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Rollup merge of #97109 - TaKO8Ki:fix-misleading-cannot-infer-type-for-type-parameter-error, r=oli-obk

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Fix misleading `cannot infer type for type parameter` error

closes #93198
This commit is contained in:
Matthias Krüger 2022-05-20 19:54:39 +02:00 • committed by GitHub
commit 76f662c963
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17 changed files with 150 additions and 0 deletions
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23
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 +934,28 @@ 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(_, Some(def_id)) =
var_origin.kind
&& let Some(parent_def_id) = self.tcx.parent(def_id).as_local()
&& let Some(node) = self.tcx.hir().find_by_def_id(parent_def_id)
{
match node {
hir::Node::Item(item) if matches!(item.kind, hir::ItemKind::Impl(_) | hir::ItemKind::Fn(..)) => (),
hir::Node::ImplItem(impl_item) if matches!(impl_item.kind, hir::ImplItemKind::Fn(..)) => (),
_ => return,
}
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,