Rollup merge of #143856 - mladedav:dm/private-reexport, r=petrochenkov

Linting public reexport of private dependencies

Part of public/private dependencies rust-lang/rust#44663
Partially addresses rust-lang/rust#71043

I'm adding a warning for reexports of private dependencies into `rustc_resolve`. I get that this should not be a warning, but should instead be a lint to be controlled by the feature gate, but I did not figure out how exactly to do that at that point. I tried doing the same thing as is done in `rustc_privacy`, but the linting system is not ready yet as far as I understand the error I got, so I made a warning for now instead. Some guidance on how to emit lints with `dcx` would be appreciated.

This also sets the `std_detect` crate as a public dependency of `std` because some macros are reexported from there. I did not check closer, but the other option may be to allow the specific reexports instead.

2 files changed, 25 insertions, 9 deletions

diff --git a/compiler/rustc_resolve/src/imports.rs b/compiler/rustc_resolve/src/imports.rs
index 9a031ee03e0..c3e39d2071b 100644
--- a/compiler/rustc_resolve/src/imports.rs
+++ b/compiler/rustc_resolve/src/imports.rs
@@ -15,8 +15,8 @@ use rustc_middle::span_bug;
 use rustc_middle::ty::Visibility;
 use rustc_session::lint::BuiltinLintDiag;
 use rustc_session::lint::builtin::{
-    AMBIGUOUS_GLOB_REEXPORTS, HIDDEN_GLOB_REEXPORTS, PUB_USE_OF_PRIVATE_EXTERN_CRATE,
-    REDUNDANT_IMPORTS, UNUSED_IMPORTS,
+    AMBIGUOUS_GLOB_REEXPORTS, EXPORTED_PRIVATE_DEPENDENCIES, HIDDEN_GLOB_REEXPORTS,
+    PUB_USE_OF_PRIVATE_EXTERN_CRATE, REDUNDANT_IMPORTS, UNUSED_IMPORTS,
 };
 use rustc_session::parse::feature_err;
 use rustc_span::edit_distance::find_best_match_for_name;
@@ -635,10 +635,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
         }
     }
 
-    pub(crate) fn check_hidden_glob_reexports(
-        &mut self,
-        exported_ambiguities: FxHashSet<NameBinding<'ra>>,
-    ) {
+    pub(crate) fn lint_reexports(&mut self, exported_ambiguities: FxHashSet<NameBinding<'ra>>) {
         for module in self.arenas.local_modules().iter() {
             for (key, resolution) in self.resolutions(*module).borrow().iter() {
                 let resolution = resolution.borrow();
@@ -697,6 +694,27 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
                         }
                     }
                 }
+
+                if let NameBindingKind::Import { import, .. } = binding.kind
+                    && let Some(binding_id) = import.id()
+                    && let import_def_id = self.local_def_id(binding_id)
+                    && self.effective_visibilities.is_exported(import_def_id)
+                    && let Res::Def(reexported_kind, reexported_def_id) = binding.res()
+                    && !matches!(reexported_kind, DefKind::Ctor(..))
+                    && !reexported_def_id.is_local()
+                    && self.tcx.is_private_dep(reexported_def_id.krate)
+                {
+                    self.lint_buffer.buffer_lint(
+                        EXPORTED_PRIVATE_DEPENDENCIES,
+                        binding_id,
+                        binding.span,
+                        BuiltinLintDiag::ReexportPrivateDependency {
+                            kind: binding.res().descr().to_string(),
+                            name: key.ident.name.to_string(),
+                            krate: self.tcx.crate_name(reexported_def_id.krate),
+                        },
+                    );
+                }
             }
         }
     }
diff --git a/compiler/rustc_resolve/src/lib.rs b/compiler/rustc_resolve/src/lib.rs
index b0b29bc2eae..f904f326296 100644
--- a/compiler/rustc_resolve/src/lib.rs
+++ b/compiler/rustc_resolve/src/lib.rs
@@ -1773,9 +1773,7 @@ impl<'ra, 'tcx> Resolver<'ra, 'tcx> {
             let exported_ambiguities = self.tcx.sess.time("compute_effective_visibilities", || {
                 EffectiveVisibilitiesVisitor::compute_effective_visibilities(self, krate)
             });
-            self.tcx.sess.time("check_hidden_glob_reexports", || {
-                self.check_hidden_glob_reexports(exported_ambiguities)
-            });
+            self.tcx.sess.time("lint_reexports", || self.lint_reexports(exported_ambiguities));
             self.tcx
                 .sess
                 .time("finalize_macro_resolutions", || self.finalize_macro_resolutions(krate));