Add visitors for PatField and ExprField.

This helps simplify the code. It also fixes it to use the correct parent
when lowering. One consequence is the `non_snake_case` lint needed
to change the way it looked for parent nodes in a struct pattern.

This also includes a small fix to use the correct `Target` for
expression field attribute validation.

1 files changed, 1 insertions, 1 deletions

diff --git a/src/test/ui/lint/unused/unused_attributes-must_use.stderr b/src/test/ui/lint/unused/unused_attributes-must_use.stderr
index 69cd5302c5c..dd112c23e5d 100644
--- a/src/test/ui/lint/unused/unused_attributes-must_use.stderr
+++ b/src/test/ui/lint/unused/unused_attributes-must_use.stderr
@@ -105,7 +105,7 @@ error: `#[must_use]` has no effect when applied to an match arm
 LL |         #[must_use]
    |         ^^^^^^^^^^^
 
-error: `#[must_use]` has no effect when applied to a pattern field
+error: `#[must_use]` has no effect when applied to a struct field
   --> $DIR/unused_attributes-must_use.rs:129:28
    |
 LL |     let s = PatternField { #[must_use]  foo: 123 };