diff options
Diffstat (limited to 'src/tools/clippy/clippy_lints/src/panic_in_result_fn.rs')
-rw-r--r-- | src/tools/clippy/clippy_lints/src/panic_in_result_fn.rs | 87 |
1 files changed, 87 insertions, 0 deletions
diff --git a/src/tools/clippy/clippy_lints/src/panic_in_result_fn.rs b/src/tools/clippy/clippy_lints/src/panic_in_result_fn.rs new file mode 100644 index 000000000..21acf003d --- /dev/null +++ b/src/tools/clippy/clippy_lints/src/panic_in_result_fn.rs @@ -0,0 +1,87 @@ +use clippy_utils::diagnostics::span_lint_and_then; +use clippy_utils::macros::root_macro_call_first_node; +use clippy_utils::return_ty; +use clippy_utils::ty::is_type_diagnostic_item; +use clippy_utils::visitors::expr_visitor_no_bodies; +use rustc_hir as hir; +use rustc_hir::intravisit::{FnKind, Visitor}; +use rustc_lint::{LateContext, LateLintPass}; +use rustc_session::{declare_lint_pass, declare_tool_lint}; +use rustc_span::{sym, Span}; + +declare_clippy_lint! { + /// ### What it does + /// Checks for usage of `panic!`, `unimplemented!`, `todo!`, `unreachable!` or assertions in a function of type result. + /// + /// ### 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. + /// + /// ### Known problems + /// Functions called from a function returning a `Result` may invoke a panicking macro. This is not checked. + /// + /// ### Example + /// ```rust + /// fn result_with_panic() -> Result<bool, String> + /// { + /// panic!("error"); + /// } + /// ``` + /// Use instead: + /// ```rust + /// fn result_without_panic() -> Result<bool, String> { + /// Err(String::from("error")) + /// } + /// ``` + #[clippy::version = "1.48.0"] + pub PANIC_IN_RESULT_FN, + restriction, + "functions of type `Result<..>` that contain `panic!()`, `todo!()`, `unreachable()`, `unimplemented()` or assertion" +} + +declare_lint_pass!(PanicInResultFn => [PANIC_IN_RESULT_FN]); + +impl<'tcx> LateLintPass<'tcx> for PanicInResultFn { + fn check_fn( + &mut self, + cx: &LateContext<'tcx>, + fn_kind: FnKind<'tcx>, + _: &'tcx hir::FnDecl<'tcx>, + body: &'tcx hir::Body<'tcx>, + span: Span, + hir_id: hir::HirId, + ) { + if !matches!(fn_kind, FnKind::Closure) && is_type_diagnostic_item(cx, return_ty(cx, hir_id), sym::Result) { + lint_impl_body(cx, span, body); + } + } +} + +fn lint_impl_body<'tcx>(cx: &LateContext<'tcx>, impl_span: Span, body: &'tcx hir::Body<'tcx>) { + let mut panics = Vec::new(); + expr_visitor_no_bodies(|expr| { + let Some(macro_call) = root_macro_call_first_node(cx, expr) else { return true }; + if matches!( + cx.tcx.item_name(macro_call.def_id).as_str(), + "unimplemented" | "unreachable" | "panic" | "todo" | "assert" | "assert_eq" | "assert_ne" + ) { + panics.push(macro_call.span); + return false; + } + true + }) + .visit_expr(&body.value); + if !panics.is_empty() { + span_lint_and_then( + cx, + PANIC_IN_RESULT_FN, + impl_span, + "used `unimplemented!()`, `unreachable!()`, `todo!()`, `panic!()` or assertion in a function that returns `Result`", + move |diag| { + diag.help( + "`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", + ); + diag.span_note(panics, "return Err() instead of panicking"); + }, + ); + } +} |