Auto merge of #138464 - compiler-errors:less-type-ir, r=lcnr

Use `rustc_type_ir` directly less in the codebase

cc https://github.com/rust-lang/rust/issues/138449

This is a somewhat opinionated bundle of changes that will make working on https://github.com/rust-lang/rust/issues/138449 more easy, since it cuts out the bulk of the changes that would be necessitated by the lint. Namely:

1. Fold `rustc_middle::ty::fold` and `rustc_middle::ty::visit` into `rustc_middle::ty`. This is because we already reexport some parts of these modules into `rustc_middle::ty`, and there's really no benefit from namespacing away the rest of these modules's functionality given how important folding and visiting is to the type layer.
2. Rename `{Decodable,Encodable}_Generic` to `{Decodable,Encodable}_NoContext`[^why], change it to be "perfect derive" (`synstructure::AddBounds::Fields`), use it throughout `rustc_type_ir` instead of `TyEncodable`/`TyDecodable`.
3. Make `TyEncodable` and `TyDecodable` derives use `::rustc_middle::ty::codec::TyEncoder` (etc) for its generated paths, and move the `rustc_type_ir::codec` module back to `rustc_middle::ty::codec` :tada:.
4. Stop using `rustc_type_ir` in crates that aren't "fundamental" to the type system, namely middle/infer/trait-selection. This amounted mostly to changing imports from `use rustc_type_ir::...` to `use rustc_middle::ty::...`, but also this means that we can't glob import `TyKind::*` since the reexport into `rustc_middle::ty::TyKind` is a type alias. Instead, use the prefixed variants like `ty::Str` everywhere -- IMO this is a good change, since it makes it more regularized with most of the rest of the compiler.

[^why]: `_NoContext` is the name for derive macros with no additional generic bounds and which do "perfect derive" by generating bounds based on field types. See `HashStable_NoContext`.

I'm happy to cut out some of these changes into separate PRs to make landing it a bit easier, though I don't expect to have much trouble with bitrot.

r? lcnr

13 files changed, 24 insertions, 27 deletions

diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
index baf2489b2b8..6510dbbbe9d 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/mod.rs
@@ -1466,7 +1466,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
             }
         }
 
-        impl<'tcx> ty::visit::TypeVisitor<TyCtxt<'tcx>> for OpaqueTypesVisitor<'tcx> {
+        impl<'tcx> ty::TypeVisitor<TyCtxt<'tcx>> for OpaqueTypesVisitor<'tcx> {
             fn visit_ty(&mut self, t: Ty<'tcx>) {
                 if let Some((kind, def_id)) = TyCategory::from_ty(self.tcx, t) {
                     let span = self.tcx.def_span(def_id);
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs
index 40958ec1088..0bcb5f6f3b2 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/need_type_info.rs
@@ -18,7 +18,7 @@ use rustc_middle::ty::{
     TypeFoldable, TypeFolder, TypeSuperFoldable, TypeckResults,
 };
 use rustc_span::{BytePos, DUMMY_SP, FileName, Ident, Span, sym};
-use rustc_type_ir::visit::TypeVisitableExt;
+use rustc_type_ir::TypeVisitableExt;
 use tracing::{debug, instrument, warn};
 
 use super::nice_region_error::placeholder_error::Highlighted;
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/trait_impl_difference.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/trait_impl_difference.rs
index cc2ab1c3432..74205922851 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/trait_impl_difference.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/trait_impl_difference.rs
@@ -71,7 +71,7 @@ impl<'a, 'tcx> NiceRegionError<'a, 'tcx> {
             }
         }
 
-        impl<'tcx> ty::visit::TypeVisitor<TyCtxt<'tcx>> for HighlightBuilder<'tcx> {
+        impl<'tcx> ty::TypeVisitor<TyCtxt<'tcx>> for HighlightBuilder<'tcx> {
             fn visit_region(&mut self, r: ty::Region<'tcx>) {
                 if !r.has_name() && self.counter <= 3 {
                     self.highlight.highlighting_region(r, self.counter);
diff --git a/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/util.rs b/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/util.rs
index 245764c94ab..00f053fa599 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/util.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/infer/nice_region_error/util.rs
@@ -3,8 +3,7 @@
 
 use rustc_hir as hir;
 use rustc_hir::def_id::{DefId, LocalDefId};
-use rustc_middle::ty::fold::fold_regions;
-use rustc_middle::ty::{self, Binder, Region, Ty, TyCtxt, TypeFoldable};
+use rustc_middle::ty::{self, Binder, Region, Ty, TyCtxt, TypeFoldable, fold_regions};
 use rustc_span::Span;
 use tracing::instrument;
 
