Auto merge of #34199 - jseyfried:visit_all_attrs, r=nrc

Visit statement and expression attributes in the AST visitor

Currently, these attributes are not visited, so they are not gated feature checked in the post expansion visitor. This only affects crates using `#![feature(stmt_expr_attributes)]`.
r? @nrc

src/libsyntax/visit.rs

@@ -185,6 +185,9 @@ pub fn walk_mod<'v, V: Visitor<'v>>(visitor: &mut V, module: &'v Mod) {
 }
 
 pub fn walk_local<'v, V: Visitor<'v>>(visitor: &mut V, local: &'v Local) {
+    for attr in local.attrs.as_attr_slice() {
+        visitor.visit_attribute(attr);
+    }
     visitor.visit_pat(&local.pat);
     walk_list!(visitor, visit_ty, &local.ty);
     walk_list!(visitor, visit_expr, &local.init);
@@ -635,6 +638,9 @@ pub fn walk_mac<'v, V: Visitor<'v>>(_: &mut V, _: &'v Mac) {
 }
 
 pub fn walk_expr<'v, V: Visitor<'v>>(visitor: &mut V, expression: &'v Expr) {
+    for attr in expression.attrs.as_attr_slice() {
+        visitor.visit_attribute(attr);
+    }
     match expression.node {
         ExprKind::Box(ref subexpression) => {
             visitor.visit_expr(subexpression)

src/test/compile-fail/custom_attribute.rs

@@ -8,7 +8,12 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 
+#![feature(stmt_expr_attributes)]
+
 #[foo] //~ ERROR The attribute `foo`
 fn main() {
-
+    #[foo] //~ ERROR The attribute `foo`
+    let x = ();
+    #[foo] //~ ERROR The attribute `foo`
+    x
 }