| use crate::utils::paths::{BEGIN_PANIC, BEGIN_PANIC_FMT, FROM_TRAIT}; |
| use crate::utils::{ |
| is_expn_of, is_type_diagnostic_item, match_def_path, method_chain_args, span_lint_and_then, walk_ptrs_ty, |
| }; |
| use if_chain::if_chain; |
| use rustc_hir as hir; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_middle::hir::map::Map; |
| use rustc_middle::ty; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| use rustc_span::Span; |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for impls of `From<..>` that contain `panic!()` or `unwrap()` |
| /// |
| /// **Why is this bad?** `TryFrom` should be used if there's a possibility of failure. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// struct Foo(i32); |
| /// |
| /// // Bad |
| /// impl From<String> for Foo { |
| /// fn from(s: String) -> Self { |
| /// Foo(s.parse().unwrap()) |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// ```rust |
| /// // Good |
| /// struct Foo(i32); |
| /// |
| /// use std::convert::TryFrom; |
| /// impl TryFrom<String> for Foo { |
| /// type Error = (); |
| /// fn try_from(s: String) -> Result<Self, Self::Error> { |
| /// if let Ok(parsed) = s.parse() { |
| /// Ok(Foo(parsed)) |
| /// } else { |
| /// Err(()) |
| /// } |
| /// } |
| /// } |
| /// ``` |
| pub FALLIBLE_IMPL_FROM, |
| nursery, |
| "Warn on impls of `From<..>` that contain `panic!()` or `unwrap()`" |
| } |
| |
| declare_lint_pass!(FallibleImplFrom => [FALLIBLE_IMPL_FROM]); |
| |
| impl<'tcx> LateLintPass<'tcx> for FallibleImplFrom { |
| fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx hir::Item<'_>) { |
| // check for `impl From<???> for ..` |
| let impl_def_id = cx.tcx.hir().local_def_id(item.hir_id); |
| if_chain! { |
| if let hir::ItemKind::Impl{ items: impl_items, .. } = item.kind; |
| if let Some(impl_trait_ref) = cx.tcx.impl_trait_ref(impl_def_id); |
| if match_def_path(cx, impl_trait_ref.def_id, &FROM_TRAIT); |
| then { |
| lint_impl_body(cx, item.span, impl_items); |
| } |
| } |
| } |
| } |
| |
| fn lint_impl_body<'tcx>(cx: &LateContext<'tcx>, impl_span: Span, impl_items: &[hir::ImplItemRef<'_>]) { |
| use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor}; |
| use rustc_hir::{Expr, ExprKind, ImplItemKind, QPath}; |
| |
| struct FindPanicUnwrap<'a, 'tcx> { |
| lcx: &'a LateContext<'tcx>, |
| tables: &'tcx ty::TypeckTables<'tcx>, |
| result: Vec<Span>, |
| } |
| |
| impl<'a, 'tcx> Visitor<'tcx> for FindPanicUnwrap<'a, 'tcx> { |
| type Map = Map<'tcx>; |
| |
| fn visit_expr(&mut self, expr: &'tcx Expr<'_>) { |
| // check for `begin_panic` |
| if_chain! { |
| if let ExprKind::Call(ref func_expr, _) = expr.kind; |
| if let ExprKind::Path(QPath::Resolved(_, ref path)) = func_expr.kind; |
| if let Some(path_def_id) = path.res.opt_def_id(); |
| if match_def_path(self.lcx, path_def_id, &BEGIN_PANIC) || |
| match_def_path(self.lcx, path_def_id, &BEGIN_PANIC_FMT); |
| if is_expn_of(expr.span, "unreachable").is_none(); |
| then { |
| self.result.push(expr.span); |
| } |
| } |
| |
| // check for `unwrap` |
| if let Some(arglists) = method_chain_args(expr, &["unwrap"]) { |
| let reciever_ty = walk_ptrs_ty(self.tables.expr_ty(&arglists[0][0])); |
| if is_type_diagnostic_item(self.lcx, reciever_ty, sym!(option_type)) |
| || is_type_diagnostic_item(self.lcx, reciever_ty, sym!(result_type)) |
| { |
| self.result.push(expr.span); |
| } |
| } |
| |
| // and check sub-expressions |
| intravisit::walk_expr(self, expr); |
| } |
| |
| fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { |
| NestedVisitorMap::None |
| } |
| } |
| |
| for impl_item in impl_items { |
| if_chain! { |
| if impl_item.ident.name == sym!(from); |
| if let ImplItemKind::Fn(_, body_id) = |
| cx.tcx.hir().impl_item(impl_item.id).kind; |
| then { |
| // check the body for `begin_panic` or `unwrap` |
| let body = cx.tcx.hir().body(body_id); |
| let impl_item_def_id = cx.tcx.hir().local_def_id(impl_item.id.hir_id); |
| let mut fpu = FindPanicUnwrap { |
| lcx: cx, |
| tables: cx.tcx.typeck_tables_of(impl_item_def_id), |
| result: Vec::new(), |
| }; |
| fpu.visit_expr(&body.value); |
| |
| // if we've found one, lint |
| if !fpu.result.is_empty() { |
| span_lint_and_then( |
| cx, |
| FALLIBLE_IMPL_FROM, |
| impl_span, |
| "consider implementing `TryFrom` instead", |
| move |diag| { |
| diag.help( |
| "`From` is intended for infallible conversions only. \ |
| Use `TryFrom` if there's a possibility for the conversion to fail."); |
| diag.span_note(fpu.result, "potential failure(s)"); |
| }); |
| } |
| } |
| } |
| } |
| } |