X-Git-Url: https://git.lizzy.rs/?a=blobdiff_plain;f=compiler%2Frustc_trait_selection%2Fsrc%2Ftraits%2Ferror_reporting%2Fsuggestions.rs;h=40c8102547112956468b8c18f39e5dc2ce9a85b3;hb=aa5b179599427ef233c4e47db8dac6edae22b4f8;hp=443d57aaf3dce8cc63b9606b1786b5be6d963e14;hpb=b66e123677ac5f4fade3bb67888f8f40f0bb28ec;p=rust.git diff --git a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs index 443d57aaf3d..40c81025471 100644 --- a/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs +++ b/compiler/rustc_trait_selection/src/traits/error_reporting/suggestions.rs @@ -1,8 +1,9 @@ +// ignore-tidy-filelength use super::{DefIdOrName, Obligation, ObligationCause, ObligationCauseCode, PredicateObligation}; use crate::autoderef::Autoderef; use crate::infer::InferCtxt; -use crate::traits::NormalizeExt; +use crate::traits::{NormalizeExt, ObligationCtxt}; use hir::def::CtorOf; use hir::HirId; @@ -22,21 +23,24 @@ use rustc_infer::infer::type_variable::{TypeVariableOrigin, TypeVariableOriginKind}; use rustc_infer::infer::{InferOk, LateBoundRegionConversionTime}; use rustc_middle::hir::map; +use rustc_middle::ty::error::TypeError::{self, Sorts}; +use rustc_middle::ty::relate::TypeRelation; use rustc_middle::ty::{ self, suggest_arbitrary_trait_bound, suggest_constraining_type_param, AdtKind, DefIdTree, - GeneratorDiagnosticData, GeneratorInteriorTypeCause, Infer, InferTy, IsSuggestable, - ToPredicate, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitable, + GeneratorDiagnosticData, GeneratorInteriorTypeCause, Infer, InferTy, InternalSubsts, + IsSuggestable, ToPredicate, Ty, TyCtxt, TypeAndMut, TypeFoldable, TypeFolder, + TypeSuperFoldable, TypeVisitable, TypeckResults, }; -use rustc_middle::ty::{TypeAndMut, TypeckResults}; use rustc_span::symbol::{sym, Ident, Symbol}; use rustc_span::{BytePos, DesugaringKind, ExpnKind, Span, DUMMY_SP}; use rustc_target::spec::abi; -use std::fmt; +use std::ops::Deref; +use super::method_chain::CollectAllMismatches; use super::InferCtxtPrivExt; use crate::infer::InferCtxtExt as _; use crate::traits::query::evaluate_obligation::InferCtxtExt as _; -use rustc_middle::ty::print::with_no_trimmed_paths; +use rustc_middle::ty::print::{with_forced_trimmed_paths, with_no_trimmed_paths}; #[derive(Debug)] pub enum GeneratorInteriorOrUpvar { @@ -292,13 +296,13 @@ fn note_obligation_cause_for_async_await( fn note_obligation_cause_code( &self, err: &mut Diagnostic, - predicate: &T, + predicate: T, param_env: ty::ParamEnv<'tcx>, cause_code: &ObligationCauseCode<'tcx>, obligated_types: &mut Vec>, seen_requirements: &mut FxHashSet, ) where - T: fmt::Display + ToPredicate<'tcx>; + T: ToPredicate<'tcx>; /// Suggest to await before try: future? => future.await? fn suggest_await_before_try( @@ -329,6 +333,23 @@ fn suggest_dereferencing_index( err: &mut Diagnostic, trait_pred: ty::PolyTraitPredicate<'tcx>, ); + fn function_argument_obligation( + &self, + arg_hir_id: HirId, + err: &mut Diagnostic, + parent_code: &ObligationCauseCode<'tcx>, + param_env: ty::ParamEnv<'tcx>, + predicate: ty::Predicate<'tcx>, + call_hir_id: HirId, + ); + fn point_at_chain( + &self, + expr: &hir::Expr<'_>, + typeck_results: &TypeckResults<'tcx>, + type_diffs: Vec>, + param_env: ty::ParamEnv<'tcx>, + err: &mut Diagnostic, + ); } fn predicate_constraint(generics: &hir::Generics<'_>, pred: ty::Predicate<'_>) -> (Span, String) { @@ -2336,7 +2357,7 @@ fn note_obligation_cause_for_async_await( debug!