Use visible_traits where possible

Author: tgross35

compiler/rustc_hir_analysis/src/hir_ty_lowering/errors.rs

@@ -179,7 +179,7 @@ impl<'tcx> dyn HirTyLowerer<'tcx> + '_ {
         // all visible traits. If there's one clear winner, just suggest that.
 
         let visible_traits: Vec<_> = tcx
-            .all_traits()
+            .visible_traits()
             .filter(|trait_def_id| {
                 let viz = tcx.visibility(*trait_def_id);
                 let def_id = self.item_def_id();

compiler/rustc_middle/src/ty/context.rs

@@ -2078,10 +2078,20 @@ impl<'tcx> TyCtxt<'tcx> {
         self.limits(()).move_size_limit
     }
 
-    /// All traits that are visible within the crate graph (i.e. excluding private dependencies).
+    /// All traits in the crate graph, including those not visible to the user.
     pub fn all_traits(self) -> impl Iterator<Item = DefId> + 'tcx {
         iter::once(LOCAL_CRATE)
-            .chain(self.visible_crates(()).iter().copied())
+            .chain(self.crates(()).iter().copied())
+            .flat_map(move |cnum| self.traits(cnum).iter().copied())
+    }
+
+    /// All traits that are visible within the crate graph (i.e. excluding private dependencies).
+    pub fn visible_traits(self) -> impl Iterator<Item = DefId> + 'tcx {
+        let visible_crates =
+            self.crates(()).iter().copied().filter(move |cnum| self.is_user_visible_dep(*cnum));
+
+        iter::once(LOCAL_CRATE)
+            .chain(visible_crates)
             .flat_map(move |cnum| self.traits(cnum).iter().copied())
     }
 

compiler/rustc_passes/src/diagnostic_items.rs

@@ -79,8 +79,14 @@ fn all_diagnostic_items(tcx: TyCtxt<'_>, (): ()) -> DiagnosticItems {
     // Initialize the collector.
     let mut items = DiagnosticItems::default();
 
-    // Collect diagnostic items in other crates.
-    for &cnum in tcx.visible_crates(()).iter().chain(std::iter::once(&LOCAL_CRATE)) {
+    // Collect diagnostic items in visible crates.
+    for cnum in tcx
+        .crates(())
+        .iter()
+        .copied()
+        .filter(|cnum| tcx.is_user_visible_dep(*cnum))
+        .chain(std::iter::once(LOCAL_CRATE))
+    {
         for (&name, &def_id) in &tcx.diagnostic_items(cnum).name_to_id {
             collect_item(tcx, &mut items, name, def_id);
         }

compiler/rustc_trait_selection/src/error_reporting/traits/fulfillment_errors.rs

@@ -1730,7 +1730,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let trait_def_id = trait_ref.def_id();
         let trait_name = self.tcx.item_name(trait_def_id);
         let crate_name = self.tcx.crate_name(trait_def_id.krate);
-        if let Some(other_trait_def_id) = self.tcx.all_traits().find(|def_id| {
+        if let Some(other_trait_def_id) = self.tcx.visible_traits().find(|def_id| {
             trait_name == self.tcx.item_name(trait_def_id)
                 && trait_def_id.krate != def_id.krate
                 && crate_name == self.tcx.crate_name(def_id.krate)
@@ -2189,7 +2189,7 @@ impl<'a, 'tcx> TypeErrCtxt<'a, 'tcx> {
         let required_trait_path = self.tcx.def_path_str(trait_ref.def_id());
         let traits_with_same_path: UnordSet<_> = self
             .tcx
-            .all_traits()
+            .visible_traits()
             .filter(|trait_def_id| *trait_def_id != trait_ref.def_id())
             .map(|trait_def_id| (self.tcx.def_path_str(trait_def_id), trait_def_id))
             .filter(|(p, _)| *p == required_trait_path)