Move trait selection error reporting to its own top-level module

compiler/rustc_borrowck/src/diagnostics/conflict_errors.rs

@@ -34,9 +34,9 @@ use rustc_span::def_id::LocalDefId;
 use rustc_span::hygiene::DesugaringKind;
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{BytePos, Span, Symbol};
+use rustc_trait_selection::error_reporting::traits::suggestions::TypeErrCtxtExt;
+use rustc_trait_selection::error_reporting::traits::FindExprBySpan;
 use rustc_trait_selection::infer::InferCtxtExt;
-use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt;
-use rustc_trait_selection::traits::error_reporting::FindExprBySpan;
 use rustc_trait_selection::traits::{Obligation, ObligationCause, ObligationCtxt};
 use std::iter;
 use std::ops::ControlFlow;

compiler/rustc_borrowck/src/diagnostics/explain_borrow.rs

@@ -17,7 +17,7 @@ use rustc_middle::ty::adjustment::PointerCoercion;
 use rustc_middle::ty::{self, RegionVid, Ty, TyCtxt};
 use rustc_span::symbol::{kw, Symbol};
 use rustc_span::{sym, DesugaringKind, Span};
-use rustc_trait_selection::traits::error_reporting::FindExprBySpan;
+use rustc_trait_selection::error_reporting::traits::FindExprBySpan;
 
 use crate::region_infer::{BlameConstraint, ExtraConstraintInfo};
 use crate::{

compiler/rustc_borrowck/src/diagnostics/mod.rs

@@ -27,8 +27,8 @@ use rustc_span::def_id::LocalDefId;
 use rustc_span::source_map::Spanned;
 use rustc_span::{symbol::sym, Span, Symbol, DUMMY_SP};
 use rustc_target::abi::{FieldIdx, VariantIdx};
+use rustc_trait_selection::error_reporting::traits::suggestions::TypeErrCtxtExt as _;
 use rustc_trait_selection::infer::InferCtxtExt;
-use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::{
     type_known_to_meet_bound_modulo_regions, FulfillmentErrorCode,
 };

compiler/rustc_borrowck/src/diagnostics/move_errors.rs

@@ -9,7 +9,7 @@ use rustc_middle::mir::*;
 use rustc_middle::ty::{self, Ty};
 use rustc_mir_dataflow::move_paths::{LookupResult, MovePathIndex};
 use rustc_span::{BytePos, ExpnKind, MacroKind, Span};
-use rustc_trait_selection::traits::error_reporting::FindExprBySpan;
+use rustc_trait_selection::error_reporting::traits::FindExprBySpan;
 
 use crate::diagnostics::CapturedMessageOpt;
 use crate::diagnostics::{DescribePlaceOpt, UseSpans};

compiler/rustc_borrowck/src/diagnostics/mutability_errors.rs

@@ -16,9 +16,9 @@ use rustc_middle::{
 use rustc_span::symbol::{kw, Symbol};
 use rustc_span::{sym, BytePos, DesugaringKind, Span};
 use rustc_target::abi::FieldIdx;
+use rustc_trait_selection::error_reporting::traits::suggestions::TypeErrCtxtExt;
 use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits;
-use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt;
 
 use crate::diagnostics::BorrowedContentSource;
 use crate::util::FindAssignments;

compiler/rustc_borrowck/src/region_infer/opaque_types.rs

@@ -11,7 +11,7 @@ use rustc_middle::ty::visit::TypeVisitableExt;
 use rustc_middle::ty::{self, OpaqueHiddenType, OpaqueTypeKey, Ty, TyCtxt, TypeFoldable};
 use rustc_middle::ty::{GenericArgKind, GenericArgs};
 use rustc_span::Span;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::ObligationCtxt;
 
 use crate::session_diagnostics::LifetimeMismatchOpaqueParam;

compiler/rustc_borrowck/src/type_check/free_region_relations.rs

@@ -11,8 +11,8 @@ use rustc_middle::traits::query::OutlivesBound;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::ty::{self, RegionVid, Ty, TypeVisitableExt};
 use rustc_span::{ErrorGuaranteed, Span};
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::solve::deeply_normalize;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::query::type_op::{self, TypeOp};
 use std::rc::Rc;
 use type_op::TypeOpOutput;

compiler/rustc_const_eval/src/check_consts/check.rs

@@ -13,7 +13,7 @@ use rustc_middle::ty::{self, adjustment::PointerCoercion, Ty, TyCtxt};
 use rustc_middle::ty::{Instance, InstanceKind, TypeVisitableExt};
 use rustc_mir_dataflow::Analysis;
 use rustc_span::{sym, Span, Symbol, DUMMY_SP};
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::{self, ObligationCauseCode, ObligationCtxt};
 use rustc_type_ir::visit::{TypeSuperVisitable, TypeVisitor};
 

