Auto merge of #120926 - fmease:astconv-no-mo, r=oli-obk

[MCP 723] Rename `astconv::AstConv` and related items

See rust-lang/compiler-team#723.
Corresponding rustc-dev-guide PR: rust-lang/rustc-dev-guide#1916.

Please consult the following *normative* list of changes here:
https://fmease.dev/rustc-dev/astconv-no-mo.html ([2024-03-22 archive link](https://web.archive.org/web/20240322054711/https://fmease.dev/rustc-dev/astconv-no-mo.html)).

compiler/rustc_ast/src/ast.rs

@@ -303,10 +303,6 @@ impl TraitBoundModifiers {
     };
 }
 
-/// The AST represents all type param bounds as types.
-/// `typeck::collect::compute_bounds` matches these against
-/// the "special" built-in traits (see `middle::lang_items`) and
-/// detects `Copy`, `Send` and `Sync`.
 #[derive(Clone, Encodable, Decodable, Debug)]
 pub enum GenericBound {
     Trait(PolyTraitRef, TraitBoundModifiers),

compiler/rustc_ast/src/visit.rs

@@ -480,7 +480,7 @@ pub fn walk_use_tree<'a, V: Visitor<'a>>(
     try_visit!(visitor.visit_path(&use_tree.prefix, id));
     match use_tree.kind {
         UseTreeKind::Simple(rename) => {
-            // The extra IDs are handled during HIR lowering.
+            // The extra IDs are handled during AST lowering.
             visit_opt!(visitor, visit_ident, rename);
         }
         UseTreeKind::Glob => {}

compiler/rustc_ast_lowering/src/delegation.rs

@@ -29,11 +29,12 @@
 //! item id (`item_id`) in case of impl trait or path resolution id (`path_id`) otherwise.
 //!
 //! Since we do not have a proper way to obtain function type information by path resolution
-//! in AST, we mark each function parameter type as `InferDelegation` and inherit it in `AstConv`.
+//! in AST, we mark each function parameter type as `InferDelegation` and inherit it during
+//! HIR ty lowering.
 //!
 //! Similarly generics, predicates and header are set to the "default" values.
 //! In case of discrepancy with callee function the `NotSupportedDelegation` error will
-//! also be emitted in `AstConv`.
+//! also be emitted during HIR ty lowering.
 
 use crate::{ImplTraitPosition, ResolverAstLoweringExt};
 
@@ -129,7 +130,7 @@ impl<'hir> LoweringContext<'_, 'hir> {
     ) -> &'hir hir::FnDecl<'hir> {
         let args_count = if let Some(local_sig_id) = sig_id.as_local() {
             // Map may be filled incorrectly due to recursive delegation.
-            // Error will be emmited later in astconv.
+            // Error will be emitted later during HIR ty lowering.
             self.resolver.fn_parameter_counts.get(&local_sig_id).cloned().unwrap_or_default()
         } else {
             self.tcx.fn_arg_names(sig_id).len()

compiler/rustc_ast_lowering/src/item.rs

@@ -1427,8 +1427,8 @@ impl<'hir> LoweringContext<'_, 'hir> {
         // Error if `?Trait` bounds in where clauses don't refer directly to type parameters.
         // Note: we used to clone these bounds directly onto the type parameter (and avoid lowering
         // these into hir when we lower thee where clauses), but this makes it quite difficult to
-        // keep track of the Span info. Now, `add_implicitly_sized` in `AstConv` checks both param bounds and
-        // where clauses for `?Sized`.
+        // keep track of the Span info. Now, `<dyn HirTyLowerer>::add_implicit_sized_bound`
+        // checks both param bounds and where clauses for `?Sized`.
         for pred in &generics.where_clause.predicates {
             let WherePredicate::BoundPredicate(bound_pred) = pred else {
                 continue;

