Don't export rustc_hir_analysis::collect.

Instead re-export `rustc_hir_analysis::collect::suggest_impl_trait`,
which is the only thing from the module used in another crate. This
fixes a `FIXME` comment. Also adjust some visibilities to satisfy the
`unreachable_pub` lint.

This changes requires downgrading a link in a comment on `FnCtxt`
because `collect` is no longer public and rustdoc complains otherwise.
This is annoying but I can't see how to avoid it.

compiler/rustc_hir_analysis/src/collect.rs

@@ -57,7 +57,7 @@ mod type_of;
 
 ///////////////////////////////////////////////////////////////////////////
 
-pub fn provide(providers: &mut Providers) {
+pub(crate) fn provide(providers: &mut Providers) {
     resolve_bound_vars::provide(providers);
     *providers = Providers {
         type_of: type_of::type_of,
@@ -122,7 +122,7 @@ pub fn provide(providers: &mut Providers) {
 /// `ItemCtxt` is parameterized by a `DefId` that it uses to satisfy
 /// `probe_ty_param_bounds` requests, drawing the information from
 /// the HIR (`hir::Generics`), recursively.
-pub struct ItemCtxt<'tcx> {
+pub(crate) struct ItemCtxt<'tcx> {
     tcx: TyCtxt<'tcx>,
     item_def_id: LocalDefId,
     tainted_by_errors: Cell<Option<ErrorGuaranteed>>,
@@ -148,7 +148,7 @@ impl<'v> Visitor<'v> for HirPlaceholderCollector {
     }
 }
 
-pub struct CollectItemTypesVisitor<'tcx> {
+pub(crate) struct CollectItemTypesVisitor<'tcx> {
     pub tcx: TyCtxt<'tcx>,
 }
 
@@ -364,19 +364,19 @@ fn bad_placeholder<'cx, 'tcx>(
 }
 
 impl<'tcx> ItemCtxt<'tcx> {
-    pub fn new(tcx: TyCtxt<'tcx>, item_def_id: LocalDefId) -> ItemCtxt<'tcx> {
+    pub(crate) fn new(tcx: TyCtxt<'tcx>, item_def_id: LocalDefId) -> ItemCtxt<'tcx> {
         ItemCtxt { tcx, item_def_id, tainted_by_errors: Cell::new(None) }
     }
 
-    pub fn lower_ty(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
+    pub(crate) fn lower_ty(&self, hir_ty: &hir::Ty<'tcx>) -> Ty<'tcx> {
         self.lowerer().lower_ty(hir_ty)
     }
 
-    pub fn hir_id(&self) -> hir::HirId {
+    pub(crate) fn hir_id(&self) -> hir::HirId {
         self.tcx.local_def_id_to_hir_id(self.item_def_id)
     }
 
-    pub fn node(&self) -> hir::Node<'tcx> {
+    pub(crate) fn node(&self) -> hir::Node<'tcx> {
         self.tcx.hir_node(self.hir_id())
     }
 

compiler/rustc_hir_analysis/src/lib.rs

@@ -83,12 +83,11 @@ pub mod autoderef;
 mod bounds;
 mod check_unused;
 mod coherence;
-mod delegation;
+mod collect;
-pub mod hir_ty_lowering;
-// FIXME: This module shouldn't be public.
-pub mod collect;
 mod constrained_generic_params;
+mod delegation;
 mod errors;
+pub mod hir_ty_lowering;
 pub mod hir_wf_check;
 mod impl_wf_check;
 mod outlives;
@@ -104,7 +103,8 @@ use rustc_middle::ty::{self, Const, Ty, TyCtxt};
 use rustc_span::Span;
 use rustc_trait_selection::traits;
 
-use self::hir_ty_lowering::{FeedConstTy, HirTyLowerer};
+pub use crate::collect::suggest_impl_trait;
+use crate::hir_ty_lowering::{FeedConstTy, HirTyLowerer};
 
 rustc_fluent_macro::fluent_messages! { "../messages.ftl" }
 

compiler/rustc_hir_typeck/src/fn_ctxt/mod.rs

@@ -31,12 +31,12 @@ use crate::{CoroutineTypes, Diverges, EnclosingBreakables, TypeckRootCtxt};
 /// functions, closures, and `const`s, including performing type inference
 /// with [`InferCtxt`].
 ///
-/// This is in contrast to [`ItemCtxt`], which is used to type-check item *signatures*
+/// This is in contrast to `rustc_hir_analysis::collect::ItemCtxt`, which is
-/// and thus does not perform type inference.
+/// used to type-check item *signatures* and thus does not perform type
+/// inference.
 ///
-/// See [`ItemCtxt`]'s docs for more.
+/// See `ItemCtxt`'s docs for more.
 ///
-/// [`ItemCtxt`]: rustc_hir_analysis::collect::ItemCtxt
 /// [`InferCtxt`]: infer::InferCtxt
 pub(crate) struct FnCtxt<'a, 'tcx> {
     pub(super) body_id: LocalDefId,

compiler/rustc_hir_typeck/src/fn_ctxt/suggestions.rs

@@ -12,8 +12,8 @@ use rustc_hir::{
     GenericBound, HirId, Node, PatExpr, PatExprKind, Path, QPath, Stmt, StmtKind, TyKind,
     WherePredicateKind, expr_needs_parens,
 };
-use rustc_hir_analysis::collect::suggest_impl_trait;
 use rustc_hir_analysis::hir_ty_lowering::HirTyLowerer;
+use rustc_hir_analysis::suggest_impl_trait;
 use rustc_middle::lint::in_external_macro;
 use rustc_middle::middle::stability::EvalResult;
 use rustc_middle::span_bug;