(?next_code); self.note_obligation_cause_code( err, - &obligation.predicate, + obligation.predicate, obligation.param_env, next_code.unwrap(), &mut Vec::new(), @@ -2347,15 +2368,16 @@ fn note_obligation_cause_for_async_await( fn note_obligation_cause_code( &self, err: &mut Diagnostic, - predicate: &T, + predicate: T, param_env: ty::ParamEnv<'tcx>, cause_code: &ObligationCauseCode<'tcx>, obligated_types: &mut Vec>, seen_requirements: &mut FxHashSet, ) where - T: fmt::Display + ToPredicate<'tcx>, + T: ToPredicate<'tcx>, { let tcx = self.tcx; + let predicate = predicate.to_predicate(tcx); match *cause_code { ObligationCauseCode::ExprAssignable | ObligationCauseCode::MatchExpressionArm { .. } @@ -2390,12 +2412,11 @@ fn note_obligation_cause_code( err.note("only the last element of a tuple may have a dynamically sized type"); } ObligationCauseCode::ProjectionWf(data) => { - err.note(&format!("required so that the projection `{}` is well-formed", data,)); + err.note(&format!("required so that the projection `{data}` is well-formed")); } ObligationCauseCode::ReferenceOutlivesReferent(ref_ty) => { err.note(&format!( - "required so that reference `{}` does not outlive its referent", - ref_ty, + "required so that reference `{ref_ty}` does not outlive its referent" )); } ObligationCauseCode::ObjectTypeBound(object_ty, region) => { @@ -2412,6 +2433,7 @@ fn note_obligation_cause_code( ObligationCauseCode::BindingObligation(item_def_id, span) | ObligationCauseCode::ExprBindingObligation(item_def_id, span, ..) => { let item_name = tcx.def_path_str(item_def_id); + let short_item_name = with_forced_trimmed_paths!(tcx.def_path_str(item_def_id)); let mut multispan = MultiSpan::from(span); let sm = tcx.sess.source_map(); if let Some(ident) = tcx.opt_item_ident(item_def_id) { @@ -2424,9 +2446,9 @@ fn note_obligation_cause_code( multispan.push_span_label(ident.span, "required by a bound in this"); } } - let descr = format!("required by a bound in `{}`", item_name); + let descr = format!("required by a bound in `{item_name}`"); if span.is_visible(sm) { - let msg = format!("required by this bound in `{}`", item_name); + let msg = format!("required by this bound in `{short_item_name}`"); multispan.push_span_label(span, msg); err.span_note(multispan, &descr); } else { @@ -2688,7 +2710,7 @@ fn note_obligation_cause_code( ensure_sufficient_stack(|| { self.note_obligation_cause_code( err, - &parent_predicate, + parent_predicate, param_env, &data.parent_code, obligated_types, @@ -2699,7 +2721,7 @@ fn note_obligation_cause_code( ensure_sufficient_stack(|| { self.note_obligation_cause_code( err, - &parent_predicate, + parent_predicate, param_env, cause_code.peel_derives(), obligated_types, @@ -2808,7 +2830,7 @@ fn note_obligation_cause_code( ensure_sufficient_stack(|| { self.note_obligation_cause_code( err, - &parent_predicate, + parent_predicate, param_env, &data.parent_code, obligated_types, @@ -2823,7 +2845,7 @@ fn note_obligation_cause_code( ensure_sufficient_stack(|| { self.note_obligation_cause_code( err, - &parent_predicate, + parent_predicate, param_env, &data.parent_code, obligated_types, @@ -2836,43 +2858,14 @@ fn note_obligation_cause_code( call_hir_id, ref parent_code, } => { - let hir = self.tcx.hir(); - if let Some(Node::Expr(expr @ hir::Expr { kind: hir::ExprKind::Block(..), .. })) = - hir.find(arg_hir_id) - { - let parent_id = hir.get_parent_item(arg_hir_id); - let typeck_results: &TypeckResults<'tcx> = match &self.typeck_results { - Some(t) if t.hir_owner == parent_id => t, - _ => self.tcx.typeck(parent_id.def_id), - }; - let expr = expr.peel_blocks(); - let ty = typeck_results.expr_ty_adjusted_opt(expr).unwrap_or(tcx.ty_error()); - let span = expr.span; - if Some(span) != err.span.primary_span() { - err.span_label( - span, - if ty.references_error() { - String::new() - } else { - format!("this tail expression is of type `{:?}`", ty) - }, - ); - } - } - if let Some(Node::Expr(hir::Expr { - kind: - hir::ExprKind::Call(hir::Expr { span, .. }, _) - | hir::ExprKind::MethodCall( - hir::PathSegment { ident: Ident { span, .. }, .. }, - .., - ), - .. - })) = hir.find(call_hir_id) - { - if Some(*span) != err.span.primary_span() { - err.span_label(*span, "required by a bound introduced by this call"); - } - } + self.function_argument_obligation( + arg_hir_id, + err, + parent_code, + param_env, + predicate, + call_hir_id, + ); ensure_sufficient_stack(|| { self.note_obligation_cause_code( err, @@ -2887,9 +2880,8 @@ fn note_obligation_cause_code( ObligationCauseCode::CompareImplItemObligation { trait_item_def_id, kind, .. } => { let item_name = self.tcx.item_name(trait_item_def_id); let msg = format!