Visit patterns in THIR let expressions

This fixes some THIR unsafety checking errors not being emitted for
let expressions in these situations.

2 files changed, 2 insertions, 9 deletions

diff --git a/compiler/rustc_middle/src/thir/visit.rs b/compiler/rustc_middle/src/thir/visit.rs
index d03d92c3a4b..8feefb4c03c 100644
--- a/compiler/rustc_middle/src/thir/visit.rs
+++ b/compiler/rustc_middle/src/thir/visit.rs
@@ -66,8 +66,9 @@ pub fn walk_expr<'a, 'tcx: 'a, V: Visitor<'a, 'tcx>>(visitor: &mut V, expr: &Exp
         Use { source } => visitor.visit_expr(&visitor.thir()[source]),
         NeverToAny { source } => visitor.visit_expr(&visitor.thir()[source]),
         PointerCoercion { source, cast: _ } => visitor.visit_expr(&visitor.thir()[source]),
-        Let { expr, .. } => {
+        Let { expr, ref pat } => {
             visitor.visit_expr(&visitor.thir()[expr]);
+            visitor.visit_pat(pat);
         }
         Loop { body } => visitor.visit_expr(&visitor.thir()[body]),
         Match { scrutinee, ref arms, .. } => {
diff --git a/compiler/rustc_mir_build/src/check_unsafety.rs b/compiler/rustc_mir_build/src/check_unsafety.rs
index 373ed61ff87..3d895c131a8 100644
--- a/compiler/rustc_mir_build/src/check_unsafety.rs
+++ b/compiler/rustc_mir_build/src/check_unsafety.rs
@@ -495,14 +495,6 @@ impl<'a, 'tcx> Visitor<'a, 'tcx> for UnsafetyVisitor<'a, 'tcx> {
                     }
                 }
             }
-            ExprKind::Let { expr: expr_id, .. } => {
-                let let_expr = &self.thir[expr_id];
-                if let ty::Adt(adt_def, _) = let_expr.ty.kind()
-                    && adt_def.is_union()
-                {
-                    self.requires_unsafe(expr.span, AccessToUnionField);
-                }
-            }
             _ => {}
         }
         visit::walk_expr(self, expr);