Split fn_ctxt/adjust_fulfillment_errors from fn_ctxt/checks
This commit is contained in:
Nathan Fenner
parent
e1eaa2d5d4
commit
4c053668d6
2 changed files with 374 additions and 370 deletions
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@ -1,10 +1,382 @@
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use crate::FnCtxt;
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use crate::FnCtxt;
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use rustc_hir as hir;
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use rustc_hir as hir;
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use rustc_hir::def::Res;
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use rustc_hir::def::Res;
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use rustc_middle::ty::{self, DefIdTree, Ty};
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use rustc_hir::def_id::DefId;
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use rustc_infer::traits::ObligationCauseCode;
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use rustc_middle::ty::{self, DefIdTree, Ty, TypeSuperVisitable, TypeVisitable, TypeVisitor};
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use rustc_span::{self, Span};
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use rustc_trait_selection::traits;
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use rustc_trait_selection::traits;
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use std::ops::ControlFlow;
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impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
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pub fn adjust_fulfillment_error_for_expr_obligation(
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&self,
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error: &mut traits::FulfillmentError<'tcx>,
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) -> bool {
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let (traits::ExprItemObligation(def_id, hir_id, idx) | traits::ExprBindingObligation(def_id, _, hir_id, idx))
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= *error.obligation.cause.code().peel_derives() else { return false; };
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let hir = self.tcx.hir();
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let hir::Node::Expr(expr) = hir.get(hir_id) else { return false; };
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let Some(unsubstituted_pred) =
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self.tcx.predicates_of(def_id).instantiate_identity(self.tcx).predicates.into_iter().nth(idx)
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else { return false; };
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let generics = self.tcx.generics_of(def_id);
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let predicate_substs = match unsubstituted_pred.kind().skip_binder() {
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ty::PredicateKind::Clause(ty::Clause::Trait(pred)) => pred.trait_ref.substs,
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ty::PredicateKind::Clause(ty::Clause::Projection(pred)) => pred.projection_ty.substs,
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_ => ty::List::empty(),
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};
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let find_param_matching = |matches: &dyn Fn(&ty::ParamTy) -> bool| {
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predicate_substs.types().find_map(|ty| {
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ty.walk().find_map(|arg| {
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if let ty::GenericArgKind::Type(ty) = arg.unpack()
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&& let ty::Param(param_ty) = ty.kind()
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&& matches(param_ty)
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{
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Some(arg)
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} else {
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None
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}
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})
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})
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};
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// Prefer generics that are local to the fn item, since these are likely
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// to be the cause of the unsatisfied predicate.
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let mut param_to_point_at = find_param_matching(&|param_ty| {
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self.tcx.parent(generics.type_param(param_ty, self.tcx).def_id) == def_id
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});
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// Fall back to generic that isn't local to the fn item. This will come
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// from a trait or impl, for example.
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let mut fallback_param_to_point_at = find_param_matching(&|param_ty| {
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self.tcx.parent(generics.type_param(param_ty, self.tcx).def_id) != def_id
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&& param_ty.name != rustc_span::symbol::kw::SelfUpper
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});
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// Finally, the `Self` parameter is possibly the reason that the predicate
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// is unsatisfied. This is less likely to be true for methods, because
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// method probe means that we already kinda check that the predicates due
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// to the `Self` type are true.
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let mut self_param_to_point_at =
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find_param_matching(&|param_ty| param_ty.name == rustc_span::symbol::kw::SelfUpper);
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// Finally, for ambiguity-related errors, we actually want to look
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// for a parameter that is the source of the inference type left
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// over in this predicate.
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if let traits::FulfillmentErrorCode::CodeAmbiguity = error.code {
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fallback_param_to_point_at = None;
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self_param_to_point_at = None;
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param_to_point_at =
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self.find_ambiguous_parameter_in(def_id, error.root_obligation.predicate);
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}
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if self.closure_span_overlaps_error(error, expr.span) {
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return false;
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}
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match &expr.kind {
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hir::ExprKind::Path(qpath) => {
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if let hir::Node::Expr(hir::Expr {
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kind: hir::ExprKind::Call(callee, args),
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hir_id: call_hir_id,
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span: call_span,
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..
