1 use crate::utils::paths::{BEGIN_PANIC, BEGIN_PANIC_FMT, FROM_TRAIT, OPTION, RESULT};
2 use crate::utils::{is_expn_of, match_def_path, method_chain_args, span_lint_and_then, walk_ptrs_ty};
3 use if_chain::if_chain;
4 use rustc::declare_lint_pass;
6 use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
7 use rustc::ty::{self, Ty};
8 use rustc_session::declare_tool_lint;
11 declare_clippy_lint! {
12 /// **What it does:** Checks for impls of `From<..>` that contain `panic!()` or `unwrap()`
14 /// **Why is this bad?** `TryFrom` should be used if there's a possibility of failure.
16 /// **Known problems:** None.
21 /// impl From<String> for Foo {
22 /// fn from(s: String) -> Self {
23 /// Foo(s.parse().unwrap())
27 pub FALLIBLE_IMPL_FROM,
29 "Warn on impls of `From<..>` that contain `panic!()` or `unwrap()`"
32 declare_lint_pass!(FallibleImplFrom => [FALLIBLE_IMPL_FROM]);
34 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for FallibleImplFrom {
35 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
36 // check for `impl From<???> for ..`
37 let impl_def_id = cx.tcx.hir().local_def_id(item.hir_id);
39 if let hir::ItemKind::Impl(.., ref impl_items) = item.kind;
40 if let Some(impl_trait_ref) = cx.tcx.impl_trait_ref(impl_def_id);
41 if match_def_path(cx, impl_trait_ref.def_id, &FROM_TRAIT);
43 lint_impl_body(cx, item.span, impl_items);
49 fn lint_impl_body<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, impl_span: Span, impl_items: &hir::HirVec<hir::ImplItemRef>) {
50 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
53 struct FindPanicUnwrap<'a, 'tcx> {
54 lcx: &'a LateContext<'a, 'tcx>,
55 tables: &'tcx ty::TypeckTables<'tcx>,
59 impl<'a, 'tcx> Visitor<'tcx> for FindPanicUnwrap<'a, 'tcx> {
60 fn visit_expr(&mut self, expr: &'tcx Expr) {
61 // check for `begin_panic`
63 if let ExprKind::Call(ref func_expr, _) = expr.kind;
64 if let ExprKind::Path(QPath::Resolved(_, ref path)) = func_expr.kind;
65 if let Some(path_def_id) = path.res.opt_def_id();
66 if match_def_path(self.lcx, path_def_id, &BEGIN_PANIC) ||
67 match_def_path(self.lcx, path_def_id, &BEGIN_PANIC_FMT);
68 if is_expn_of(expr.span, "unreachable").is_none();
70 self.result.push(expr.span);
75 if let Some(arglists) = method_chain_args(expr, &["unwrap"]) {
76 let reciever_ty = walk_ptrs_ty(self.tables.expr_ty(&arglists[0][0]));
77 if match_type(self.lcx, reciever_ty, &OPTION) || match_type(self.lcx, reciever_ty, &RESULT) {
78 self.result.push(expr.span);
82 // and check sub-expressions
83 intravisit::walk_expr(self, expr);
86 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
87 NestedVisitorMap::None
91 for impl_item in impl_items {
93 if impl_item.ident.name == sym!(from);
94 if let ImplItemKind::Method(_, body_id) =
95 cx.tcx.hir().impl_item(impl_item.id).kind;
97 // check the body for `begin_panic` or `unwrap`
98 let body = cx.tcx.hir().body(body_id);
99 let impl_item_def_id = cx.tcx.hir().local_def_id(impl_item.id.hir_id);
100 let mut fpu = FindPanicUnwrap {
102 tables: cx.tcx.typeck_tables_of(impl_item_def_id),
105 fpu.visit_expr(&body.value);
107 // if we've found one, lint
108 if !fpu.result.is_empty() {
113 "consider implementing `TryFrom` instead",
116 "`From` is intended for infallible conversions only. \
117 Use `TryFrom` if there's a possibility for the conversion to fail.");
118 db.span_note(fpu.result, "potential failure(s)");
126 fn match_type(cx: &LateContext<'_, '_>, ty: Ty<'_>, path: &[&str]) -> bool {
128 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),