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Handle ambiguous cases

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This commit is contained in:
scalexm 2017-08-02 12:17:34 +02:00
parent ac919d527c
commit da12c4f8e5
1 changed files with 34 additions and 21 deletions
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55
src/librustc_typeck/check/method/mod.rs
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@ -167,27 +167,40 @@ impl<'a, 'gcx, 'tcx> FnCtxt<'a, 'gcx, 'tcx> {
if result.rerun {
// We probe again, taking all traits into account (not only those in scope).
if let Ok(new_pick) = self.lookup_probe(span,
segment.name,
self_ty,
call_expr,
ProbeScope::AllTraits) {
// If we find a different result, the caller probably forgot to import the trait.
// We span an error with an appropriate help message.
if new_pick != pick {
let error = MethodError::NoMatch(
NoMatchData::new(Vec::new(),
Vec::new(),
vec![new_pick.item.container.id()],
probe::Mode::MethodCall)
);
self.report_method_error(span,
self_ty,
segment.name,
Some(self_expr),
error,
None);
}
let candidates =
match self.lookup_probe(span,
segment.name,
self_ty,
call_expr,
ProbeScope::AllTraits) {
Ok(ref new_pick) if *new_pick != pick => vec![new_pick.item.container.id()],
Err(MethodError::Ambiguity(ref sources)) => {
sources.iter()
.filter_map(|source| {
match *source {
// Note: this cannot come from an inherent impl,
// because the first probe succeeded.
ImplSource(def) => self.tcx.trait_id_of_impl(def),
TraitSource(_) => None,
}
})
.collect()
}
_ => Vec::new(),
};
// If we find a different result, the caller probably forgot to import a trait.
// We span an error with an appropriate help message.
if !candidates.is_empty() {
let error = MethodError::NoMatch(
NoMatchData::new(Vec::new(), Vec::new(), candidates, probe::Mode::MethodCall)
);
self.report_method_error(span,
self_ty,
segment.name,
Some(self_expr),
error,
None);
}
}