevant_impl(
infcx.tcx,
trait_ref.self_ty(),
|impl_def_id| {
match infcx.tcx.impl_trait_ref(impl_def_id) {
Some(ref imp) => {
impl_candidates.push(format!(" {}", imp));
},
None => (),
infcx.tcx.populate_implementations_for_trait_if_necessary(
trait_ref.def_id());
let trait_def = infcx.tcx.lookup_trait_def(trait_ref.def_id());
let blanket_impls = trait_def.blanket_impls.borrow();
let impl_iter = blanket_impls.iter()
.filter_map(|&id|
infcx.tcx.impl_trait_ref(id));
let nonblanket = trait_def.nonblanket_impls.borrow();
let nonblanket_iter = nonblanket.values()
.flat_map(|ids|
ids.iter().filter_map(|&id|
infcx.tcx.impl_trait_ref(id)));
let simp = fast_reject::simplify_type(infcx.tcx, trait_ref.self_ty(), true);
let nonblanket_iter = nonblanket_iter.filter(|def| {
if let Some(simp) = simp {
let imp_simp = fast_reject::simplify_type(infcx.tcx, def.self_ty(), true);
if let Some(imp_simp) = imp_simp {
simp == imp_simp
} else {
false
}
} else {
true
}
);
});
let impl_candidates = impl_iter.chain(nonblanket_iter)
.map(|imp| format!(" {}", imp))
.take(5).collect::<Vec<_>>();
if impl_candidates.len() > 0 {
err.fileline_help(