1 use crate::utils::paths::{BEGIN_PANIC, BEGIN_PANIC_FMT, FROM_TRAIT, OPTION, RESULT};
3 use crate::utils::{is_expn_of, match_def_path, method_chain_args, span_lint_and_then, walk_ptrs_ty};
4 use if_chain::if_chain;
6 use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
7 use rustc::ty::{self, Ty};
8 use rustc::{declare_lint_pass, declare_tool_lint};
9 use syntax::symbol::Symbol;
12 declare_clippy_lint! {
13 /// **What it does:** Checks for impls of `From<..>` that contain `panic!()` or `unwrap()`
15 /// **Why is this bad?** `TryFrom` should be used if there's a possibility of failure.
17 /// **Known problems:** None.
22 /// impl From<String> for Foo {
23 /// fn from(s: String) -> Self {
24 /// Foo(s.parse().unwrap())
28 pub FALLIBLE_IMPL_FROM,
30 "Warn on impls of `From<..>` that contain `panic!()` or `unwrap()`"
33 declare_lint_pass!(FallibleImplFrom => [FALLIBLE_IMPL_FROM]);
35 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for FallibleImplFrom {
36 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) {
37 // check for `impl From<???> for ..`
38 let impl_def_id = cx.tcx.hir().local_def_id_from_hir_id(item.hir_id);
40 if let hir::ItemKind::Impl(.., ref impl_items) = item.node;
41 if let Some(impl_trait_ref) = cx.tcx.impl_trait_ref(impl_def_id);
42 if match_def_path(cx, impl_trait_ref.def_id, &*FROM_TRAIT);
44 lint_impl_body(cx, item.span, impl_items);
50 fn lint_impl_body<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, impl_span: Span, impl_items: &hir::HirVec<hir::ImplItemRef>) {
51 use rustc::hir::intravisit::{self, NestedVisitorMap, Visitor};
54 struct FindPanicUnwrap<'a, 'tcx: 'a> {
55 lcx: &'a LateContext<'a, 'tcx>,
56 tables: &'tcx ty::TypeckTables<'tcx>,
60 impl<'a, 'tcx: 'a> Visitor<'tcx> for FindPanicUnwrap<'a, 'tcx> {
61 fn visit_expr(&mut self, expr: &'tcx Expr) {
62 // check for `begin_panic`
64 if let ExprKind::Call(ref func_expr, _) = expr.node;
65 if let ExprKind::Path(QPath::Resolved(_, ref path)) = func_expr.node;
66 if let Some(path_def_id) = path.res.opt_def_id();
67 if match_def_path(self.lcx, path_def_id, &*BEGIN_PANIC) ||
68 match_def_path(self.lcx, path_def_id, &*BEGIN_PANIC_FMT);
69 if is_expn_of(expr.span, *sym::unreachable).is_none();
71 self.result.push(expr.span);
76 if let Some(arglists) = method_chain_args(expr, &[*sym::unwrap]) {
77 let reciever_ty = walk_ptrs_ty(self.tables.expr_ty(&arglists[0][0]));
78 if match_type(self.lcx, reciever_ty, &*OPTION) || match_type(self.lcx, reciever_ty, &*RESULT) {
79 self.result.push(expr.span);
83 // and check sub-expressions
84 intravisit::walk_expr(self, expr);
87 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
88 NestedVisitorMap::None
92 for impl_item in impl_items {
94 if impl_item.ident.name == *sym::from;
95 if let ImplItemKind::Method(_, body_id) =
96 cx.tcx.hir().impl_item(impl_item.id).node;
98 // check the body for `begin_panic` or `unwrap`
99 let body = cx.tcx.hir().body(body_id);
100 let impl_item_def_id = cx.tcx.hir().local_def_id_from_hir_id(impl_item.id.hir_id);
101 let mut fpu = FindPanicUnwrap {
103 tables: cx.tcx.typeck_tables_of(impl_item_def_id),
106 fpu.visit_expr(&body.value);
108 // if we've found one, lint
109 if !fpu.result.is_empty() {
114 "consider implementing `TryFrom` instead",
117 "`From` is intended for infallible conversions only. \
118 Use `TryFrom` if there's a possibility for the conversion to fail.");
119 db.span_note(fpu.result, "potential failure(s)");
127 fn match_type(cx: &LateContext<'_, '_>, ty: Ty<'_>, path: &[Symbol]) -> bool {
129 ty::Adt(adt, _) => match_def_path(cx, adt.did, path),