| //! Checks for usage of `&Vec[_]` and `&String`. |
| |
| use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg, span_lint_and_then}; |
| use clippy_utils::source::snippet_opt; |
| use clippy_utils::ty::expr_sig; |
| use clippy_utils::{get_expr_use_or_unification_node, is_lint_allowed, path_def_id, path_to_local, paths}; |
| use if_chain::if_chain; |
| use rustc_errors::{Applicability, MultiSpan}; |
| use rustc_hir::def_id::DefId; |
| use rustc_hir::hir_id::HirIdMap; |
| use rustc_hir::intravisit::{walk_expr, Visitor}; |
| use rustc_hir::{ |
| self as hir, AnonConst, BinOpKind, BindingAnnotation, Body, Expr, ExprKind, FnDecl, FnRetTy, GenericArg, |
| ImplItemKind, ItemKind, Lifetime, LifetimeName, Mutability, Node, Param, ParamName, PatKind, QPath, TraitFn, |
| TraitItem, TraitItemKind, TyKind, |
| }; |
| use rustc_lint::{LateContext, LateLintPass}; |
| use rustc_middle::hir::nested_filter; |
| use rustc_middle::ty::{self, Ty}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint}; |
| use rustc_span::source_map::Span; |
| use rustc_span::sym; |
| use rustc_span::symbol::Symbol; |
| use std::fmt; |
| use std::iter; |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// This lint checks for function arguments of type `&String`, `&Vec`, |
| /// `&PathBuf`, and `Cow<_>`. It will also suggest you replace `.clone()` calls |
| /// with the appropriate `.to_owned()`/`to_string()` calls. |
| /// |
| /// ### Why is this bad? |
| /// Requiring the argument to be of the specific size |
| /// makes the function less useful for no benefit; slices in the form of `&[T]` |
| /// or `&str` usually suffice and can be obtained from other types, too. |
| /// |
| /// ### Known problems |
| /// There may be `fn(&Vec)`-typed references pointing to your function. |
| /// If you have them, you will get a compiler error after applying this lint's |
| /// suggestions. You then have the choice to undo your changes or change the |
| /// type of the reference. |
| /// |
| /// Note that if the function is part of your public interface, there may be |
| /// other crates referencing it, of which you may not be aware. Carefully |
| /// deprecate the function before applying the lint suggestions in this case. |
| /// |
| /// ### Example |
| /// ```ignore |
| /// // Bad |
| /// fn foo(&Vec<u32>) { .. } |
| /// |
| /// // Good |
| /// fn foo(&[u32]) { .. } |
| /// ``` |
| #[clippy::version = "pre 1.29.0"] |
| pub PTR_ARG, |
| style, |
| "fn arguments of the type `&Vec<...>` or `&String`, suggesting to use `&[...]` or `&str` instead, respectively" |
| } |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// This lint checks for equality comparisons with `ptr::null` |
| /// |
| /// ### Why is this bad? |
| /// It's easier and more readable to use the inherent |
| /// `.is_null()` |
| /// method instead |
| /// |
| /// ### Example |
| /// ```ignore |
| /// // Bad |
| /// if x == ptr::null { |
| /// .. |
| /// } |
| /// |
| /// // Good |
| /// if x.is_null() { |
| /// .. |
| /// } |
| /// ``` |
| #[clippy::version = "pre 1.29.0"] |
| pub CMP_NULL, |
| style, |
| "comparing a pointer to a null pointer, suggesting to use `.is_null()` instead" |
| } |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// This lint checks for functions that take immutable |