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}) = hir.get_parent(expr.hir_id)
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&& callee.hir_id == expr.hir_id
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{
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if self.closure_span_overlaps_error(error, *call_span) {
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return false;
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}
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for param in
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[param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
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.into_iter()
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.flatten()
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{
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if self.blame_specific_arg_if_possible(
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error,
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def_id,
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param,
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*call_hir_id,
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callee.span,
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None,
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args,
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)
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{
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return true;
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}
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}
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}
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// Notably, we only point to params that are local to the
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// item we're checking, since those are the ones we are able
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// to look in the final `hir::PathSegment` for. Everything else
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// would require a deeper search into the `qpath` than I think
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// is worthwhile.
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if let Some(param_to_point_at) = param_to_point_at
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&& self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath)
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{
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return true;
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}
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}
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hir::ExprKind::MethodCall(segment, receiver, args, ..) => {
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for param in [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
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.into_iter()
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.flatten()
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{
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if self.blame_specific_arg_if_possible(
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error,
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def_id,
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param,
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hir_id,
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segment.ident.span,
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Some(receiver),
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args,
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) {
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return true;
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}
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}
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if let Some(param_to_point_at) = param_to_point_at
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&& self.point_at_generic_if_possible(error, def_id, param_to_point_at, segment)
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{
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return true;
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}
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}
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hir::ExprKind::Struct(qpath, fields, ..) => {
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if let Res::Def(
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hir::def::DefKind::Struct | hir::def::DefKind::Variant,
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variant_def_id,
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) = self.typeck_results.borrow().qpath_res(qpath, hir_id)
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{
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for param in
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[param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
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{
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if let Some(param) = param {
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let refined_expr = self.point_at_field_if_possible(
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def_id,
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param,
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variant_def_id,
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fields,
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);
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match refined_expr {
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None => {}
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Some((refined_expr, _)) => {
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error.obligation.cause.span = refined_expr
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.span
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.find_ancestor_in_same_ctxt(error.obligation.cause.span)
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.unwrap_or(refined_expr.span);
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return true;
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}
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}
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}
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}
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}
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if let Some(param_to_point_at) = param_to_point_at
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&& self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath)
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{
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return true;
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}
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}
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_ => {}
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}
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false
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}
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fn point_at_path_if_possible(
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&self,
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error: &mut traits::FulfillmentError<'tcx>,
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def_id: DefId,
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param: ty::GenericArg<'tcx>,
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qpath: &hir::QPath<'tcx>,
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) -> bool {
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match qpath {
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hir::QPath::Resolved(_, path) => {
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if let Some(segment) = path.segments.last()
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&& self.point_at_generic_if_possible(error, def_id, param, segment)
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{
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return true;
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}
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}
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hir::QPath::TypeRelative(_, segment) => {
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if self.point_at_generic_if_possible(error, def_id, param, segment) {
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return true;
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}
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}
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_ => {}
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}
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false
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}
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fn point_at_generic_if_possible(
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&self,
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error: &mut traits::FulfillmentError<'tcx>,
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def_id: DefId,
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param_to_point_at: ty::GenericArg<'tcx>,
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segment: &hir::PathSegment<'tcx>,
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) -> bool {
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let own_substs = self
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.tcx
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.generics_of(def_id)
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.own_substs(ty::InternalSubsts::identity_for_item(self.tcx, def_id));
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let Some((index, _)) = own_substs
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.iter()
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.filter(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_)))
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.enumerate()
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.find(|(_, arg)| **arg == param_to_point_at) else { return false };