compiler/rustc_hir_analysis/src/check/check.rs

@@ -25,9 +25,9 @@ use rustc_middle::ty::{
 };
 use rustc_session::lint::builtin::{UNINHABITED_STATIC, UNSUPPORTED_CALLING_CONVENTIONS};
 use rustc_target::abi::FieldIdx;
+use rustc_trait_selection::error_reporting::traits::on_unimplemented::OnUnimplementedDirective;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits;
-use rustc_trait_selection::traits::error_reporting::on_unimplemented::OnUnimplementedDirective;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
 use rustc_type_ir::fold::TypeFoldable;
 

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -21,9 +21,9 @@ use rustc_middle::ty::{
 use rustc_middle::ty::{GenericParamDefKind, TyCtxt};
 use rustc_middle::{bug, span_bug};
 use rustc_span::Span;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::regions::InferCtxtRegionExt;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
 use rustc_trait_selection::traits::{
     self, FulfillmentError, ObligationCause, ObligationCauseCode, ObligationCtxt, Reveal,

compiler/rustc_hir_analysis/src/check/entry.rs

@@ -7,7 +7,7 @@ use rustc_session::config::EntryFnType;
 use rustc_span::def_id::{DefId, LocalDefId, CRATE_DEF_ID};
 use rustc_span::{symbol::sym, Span};
 use rustc_target::spec::abi::Abi;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::{self, ObligationCause, ObligationCauseCode};
 
 use std::ops::Not;

compiler/rustc_hir_analysis/src/check/mod.rs

@@ -96,10 +96,10 @@ use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{def_id::CRATE_DEF_ID, BytePos, Span, Symbol, DUMMY_SP};
 use rustc_target::abi::VariantIdx;
 use rustc_target::spec::abi::Abi;
-use rustc_trait_selection::traits::error_reporting::suggestions::{
+use rustc_trait_selection::error_reporting::traits::suggestions::{
     ReturnsVisitor, TypeErrCtxtExt as _,
 };
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::ObligationCtxt;
 
 use crate::errors;

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -29,8 +29,8 @@ use rustc_session::parse::feature_err;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::spec::abi::Abi;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::regions::InferCtxtRegionExt;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::misc::{
     type_allowed_to_implement_const_param_ty, ConstParamTyImplementationError,
 };

compiler/rustc_hir_analysis/src/coherence/builtin.rs

@@ -17,7 +17,7 @@ use rustc_middle::ty::adjustment::CoerceUnsizedInfo;
 use rustc_middle::ty::print::PrintTraitRefExt as _;
 use rustc_middle::ty::{self, suggest_constraining_type_params, Ty, TyCtxt, TypeVisitableExt};
 use rustc_span::{Span, DUMMY_SP};
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::traits::misc::{
     type_allowed_to_implement_const_param_ty, type_allowed_to_implement_copy,
     ConstParamTyImplementationError, CopyImplementationError, InfringingFieldsReason,

compiler/rustc_hir_analysis/src/collect.rs

@@ -35,8 +35,8 @@ use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::{Span, DUMMY_SP};
 use rustc_target::abi::FieldIdx;
 use rustc_target::spec::abi;
+use rustc_trait_selection::error_reporting::traits::suggestions::NextTypeParamName;
 use rustc_trait_selection::infer::InferCtxtExt;
-use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
 use rustc_trait_selection::traits::ObligationCtxt;
 use std::cell::Cell;
 use std::iter;

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

@@ -4,7 +4,6 @@ use crate::errors::{
 };
 use crate::fluent_generated as fluent;
 use crate::hir_ty_lowering::HirTyLowerer;
-use crate::traits::error_reporting::report_object_safety_error;
 use rustc_data_structures::fx::{FxIndexMap, FxIndexSet};
 use rustc_data_structures::sorted_map::SortedMap;
 use rustc_data_structures::unord::UnordMap;
@@ -27,6 +26,7 @@ use rustc_span::edit_distance::find_best_match_for_name;
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::BytePos;
 use rustc_span::{Span, Symbol, DUMMY_SP};
+use rustc_trait_selection::error_reporting::traits::report_object_safety_error;
 use rustc_trait_selection::traits::FulfillmentError;
 use rustc_trait_selection::traits::{
     object_safety_violations_for_assoc_item, TraitAliasExpansionInfo,