| /// references and return mutable ones. |
| /// |
| /// ### Why is this bad? |
| /// This is trivially unsound, as one can create two |
| /// mutable references from the same (immutable!) source. |
| /// This [error](https://github.com/rust-lang/rust/issues/39465) |
| /// actually lead to an interim Rust release 1.15.1. |
| /// |
| /// ### Known problems |
| /// To be on the conservative side, if there's at least one |
| /// mutable reference with the output lifetime, this lint will not trigger. |
| /// In practice, this case is unlikely anyway. |
| /// |
| /// ### Example |
| /// ```ignore |
| /// fn foo(&Foo) -> &mut Bar { .. } |
| /// ``` |
| #[clippy::version = "pre 1.29.0"] |
| pub MUT_FROM_REF, |
| correctness, |
| "fns that create mutable refs from immutable ref args" |
| } |
| |
| declare_clippy_lint! { |
| /// ### What it does |
| /// This lint checks for invalid usages of `ptr::null`. |
| /// |
| /// ### Why is this bad? |
| /// This causes undefined behavior. |
| /// |
| /// ### Example |
| /// ```ignore |
| /// // Bad. Undefined behavior |
| /// unsafe { std::slice::from_raw_parts(ptr::null(), 0); } |
| /// ``` |
| /// |
| /// ```ignore |
| /// // Good |
| /// unsafe { std::slice::from_raw_parts(NonNull::dangling().as_ptr(), 0); } |
| /// ``` |
| #[clippy::version = "1.53.0"] |
| pub INVALID_NULL_PTR_USAGE, |
| correctness, |
| "invalid usage of a null pointer, suggesting `NonNull::dangling()` instead" |
| } |
| |
| declare_lint_pass!(Ptr => [PTR_ARG, CMP_NULL, MUT_FROM_REF, INVALID_NULL_PTR_USAGE]); |
| |
| impl<'tcx> LateLintPass<'tcx> for Ptr { |
| fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) { |
| if let TraitItemKind::Fn(sig, trait_method) = &item.kind { |
| if matches!(trait_method, TraitFn::Provided(_)) { |
| // Handled by check body. |
| return; |
| } |
| |
| check_mut_from_ref(cx, sig.decl); |
| for arg in check_fn_args( |
| cx, |
| cx.tcx.fn_sig(item.def_id).skip_binder().inputs(), |
| sig.decl.inputs, |
| &[], |
| ) |
| .filter(|arg| arg.mutability() == Mutability::Not) |
| { |
| span_lint_and_sugg( |
| cx, |
| PTR_ARG, |
| arg.span, |
| &arg.build_msg(), |
| "change this to", |
| format!("{}{}", arg.ref_prefix, arg.deref_ty.display(cx)), |
| Applicability::Unspecified, |
| ); |
| } |
| } |
| } |
| |
| fn check_body(&mut self, cx: &LateContext<'tcx>, body: &'tcx Body<'_>) { |
| let hir = cx.tcx.hir(); |
| let mut parents = hir.parent_iter(body.value.hir_id); |
| let (item_id, decl, is_trait_item) = match parents.next() { |
| Some((_, Node::Item(i))) => { |
| if let ItemKind::Fn(sig, ..) = &i.kind { |
| (i.def_id, sig.decl, false) |
| } else { |
| return; |
| } |
| }, |
| Some((_, Node::ImplItem(i))) => { |
| if !matches!(parents.next(), |
| Some((_, Node::Item(i))) if matches!(&i.kind, ItemKind::Impl(i) if i.of_trait.is_none()) |
| ) { |
| return; |
| } |
| if let ImplItemKind::Fn(sig, _) = &i.kind { |
| (i.def_id, sig.decl, false) |
| } else { |
| return; |
| } |
| }, |
| Some((_, Node::TraitItem(i))) => { |
| if let TraitItemKind::Fn(sig, _) = &i.kind { |
| (i.def_id, sig.decl, true) |
| } else { |
| return; |
| } |
| }, |
| _ => return, |
| }; |
| |
| check_mut_from_ref(cx, decl); |