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let Some(arg) = segment
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.args()
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.args
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.iter()
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.filter(|arg| matches!(arg, hir::GenericArg::Type(_)))
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.nth(index) else { return false; };
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error.obligation.cause.span = arg
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.span()
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.find_ancestor_in_same_ctxt(error.obligation.cause.span)
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.unwrap_or(arg.span());
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true
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}
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fn find_ambiguous_parameter_in<T: TypeVisitable<'tcx>>(
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&self,
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item_def_id: DefId,
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t: T,
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) -> Option<ty::GenericArg<'tcx>> {
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struct FindAmbiguousParameter<'a, 'tcx>(&'a FnCtxt<'a, 'tcx>, DefId);
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impl<'tcx> TypeVisitor<'tcx> for FindAmbiguousParameter<'_, 'tcx> {
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type BreakTy = ty::GenericArg<'tcx>;
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fn visit_ty(&mut self, ty: Ty<'tcx>) -> std::ops::ControlFlow<Self::BreakTy> {
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if let Some(origin) = self.0.type_var_origin(ty)
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&& let rustc_infer::infer::type_variable::TypeVariableOriginKind::TypeParameterDefinition(_, Some(def_id)) =
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origin.kind
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&& let generics = self.0.tcx.generics_of(self.1)
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&& let Some(index) = generics.param_def_id_to_index(self.0.tcx, def_id)
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&& let Some(subst) = ty::InternalSubsts::identity_for_item(self.0.tcx, self.1)
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.get(index as usize)
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{
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ControlFlow::Break(*subst)
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} else {
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ty.super_visit_with(self)
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}
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}
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}
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t.visit_with(&mut FindAmbiguousParameter(self, item_def_id)).break_value()
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}
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fn closure_span_overlaps_error(
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&self,
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error: &traits::FulfillmentError<'tcx>,
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span: Span,
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) -> bool {
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if let traits::FulfillmentErrorCode::CodeSelectionError(
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traits::SelectionError::OutputTypeParameterMismatch(_, expected, _),
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) = error.code
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&& let ty::Closure(def_id, _) | ty::Generator(def_id, ..) = expected.skip_binder().self_ty().kind()
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&& span.overlaps(self.tcx.def_span(*def_id))
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{
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true
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} else {
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false
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}
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}
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fn point_at_field_if_possible(
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&self,
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def_id: DefId,
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param_to_point_at: ty::GenericArg<'tcx>,
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variant_def_id: DefId,
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expr_fields: &[hir::ExprField<'tcx>],
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) -> Option<(&'tcx hir::Expr<'tcx>, Ty<'tcx>)> {
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let def = self.tcx.adt_def(def_id);
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let identity_substs = ty::InternalSubsts::identity_for_item(self.tcx, def_id);
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let fields_referencing_param: Vec<_> = def
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.variant_with_id(variant_def_id)
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.fields
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.iter()
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.filter(|field| {
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let field_ty = field.ty(self.tcx, identity_substs);
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Self::find_param_in_ty(field_ty.into(), param_to_point_at)
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})
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.collect();
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if let [field] = fields_referencing_param.as_slice() {
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for expr_field in expr_fields {
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// Look for the ExprField that matches the field, using the
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// same rules that check_expr_struct uses for macro hygiene.
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if self.tcx.adjust_ident(expr_field.ident, variant_def_id) == field.ident(self.tcx)
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{
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return Some((expr_field.expr, self.tcx.type_of(field.did)));
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}
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}
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}
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None
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}
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/// - `blame_specific_*` means that the function will recursively traverse the expression,
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/// looking for the most-specific-possible span to blame.
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///
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/// - `point_at_*` means that the function will only go "one level", pointing at the specific
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/// expression mentioned.
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///
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/// `blame_specific_arg_if_possible` will find the most-specific expression anywhere inside
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/// the provided function call expression, and mark it as responsible for the fullfillment
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/// error.
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fn blame_specific_arg_if_possible(
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&self,
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error: &mut traits::FulfillmentError<'tcx>,
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def_id: DefId,
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param_to_point_at: ty::GenericArg<'tcx>,
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call_hir_id: hir::HirId,
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callee_span: Span,
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receiver: Option<&'tcx hir::Expr<'tcx>>,
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args: &'tcx [hir::Expr<'tcx>],
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) -> bool {
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let ty = self.tcx.type_of(def_id);
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if !ty.is_fn() {
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return false;
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}
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let sig = ty.fn_sig(self.tcx).skip_binder();
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let args_referencing_param: Vec<_> = sig
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.inputs()
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.iter()
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.enumerate()
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.filter(|(_, ty)| Self::find_param_in_ty((**ty).into(), param_to_point_at))
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.collect();
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// If there's one field that references the given generic, great!
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if let [(idx, _)] = args_referencing_param.as_slice()
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&& let Some(arg) = receiver
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.map_or(args.get(*idx), |rcvr| if *idx == 0 { Some(rcvr) } else { args.get(*idx - 1) }) {
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||||||
|
error.obligation.cause.span = arg.span.find_ancestor_in_same_ctxt(error.obligation.cause.span).unwrap_or(arg.span);
|
||||||
|
|
||||||
|
if let hir::Node::Expr(arg_expr) = self.tcx.hir().get(arg.hir_id) {
|
||||||
|
// This is more specific than pointing at the entire argument.
