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
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
|
use clippy_utils::diagnostics::span_lint_and_help;
use clippy_utils::source::snippet_with_macro_callsite;
use clippy_utils::{contains_return, higher, is_else_clause, is_lang_ctor, meets_msrv, msrvs, peel_blocks};
use if_chain::if_chain;
use rustc_hir::LangItem::{OptionNone, OptionSome};
use rustc_hir::{Expr, ExprKind, Stmt, StmtKind};
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_middle::lint::in_external_macro;
use rustc_semver::RustcVersion;
use rustc_session::{declare_tool_lint, impl_lint_pass};
declare_clippy_lint! {
/// ### What it does
/// Checks for if-else that could be written to `bool::then`.
///
/// ### Why is this bad?
/// Looks a little redundant. Using `bool::then` helps it have less lines of code.
///
/// ### Example
/// ```rust
/// # let v = vec![0];
/// let a = if v.is_empty() {
/// println!("true!");
/// Some(42)
/// } else {
/// None
/// };
/// ```
///
/// Could be written:
///
/// ```rust
/// # let v = vec![0];
/// let a = v.is_empty().then(|| {
/// println!("true!");
/// 42
/// });
/// ```
#[clippy::version = "1.53.0"]
pub IF_THEN_SOME_ELSE_NONE,
restriction,
"Finds if-else that could be written using `bool::then`"
}
pub struct IfThenSomeElseNone {
msrv: Option<RustcVersion>,
}
impl IfThenSomeElseNone {
#[must_use]
pub fn new(msrv: Option<RustcVersion>) -> Self {
Self { msrv }
}
}
impl_lint_pass!(IfThenSomeElseNone => [IF_THEN_SOME_ELSE_NONE]);
impl<'tcx> LateLintPass<'tcx> for IfThenSomeElseNone {
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'tcx Expr<'_>) {
if !meets_msrv(self.msrv, msrvs::BOOL_THEN) {
return;
}
if in_external_macro(cx.sess(), expr.span) {
return;
}
// We only care about the top-most `if` in the chain
if is_else_clause(cx.tcx, expr) {
return;
}
if_chain! {
if let Some(higher::If { cond, then, r#else: Some(els) }) = higher::If::hir(expr);
if let ExprKind::Block(then_block, _) = then.kind;
if let Some(then_expr) = then_block.expr;
if let ExprKind::Call(then_call, [then_arg]) = then_expr.kind;
if let ExprKind::Path(ref then_call_qpath) = then_call.kind;
if is_lang_ctor(cx, then_call_qpath, OptionSome);
if let ExprKind::Path(ref qpath) = peel_blocks(els).kind;
if is_lang_ctor(cx, qpath, OptionNone);
if !stmts_contains_early_return(then_block.stmts);
then {
let cond_snip = snippet_with_macro_callsite(cx, cond.span, "[condition]");
let cond_snip = if matches!(cond.kind, ExprKind::Unary(_, _) | ExprKind::Binary(_, _, _)) {
format!("({})", cond_snip)
} else {
cond_snip.into_owned()
};
let arg_snip = snippet_with_macro_callsite(cx, then_arg.span, "");
let closure_body = if then_block.stmts.is_empty() {
arg_snip.into_owned()
} else {
format!("{{ /* snippet */ {} }}", arg_snip)
};
let help = format!(
"consider using `bool::then` like: `{}.then(|| {})`",
cond_snip,
closure_body,
);
span_lint_and_help(
cx,
IF_THEN_SOME_ELSE_NONE,
expr.span,
"this could be simplified with `bool::then`",
None,
&help,
);
}
}
}
extract_msrv_attr!(LateContext);
}
fn stmts_contains_early_return(stmts: &[Stmt<'_>]) -> bool {
stmts.iter().any(|stmt| {
let Stmt { kind: StmtKind::Semi(e), .. } = stmt else { return false };
contains_return(e)
})
}
|