diff --git a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
index e2bdd52ba7c..07a67cde3be 100644
--- a/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
+++ b/compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs
@@ -18,12 +18,14 @@ use rustc_middle::traits::SignatureMismatchData;
 use rustc_middle::traits::select::OverflowError;
 use rustc_middle::ty::abstract_const::NotConstEvaluatable;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
-use rustc_middle::ty::fold::{TypeFolder, TypeSuperFoldable};
 use rustc_middle::ty::print::{
     PrintPolyTraitPredicateExt, PrintTraitPredicateExt as _, PrintTraitRefExt as _,
     with_forced_trimmed_paths,
 };
-use rustc_middle::ty::{self, TraitRef, Ty, TyCtxt, TypeFoldable, TypeVisitableExt, Upcast};
+use rustc_middle::ty::{
+    self, TraitRef, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable, TypeVisitableExt,
+    Upcast,
+};
 use rustc_middle::{bug, span_bug};
 use rustc_span::{BytePos, DUMMY_SP, STDLIB_STABLE_CRATES, Span, Symbol, sym};
 use tracing::{debug, instrument};
diff --git a/compiler/rustc_trait_selection/src/solve/delegate.rs b/compiler/rustc_trait_selection/src/solve/delegate.rs
index e69bad095e3..af5a60027ba 100644
--- a/compiler/rustc_trait_selection/src/solve/delegate.rs
+++ b/compiler/rustc_trait_selection/src/solve/delegate.rs
@@ -8,8 +8,7 @@ use rustc_infer::infer::canonical::{
 };
 use rustc_infer::infer::{InferCtxt, RegionVariableOrigin, TyCtxtInferExt};
 use rustc_infer::traits::solve::Goal;
-use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitableExt as _};
+use rustc_middle::ty::{self, Ty, TyCtxt, TypeFoldable, TypeVisitableExt as _};
 use rustc_span::{DUMMY_SP, ErrorGuaranteed, Span};
 use rustc_type_ir::TypingMode;
 use rustc_type_ir::solve::{Certainty, NoSolution};
diff --git a/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs b/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
index 4b1bc316d5f..48a05ad29fb 100644
--- a/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
+++ b/compiler/rustc_trait_selection/src/solve/inspect/analyse.rs
@@ -15,8 +15,7 @@ use rustc_infer::infer::{DefineOpaqueTypes, InferCtxt, InferOk};
 use rustc_macros::extension;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::traits::solve::{Certainty, Goal, GoalSource, NoSolution, QueryResult};
-use rustc_middle::ty::visit::{VisitorResult, try_visit};
-use rustc_middle::ty::{TyCtxt, TypeFoldable};
+use rustc_middle::ty::{TyCtxt, TypeFoldable, VisitorResult, try_visit};
 use rustc_middle::{bug, ty};
 use rustc_next_trait_solver::resolve::EagerResolver;
 use rustc_next_trait_solver::solve::inspect::{self, instantiate_canonical_state};
diff --git a/compiler/rustc_trait_selection/src/traits/coherence.rs b/compiler/rustc_trait_selection/src/traits/coherence.rs
index 3b40882ef57..4c7172c3278 100644
--- a/compiler/rustc_trait_selection/src/traits/coherence.rs
+++ b/compiler/rustc_trait_selection/src/traits/coherence.rs
@@ -17,8 +17,9 @@ use rustc_middle::traits::query::NoSolution;
 use rustc_middle::traits::solve::{CandidateSource, Certainty, Goal};
 use rustc_middle::traits::specialization_graph::OverlapMode;
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
-use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor};
-use rustc_middle::ty::{self, Ty, TyCtxt, TypingMode};
+use rustc_middle::ty::{
+    self, Ty, TyCtxt, TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypeVisitor, TypingMode,
+};
 pub use rustc_next_trait_solver::coherence::*;
 use rustc_next_trait_solver::solve::SolverDelegateEvalExt;
 use rustc_span::{DUMMY_SP, Span, sym};
diff --git a/compiler/rustc_trait_selection/src/traits/mod.rs b/compiler/rustc_trait_selection/src/traits/mod.rs
index 105cb917571..de337710b5e 100644
--- a/compiler/rustc_trait_selection/src/traits/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/mod.rs
@@ -32,11 +32,9 @@ pub use rustc_infer::traits::*;
 use rustc_middle::query::Providers;
 use rustc_middle::span_bug;
 use rustc_middle::ty::error::{ExpectedFound, TypeError};
-use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::visit::{TypeVisitable, TypeVisitableExt};
 use rustc_middle::ty::{
-    self, GenericArgs, GenericArgsRef, Ty, TyCtxt, TypeFolder, TypeSuperFoldable,
-    TypeSuperVisitable, TypingMode, Upcast,
+    self, GenericArgs, GenericArgsRef, Ty, TyCtxt, TypeFoldable, TypeFolder, TypeSuperFoldable,
+    TypeSuperVisitable, TypeVisitable, TypeVisitableExt, TypingMode, Upcast,
 };
 use rustc_span::def_id::DefId;
 use rustc_span::{DUMMY_SP, Span};
diff --git a/compiler/rustc_trait_selection/src/traits/project.rs b/compiler/rustc_trait_selection/src/traits/project.rs
index 4d9cf6620d6..be5d6286e26 100644
--- a/compiler/rustc_trait_selection/src/traits/project.rs
+++ b/compiler/rustc_trait_selection/src/traits/project.rs
@@ -13,9 +13,9 @@ use rustc_infer::traits::{ObligationCauseCode, PredicateObligations};
 use rustc_middle::traits::select::OverflowError;
 use rustc_middle::traits::{BuiltinImplSource, ImplSource, ImplSourceUserDefinedData};
 use rustc_middle::ty::fast_reject::DeepRejectCtxt;
-use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::visit::TypeVisitableExt;
-use rustc_middle::ty::{self, Term, Ty, TyCtxt, TypingMode, Upcast};
+use rustc_middle::ty::{
+    self, Term, Ty, TyCtxt, TypeFoldable, TypeVisitableExt, TypingMode, Upcast,
+};
 use rustc_middle::{bug, span_bug};
 use rustc_span::sym;
 use rustc_type_ir::elaborate;
diff --git a/compiler/rustc_trait_selection/src/traits/query/normalize.rs b/compiler/rustc_trait_selection/src/traits/query/normalize.rs
index 6bf76eaee5c..165c63f3745 100644
--- a/compiler/rustc_trait_selection/src/traits/query/normalize.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/normalize.rs
@@ -7,9 +7,10 @@ use rustc_data_structures::stack::ensure_sufficient_stack;
 use rustc_infer::traits::PredicateObligations;
 use rustc_macros::extension;
 pub use rustc_middle::traits::query::NormalizationResult;
-use rustc_middle::ty::fold::{FallibleTypeFolder, TypeFoldable, TypeSuperFoldable};
-use rustc_middle::ty::visit::{TypeSuperVisitable, TypeVisitable, TypeVisitableExt};
-use rustc_middle::ty::{self, Ty, TyCtxt, TypeVisitor, TypingMode};
+use rustc_middle::ty::{
+    self, FallibleTypeFolder, Ty, TyCtxt, TypeFoldable, TypeSuperFoldable, TypeSuperVisitable,
+    TypeVisitable, TypeVisitableExt, TypeVisitor, TypingMode,
+};
 use rustc_span::DUMMY_SP;
 use tracing::{debug, info, instrument};
 