|
||||||
|
self.blame_specific_expr_if_possible(error, arg_expr)
|
||||||
|
}
|
||||||
|
|
||||||
|
error.obligation.cause.map_code(|parent_code| {
|
||||||
|
ObligationCauseCode::FunctionArgumentObligation {
|
||||||
|
arg_hir_id: arg.hir_id,
|
||||||
|
call_hir_id,
|
||||||
|
parent_code,
|
||||||
|
}
|
||||||
|
});
|
||||||
|
return true;
|
||||||
|
} else if args_referencing_param.len() > 0 {
|
||||||
|
// If more than one argument applies, then point to the callee span at least...
|
||||||
|
// We have chance to fix this up further in `point_at_generics_if_possible`
|
||||||
|
error.obligation.cause.span = callee_span;
|
||||||
|
}
|
||||||
|
|
||||||
|
false
|
||||||
|
}
|
||||||
|
|
||||||
/**
|
/**
|
||||||
* Recursively searches for the most-specific blamable expression.
|
* Recursively searches for the most-specific blamable expression.
|
||||||
* For example, if you have a chain of constraints like:
|
* For example, if you have a chain of constraints like:
|
||||||
|
|
|
||||||
|
|
@ -26,7 +26,7 @@ use rustc_infer::infer::InferOk;
|
||||||
use rustc_infer::infer::TypeTrace;
|
use rustc_infer::infer::TypeTrace;
|
||||||
use rustc_middle::ty::adjustment::AllowTwoPhase;
|
use rustc_middle::ty::adjustment::AllowTwoPhase;
|
||||||
use rustc_middle::ty::visit::TypeVisitable;
|
use rustc_middle::ty::visit::TypeVisitable;
|
||||||
use rustc_middle::ty::{self, DefIdTree, IsSuggestable, Ty, TypeSuperVisitable, TypeVisitor};
|
use rustc_middle::ty::{self, DefIdTree, IsSuggestable, Ty};
|
||||||
use rustc_session::Session;
|
use rustc_session::Session;
|
||||||
use rustc_span::symbol::{kw, Ident};
|
use rustc_span::symbol::{kw, Ident};
|
||||||
use rustc_span::{self, sym, Span};
|
use rustc_span::{self, sym, Span};
|
||||||
|
|
@ -36,8 +36,6 @@ use std::iter;
|
||||||
use std::mem;
|
use std::mem;
|
||||||
use std::slice;
|
use std::slice;
|
||||||
|
|
||||||
use std::ops::ControlFlow;
|
|
||||||
|
|
||||||
impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
||||||
pub(in super::super) fn check_casts(&mut self) {
|
pub(in super::super) fn check_casts(&mut self) {
|
||||||
// don't hold the borrow to deferred_cast_checks while checking to avoid borrow checker errors
|
// don't hold the borrow to deferred_cast_checks while checking to avoid borrow checker errors
|
||||||
|
|
@ -1758,372 +1756,6 @@ impl<'a, 'tcx> FnCtxt<'a, 'tcx> {
|
||||||
}
|
}
|
||||||
}
|
}
|
||||||
|
|
||||||
fn adjust_fulfillment_error_for_expr_obligation(
|
|
||||||
&self,
|
|
||||||
error: &mut traits::FulfillmentError<'tcx>,
|
|
||||||
) -> bool {
|
|
||||||
let (traits::ExprItemObligation(def_id, hir_id, idx) | traits::ExprBindingObligation(def_id, _, hir_id, idx))
|
|
||||||
= *error.obligation.cause.code().peel_derives() else { return false; };
|
|
||||||
let hir = self.tcx.hir();
|
|
||||||
let hir::Node::Expr(expr) = hir.get(hir_id) else { return false; };
|
|
||||||
|
|
||||||
let Some(unsubstituted_pred) =
|
|
||||||
self.tcx.predicates_of(def_id).instantiate_identity(self.tcx).predicates.into_iter().nth(idx)
|
|
||||||
else { return false; };
|
|
||||||
|
|
||||||
let generics = self.tcx.generics_of(def_id);
|
|
||||||
let predicate_substs = match unsubstituted_pred.kind().skip_binder() {
|
|
||||||
ty::PredicateKind::Clause(ty::Clause::Trait(pred)) => pred.trait_ref.substs,
|
|
||||||
ty::PredicateKind::Clause(ty::Clause::Projection(pred)) => pred.projection_ty.substs,
|
|
||||||
_ => ty::List::empty(),
|
|
||||||
};
|
|
||||||
|
|
||||||
let find_param_matching = |matches: &dyn Fn(&ty::ParamTy) -> bool| {
|
|
||||||
predicate_substs.types().find_map(|ty| {
|
|
||||||
ty.walk().find_map(|arg| {
|
|
||||||
if let ty::GenericArgKind::Type(ty) = arg.unpack()
|
|
||||||
&& let ty::Param(param_ty) = ty.kind()
|
|
||||||
&& matches(param_ty)
|
|
||||||
{
|
|
||||||
Some(arg)
|
|
||||||
} else {
|
|
||||||
None
|
|
||||||
}
|
|
||||||
})
|
|
||||||
})
|
|
||||||
};
|
|
||||||
|
|
||||||
// Prefer generics that are local to the fn item, since these are likely
|
|
||||||
// to be the cause of the unsatisfied predicate.