( - "the requirement `{}` appears on the `impl`'s {kind} `{}` but not on the \ - corresponding trait's {kind}", - predicate, item_name, + "the requirement `{predicate}` appears on the `impl`'s {kind} \ + `{item_name}` but not on the corresponding trait's {kind}", ); let sp = self .tcx @@ -2899,7 +2891,7 @@ fn note_obligation_cause_code( let mut assoc_span: MultiSpan = sp.into(); assoc_span.push_span_label( sp, - format!("this trait's {kind} doesn't have the requirement `{}`", predicate), + format!("this trait's {kind} doesn't have the requirement `{predicate}`"), ); if let Some(ident) = self .tcx @@ -2918,7 +2910,7 @@ fn note_obligation_cause_code( } ObligationCauseCode::OpaqueReturnType(expr_info) => { if let Some((expr_ty, expr_span)) = expr_info { - let expr_ty = self.resolve_vars_if_possible(expr_ty); + let expr_ty = with_forced_trimmed_paths!(self.ty_to_string(expr_ty)); err.span_label( expr_span, format!("return type was inferred to be `{expr_ty}` here"), @@ -3098,6 +3090,298 @@ fn suggest_dereferencing_index( ); } } + fn function_argument_obligation( + &self, + arg_hir_id: HirId, + err: &mut Diagnostic, + parent_code: &ObligationCauseCode<'tcx>, + param_env: ty::ParamEnv<'tcx>, + predicate: ty::Predicate<'tcx>, + call_hir_id: HirId, + ) { + let tcx = self.tcx; + let hir = tcx.hir(); + if let Some(Node::Expr(expr)) = hir.find(arg_hir_id) { + let parent_id = hir.get_parent_item(arg_hir_id); + let typeck_results: &TypeckResults<'tcx> = match &self.typeck_results { + Some(t) if t.hir_owner == parent_id => t, + _ => self.tcx.typeck(parent_id.def_id), + }; + if let hir::Expr { kind: hir::ExprKind::Block(..), .. } = expr { + let expr = expr.peel_blocks(); + let ty = typeck_results.expr_ty_adjusted_opt(expr).unwrap_or(tcx.ty_error()); + let span = expr.span; + if Some(span) != err.span.primary_span() { + err.span_label( + span, + if ty.references_error() { + String::new() + } else { + let ty = with_forced_trimmed_paths!(self.ty_to_string(ty)); + format!("this tail expression is of type `{ty}`") + }, + ); + } + } + + // FIXME: visit the ty to see if there's any closure involved, and if there is, + // check whether its evaluated return type is the same as the one corresponding + // to an associated type (as seen from `trait_pred`) in the predicate. Like in + // trait_pred `S: Sum<::Item>` and predicate `i32: Sum<&()>` + let mut type_diffs = vec![]; + + if let ObligationCauseCode::ExprBindingObligation(def_id, _, _, idx) = parent_code.deref() + && let predicates = self.tcx.predicates_of(def_id).instantiate_identity(self.tcx) + && let Some(pred) = predicates.predicates.get(*idx) + && let Ok(trait_pred) = pred.kind().try_map_bound(|pred| match pred { + ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred)) => Ok(trait_pred), + _ => Err(()), + }) + { + let mut c = CollectAllMismatches { + infcx: self.infcx, + param_env, + errors: vec![], + }; + if let Ok(trait_predicate) = predicate.kind().try_map_bound(|pred| match pred { + ty::PredicateKind::Clause(ty::Clause::Trait(trait_pred)) => Ok(trait_pred), + _ => Err(()), + }) { + if let Ok(_) = c.relate(trait_pred, trait_predicate) { + type_diffs = c.errors; + } + } + } + if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = expr.kind + && let hir::Path { res: hir::def::Res::Local(hir_id), .. } = path + && let Some(hir::Node::Pat(binding)) = self.tcx.hir().find(*hir_id) + && let parent_hir_id = self.tcx.hir().get_parent_node(binding.hir_id) + && let