1 use clippy_utils::diagnostics::span_lint_and_sugg;
2 use clippy_utils::higher::PanicExpn;
3 use clippy_utils::is_expn_of;
4 use clippy_utils::source::snippet_with_applicability;
5 use rustc_errors::Applicability;
6 use rustc_hir::{Block, Expr, ExprKind, StmtKind, UnOp};
7 use rustc_lint::{LateContext, LateLintPass};
8 use rustc_session::{declare_lint_pass, declare_tool_lint};
10 declare_clippy_lint! {
12 /// Detects `if`-then-`panic!` that can be replaced with `assert!`.
14 /// ### Why is this bad?
15 /// `assert!` is simpler than `if`-then-`panic!`.
19 /// let sad_people: Vec<&str> = vec![];
20 /// if !sad_people.is_empty() {
21 /// panic!("there are sad people: {:?}", sad_people);
26 /// let sad_people: Vec<&str> = vec![];
27 /// assert!(sad_people.is_empty(), "there are sad people: {:?}", sad_people);
31 "`panic!` and only a `panic!` in `if`-then statement"
34 declare_lint_pass!(IfThenPanic => [IF_THEN_PANIC]);
36 impl LateLintPass<'_> for IfThenPanic {
37 fn check_expr(&mut self, cx: &LateContext<'_>, expr: &Expr<'_>) {
40 kind: ExprKind:: If(cond, Expr {
41 kind: ExprKind::Block(
51 if is_expn_of(stmt.span, "panic").is_some();
52 if !matches!(cond.kind, ExprKind::Let(_, _, _));
53 if let StmtKind::Semi(semi) = stmt.kind;
54 if !cx.tcx.sess.source_map().is_multiline(cond.span);
57 let span = if let Some(panic_expn) = PanicExpn::parse(semi) {
58 match *panic_expn.format_args.value_args {
59 [] => panic_expn.format_args.format_string_span,
60 [.., last] => panic_expn.format_args.format_string_span.to(last.span),
64 if let ExprKind::Block(block, _) = semi.kind;
65 if let Some(init) = block.expr;
66 if let ExprKind::Call(_, [format_args]) = init.kind;
75 let mut applicability = Applicability::MachineApplicable;
76 let sugg = snippet_with_applicability(cx, span, "..", &mut applicability);
79 if let ExprKind::DropTemps(Expr{kind: ExprKind::Unary(UnOp::Not, not_expr), ..}) = cond.kind {
80 snippet_with_applicability(cx, not_expr.span, "..", &mut applicability).to_string()
82 format!("!{}", snippet_with_applicability(cx, cond.span, "..", &mut applicability))
89 "only a `panic!` in `if`-then statement",
91 format!("assert!({}, {});", cond_sugg, sugg),
92 Applicability::MachineApplicable,