Account for multiple impl/dyn Trait in return type when suggesting `'_`

[rust.git] / src / librustc_middle / ty / diagnostics.rs

diff --git a/src/librustc_middle/ty/diagnostics.rs b/src/librustc_middle/ty/diagnostics.rs
index ba3cc0a7af2c6dad9e0b626a0df152bfaf84682d..b22727bdd7587b71848ce692971577f2cf1cdc3c 100644 (file)
--- a/src/librustc_middle/ty/diagnostics.rs
+++ b/src/librustc_middle/ty/diagnostics.rs
@@ -235,3 +235,36 @@ pub fn suggest_constraining_type_param(
         true
     }
 }
+
+/// Collect al types that have an implicit `'static` obligation that we could suggest `'_` for.
+pub struct TraitObjectVisitor<'tcx>(pub Vec<&'tcx hir::Ty<'tcx>>, pub crate::hir::map::Map<'tcx>);
+
+impl<'v> hir::intravisit::Visitor<'v> for TraitObjectVisitor<'v> {
+    type Map = rustc_hir::intravisit::ErasedMap<'v>;
+
+    fn nested_visit_map(&mut self) -> hir::intravisit::NestedVisitorMap<Self::Map> {
+        hir::intravisit::NestedVisitorMap::None
+    }
+
+    fn visit_ty(&mut self, ty: &'v hir::Ty<'v>) {
+        match ty.kind {
+            hir::TyKind::TraitObject(
+                _,
+                hir::Lifetime {
+                    name:
+                        hir::LifetimeName::ImplicitObjectLifetimeDefault | hir::LifetimeName::Static,
+                    ..
+                },
+            ) => {
+                self.0.push(ty);
+            }
+            hir::TyKind::OpaqueDef(item_id, _) => {
+                self.0.push(ty);
+                let item = self.1.expect_item(item_id.id);
+                hir::intravisit::walk_item(self, item);
+            }
+            _ => {}
+        }
+        hir::intravisit::walk_ty(self, ty);
+    }
+}