|
|
||||||
let mut param_to_point_at = find_param_matching(&|param_ty| {
|
|
||||||
self.tcx.parent(generics.type_param(param_ty, self.tcx).def_id) == def_id
|
|
||||||
});
|
|
||||||
// Fall back to generic that isn't local to the fn item. This will come
|
|
||||||
// from a trait or impl, for example.
|
|
||||||
let mut fallback_param_to_point_at = find_param_matching(&|param_ty| {
|
|
||||||
self.tcx.parent(generics.type_param(param_ty, self.tcx).def_id) != def_id
|
|
||||||
&& param_ty.name != rustc_span::symbol::kw::SelfUpper
|
|
||||||
});
|
|
||||||
// Finally, the `Self` parameter is possibly the reason that the predicate
|
|
||||||
// is unsatisfied. This is less likely to be true for methods, because
|
|
||||||
// method probe means that we already kinda check that the predicates due
|
|
||||||
// to the `Self` type are true.
|
|
||||||
let mut self_param_to_point_at =
|
|
||||||
find_param_matching(&|param_ty| param_ty.name == rustc_span::symbol::kw::SelfUpper);
|
|
||||||
|
|
||||||
// Finally, for ambiguity-related errors, we actually want to look
|
|
||||||
// for a parameter that is the source of the inference type left
|
|
||||||
// over in this predicate.
|
|
||||||
if let traits::FulfillmentErrorCode::CodeAmbiguity = error.code {
|
|
||||||
fallback_param_to_point_at = None;
|
|
||||||
self_param_to_point_at = None;
|
|
||||||
param_to_point_at =
|
|
||||||
self.find_ambiguous_parameter_in(def_id, error.root_obligation.predicate);
|
|
||||||
}
|
|
||||||
|
|
||||||
if self.closure_span_overlaps_error(error, expr.span) {
|
|
||||||
return false;
|
|
||||||
}
|
|
||||||
|
|
||||||
match &expr.kind {
|
|
||||||
hir::ExprKind::Path(qpath) => {
|
|
||||||
if let hir::Node::Expr(hir::Expr {
|
|
||||||
kind: hir::ExprKind::Call(callee, args),
|
|
||||||
hir_id: call_hir_id,
|
|
||||||
span: call_span,
|
|
||||||
..
|
|
||||||
}) = hir.get_parent(expr.hir_id)
|
|
||||||
&& callee.hir_id == expr.hir_id
|
|
||||||
{
|
|
||||||
if self.closure_span_overlaps_error(error, *call_span) {
|
|
||||||
return false;
|
|
||||||
}
|
|
||||||
|
|
||||||
for param in
|
|
||||||
[param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
|
|
||||||
.into_iter()
|
|
||||||
.flatten()
|
|
||||||
{
|
|
||||||
if self.blame_specific_arg_if_possible(
|
|
||||||
error,
|
|
||||||
def_id,
|
|
||||||
param,
|
|
||||||
*call_hir_id,
|
|
||||||
callee.span,
|
|
||||||
None,
|
|
||||||
args,
|
|
||||||
)
|
|
||||||
{
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
}
|
|
||||||
// Notably, we only point to params that are local to the
|
|
||||||
// item we're checking, since those are the ones we are able
|
|
||||||
// to look in the final `hir::PathSegment` for. Everything else
|
|
||||||
// would require a deeper search into the `qpath` than I think
|
|
||||||
// is worthwhile.
