1 use clippy_utils::diagnostics::span_lint_and_help;
2 use clippy_utils::source::snippet_with_macro_callsite;
3 use clippy_utils::{contains_return, higher, is_else_clause, is_lang_ctor, meets_msrv, msrvs, peel_blocks};
4 use if_chain::if_chain;
5 use rustc_hir::LangItem::{OptionNone, OptionSome};
6 use rustc_hir::{Expr, ExprKind, Stmt, StmtKind};
7 use rustc_lint::{LateContext, LateLintPass, LintContext};
8 use rustc_middle::lint::in_external_macro;
9 use rustc_semver::RustcVersion;
10 use rustc_session::{declare_tool_lint, impl_lint_pass};
12 declare_clippy_lint! {
14 /// Checks for if-else that could be written to `bool::then`.
16 /// ### Why is this bad?
17 /// Looks a little redundant. Using `bool::then` helps it have less lines of code.
21 /// # let v = vec![0];
22 /// let a = if v.is_empty() {
23 /// println!("true!");
33 /// # let v = vec![0];
34 /// let a = v.is_empty().then(|| {
35 /// println!("true!");
39 #[clippy::version = "1.53.0"]
40 pub IF_THEN_SOME_ELSE_NONE,
42 "Finds if-else that could be written using `bool::then`"
45 pub struct IfThenSomeElseNone {
46 msrv: Option<RustcVersion>,
49 impl IfThenSomeElseNone {
51 pub fn new(msrv: Option<RustcVersion>) -> Self {
56 impl_lint_pass!(IfThenSomeElseNone => [IF_THEN_SOME_ELSE_NONE]);
58 impl<'tcx> LateLintPass<'tcx> for IfThenSomeElseNone {
59 fn check_expr(&mut self, cx: &LateContext<'_>, expr: &'tcx Expr<'_>) {
60 if !meets_msrv(self.msrv.as_ref(), &msrvs::BOOL_THEN) {
64 if in_external_macro(cx.sess(), expr.span) {
68 // We only care about the top-most `if` in the chain
69 if is_else_clause(cx.tcx, expr) {
74 if let Some(higher::If { cond, then, r#else: Some(els) }) = higher::If::hir(expr);
75 if let ExprKind::Block(then_block, _) = then.kind;
76 if let Some(then_expr) = then_block.expr;
77 if let ExprKind::Call(then_call, [then_arg]) = then_expr.kind;
78 if let ExprKind::Path(ref then_call_qpath) = then_call.kind;
79 if is_lang_ctor(cx, then_call_qpath, OptionSome);
80 if let ExprKind::Path(ref qpath) = peel_blocks(els).kind;
81 if is_lang_ctor(cx, qpath, OptionNone);
82 if !stmts_contains_early_return(then_block.stmts);
84 let cond_snip = snippet_with_macro_callsite(cx, cond.span, "[condition]");
85 let cond_snip = if matches!(cond.kind, ExprKind::Unary(_, _) | ExprKind::Binary(_, _, _)) {
86 format!("({})", cond_snip)
88 cond_snip.into_owned()
90 let arg_snip = snippet_with_macro_callsite(cx, then_arg.span, "");
91 let closure_body = if then_block.stmts.is_empty() {
94 format!("{{ /* snippet */ {} }}", arg_snip)
97 "consider using `bool::then` like: `{}.then(|| {})`",
103 IF_THEN_SOME_ELSE_NONE,
105 "this could be simplified with `bool::then`",
113 extract_msrv_attr!(LateContext);
116 fn stmts_contains_early_return(stmts: &[Stmt<'_>]) -> bool {
117 stmts.iter().any(|stmt| {
118 let Stmt { kind: StmtKind::Semi(e), .. } = stmt else { return false };