1 use crate::utils::{find_macro_calls, is_type_diagnostic_item, return_ty, span_lint_and_then};
3 use rustc_hir::intravisit::FnKind;
4 use rustc_lint::{LateContext, LateLintPass};
5 use rustc_session::{declare_lint_pass, declare_tool_lint};
6 use rustc_span::{sym, Span};
9 /// **What it does:** Checks for usage of `panic!`, `unimplemented!`, `todo!`, `unreachable!` or assertions in a function of type result.
11 /// **Why is this bad?** For some codebases, it is desirable for functions of type result to return an error instead of crashing. Hence panicking macros should be avoided.
13 /// **Known problems:** Functions called from a function returning a `Result` may invoke a panicking macro. This is not checked.
18 /// fn result_with_panic() -> Result<bool, String>
25 /// fn result_without_panic() -> Result<bool, String> {
26 /// Err(String::from("error"))
29 pub PANIC_IN_RESULT_FN,
31 "functions of type `Result<..>` that contain `panic!()`, `todo!()`, `unreachable()`, `unimplemented()` or assertion"
34 declare_lint_pass!(PanicInResultFn => [PANIC_IN_RESULT_FN]);
36 impl<'tcx> LateLintPass<'tcx> for PanicInResultFn {
39 cx: &LateContext<'tcx>,
40 fn_kind: FnKind<'tcx>,
41 _: &'tcx hir::FnDecl<'tcx>,
42 body: &'tcx hir::Body<'tcx>,
46 if !matches!(fn_kind, FnKind::Closure(_))
47 && is_type_diagnostic_item(cx, return_ty(cx, hir_id), sym::result_type)
49 lint_impl_body(cx, span, body);
54 fn lint_impl_body<'tcx>(cx: &LateContext<'tcx>, impl_span: Span, body: &'tcx hir::Body<'tcx>) {
55 let panics = find_macro_calls(
70 if !panics.is_empty() {
75 "used `unimplemented!()`, `unreachable!()`, `todo!()`, `panic!()` or assertion in a function that returns `Result`",
78 "`unimplemented!()`, `unreachable!()`, `todo!()`, `panic!()` or assertions should not be used in a function that returns `Result` as `Result` is expected to return an error instead of crashing",
80 diag.span_note(panics, "return Err() instead of panicking");