Clean up trivial traversal/lift impl generator macro calls.

We have four macros for generating trivial traversal (fold/visit) and
lift impls.
- `rustc_ir::TrivialTypeTraversalImpls`
- `rustc_middle::TrivialTypeTraversalImpls`
- `rustc_middle::TrivialLiftImpls`
- `rustc_middle::TrivialTypeTraversalAndLiftImpls`

The first two are very similar. The last one just combines the second
and third one.

The macros themselves are ok, but their use is a mess. This commit does
the following.
- Removes types that no longer need a lift and/or traversal impl from
  the macro calls.
- Consolidates the macro calls into the smallest number of calls
  possible, with each one mentioning as many types as possible.
- Orders the types within those macro calls alphabetically, and makes
  the module qualification more consistent.
- Eliminates `rustc_middle::mir::type_foldable`, because the macro calls
  were merged and the manual `TypeFoldable` impls are better placed in
  `structural_impls.rs`, alongside all the other ones.

This makes the code more concise. Moving forward, it also makes it more
obvious where new types should be added.

4 files changed, 1 insertions, 73 deletions

diff --git a/compiler/rustc_middle/src/mir/basic_blocks.rs b/compiler/rustc_middle/src/mir/basic_blocks.rs
index 3eb563d7d6e..c32cf5f8253 100644
--- a/compiler/rustc_middle/src/mir/basic_blocks.rs
+++ b/compiler/rustc_middle/src/mir/basic_blocks.rs
@@ -163,6 +163,7 @@ impl<'tcx> graph::Predecessors for BasicBlocks<'tcx> {
     }
 }
 
+// Done here instead of in `structural_impls.rs` because `Cache` is private, as is `basic_blocks`.
 TrivialTypeTraversalImpls! { Cache }
 
 impl<S: Encoder> Encodable<S> for Cache {
diff --git a/compiler/rustc_middle/src/mir/interpret/error.rs b/compiler/rustc_middle/src/mir/interpret/error.rs
index 8c085fa310a..1222ba052cc 100644
--- a/compiler/rustc_middle/src/mir/interpret/error.rs
+++ b/compiler/rustc_middle/src/mir/interpret/error.rs
@@ -95,8 +95,6 @@ impl From<ReportedErrorInfo> for ErrorGuaranteed {
     }
 }
 
-TrivialTypeTraversalImpls! { ErrorHandled }
-
 pub type EvalToAllocationRawResult<'tcx> = Result<ConstAlloc<'tcx>, ErrorHandled>;
 pub type EvalStaticInitializerRawResult<'tcx> = Result<ConstAllocation<'tcx>, ErrorHandled>;
 pub type EvalToConstValueResult<'tcx> = Result<ConstValue<'tcx>, ErrorHandled>;
diff --git a/compiler/rustc_middle/src/mir/mod.rs b/compiler/rustc_middle/src/mir/mod.rs
index cfb78e5dddf..68d5e5f4dd2 100644
--- a/compiler/rustc_middle/src/mir/mod.rs
+++ b/compiler/rustc_middle/src/mir/mod.rs
@@ -34,7 +34,6 @@ use self::visit::TyContext;
 use crate::mir::interpret::{AllocRange, Scalar};
 use crate::mir::visit::MirVisitable;
 use crate::ty::codec::{TyDecoder, TyEncoder};
-use crate::ty::fold::{FallibleTypeFolder, TypeFoldable};
 use crate::ty::print::{FmtPrinter, Printer, pretty_print_const, with_no_trimmed_paths};
 use crate::ty::visit::TypeVisitableExt;
 use crate::ty::{
@@ -59,7 +58,6 @@ pub mod tcx;
 mod terminator;
 
 pub mod traversal;
-mod type_foldable;
 pub mod visit;
 
 pub use consts::*;
@@ -927,8 +925,6 @@ pub enum BindingForm<'tcx> {
     RefForGuard,
 }
 
-TrivialTypeTraversalImpls! { BindingForm<'tcx> }
-
 mod binding_form_impl {
     use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
     use rustc_query_system::ich::StableHashingContext;
diff --git a/compiler/rustc_middle/src/mir/type_foldable.rs b/compiler/rustc_middle/src/mir/type_foldable.rs
deleted file mode 100644
index 9893dd0484c..00000000000
--- a/compiler/rustc_middle/src/mir/type_foldable.rs
+++ /dev/null
@@ -1,67 +0,0 @@
-//! `TypeFoldable` implementations for MIR types
-
-use rustc_ast::InlineAsmTemplatePiece;
-use rustc_hir::UnsafeBinderCastKind;
-use rustc_hir::def_id::LocalDefId;
-
-use super::*;
-
-TrivialTypeTraversalImpls! {
-    BlockTailInfo,
-    MirPhase,
-    SourceInfo,
-    FakeReadCause,
-    RetagKind,
-    SourceScope,
-    SourceScopeLocalData,
-    UserTypeAnnotationIndex,
-    BorrowKind,
-    RawPtrKind,
-    CastKind,
-    BasicBlock,
-    SwitchTargets,
-    CoroutineKind,
-    CoroutineSavedLocal,
-    UnsafeBinderCastKind,
-}
-
-TrivialTypeTraversalImpls! {
-    ConstValue<'tcx>,
-    NullOp<'tcx>,
-}
-
-impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx [InlineAsmTemplatePiece] {
-    fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
-        self,
-        _folder: &mut F,
-    ) -> Result<Self, F::Error> {
-        Ok(self)
-    }
-}
-
-impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx [Span] {
-    fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
-        self,
-        _folder: &mut F,
-    ) -> Result<Self, F::Error> {
-        Ok(self)
-    }
-}
-
-impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<LocalDefId> {
-    fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
-        self,
-        _folder: &mut F,
-    ) -> Result<Self, F::Error> {
-        Ok(self)
-    }
-}
-
-impl<'tcx> TypeFoldable<TyCtxt<'tcx>> for &'tcx ty::List<PlaceElem<'tcx>> {
-    fn try_fold_with<F: FallibleTypeFolder<TyCtxt<'tcx>>>(
-        self,
-        folder: &mut F,
-    ) -> Result<Self, F::Error> {
-        ty::util::fold_list(self, folder, |tcx, v| tcx.mk_place_elems(v))
-    }
-}