| let sig = cx.tcx.fn_sig(item_id).skip_binder(); |
| let lint_args: Vec<_> = check_fn_args(cx, sig.inputs(), decl.inputs, body.params) |
| .filter(|arg| !is_trait_item || arg.mutability() == Mutability::Not) |
| .collect(); |
| let results = check_ptr_arg_usage(cx, body, &lint_args); |
| |
| for (result, args) in results.iter().zip(lint_args.iter()).filter(|(r, _)| !r.skip) { |
| span_lint_and_then(cx, PTR_ARG, args.span, &args.build_msg(), |diag| { |
| diag.multipart_suggestion( |
| "change this to", |
| iter::once((args.span, format!("{}{}", args.ref_prefix, args.deref_ty.display(cx)))) |
| .chain(result.replacements.iter().map(|r| { |
| ( |
| r.expr_span, |
| format!("{}{}", snippet_opt(cx, r.self_span).unwrap(), r.replacement), |
| ) |
| })) |
| .collect(), |
| Applicability::Unspecified, |
| ); |
| }); |
| } |
| } |
| |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| if let ExprKind::Binary(ref op, l, r) = expr.kind { |
| if (op.node == BinOpKind::Eq || op.node == BinOpKind::Ne) && (is_null_path(cx, l) || is_null_path(cx, r)) { |
| span_lint( |
| cx, |
| CMP_NULL, |
| expr.span, |
| "comparing with null is better expressed by the `.is_null()` method", |
| ); |
| } |
| } else { |
| check_invalid_ptr_usage(cx, expr); |
| } |
| } |
| } |
| |
| fn check_invalid_ptr_usage<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| // (fn_path, arg_indices) - `arg_indices` are the `arg` positions where null would cause U.B. |
| const INVALID_NULL_PTR_USAGE_TABLE: [(&[&str], &[usize]); 16] = [ |
| (&paths::SLICE_FROM_RAW_PARTS, &[0]), |
| (&paths::SLICE_FROM_RAW_PARTS_MUT, &[0]), |
| (&paths::PTR_COPY, &[0, 1]), |
| (&paths::PTR_COPY_NONOVERLAPPING, &[0, 1]), |
| (&paths::PTR_READ, &[0]), |
| (&paths::PTR_READ_UNALIGNED, &[0]), |
| (&paths::PTR_READ_VOLATILE, &[0]), |
| (&paths::PTR_REPLACE, &[0]), |
| (&paths::PTR_SLICE_FROM_RAW_PARTS, &[0]), |
| (&paths::PTR_SLICE_FROM_RAW_PARTS_MUT, &[0]), |
| (&paths::PTR_SWAP, &[0, 1]), |
| (&paths::PTR_SWAP_NONOVERLAPPING, &[0, 1]), |
| (&paths::PTR_WRITE, &[0]), |
| (&paths::PTR_WRITE_UNALIGNED, &[0]), |
| (&paths::PTR_WRITE_VOLATILE, &[0]), |
| (&paths::PTR_WRITE_BYTES, &[0]), |
| ]; |
| |
| if_chain! { |
| if let ExprKind::Call(fun, args) = expr.kind; |
| if let ExprKind::Path(ref qpath) = fun.kind; |
| if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id(); |
| let fun_def_path = cx.get_def_path(fun_def_id).into_iter().map(Symbol::to_ident_string).collect::<Vec<_>>(); |
| if let Some(&(_, arg_indices)) = INVALID_NULL_PTR_USAGE_TABLE |
| .iter() |
| .find(|&&(fn_path, _)| fn_path == fun_def_path); |
| then { |
| for &arg_idx in arg_indices { |
| if let Some(arg) = args.get(arg_idx).filter(|arg| is_null_path(cx, arg)) { |
| span_lint_and_sugg( |
| cx, |
| INVALID_NULL_PTR_USAGE, |
| arg.span, |
| "pointer must be non-null", |
| "change this to", |
| "core::ptr::NonNull::dangling().as_ptr()".to_string(), |
| Applicability::MachineApplicable, |
| ); |
| } |
| } |
| } |
| } |
| } |
| |
| #[derive(Default)] |
| struct PtrArgResult { |
| skip: bool, |
| replacements: Vec<PtrArgReplacement>, |
| } |
| |
| struct PtrArgReplacement { |
| expr_span: Span, |
| self_span: Span, |
| replacement: &'static str, |
| } |
| |
| struct PtrArg<'tcx> { |
