1 use clippy_utils::diagnostics::span_lint_and_then;
2 use clippy_utils::ty::is_type_diagnostic_item;
3 use clippy_utils::visitors::for_each_expr;
4 use clippy_utils::{method_chain_args, return_ty};
5 use core::ops::ControlFlow;
6 use if_chain::if_chain;
8 use rustc_hir::ImplItemKind;
9 use rustc_lint::{LateContext, LateLintPass};
10 use rustc_session::{declare_lint_pass, declare_tool_lint};
11 use rustc_span::{sym, Span};
13 declare_clippy_lint! {
15 /// Checks for functions of type `Result` that contain `expect()` or `unwrap()`
17 /// ### Why is this bad?
18 /// These functions promote recoverable errors to non-recoverable errors which may be undesirable in code bases which wish to avoid panics.
20 /// ### Known problems
21 /// This can cause false positives in functions that handle both recoverable and non recoverable errors.
26 /// fn divisible_by_3(i_str: String) -> Result<(), String> {
29 /// .expect("cannot divide the input by three");
32 /// Err("Number is not divisible by 3")?
41 /// fn divisible_by_3(i_str: String) -> Result<(), String> {
44 /// .map_err(|e| format!("cannot divide the input by three: {}", e))?;
47 /// Err("Number is not divisible by 3")?
53 #[clippy::version = "1.48.0"]
56 "functions of type `Result<..>` or `Option`<...> that contain `expect()` or `unwrap()`"
59 declare_lint_pass!(UnwrapInResult=> [UNWRAP_IN_RESULT]);
61 impl<'tcx> LateLintPass<'tcx> for UnwrapInResult {
62 fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx hir::ImplItem<'_>) {
64 // first check if it's a method or function
65 if let hir::ImplItemKind::Fn(ref _signature, _) = impl_item.kind;
66 // checking if its return type is `result` or `option`
67 if is_type_diagnostic_item(cx, return_ty(cx, impl_item.hir_id()), sym::Result)
68 || is_type_diagnostic_item(cx, return_ty(cx, impl_item.hir_id()), sym::Option);
70 lint_impl_body(cx, impl_item.span, impl_item);
76 fn lint_impl_body<'tcx>(cx: &LateContext<'tcx>, impl_span: Span, impl_item: &'tcx hir::ImplItem<'_>) {
77 if let ImplItemKind::Fn(_, body_id) = impl_item.kind {
78 let body = cx.tcx.hir().body(body_id);
79 let typeck = cx.tcx.typeck(impl_item.owner_id.def_id);
80 let mut result = Vec::new();
81 let _: Option<!> = for_each_expr(body.value, |e| {
83 if let Some(arglists) = method_chain_args(e, &["expect"]) {
84 let receiver_ty = typeck.expr_ty(arglists[0].0).peel_refs();
85 if is_type_diagnostic_item(cx, receiver_ty, sym::Option)
86 || is_type_diagnostic_item(cx, receiver_ty, sym::Result)
93 if let Some(arglists) = method_chain_args(e, &["unwrap"]) {
94 let receiver_ty = typeck.expr_ty(arglists[0].0).peel_refs();
95 if is_type_diagnostic_item(cx, receiver_ty, sym::Option)
96 || is_type_diagnostic_item(cx, receiver_ty, sym::Result)
102 ControlFlow::Continue(())
105 // if we've found one, lint
106 if !result.is_empty() {
111 "used unwrap or expect in a function that returns result or option",
113 diag.help("unwrap and expect should not be used in a function that returns result or option");
114 diag.span_note(result, "potential non-recoverable error(s)");