Some(hir::Node::Local(local)) = self.tcx.hir().find(parent_hir_id) + && let Some(binding_expr) = local.init + { + // If the expression we're calling on is a binding, we want to point at the + // `let` when talking about the type. Otherwise we'll point at every part + // of the method chain with the type. + self.point_at_chain(binding_expr, typeck_results, type_diffs, param_env, err); + } else { + self.point_at_chain(expr, typeck_results, type_diffs, param_env, err); + } + } + let call_node = hir.find(call_hir_id); + if let Some(Node::Expr(hir::Expr { + kind: hir::ExprKind::MethodCall(path, rcvr, ..), .. + })) = call_node + { + if Some(rcvr.span) == err.span.primary_span() { + err.replace_span_with(path.ident.span); + } + } + if let Some(Node::Expr(hir::Expr { + kind: + hir::ExprKind::Call(hir::Expr { span, .. }, _) + | hir::ExprKind::MethodCall(hir::PathSegment { ident: Ident { span, .. }, .. }, ..), + .. + })) = hir.find(call_hir_id) + { + if Some(*span) != err.span.primary_span() { + err.span_label(*span, "required by a bound introduced by this call"); + } + } + } + + fn point_at_chain( + &self, + expr: &hir::Expr<'_>, + typeck_results: &TypeckResults<'tcx>, + type_diffs: Vec>, + param_env: ty::ParamEnv<'tcx>, + err: &mut Diagnostic, + ) { + let mut primary_spans = vec![]; + let mut span_labels = vec![]; + + let tcx = self.tcx; + + let mut assocs = vec![]; + // We still want to point at the different methods even if there hasn't + // been a change of assoc type. + let mut call_spans = vec![]; + let mut expr = expr; + let mut prev_ty = self.resolve_vars_if_possible( + typeck_results.expr_ty_adjusted_opt(expr).unwrap_or(tcx.ty_error()), + ); + while let hir::ExprKind::MethodCall(_path_segment, rcvr_expr, _args, span) = expr.kind { + // Point at every method call in the chain with the resulting type. + // vec![1, 2, 3].iter().map(mapper).sum() + // ^^^^^^ ^^^^^^^^^^^ + expr = rcvr_expr; + let mut assocs_in_this_method = Vec::with_capacity(type_diffs.len()); + call_spans.push(span); + + let ocx = ObligationCtxt::new_in_snapshot(self.infcx); + for diff in &type_diffs { + let Sorts(expected_found) = diff else { continue; }; + let ty::Projection(proj) = expected_found.expected.kind() else { continue; }; + + let origin = + TypeVariableOrigin { kind: TypeVariableOriginKind::TypeInference, span }; + let trait_def_id = proj.trait_def_id(self.tcx); + // Make `Self` be equivalent to the type of the call chain + // expression we're looking at now, so that we can tell what + // for example `Iterator::Item` is at this point in the chain. + let substs = InternalSubsts::for_item(self.tcx, trait_def_id, |param, _| { + match param.kind { + ty::GenericParamDefKind::Type { .. } => { + if param.index == 0 { + return prev_ty.into(); + } + } + ty::GenericParamDefKind::Lifetime + | ty::GenericParamDefKind::Const { .. } => {} + } + self.var_for_def(span, param) + }); + // This will hold the resolved type of the associated type, if the + // current expression implements the trait that associated type is + // in. For example, this would be what `Iterator::Item` is here. + let ty_var = self.infcx.next_ty_var(origin); + // This corresponds to `::Item = _`. + let trait_ref = ty::Binder::dummy(ty::PredicateKind::Clause( + ty::Clause::Projection(ty::ProjectionPredicate { + projection_ty: ty::ProjectionTy { substs, item_def_id: proj.item_def_id }, + term: ty_var.into(), + }), + )); + // Add `::Item = _` obligation. + ocx.register_obligation(Obligation::misc( + self.tcx, + span, + expr.hir_id, + param_env, + trait_ref, + )); + if ocx.select_where_possible().is_empty() { + // `ty_var` now holds the type that `Item` is for `ExprTy`. + let ty_var = self.resolve_vars_if_possible(ty_var); + assocs_in_this_method.push(Some((span, (proj.item_def_id, ty_var)))); + } else { + // `` didn't select, so likely we've + // reached the end of the iterator chain, like