compiler/rustc_hir_analysis/src/hir_ty_lowering/lint.rs

@@ -4,7 +4,7 @@ use rustc_hir as hir;
 use rustc_hir::def::{DefKind, Res};
 use rustc_lint_defs::{builtin::BARE_TRAIT_OBJECTS, Applicability};
 use rustc_span::Span;
-use rustc_trait_selection::traits::error_reporting::suggestions::NextTypeParamName;
+use rustc_trait_selection::error_reporting::traits::suggestions::NextTypeParamName;
 
 use super::HirTyLowerer;
 

compiler/rustc_hir_analysis/src/hir_ty_lowering/object_safety.rs

@@ -13,7 +13,7 @@ use rustc_middle::ty::fold::BottomUpFolder;
 use rustc_middle::ty::{self, ExistentialPredicateStableCmpExt as _, Ty, TyCtxt, TypeFoldable};
 use rustc_middle::ty::{DynKind, Upcast};
 use rustc_span::{ErrorGuaranteed, Span};
-use rustc_trait_selection::traits::error_reporting::report_object_safety_error;
+use rustc_trait_selection::error_reporting::traits::report_object_safety_error;
 use rustc_trait_selection::traits::{self, hir_ty_lowering_object_safety_violations};
 
 use smallvec::{smallvec, SmallVec};

compiler/rustc_hir_analysis/src/impl_wf_check/min_specialization.rs

@@ -78,7 +78,7 @@ use rustc_middle::ty::trait_def::TraitSpecializationKind;
 use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt};
 use rustc_middle::ty::{GenericArg, GenericArgs, GenericArgsRef};
 use rustc_span::{ErrorGuaranteed, Span};
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::traits::outlives_bounds::InferCtxtExt as _;
 use rustc_trait_selection::traits::{self, translate_args_with_cause, wf, ObligationCtxt};
 

compiler/rustc_hir_typeck/src/callee.rs

@@ -24,8 +24,8 @@ use rustc_span::def_id::LocalDefId;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::Span;
 use rustc_target::spec::abi;
+use rustc_trait_selection::error_reporting::traits::DefIdOrName;
 use rustc_trait_selection::infer::InferCtxtExt as _;
-use rustc_trait_selection::traits::error_reporting::DefIdOrName;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
 
 use std::{iter, slice};

compiler/rustc_hir_typeck/src/closure.rs

@@ -17,9 +17,9 @@ use rustc_middle::ty::{self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitor};
 use rustc_span::def_id::LocalDefId;
 use rustc_span::Span;
 use rustc_target::spec::abi::Abi;
+use rustc_trait_selection::error_reporting::traits::ArgKind;
+use rustc_trait_selection::error_reporting::traits::InferCtxtExt as _;
 use rustc_trait_selection::traits;
-use rustc_trait_selection::traits::error_reporting::ArgKind;
-use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
 use rustc_type_ir::ClosureKind;
 use std::iter;
 use std::ops::ControlFlow;

compiler/rustc_hir_typeck/src/coercion.rs

@@ -58,9 +58,9 @@ use rustc_session::parse::feature_err;
 use rustc_span::symbol::sym;
 use rustc_span::{BytePos, DesugaringKind, Span, DUMMY_SP};
 use rustc_target::spec::abi::Abi;
+use rustc_trait_selection::error_reporting::traits::suggestions::TypeErrCtxtExt;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt as _;
 use rustc_trait_selection::infer::InferCtxtExt as _;
-use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt;
 use rustc_trait_selection::traits::{
     self, NormalizeExt, ObligationCause, ObligationCauseCode, ObligationCtxt,

compiler/rustc_hir_typeck/src/expr.rs

@@ -53,9 +53,9 @@ use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{kw, sym, Ident, Symbol};
 use rustc_span::Span;
 use rustc_target::abi::{FieldIdx, FIRST_VARIANT};
+use rustc_trait_selection::error_reporting::traits::suggestions::TypeErrCtxtExt as _;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::infer::InferCtxtExt;
-use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt as _;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::ObligationCtxt;
 use rustc_trait_selection::traits::{self, ObligationCauseCode};
 

compiler/rustc_hir_typeck/src/fn_ctxt/_impl.rs

@@ -37,7 +37,7 @@ use rustc_span::hygiene::DesugaringKind;
 use rustc_span::symbol::{kw, sym};
 use rustc_span::Span;
 use rustc_target::abi::FieldIdx;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::{
     self, NormalizeExt, ObligationCauseCode, ObligationCtxt, StructurallyNormalizeExt,
 };