|
|
||||||
if let Some(param_to_point_at) = param_to_point_at
|
|
||||||
&& self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath)
|
|
||||||
{
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
hir::ExprKind::MethodCall(segment, receiver, args, ..) => {
|
|
||||||
for param in [param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
|
|
||||||
.into_iter()
|
|
||||||
.flatten()
|
|
||||||
{
|
|
||||||
if self.blame_specific_arg_if_possible(
|
|
||||||
error,
|
|
||||||
def_id,
|
|
||||||
param,
|
|
||||||
hir_id,
|
|
||||||
segment.ident.span,
|
|
||||||
Some(receiver),
|
|
||||||
args,
|
|
||||||
) {
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
if let Some(param_to_point_at) = param_to_point_at
|
|
||||||
&& self.point_at_generic_if_possible(error, def_id, param_to_point_at, segment)
|
|
||||||
{
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
hir::ExprKind::Struct(qpath, fields, ..) => {
|
|
||||||
if let Res::Def(DefKind::Struct | DefKind::Variant, variant_def_id) =
|
|
||||||
self.typeck_results.borrow().qpath_res(qpath, hir_id)
|
|
||||||
{
|
|
||||||
for param in
|
|
||||||
[param_to_point_at, fallback_param_to_point_at, self_param_to_point_at]
|
|
||||||
{
|
|
||||||
if let Some(param) = param {
|
|
||||||
let refined_expr = self.point_at_field_if_possible(
|
|
||||||
def_id,
|
|
||||||
param,
|
|
||||||
variant_def_id,
|
|
||||||
fields,
|
|
||||||
);
|
|
||||||
|
|
||||||
match refined_expr {
|
|
||||||
None => {}
|
|
||||||
Some((refined_expr, _)) => {
|
|
||||||
error.obligation.cause.span = refined_expr
|
|
||||||
.span
|
|
||||||
.find_ancestor_in_same_ctxt(error.obligation.cause.span)
|
|
||||||
.unwrap_or(refined_expr.span);
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
}
|
|
||||||
}
|
|
||||||
}
|
|
||||||
if let Some(param_to_point_at) = param_to_point_at
|
|
||||||
&& self.point_at_path_if_possible(error, def_id, param_to_point_at, qpath)
|
|
||||||
{
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
_ => {}
|
|
||||||
}
|
|
||||||
|
|
||||||
false
|
|
||||||
}
|
|
||||||
|
|
||||||
fn closure_span_overlaps_error(
|
|
||||||
&self,
|
|
||||||
error: &traits::FulfillmentError<'tcx>,
|
|
||||||
span: Span,
|
|
||||||
) -> bool {
|
|
||||||
if let traits::FulfillmentErrorCode::CodeSelectionError(
|
|
||||||
traits::SelectionError::OutputTypeParameterMismatch(_, expected, _),
|
|
||||||
) = error.code
|
|
||||||
&& let ty::Closure(def_id, _) | ty::Generator(def_id, ..) = expected.skip_binder().self_ty().kind()
|
|
||||||
&& span.overlaps(self.tcx.def_span(*def_id))
|
|
||||||
{
|
|
||||||
true
|
|
||||||
} else {
|
|
||||||
false
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
/// - `blame_specific_*` means that the function will recursively traverse the expression,
|
|
||||||
/// looking for the most-specific-possible span to blame.
|
|
||||||
///
|
|
||||||
/// - `point_at_*` means that the function will only go "one level", pointing at the specific
|
|
||||||
/// expression mentioned.
|
|
||||||
///
|
|
||||||
/// `blame_specific_arg_if_possible` will find the most-specific expression anywhere inside
|
|
||||||
/// the provided function call expression, and mark it as responsible for the fullfillment
|
|
||||||
/// error.
|
|
||||||
fn blame_specific_arg_if_possible(
|
|
||||||
&self,
|
|
||||||
error: &mut traits::FulfillmentError<'tcx>,
|
|
||||||
def_id: DefId,
|
|
||||||
param_to_point_at: ty::GenericArg<'tcx>,
|
|
||||||
call_hir_id: hir::HirId,
|
|
||||||
callee_span: Span,
|
|
||||||
receiver: Option<&'tcx hir::Expr<'tcx>>,
|
|
||||||
args: &'tcx [hir::Expr<'tcx>],
|
|
||||||
) -> bool {
|
|
||||||
let ty = self.tcx.type_of(def_id);
|
|
||||||
if !ty.is_fn() {
|
|
||||||
return false;
|
|
||||||
}
|
|
||||||
let sig = ty.fn_sig(self.tcx).skip_binder();
|
|
||||||
let args_referencing_param: Vec<_> = sig
|
|
||||||
.inputs()
|
|
||||||
.iter()
|
|
||||||
.enumerate()
|
|
||||||
.filter(|(_, ty)| Self::find_param_in_ty((**ty).into(), param_to_point_at))
|
|
||||||
.collect();
|
|
||||||
// If there's one field that references the given generic, great!