| idx: usize, |
| span: Span, |
| ty_did: DefId, |
| ty_name: Symbol, |
| method_renames: &'static [(&'static str, &'static str)], |
| ref_prefix: RefPrefix, |
| deref_ty: DerefTy<'tcx>, |
| } |
| impl PtrArg<'_> { |
| fn build_msg(&self) -> String { |
| format!( |
| "writing `&{}{}` instead of `&{}{}` involves a new object where a slice will do", |
| self.ref_prefix.mutability.prefix_str(), |
| self.ty_name, |
| self.ref_prefix.mutability.prefix_str(), |
| self.deref_ty.argless_str(), |
| ) |
| } |
| |
| fn mutability(&self) -> Mutability { |
| self.ref_prefix.mutability |
| } |
| } |
| |
| struct RefPrefix { |
| lt: LifetimeName, |
| mutability: Mutability, |
| } |
| impl fmt::Display for RefPrefix { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| use fmt::Write; |
| f.write_char('&')?; |
| match self.lt { |
| LifetimeName::Param(ParamName::Plain(name)) => { |
| name.fmt(f)?; |
| f.write_char(' ')?; |
| }, |
| LifetimeName::Underscore => f.write_str("'_ ")?, |
| LifetimeName::Static => f.write_str("'static ")?, |
| _ => (), |
| } |
| f.write_str(self.mutability.prefix_str()) |
| } |
| } |
| |
| struct DerefTyDisplay<'a, 'tcx>(&'a LateContext<'tcx>, &'a DerefTy<'tcx>); |
| impl fmt::Display for DerefTyDisplay<'_, '_> { |
| fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { |
| use std::fmt::Write; |
| match self.1 { |
| DerefTy::Str => f.write_str("str"), |
| DerefTy::Path => f.write_str("Path"), |
| DerefTy::Slice(hir_ty, ty) => { |
| f.write_char('[')?; |
| match hir_ty.and_then(|s| snippet_opt(self.0, s)) { |
| Some(s) => f.write_str(&s)?, |
| None => ty.fmt(f)?, |
| } |
| f.write_char(']') |
| }, |
| } |
| } |
| } |
| |
| enum DerefTy<'tcx> { |
| Str, |
| Path, |
| Slice(Option<Span>, Ty<'tcx>), |
| } |
| impl<'tcx> DerefTy<'tcx> { |
| fn argless_str(&self) -> &'static str { |
| match *self { |
| Self::Str => "str", |
| Self::Path => "Path", |
| Self::Slice(..) => "[_]", |
| } |
| } |
| |
| fn display<'a>(&'a self, cx: &'a LateContext<'tcx>) -> DerefTyDisplay<'a, 'tcx> { |
| DerefTyDisplay(cx, self) |
| } |
| } |
| |
| fn check_fn_args<'cx, 'tcx: 'cx>( |
| cx: &'cx LateContext<'tcx>, |
| tys: &'tcx [Ty<'_>], |
| hir_tys: &'tcx [hir::Ty<'_>], |
| params: &'tcx [Param<'_>], |
| ) -> impl Iterator<Item = PtrArg<'tcx>> + 'cx { |
| tys.iter() |
| .zip(hir_tys.iter()) |
| .enumerate() |
| .filter_map(|(i, (ty, hir_ty))| { |
| if_chain! { |
| if let ty::Ref(_, ty, mutability) = *ty.kind(); |
| if let ty::Adt(adt, substs) = *ty.kind(); |
| |
| if let TyKind::Rptr(lt, ref ty) = hir_ty.kind; |
| if let TyKind::Path(QPath::Resolved(None, path)) = ty.ty.kind; |
| |
| // Check that the name as typed matches the actual name of the type. |
| // e.g. `fn foo(_: &Foo)` shouldn't trigger the lint when `Foo` is an alias for `Vec` |
| if let [.., name] = path.segments; |
| if cx.tcx.item_name(adt.did()) == name.ident.name; |
| |
| if !is_lint_allowed(cx, PTR_ARG, hir_ty.hir_id); |
| if params.get(i).map_or(true, |p| !is_lint_allowed(cx, PTR_ARG, p.hir_id)); |
| |
| then { |
| let (method_renames, deref_ty) = match cx.tcx.get_diagnostic_name(adt.did()) { |
| Some(sym::Vec) => ( |
| [("clone", ".to_owned()")].as_slice(), |
| DerefTy::Slice( |
| name.args |
