1 use crate::rustc_lint::LintContext;
2 use clippy_utils::diagnostics::span_lint_and_then;
3 use clippy_utils::macros::{root_macro_call, FormatArgsExpn};
4 use clippy_utils::source::snippet_with_applicability;
5 use clippy_utils::{peel_blocks_with_stmt, span_extract_comment, sugg};
6 use rustc_errors::Applicability;
7 use rustc_hir::{Expr, ExprKind, UnOp};
8 use rustc_lint::{LateContext, LateLintPass};
9 use rustc_session::{declare_lint_pass, declare_tool_lint};
12 declare_clippy_lint! {
14 /// Detects `if`-then-`panic!` that can be replaced with `assert!`.
16 /// ### Why is this bad?
17 /// `assert!` is simpler than `if`-then-`panic!`.
21 /// let sad_people: Vec<&str> = vec![];
22 /// if !sad_people.is_empty() {
23 /// panic!("there are sad people: {:?}", sad_people);
28 /// let sad_people: Vec<&str> = vec![];
29 /// assert!(sad_people.is_empty(), "there are sad people: {:?}", sad_people);
31 #[clippy::version = "1.57.0"]
34 "`panic!` and only a `panic!` in `if`-then statement"
37 declare_lint_pass!(ManualAssert => [MANUAL_ASSERT]);
39 impl<'tcx> LateLintPass<'tcx> for ManualAssert {
40 fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &Expr<'tcx>) {
42 if let ExprKind::If(cond, then, None) = expr.kind;
43 if !matches!(cond.kind, ExprKind::Let(_));
44 if !expr.span.from_expansion();
45 let then = peel_blocks_with_stmt(then);
46 if let Some(macro_call) = root_macro_call(then.span);
47 if cx.tcx.item_name(macro_call.def_id) == sym::panic;
48 if !cx.tcx.sess.source_map().is_multiline(cond.span);
49 if let Some(format_args) = FormatArgsExpn::find_nested(cx, then, macro_call.expn);
51 let mut applicability = Applicability::MachineApplicable;
52 let format_args_snip = snippet_with_applicability(cx, format_args.inputs_span(), "..", &mut applicability);
53 let cond = cond.peel_drop_temps();
54 let mut comments = span_extract_comment(cx.sess().source_map(), expr.span);
55 if !comments.is_empty() {
58 let (cond, not) = match cond.kind {
59 ExprKind::Unary(UnOp::Not, e) => (e, ""),
62 let cond_sugg = sugg::Sugg::hir_with_applicability(cx, cond, "..", &mut applicability).maybe_par();
63 let sugg = format!("assert!({not}{cond_sugg}, {format_args_snip});");
64 // we show to the user the suggestion without the comments, but when applicating the fix, include the comments in the block
69 "only a `panic!` in `if`-then statement",
71 // comments can be noisy, do not show them to the user
72 diag.tool_only_span_suggestion(
73 expr.span.shrink_to_lo(),