the originating + // `Vec<_>`. + // Keep the space consistent for later zipping. + assocs_in_this_method.push(None); + } + } + assocs.push(assocs_in_this_method); + prev_ty = self.resolve_vars_if_possible( + typeck_results.expr_ty_adjusted_opt(expr).unwrap_or(tcx.ty_error()), + ); + + if let hir::ExprKind::Path(hir::QPath::Resolved(None, path)) = expr.kind + && let hir::Path { res: hir::def::Res::Local(hir_id), .. } = path + && let Some(hir::Node::Pat(binding)) = self.tcx.hir().find(*hir_id) + && let parent_hir_id = self.tcx.hir().get_parent_node(binding.hir_id) + && let Some(hir::Node::Local(local)) = self.tcx.hir().find(parent_hir_id) + && let Some(binding_expr) = local.init + { + // We've reached the root of the method call chain and it is a + // binding. Get the binding creation and try to continue the chain. + expr = binding_expr; + } + } + // We want the type before deref coercions, otherwise we talk about `&[_]` + // instead of `Vec<_>`. + if let Some(ty) = typeck_results.expr_ty_opt(expr) { + let ty = with_forced_trimmed_paths!(self.ty_to_string(ty)); + // Point at the root expression + // vec![1, 2, 3].iter().map(mapper).sum() + // ^^^^^^^^^^^^^ + span_labels.push((expr.span, format!("this expression has type `{ty}`"))); + }; + // Only show this if it is not a "trivial" expression (not a method + // chain) and there are associated types to talk about. + let mut assocs = assocs.into_iter().peekable(); + while let Some(assocs_in_method) = assocs.next() { + let Some(prev_assoc_in_method) = assocs.peek() else { + for entry in assocs_in_method { + let Some((span, (assoc, ty))) = entry else { continue; }; + if type_diffs.iter().any(|diff| { + let Sorts(expected_found) = diff else { return false; }; + self.can_eq(param_env, expected_found.found, ty).is_ok() + }) { + // FIXME: this doesn't quite work for `Iterator::collect` + // because we have `Vec` and `()`, but we'd want `i32` + // to point at the `.into_iter()` call, but as long as we + // still point at the other method calls that might have + // introduced the issue, this is fine for now. + primary_spans.push(span); + } + span_labels.push(( + span, + with_forced_trimmed_paths!(format!( + "`{}` is `{ty}` here", + self.tcx.def_path_str(assoc), + )), + )); + } + break; + }; + for (entry, prev_entry) in + assocs_in_method.into_iter().zip(prev_assoc_in_method.into_iter()) + { + match (entry, prev_entry) { + (Some((span, (assoc, ty))), Some((_, (_, prev_ty)))) => { + let ty_str = with_forced_trimmed_paths!(self.ty_to_string(ty)); + + let assoc = with_forced_trimmed_paths!(self.tcx.def_path_str(assoc)); + if ty != *prev_ty { + if type_diffs.iter().any(|diff| { + let Sorts(expected_found) = diff else { return false; }; + self.can_eq(param_env, expected_found.found, ty).is_ok() + }) { + primary_spans.push(span); + } + span_labels + .push((span, format!("`{assoc}` changed to `{ty_str}` here"))); + } else { + span_labels.push((span, format!("`{assoc}` remains `{ty_str}` here"))); + } + } + (Some((span, (assoc, ty))), None) => { + span_labels.push(( + span, + with_forced_trimmed_paths!(format!( + "`{}` is `{}` here", + self.tcx.def_path_str(assoc), + self.ty_to_string(ty), + )), + )); + } + (None, Some(_)) | (None, None) => {} + } + } + } + for span in call_spans { + if span_labels.iter().find(|(s, _)| *s == span).is_none() { + // Ensure we are showing the entire chain, even if the assoc types + // haven't changed. + span_labels.push((span, String::new())); + } + } + if !primary_spans.is_empty() { + let mut multi_span: MultiSpan = primary_spans.into(); + for (span, label) in span_labels { + multi_span.push_span_label(span, label); + } + err.span_note( + multi_span, + format!( + "the method call chain might not have had the expected \ + associated types", + ), + ); + } + } } /// Collect all the returned expressions within the input expression.