1 use clippy_utils::diagnostics::span_lint_and_then;
2 use clippy_utils::source::snippet_with_applicability;
3 use if_chain::if_chain;
4 use rustc_ast::LitKind;
5 use rustc_errors::Applicability;
6 use rustc_hir::{Expr, ExprKind};
7 use rustc_lint::LateContext;
8 use rustc_middle::ty::{self, UintTy};
10 use super::CHAR_LIT_AS_U8;
12 pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>) {
14 if let ExprKind::Cast(e, _) = &expr.kind;
15 if let ExprKind::Lit(l) = &e.kind;
16 if let LitKind::Char(c) = l.node;
17 if ty::Uint(UintTy::U8) == *cx.typeck_results().expr_ty(expr).kind();
19 let mut applicability = Applicability::MachineApplicable;
20 let snippet = snippet_with_applicability(cx, e.span, "'x'", &mut applicability);
26 "casting a character literal to `u8` truncates",
28 diag.note("`char` is four bytes wide, but `u8` is a single byte");
33 "use a byte literal instead",
34 format!("b{}", snippet),