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -32,10 +32,10 @@ use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::{Span, Symbol};
+use rustc_trait_selection::error_reporting::traits::suggestions::TypeErrCtxtExt;
+use rustc_trait_selection::error_reporting::traits::DefIdOrName;
 use rustc_trait_selection::infer::InferCtxtExt;
 use rustc_trait_selection::traits;
-use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt;
-use rustc_trait_selection::traits::error_reporting::DefIdOrName;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
 
 impl<'a, 'tcx> FnCtxt<'a, 'tcx> {

compiler/rustc_hir_typeck/src/method/suggest.rs

@@ -35,9 +35,9 @@ use rustc_span::def_id::DefIdSet;
 use rustc_span::symbol::{kw, sym, Ident};
 use rustc_span::{edit_distance, ErrorGuaranteed, ExpnKind, FileName, MacroKind, Span};
 use rustc_span::{Symbol, DUMMY_SP};
+use rustc_trait_selection::error_reporting::traits::on_unimplemented::OnUnimplementedNote;
+use rustc_trait_selection::error_reporting::traits::on_unimplemented::TypeErrCtxtExt as _;
 use rustc_trait_selection::infer::InferCtxtExt;
-use rustc_trait_selection::traits::error_reporting::on_unimplemented::OnUnimplementedNote;
-use rustc_trait_selection::traits::error_reporting::on_unimplemented::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc_trait_selection::traits::{
     supertraits, FulfillmentError, Obligation, ObligationCause, ObligationCauseCode,

compiler/rustc_hir_typeck/src/op.rs

@@ -18,8 +18,8 @@ use rustc_session::errors::ExprParenthesesNeeded;
 use rustc_span::source_map::Spanned;
 use rustc_span::symbol::{sym, Ident};
 use rustc_span::Span;
+use rustc_trait_selection::error_reporting::traits::suggestions::TypeErrCtxtExt as _;
 use rustc_trait_selection::infer::InferCtxtExt;
-use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::{FulfillmentError, ObligationCtxt};
 use rustc_type_ir::TyKind::*;
 

compiler/rustc_hir_typeck/src/writeback.rs

@@ -18,8 +18,8 @@ use rustc_middle::ty::TypeSuperFoldable;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::symbol::sym;
 use rustc_span::Span;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::solve;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 
 use std::mem;
 

compiler/rustc_lint/src/async_fn_in_trait.rs

@@ -3,7 +3,7 @@ use crate::LateContext;
 use crate::LateLintPass;
 use rustc_hir as hir;
 use rustc_session::{declare_lint, declare_lint_pass};
-use rustc_trait_selection::traits::error_reporting::suggestions::suggest_desugaring_async_fn_to_impl_future_in_trait;
+use rustc_trait_selection::error_reporting::traits::suggestions::suggest_desugaring_async_fn_to_impl_future_in_trait;
 
 declare_lint! {
     /// The `async_fn_in_trait` lint detects use of `async fn` in the

compiler/rustc_lint/src/non_local_def.rs

@@ -11,10 +11,10 @@ use rustc_session::{declare_lint, impl_lint_pass};
 use rustc_span::def_id::{DefId, LOCAL_CRATE};
 use rustc_span::Span;
 use rustc_span::{sym, symbol::kw, ExpnKind, MacroKind, Symbol};
-use rustc_trait_selection::infer::TyCtxtInferExt;
+use rustc_trait_selection::error_reporting::traits::ambiguity::{
-use rustc_trait_selection::traits::error_reporting::ambiguity::{
     compute_applicable_impls_for_diagnostics, CandidateSource,
 };
+use rustc_trait_selection::infer::TyCtxtInferExt;
 
 use crate::fluent_generated as fluent;
 use crate::lints::{NonLocalDefinitionsCargoUpdateNote, NonLocalDefinitionsDiag};

compiler/rustc_mir_transform/src/coroutine.rs

@@ -81,8 +81,8 @@ use rustc_span::symbol::sym;
 use rustc_span::Span;
 use rustc_target::abi::{FieldIdx, VariantIdx};
 use rustc_target::spec::PanicStrategy;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt as _;
 use rustc_trait_selection::infer::TyCtxtInferExt as _;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt as _;
 use rustc_trait_selection::traits::ObligationCtxt;
 use rustc_trait_selection::traits::{ObligationCause, ObligationCauseCode};
 use std::{iter, ops};

compiler/rustc_passes/src/check_attr.rs

@@ -34,8 +34,8 @@ use rustc_session::parse::feature_err;
 use rustc_span::symbol::{kw, sym, Symbol};
 use rustc_span::{BytePos, Span, DUMMY_SP};
 use rustc_target::spec::abi::Abi;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::infer::{TyCtxtInferExt, ValuePairs};
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::ObligationCtxt;
 use std::cell::Cell;
 use std::collections::hash_map::Entry;

compiler/rustc_passes/src/layout_test.rs

@@ -8,7 +8,7 @@ use rustc_span::source_map::Spanned;
 use rustc_span::symbol::sym;
 use rustc_span::Span;
 use rustc_target::abi::{HasDataLayout, TargetDataLayout};
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::{infer::TyCtxtInferExt, traits};
 
 use crate::errors::{

compiler/rustc_trait_selection/src/error_reporting/mod.rs

@@ -0,0 +1 @@
+pub mod traits;

compiler/rustc_trait_selection/src/error_reporting/traits/mod.rs

@@ -6,10 +6,12 @@ pub mod on_unimplemented;
 pub mod suggestions;
 mod type_err_ctxt_ext;
 
