avoid `&mut P<T>` in `visit_expr` etc methods trying a different way than rust-lang/rust#141636 r? ghost
P<T>
Box<T>
rustc_lexer/unescape
rustc-literal-escaper
visit_clobber
DummyAstNode
rustc_expand
MutVisitor
Visitor
&mut P<T>
visit_expr
use
token::{Open,Close}Delim