compiler/rustc_hir/src/hir.rs

@@ -428,10 +428,6 @@ pub enum TraitBoundModifier {
     MaybeConst,
 }
 
-/// The AST represents all type param bounds as types.
-/// `typeck::collect::compute_bounds` matches these against
-/// the "special" built-in traits (see `middle::lang_items`) and
-/// detects `Copy`, `Send` and `Sync`.
 #[derive(Clone, Copy, Debug, HashStable_Generic)]
 pub enum GenericBound<'hir> {
     Trait(PolyTraitRef<'hir>, TraitBoundModifier),
@@ -1860,7 +1856,7 @@ pub enum ExprKind<'hir> {
     /// Wraps the expression in a terminating scope.
     /// This makes it semantically equivalent to `{ let _t = expr; _t }`.
     ///
-    /// This construct only exists to tweak the drop order in HIR lowering.
+    /// This construct only exists to tweak the drop order in AST lowering.
     /// An example of that is the desugaring of `for` loops.
     DropTemps(&'hir Expr<'hir>),
     /// A `let $pat = $expr` expression.
@@ -2293,7 +2289,7 @@ pub enum ImplItemKind<'hir> {
 /// Bind a type to an associated type (i.e., `A = Foo`).
 ///
 /// Bindings like `A: Debug` are represented as a special type `A =
-/// $::Debug` that is understood by the astconv code.
+/// $::Debug` that is understood by the HIR ty lowering code.
 ///
 /// FIXME(alexreg): why have a separate type for the binding case,
 /// wouldn't it be better to make the `ty` field an enum like the

compiler/rustc_hir_analysis/src/bounds.rs

@@ -1,5 +1,5 @@
-//! Bounds are restrictions applied to some types after they've been converted into the
-//! `ty` form from the HIR.
+//! Bounds are restrictions applied to some types after they've been lowered from the HIR to the
+//! [`rustc_middle::ty`] form.
 
 use rustc_hir::LangItem;
 use rustc_middle::ty::{self, ToPredicate, Ty, TyCtxt};

compiler/rustc_hir_analysis/src/check/check.rs

@@ -382,8 +382,8 @@ fn check_opaque_meets_bounds<'tcx>(
         Ok(()) => {}
         Err(ty_err) => {
             // Some types may be left "stranded" if they can't be reached
-            // from an astconv'd bound but they're mentioned in the HIR. This
-            // will happen, e.g., when a nested opaque is inside of a non-
+            // from a lowered rustc_middle bound but they're mentioned in the HIR.
+            // This will happen, e.g., when a nested opaque is inside of a non-
             // existent associated type, like `impl Trait<Missing = impl Trait>`.
             // See <tests/ui/impl-trait/stranded-opaque.rs>.
             let ty_err = ty_err.to_string(tcx);

compiler/rustc_hir_analysis/src/check/compare_impl_item.rs

@@ -746,7 +746,7 @@ pub(super) fn collect_return_position_impl_trait_in_trait_tys<'tcx>(
 
     // We may not collect all RPITITs that we see in the HIR for a trait signature
     // because an RPITIT was located within a missing item. Like if we have a sig
-    // returning `-> Missing<impl Sized>`, that gets converted to `-> [type error]`,
+    // returning `-> Missing<impl Sized>`, that gets converted to `-> {type error}`,
     // and when walking through the signature we end up never collecting the def id
     // of the `impl Sized`. Insert that here, so we don't ICE later.
     for assoc_item in tcx.associated_types_for_impl_traits_in_associated_fn(trait_m.def_id) {

compiler/rustc_hir_analysis/src/check/region.rs

@@ -760,7 +760,7 @@ impl<'tcx> RegionResolutionVisitor<'tcx> {
 
     fn enter_node_scope_with_dtor(&mut self, id: hir::ItemLocalId) {
         // If node was previously marked as a terminating scope during the
-        // recursive visit of its parent node in the AST, then we need to
+        // recursive visit of its parent node in the HIR, then we need to
         // account for the destruction scope representing the scope of
         // the destructors that run immediately after it completes.
         if self.terminating_scopes.contains(&id) {

compiler/rustc_hir_analysis/src/check/wfcheck.rs

@@ -272,7 +272,7 @@ fn check_item<'tcx>(tcx: TyCtxt<'tcx>, item: &'tcx hir::Item<'tcx>) -> Result<()
                 }
                 Some(ty::ImplPolarity::Negative) => {
                     let ast::ImplPolarity::Negative(span) = impl_.polarity else {
-                        bug!("impl_polarity query disagrees with impl's polarity in AST");
+                        bug!("impl_polarity query disagrees with impl's polarity in HIR");
                     };
                     // FIXME(#27579): what amount of WF checking do we need for neg impls?
                     if let hir::Defaultness::Default { .. } = impl_.defaultness {
@@ -1866,7 +1866,7 @@ fn check_variances_for_type_defn<'tcx>(
             .iter()
             .filter_map(|predicate| match predicate {
                 hir::WherePredicate::BoundPredicate(predicate) => {
-                    match icx.to_ty(predicate.bounded_ty).kind() {
+                    match icx.lower_ty(predicate.bounded_ty).kind() {
                         ty::Param(data) => Some(Parameter(data.index)),
                         _ => None,
                     }