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Make sure to ignore elided lifetimes when pointing at args for fulfillment errors

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This commit is contained in:
Michael Goulet 2024-11-12 02:08:30 +00:00
parent 81eef2d362
commit d128c80c7a
7 changed files with 42 additions and 13 deletions
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20
compiler/rustc_hir_typeck/src/fn_ctxt/adjust_fulfillment_errors.rs
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@ -316,12 +316,24 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
.tcx
.generics_of(def_id)
.own_args(ty::GenericArgs::identity_for_item(self.tcx, def_id));
let Some((index, _)) =
own_args.iter().enumerate().find(|(_, arg)| **arg == param_to_point_at)
else {
let Some(mut index) = own_args.iter().position(|arg| *arg == param_to_point_at) else {
return false;
};
let Some(arg) = segment.args().args.get(index) else {
// SUBTLE: We may or may not turbofish lifetime arguments, which will
// otherwise be elided. if our "own args" starts with a lifetime, but
// the args list does not, then we should chop off all of the lifetimes,
// since they're all elided.
let segment_args = segment.args().args;
if matches!(own_args[0].unpack(), ty::GenericArgKind::Lifetime(_))
&& segment_args.first().is_some_and(|arg| arg.is_ty_or_const())
&& let Some(offset) = own_args.iter().position(|arg| {
matches!(arg.unpack(), ty::GenericArgKind::Type(_) | ty::GenericArgKind::Const(_))
})
&& let Some(new_index) = index.checked_sub(offset)
{
index = new_index;
}
let Some(arg) = segment_args.get(index) else {
return false;
};
error.obligation.cause.span = arg