1 use clippy_utils::diagnostics::span_lint_and_sugg;
2 use clippy_utils::higher::PanicExpn;
3 use clippy_utils::source::snippet_with_applicability;
4 use clippy_utils::{is_expn_of, sugg};
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!(ManualAssert => [MANUAL_ASSERT]);
36 impl LateLintPass<'_> for ManualAssert {
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 call = if_chain! {
58 if let ExprKind::Block(block, _) = semi.kind;
59 if let Some(init) = block.expr;
66 let span = if let Some(panic_expn) = PanicExpn::parse(call) {
67 match *panic_expn.format_args.value_args {
68 [] => panic_expn.format_args.format_string_span,
69 [.., last] => panic_expn.format_args.format_string_span.to(last.span),
71 } else if let ExprKind::Call(_, [format_args]) = call.kind {
76 let mut applicability = Applicability::MachineApplicable;
77 let sugg = snippet_with_applicability(cx, span, "..", &mut applicability);
78 let cond_sugg = if let ExprKind::DropTemps(e, ..) = cond.kind {
79 if let Expr{kind: ExprKind::Unary(UnOp::Not, not_expr), ..} = e {
80 sugg::Sugg::hir_with_applicability(cx, not_expr, "..", &mut applicability).maybe_par().to_string()
82 format!("!{}", sugg::Sugg::hir_with_applicability(cx, e, "..", &mut applicability).maybe_par())
85 format!("!{}", sugg::Sugg::hir_with_applicability(cx, cond, "..", &mut applicability).maybe_par())
92 "only a `panic!` in `if`-then statement",
94 format!("assert!({}, {});", cond_sugg, sugg),
95 Applicability::MachineApplicable,