-use super::{Obligation, ObligationCause, ObligationCauseCode, PredicateObligation};
+use rustc_data_structures::fx::FxIndexSet;
 use rustc_hir as hir;
 use rustc_hir::def_id::DefId;
 use rustc_hir::intravisit::Visitor;
+use rustc_infer::traits::{Obligation, ObligationCause, ObligationCauseCode, PredicateObligation};
+use rustc_middle::ty::print::PrintTraitRefExt as _;
 use rustc_middle::ty::{self, Ty, TyCtxt};
 use rustc_span::Span;
 use std::ops::ControlFlow;
@@ -180,3 +182,61 @@ pub enum DefIdOrName {
     DefId(DefId),
     Name(&'static str),
 }
+
+/// Recovers the "impl X for Y" signature from `impl_def_id` and returns it as a
+/// string.
+pub(crate) fn to_pretty_impl_header(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Option<String> {
+    use std::fmt::Write;
+
+    let trait_ref = tcx.impl_trait_ref(impl_def_id)?.instantiate_identity();
+    let mut w = "impl".to_owned();
+
+    let args = ty::GenericArgs::identity_for_item(tcx, impl_def_id);
+
+    // FIXME: Currently only handles ?Sized.
+    //        Needs to support ?Move and ?DynSized when they are implemented.
+    let mut types_without_default_bounds = FxIndexSet::default();
+    let sized_trait = tcx.lang_items().sized_trait();
+
+    let arg_names = args.iter().map(|k| k.to_string()).filter(|k| k != "'_").collect::<Vec<_>>();
+    if !arg_names.is_empty() {
+        types_without_default_bounds.extend(args.types());
+        w.push('<');
+        w.push_str(&arg_names.join(", "));
+        w.push('>');
+    }
+
+    write!(
+        w,
+        " {} for {}",
+        trait_ref.print_only_trait_path(),
+        tcx.type_of(impl_def_id).instantiate_identity()
+    )
+    .unwrap();
+
+    // The predicates will contain default bounds like `T: Sized`. We need to
+    // remove these bounds, and add `T: ?Sized` to any untouched type parameters.
+    let predicates = tcx.predicates_of(impl_def_id).predicates;
+    let mut pretty_predicates =
+        Vec::with_capacity(predicates.len() + types_without_default_bounds.len());
+
+    for (p, _) in predicates {
+        if let Some(poly_trait_ref) = p.as_trait_clause() {
+            if Some(poly_trait_ref.def_id()) == sized_trait {
+                // FIXME(#120456) - is `swap_remove` correct?
+                types_without_default_bounds.swap_remove(&poly_trait_ref.self_ty().skip_binder());
+                continue;
+            }
+        }
+        pretty_predicates.push(p.to_string());
+    }
+
+    pretty_predicates.extend(types_without_default_bounds.iter().map(|ty| format!("{ty}: ?Sized")));
+
+    if !pretty_predicates.is_empty() {
+        write!(w, "\n  where {}", pretty_predicates.join(", ")).unwrap();
+    }
+
+    w.push(';');
+    Some(w)
+}

compiler/rustc_trait_selection/src/error_reporting/traits/on_unimplemented.rs

@@ -1,10 +1,10 @@
 use super::{ObligationCauseCode, PredicateObligation};
+use crate::error_reporting::traits::type_err_ctxt_ext::InferCtxtPrivExt;
 use crate::errors::{
     EmptyOnClauseInOnUnimplemented, InvalidOnClauseInOnUnimplemented, NoValueInOnUnimplemented,
 };
 use crate::infer::error_reporting::TypeErrCtxt;
 use crate::infer::InferCtxtExt;
-use crate::traits::error_reporting::type_err_ctxt_ext::InferCtxtPrivExt;
 use rustc_ast::AttrArgs;
 use rustc_ast::AttrArgsEq;
 use rustc_ast::AttrKind;

compiler/rustc_trait_selection/src/error_reporting/traits/suggestions.rs

@@ -44,8 +44,8 @@ use std::assert_matches::debug_assert_matches;
 use std::borrow::Cow;
 use std::iter;
 