|
|
||||||
if let [(idx, _)] = args_referencing_param.as_slice()
|
|
||||||
&& let Some(arg) = receiver
|
|
||||||
.map_or(args.get(*idx), |rcvr| if *idx == 0 { Some(rcvr) } else { args.get(*idx - 1) }) {
|
|
||||||
|
|
||||||
error.obligation.cause.span = arg.span.find_ancestor_in_same_ctxt(error.obligation.cause.span).unwrap_or(arg.span);
|
|
||||||
|
|
||||||
if let hir::Node::Expr(arg_expr) = self.tcx.hir().get(arg.hir_id) {
|
|
||||||
// This is more specific than pointing at the entire argument.
|
|
||||||
self.blame_specific_expr_if_possible(error, arg_expr)
|
|
||||||
}
|
|
||||||
|
|
||||||
error.obligation.cause.map_code(|parent_code| {
|
|
||||||
ObligationCauseCode::FunctionArgumentObligation {
|
|
||||||
arg_hir_id: arg.hir_id,
|
|
||||||
call_hir_id,
|
|
||||||
parent_code,
|
|
||||||
}
|
|
||||||
});
|
|
||||||
return true;
|
|
||||||
} else if args_referencing_param.len() > 0 {
|
|
||||||
// If more than one argument applies, then point to the callee span at least...
|
|
||||||
// We have chance to fix this up further in `point_at_generics_if_possible`
|
|
||||||
error.obligation.cause.span = callee_span;
|
|
||||||
}
|
|
||||||
|
|
||||||
false
|
|
||||||
}
|
|
||||||
|
|
||||||
// FIXME: Make this private and move to mod adjust_fulfillment_errors
|
|
||||||
pub fn point_at_field_if_possible(
|
|
||||||
&self,
|
|
||||||
def_id: DefId,
|
|
||||||
param_to_point_at: ty::GenericArg<'tcx>,
|
|
||||||
variant_def_id: DefId,
|
|
||||||
expr_fields: &[hir::ExprField<'tcx>],
|
|
||||||
) -> Option<(&'tcx hir::Expr<'tcx>, Ty<'tcx>)> {
|
|
||||||
let def = self.tcx.adt_def(def_id);
|
|
||||||
|
|
||||||
let identity_substs = ty::InternalSubsts::identity_for_item(self.tcx, def_id);
|
|
||||||
let fields_referencing_param: Vec<_> = def
|
|
||||||
.variant_with_id(variant_def_id)
|
|
||||||
.fields
|
|
||||||
.iter()
|
|
||||||
.filter(|field| {
|
|
||||||
let field_ty = field.ty(self.tcx, identity_substs);
|
|
||||||
Self::find_param_in_ty(field_ty.into(), param_to_point_at)
|
|
||||||
})
|
|
||||||
.collect();
|
|
||||||
|
|
||||||
if let [field] = fields_referencing_param.as_slice() {
|
|
||||||
for expr_field in expr_fields {
|
|
||||||
// Look for the ExprField that matches the field, using the
|
|
||||||
// same rules that check_expr_struct uses for macro hygiene.
