Unrolled build for #157713

Rollup merge of #157713 - petrochenkov:regr197unused, r=oli-obk

resolve: Remove exported imports from `maybe_unused_trait_imports`

If an import is visible from outside of the crate, then it's effectively used and shouldn't be reported by any kinds of unused import lints.

Fixes #157420.

Author: rust-timer

compiler/rustc_resolve/src/check_unused.rs

@@ -105,6 +105,7 @@ impl<'a, 'ra, 'tcx> UnusedImportCheckVisitor<'a, 'ra, 'tcx> {
         let def_id = self.r.owner_def_id(id);
         if self.r.effective_visibilities.is_exported(def_id) {
             self.check_import_as_underscore(use_tree, id);
+            self.r.maybe_unused_trait_imports.swap_remove(&def_id);
             return;
         }
 

tests/ui/imports/unused-import-issue-157420.rs

@@ -0,0 +1,19 @@
+//@ check-pass
+//@ edition: 2018..
+
+#![crate_type = "lib"] // needed to enable doc link collection
+#![warn(unused_imports)]
+
+pub use inner::*;
+use crate::outer::*;
+
+mod outer {
+    pub mod inner {
+        pub trait Trait {} // must be a trait
+    }
+
+    pub use inner::*;
+}
+
+/// [A::assoc] // needed to force collection of traits in scope, without filter on assoc item name
+pub struct A;