+use crate::error_reporting::traits::type_err_ctxt_ext::InferCtxtPrivExt;
 use crate::infer::InferCtxtExt as _;
-use crate::traits::error_reporting::type_err_ctxt_ext::InferCtxtPrivExt;
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc_middle::ty::print::{
     with_forced_trimmed_paths, with_no_trimmed_paths, PrintPolyTraitPredicateExt as _,

compiler/rustc_trait_selection/src/error_reporting/traits/type_err_ctxt_ext.rs

@@ -2,16 +2,16 @@
 
 use super::on_unimplemented::{AppendConstMessage, OnUnimplementedNote, TypeErrCtxtExt as _};
 use super::suggestions::{get_explanation_based_on_obligation, TypeErrCtxtExt as _};
+use crate::error_reporting::traits::infer_ctxt_ext::InferCtxtExt;
+use crate::error_reporting::traits::to_pretty_impl_header;
+use crate::error_reporting::traits::{ambiguity, ambiguity::CandidateSource::*};
 use crate::errors::{
     AsyncClosureNotFn, ClosureFnMutLabel, ClosureFnOnceLabel, ClosureKindMismatch,
 };
 use crate::infer::error_reporting::{TyCategory, TypeAnnotationNeeded as ErrorCode};
 use crate::infer::InferCtxtExt as _;
 use crate::infer::{self, InferCtxt};
-use crate::traits::error_reporting::infer_ctxt_ext::InferCtxtExt;
-use crate::traits::error_reporting::{ambiguity, ambiguity::CandidateSource::*};
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
-use crate::traits::specialize::to_pretty_impl_header;
 use crate::traits::NormalizeExt;
 use crate::traits::{
     elaborate, FulfillmentError, FulfillmentErrorCode, MismatchedProjectionTypes, Obligation,

compiler/rustc_trait_selection/src/lib.rs

@@ -33,6 +33,7 @@
 #[macro_use]
 extern crate tracing;
 
+pub mod error_reporting;
 pub mod errors;
 pub mod infer;
 pub mod regions;

compiler/rustc_trait_selection/src/solve/normalize.rs

@@ -1,7 +1,7 @@
 use std::fmt::Debug;
 use std::marker::PhantomData;
 
-use crate::traits::error_reporting::{OverflowCause, TypeErrCtxtExt};
+use crate::error_reporting::traits::{OverflowCause, TypeErrCtxtExt};
 use crate::traits::query::evaluate_obligation::InferCtxtExt;
 use crate::traits::{BoundVarReplacer, PlaceholderReplacer, ScrubbedTraitError};
 use rustc_data_structures::stack::ensure_sufficient_stack;

compiler/rustc_trait_selection/src/traits/coherence.rs

@@ -30,8 +30,8 @@ use rustc_span::symbol::sym;
 use rustc_span::{Span, DUMMY_SP};
 use std::fmt::Debug;
 
-use super::error_reporting::suggest_new_overflow_limit;
 use super::ObligationCtxt;
+use crate::error_reporting::traits::suggest_new_overflow_limit;
 
 pub struct OverlapResult<'tcx> {
     pub impl_header: ty::ImplHeader<'tcx>,

compiler/rustc_trait_selection/src/traits/engine.rs

@@ -3,10 +3,10 @@ use std::fmt::Debug;
 
 use super::{FromSolverError, TraitEngine};
 use super::{FulfillmentContext, ScrubbedTraitError};
+use crate::error_reporting::traits::TypeErrCtxtExt;
 use crate::regions::InferCtxtRegionExt;
 use crate::solve::FulfillmentCtxt as NextFulfillmentCtxt;
 use crate::solve::NextSolverError;
-use crate::traits::error_reporting::TypeErrCtxtExt;
 use crate::traits::fulfill::OldSolverError;
 use crate::traits::NormalizeExt;
 use crate::traits::StructurallyNormalizeExt;

compiler/rustc_trait_selection/src/traits/fulfill.rs

@@ -1,5 +1,5 @@
+use crate::error_reporting::traits::TypeErrCtxtExt;
 use crate::infer::{InferCtxt, TyOrConstInferVar};
-use crate::traits::error_reporting::TypeErrCtxtExt;
 use crate::traits::normalize::normalize_with_depth_to;
 use rustc_data_structures::captures::Captures;
 use rustc_data_structures::obligation_forest::ProcessResult;

compiler/rustc_trait_selection/src/traits/mod.rs

@@ -6,7 +6,6 @@ pub mod auto_trait;
 pub(crate) mod coherence;
 pub mod const_evaluatable;
 mod engine;
-pub mod error_reporting;
 mod fulfill;
 pub mod misc;
 pub mod normalize;
@@ -24,10 +23,10 @@ mod util;
 pub mod vtable;
 pub mod wf;
 
