1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
|
use clippy_utils::diagnostics::span_lint_and_then;
use clippy_utils::source::snippet_with_applicability;
use if_chain::if_chain;
use rustc_ast::LitKind;
use rustc_errors::Applicability;
use rustc_hir::{Expr, ExprKind};
use rustc_lint::LateContext;
use rustc_middle::ty::{self, UintTy};
use super::CHAR_LIT_AS_U8;
pub(super) fn check(cx: &LateContext<'_>, expr: &Expr<'_>) {
if_chain! {
if let ExprKind::Cast(e, _) = &expr.kind;
if let ExprKind::Lit(l) = &e.kind;
if let LitKind::Char(c) = l.node;
if ty::Uint(UintTy::U8) == *cx.typeck_results().expr_ty(expr).kind();
then {
let mut applicability = Applicability::MachineApplicable;
let snippet = snippet_with_applicability(cx, e.span, "'x'", &mut applicability);
span_lint_and_then(
cx,
CHAR_LIT_AS_U8,
expr.span,
"casting a character literal to `u8` truncates",
|diag| {
diag.note("`char` is four bytes wide, but `u8` is a single byte");
if c.is_ascii() {
diag.span_suggestion(
expr.span,
"use a byte literal instead",
format!("b{}", snippet),
applicability,
);
}
});
}
}
}
|
