bjoernager/rust
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fix misleading cannot infer type for type parameter error

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This commit is contained in:
Takayuki Maeda 2022-05-17 17:34:58 +09:00
parent ebb80ec4e9
commit 910979a6d4
4 changed files with 59 additions and 0 deletions
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22
compiler/rustc_infer/src/infer/error_reporting/need_type_info.rs
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@ -866,6 +866,7 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
}
}
self.report_ambiguous_type_parameter(&mut err, arg);
err.span_label(
span,
arg_data.cannot_infer_msg(use_diag.filter(|d| d.applies_to(span))),
@ -933,6 +934,27 @@ impl<'a, 'tcx> InferCtxt<'a, 'tcx> {
}
}
fn report_ambiguous_type_parameter(&self, err: &mut Diagnostic, arg: GenericArg<'tcx>) {
if let GenericArgKind::Type(ty) = arg.unpack()
&& let ty::Infer(ty::TyVar(ty_vid)) = *ty.kind()
{
let mut inner = self.inner.borrow_mut();
let ty_vars = &inner.type_variables();
let var_origin = ty_vars.var_origin(ty_vid);
if let TypeVariableOriginKind::TypeParameterDefinition(name, Some(def_id)) =
var_origin.kind
&& let Some(parent_def_id) = self.tcx.parent(def_id).as_local()
&& let Some(hir::Node::Item(item)) = self.tcx.hir().find_by_def_id(parent_def_id)
&& let hir::ItemKind::Impl(impl_item) = item.kind
&& let Some(trait_ref) = &impl_item.of_trait
&& let Some(did) = trait_ref.trait_def_id()
&& self.tcx.generics_of(did).params.iter().any(|param| param.name == name)
{
err.span_help(self.tcx.def_span(def_id), "type parameter declared here");
}
}
}
pub fn need_type_info_err_in_generator(
&self,
kind: hir::GeneratorKind,