|
|
||||||
if self.tcx.adjust_ident(expr_field.ident, variant_def_id) == field.ident(self.tcx)
|
|
||||||
{
|
|
||||||
return Some((expr_field.expr, self.tcx.type_of(field.did)));
|
|
||||||
}
|
|
||||||
}
|
|
||||||
}
|
|
||||||
|
|
||||||
None
|
|
||||||
}
|
|
||||||
|
|
||||||
fn point_at_path_if_possible(
|
|
||||||
&self,
|
|
||||||
error: &mut traits::FulfillmentError<'tcx>,
|
|
||||||
def_id: DefId,
|
|
||||||
param: ty::GenericArg<'tcx>,
|
|
||||||
qpath: &QPath<'tcx>,
|
|
||||||
) -> bool {
|
|
||||||
match qpath {
|
|
||||||
hir::QPath::Resolved(_, path) => {
|
|
||||||
if let Some(segment) = path.segments.last()
|
|
||||||
&& self.point_at_generic_if_possible(error, def_id, param, segment)
|
|
||||||
{
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
hir::QPath::TypeRelative(_, segment) => {
|
|
||||||
if self.point_at_generic_if_possible(error, def_id, param, segment) {
|
|
||||||
return true;
|
|
||||||
}
|
|
||||||
}
|
|
||||||
_ => {}
|
|
||||||
}
|
|
||||||
|
|
||||||
false
|
|
||||||
}
|
|
||||||
|
|
||||||
fn point_at_generic_if_possible(
|
|
||||||
&self,
|
|
||||||
error: &mut traits::FulfillmentError<'tcx>,
|
|
||||||
def_id: DefId,
|
|
||||||
param_to_point_at: ty::GenericArg<'tcx>,
|
|
||||||
segment: &hir::PathSegment<'tcx>,
|
|
||||||
) -> bool {
|
|
||||||
let own_substs = self
|
|
||||||
.tcx
|
|
||||||
.generics_of(def_id)
|
|
||||||
.own_substs(ty::InternalSubsts::identity_for_item(self.tcx, def_id));
|
|
||||||
let Some((index, _)) = own_substs
|
|
||||||
.iter()
|
|
||||||
.filter(|arg| matches!(arg.unpack(), ty::GenericArgKind::Type(_)))
|
|
||||||
.enumerate()
|
|
||||||
.find(|(_, arg)| **arg == param_to_point_at) else { return false };
|
|
||||||
let Some(arg) = segment
|
|
||||||
.args()
|
|
||||||
.args
|
|
||||||
.iter()
|
|
||||||
.filter(|arg| matches!(arg, hir::GenericArg::Type(_)))
|
|
||||||
.nth(index) else { return false; };
|
|
||||||
error.obligation.cause.span = arg
|
|
||||||
.span()
|
|
||||||
.find_ancestor_in_same_ctxt(error.obligation.cause.span)
|
|
||||||
.unwrap_or(arg.span());
|
|
||||||
true
|
|
||||||
}
|
|
||||||
|
|
||||||
fn find_ambiguous_parameter_in<T: TypeVisitable<'tcx>>(
|
|
||||||
&self,
|
|
||||||
item_def_id: DefId,
|
|
||||||
t: T,
|
|
||||||
) -> Option<ty::GenericArg<'tcx>> {
|
|
||||||
struct FindAmbiguousParameter<'a, 'tcx>(&'a FnCtxt<'a, 'tcx>, DefId);
|
|
||||||
impl<'tcx> TypeVisitor<'tcx> for FindAmbiguousParameter<'_, 'tcx> {
|
|
||||||
type BreakTy = ty::GenericArg<'tcx>;
|
|
||||||
fn visit_ty(&mut self, ty: Ty<'tcx>) -> std::ops::ControlFlow<Self::BreakTy> {
|
|
||||||
if let Some(origin) = self.0.type_var_origin(ty)
|
|
||||||
&& let TypeVariableOriginKind::TypeParameterDefinition(_, Some(def_id)) =
|
|
||||||
origin.kind
|
|
||||||
&& let generics = self.0.tcx.generics_of(self.1)
|
|
||||||
&& let Some(index) = generics.param_def_id_to_index(self.0.tcx, def_id)
|
|
||||||
&& let Some(subst) = ty::InternalSubsts::identity_for_item(self.0.tcx, self.1)
|
|
||||||
.get(index as usize)
|
|
||||||
{
|
|
||||||
ControlFlow::Break(*subst)
|
|
||||||
} else {
|
|
||||||
ty.super_visit_with(self)
|
|
||||||
}
|
|
||||||
}
|
|
||||||
}
|
|
||||||
t.visit_with(&mut FindAmbiguousParameter(self, item_def_id)).break_value()
|
|
||||||
}
|
|
||||||
|
|
||||||
fn label_fn_like(
|
fn label_fn_like(
|
||||||
&self,
|
&self,
|
||||||
err: &mut Diagnostic,
|
err: &mut Diagnostic,
|
||||||
|
|
|
||||||
Loading…
Add table
Add a link
Reference in a new issue