+use crate::error_reporting::traits::TypeErrCtxtExt as _;
 use crate::infer::outlives::env::OutlivesEnvironment;
 use crate::infer::{InferCtxt, TyCtxtInferExt};
 use crate::regions::InferCtxtRegionExt;
-use crate::traits::error_reporting::TypeErrCtxtExt as _;
 use crate::traits::query::evaluate_obligation::InferCtxtExt as _;
 use rustc_errors::ErrorGuaranteed;
 use rustc_middle::query::Providers;

compiler/rustc_trait_selection/src/traits/normalize.rs

@@ -1,9 +1,9 @@
 //! Deeply normalize types using the old trait solver.
 
-use super::error_reporting::OverflowCause;
-use super::error_reporting::TypeErrCtxtExt;
 use super::SelectionContext;
 use super::{project, with_replaced_escaping_bound_vars, BoundVarReplacer, PlaceholderReplacer};
+use crate::error_reporting::traits::OverflowCause;
+use crate::error_reporting::traits::TypeErrCtxtExt;
 use crate::solve::NextSolverError;
 use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_infer::infer::at::At;

compiler/rustc_trait_selection/src/traits/query/normalize.rs

@@ -2,11 +2,11 @@
 //! which folds deeply, invoking the underlying
 //! `normalize_canonicalized_projection_ty` query when it encounters projections.
 
+use crate::error_reporting::traits::OverflowCause;
+use crate::error_reporting::traits::TypeErrCtxtExt;
 use crate::infer::at::At;
 use crate::infer::canonical::OriginalQueryValues;
 use crate::infer::{InferCtxt, InferOk};
-use crate::traits::error_reporting::OverflowCause;
-use crate::traits::error_reporting::TypeErrCtxtExt;
 use crate::traits::normalize::needs_normalization;
 use crate::traits::Normalized;
 use crate::traits::{BoundVarReplacer, PlaceholderReplacer, ScrubbedTraitError};

compiler/rustc_trait_selection/src/traits/select/mod.rs

@@ -18,9 +18,9 @@ use super::{
     TraitQueryMode,
 };
 
+use crate::error_reporting::traits::TypeErrCtxtExt;
 use crate::infer::{InferCtxt, InferCtxtExt, InferOk, TypeFreshener};
 use crate::solve::InferCtxtSelectExt as _;
-use crate::traits::error_reporting::TypeErrCtxtExt;
 use crate::traits::normalize::normalize_with_depth;
 use crate::traits::normalize::normalize_with_depth_to;
 use crate::traits::project::ProjectAndUnifyResult;

compiler/rustc_trait_selection/src/traits/specialize/mod.rs

@@ -14,6 +14,7 @@ use rustc_infer::infer::DefineOpaqueTypes;
 use rustc_middle::ty::print::PrintTraitRefExt as _;
 use specialization_graph::GraphExt;
 