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
index 68feb19c55b..4bdf04311a0 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/mod.rs
@@ -3,8 +3,7 @@ use std::fmt;
 use rustc_errors::ErrorGuaranteed;
 use rustc_infer::traits::PredicateObligations;
 use rustc_middle::traits::query::NoSolution;
-use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::{ParamEnvAnd, TyCtxt};
+use rustc_middle::ty::{ParamEnvAnd, TyCtxt, TypeFoldable};
 use rustc_span::Span;
 
 use crate::infer::canonical::{
diff --git a/compiler/rustc_trait_selection/src/traits/query/type_op/normalize.rs b/compiler/rustc_trait_selection/src/traits/query/type_op/normalize.rs
index 2f6bbd7f4cf..f2a6ce855b4 100644
--- a/compiler/rustc_trait_selection/src/traits/query/type_op/normalize.rs
+++ b/compiler/rustc_trait_selection/src/traits/query/type_op/normalize.rs
@@ -3,8 +3,7 @@ use std::fmt;
 use rustc_middle::traits::ObligationCause;
 use rustc_middle::traits::query::NoSolution;
 pub use rustc_middle::traits::query::type_op::{DeeplyNormalize, Normalize};
-use rustc_middle::ty::fold::TypeFoldable;
-use rustc_middle::ty::{self, Lift, ParamEnvAnd, Ty, TyCtxt, TypeVisitableExt};
+use rustc_middle::ty::{self, Lift, ParamEnvAnd, Ty, TyCtxt, TypeFoldable, TypeVisitableExt};
 use rustc_span::Span;
 
 use crate::infer::canonical::{CanonicalQueryInput, CanonicalQueryResponse};