+use crate::error_reporting::traits::to_pretty_impl_header;
 use crate::errors::NegativePositiveConflict;
 use crate::infer::{InferCtxt, InferOk, TyCtxtInferExt};
 use crate::traits::select::IntercrateAmbiguityCause;
@@ -25,8 +26,8 @@ use rustc_errors::{codes::*, Diag, EmissionGuarantee};
 use rustc_hir::def_id::{DefId, LocalDefId};
 use rustc_middle::bug;
 use rustc_middle::query::LocalCrate;
+use rustc_middle::ty::GenericArgsRef;
 use rustc_middle::ty::{self, ImplSubject, Ty, TyCtxt, TypeVisitableExt};
-use rustc_middle::ty::{GenericArgs, GenericArgsRef};
 use rustc_session::lint::builtin::COHERENCE_LEAK_CHECK;
 use rustc_session::lint::builtin::ORDER_DEPENDENT_TRAIT_OBJECTS;
 use rustc_span::{sym, ErrorGuaranteed, Span, DUMMY_SP};
@@ -485,61 +486,3 @@ fn report_conflicting_impls<'tcx>(
         }
     }
 }
-
-/// Recovers the "impl X for Y" signature from `impl_def_id` and returns it as a
-/// string.
-pub(crate) fn to_pretty_impl_header(tcx: TyCtxt<'_>, impl_def_id: DefId) -> Option<String> {
-    use std::fmt::Write;
-
-    let trait_ref = tcx.impl_trait_ref(impl_def_id)?.instantiate_identity();
-    let mut w = "impl".to_owned();
-
-    let args = GenericArgs::identity_for_item(tcx, impl_def_id);
-
-    // FIXME: Currently only handles ?Sized.
-    //        Needs to support ?Move and ?DynSized when they are implemented.
-    let mut types_without_default_bounds = FxIndexSet::default();
-    let sized_trait = tcx.lang_items().sized_trait();
-
-    let arg_names = args.iter().map(|k| k.to_string()).filter(|k| k != "'_").collect::<Vec<_>>();
-    if !arg_names.is_empty() {
-        types_without_default_bounds.extend(args.types());
-        w.push('<');
-        w.push_str(&arg_names.join(", "));
-        w.push('>');
-    }
-
-    write!(
-        w,
-        " {} for {}",
-        trait_ref.print_only_trait_path(),
-        tcx.type_of(impl_def_id).instantiate_identity()
-    )
-    .unwrap();
-
-    // The predicates will contain default bounds like `T: Sized`. We need to
-    // remove these bounds, and add `T: ?Sized` to any untouched type parameters.
-    let predicates = tcx.predicates_of(impl_def_id).predicates;
-    let mut pretty_predicates =
-        Vec::with_capacity(predicates.len() + types_without_default_bounds.len());
-
-    for (p, _) in predicates {
-        if let Some(poly_trait_ref) = p.as_trait_clause() {
-            if Some(poly_trait_ref.def_id()) == sized_trait {
-                // FIXME(#120456) - is `swap_remove` correct?
-                types_without_default_bounds.swap_remove(&poly_trait_ref.self_ty().skip_binder());
-                continue;
-            }
-        }
-        pretty_predicates.push(p.to_string());
-    }
-
-    pretty_predicates.extend(types_without_default_bounds.iter().map(|ty| format!("{ty}: ?Sized")));
-
-    if !pretty_predicates.is_empty() {
-        write!(w, "\n  where {}", pretty_predicates.join(", ")).unwrap();
-    }
-
-    w.push(';');
-    Some(w)
-}

compiler/rustc_traits/src/codegen.rs

@@ -7,7 +7,7 @@ use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::bug;
 use rustc_middle::traits::CodegenObligationError;
 use rustc_middle::ty::{self, TyCtxt, TypeVisitableExt};
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::traits::{
     ImplSource, Obligation, ObligationCause, ObligationCtxt, ScrubbedTraitError, SelectionContext,
     Unimplemented,

compiler/rustc_traits/src/normalize_projection_ty.rs

@@ -2,8 +2,8 @@ use rustc_infer::infer::canonical::{Canonical, QueryResponse};
 use rustc_infer::infer::TyCtxtInferExt;
 use rustc_middle::query::Providers;
 use rustc_middle::ty::{ParamEnvAnd, TyCtxt};
+use rustc_trait_selection::error_reporting::traits::TypeErrCtxtExt;
 use rustc_trait_selection::infer::InferCtxtBuilderExt;
-use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
 use rustc_trait_selection::traits::query::{
     normalize::NormalizationResult, CanonicalAliasGoal, NoSolution,
 };

src/tools/clippy/clippy_lints/src/eta_reduction.rs

@@ -15,7 +15,7 @@ use rustc_middle::ty::{
 use rustc_session::declare_lint_pass;
 use rustc_span::symbol::sym;
 use rustc_target::spec::abi::Abi;
-use rustc_trait_selection::traits::error_reporting::InferCtxtExt as _;
+use rustc_trait_selection::error_reporting::traits::InferCtxtExt as _;
 
 declare_clippy_lint! {
     /// ### What it does

src/tools/clippy/clippy_lints/src/future_not_send.rs

@@ -9,7 +9,7 @@ use rustc_middle::ty::{self, AliasTy, ClauseKind, PredicateKind};
 use rustc_session::declare_lint_pass;
 use rustc_span::def_id::LocalDefId;
 use rustc_span::{sym, Span};
-use rustc_trait_selection::traits::error_reporting::suggestions::TypeErrCtxtExt;
+use rustc_trait_selection::error_reporting::traits::suggestions::TypeErrCtxtExt;
 use rustc_trait_selection::traits::{self, FulfillmentError, ObligationCtxt};
 
 declare_clippy_lint! {

src/tools/clippy/clippy_lints/src/unconditional_recursion.rs

@@ -15,7 +15,7 @@ use rustc_middle::ty::{self, AssocKind, Ty, TyCtxt};
 use rustc_session::impl_lint_pass;
 use rustc_span::symbol::{kw, Ident};
 use rustc_span::{sym, Span};
-use rustc_trait_selection::traits::error_reporting::suggestions::ReturnsVisitor;
+use rustc_trait_selection::error_reporting::traits::suggestions::ReturnsVisitor;
 
 declare_clippy_lint! {
     /// ### What it does