| .and_then(|args| args.args.first()) |
| .and_then(|arg| if let GenericArg::Type(ty) = arg { |
| Some(ty.span) |
| } else { |
| None |
| }), |
| substs.type_at(0), |
| ), |
| ), |
| Some(sym::String) => ( |
| [("clone", ".to_owned()"), ("as_str", "")].as_slice(), |
| DerefTy::Str, |
| ), |
| Some(sym::PathBuf) => ( |
| [("clone", ".to_path_buf()"), ("as_path", "")].as_slice(), |
| DerefTy::Path, |
| ), |
| Some(sym::Cow) if mutability == Mutability::Not => { |
| let ty_name = name.args |
| .and_then(|args| { |
| args.args.iter().find_map(|a| match a { |
| GenericArg::Type(x) => Some(x), |
| _ => None, |
| }) |
| }) |
| .and_then(|arg| snippet_opt(cx, arg.span)) |
| .unwrap_or_else(|| substs.type_at(1).to_string()); |
| span_lint_and_sugg( |
| cx, |
| PTR_ARG, |
| hir_ty.span, |
| "using a reference to `Cow` is not recommended", |
| "change this to", |
| format!("&{}{}", mutability.prefix_str(), ty_name), |
| Applicability::Unspecified, |
| ); |
| return None; |
| }, |
| _ => return None, |
| }; |
| return Some(PtrArg { |
| idx: i, |
| span: hir_ty.span, |
| ty_did: adt.did(), |
| ty_name: name.ident.name, |
| method_renames, |
| ref_prefix: RefPrefix { |
| lt: lt.name, |
| mutability, |
| }, |
| deref_ty, |
| }); |
| } |
| } |
| None |
| }) |
| } |
| |
| fn check_mut_from_ref(cx: &LateContext<'_>, decl: &FnDecl<'_>) { |
| if let FnRetTy::Return(ty) = decl.output { |
| if let Some((out, Mutability::Mut, _)) = get_rptr_lm(ty) { |
| let mut immutables = vec![]; |
| for (_, mutbl, argspan) in decl |
| .inputs |
| .iter() |
| .filter_map(get_rptr_lm) |
| .filter(|&(lt, _, _)| lt.name == out.name) |
| { |
| if mutbl == Mutability::Mut { |
| return; |
| } |
| immutables.push(argspan); |
| } |
| if immutables.is_empty() { |
| return; |
| } |
| span_lint_and_then( |
| cx, |
| MUT_FROM_REF, |
| ty.span, |
| "mutable borrow from immutable input(s)", |
| |diag| { |
| let ms = MultiSpan::from_spans(immutables); |
| diag.span_note(ms, "immutable borrow here"); |
| }, |
| ); |
| } |
| } |
| } |
| |
| #[allow(clippy::too_many_lines)] |
| fn check_ptr_arg_usage<'tcx>(cx: &LateContext<'tcx>, body: &'tcx Body<'_>, args: &[PtrArg<'tcx>]) -> Vec<PtrArgResult> { |
| struct V<'cx, 'tcx> { |
| cx: &'cx LateContext<'tcx>, |
| /// Map from a local id to which argument it came from (index into `Self::args` and |
| /// `Self::results`) |
| bindings: HirIdMap<usize>, |
| /// The arguments being checked. |
| args: &'cx [PtrArg<'tcx>], |
| /// The results for each argument (len should match args.len) |
| results: Vec<PtrArgResult>, |
| /// The number of arguments which can't be linted. Used to return early. |
| skip_count: usize, |
| } |
| impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> { |
| type NestedFilter = nested_filter::OnlyBodies; |
| fn nested_visit_map(&mut self) -> Self::Map { |
| self.cx.tcx.hir() |
| } |
| |
| fn visit_anon_const(&mut self, _: &'tcx AnonConst) {} |
| |
| fn visit_expr(&mut self, e: &'tcx Expr<'_>) { |
| if self.skip_count == self.args.len() { |
| return; |
| } |
| |
| // Check if this is local we care about |
| let args_idx = match path_to_local(e).and_then(|id| self.bindings.get(&id)) { |
| Some(&i) => i, |
| None => return walk_expr(self, e), |
| }; |
| let args = &self.args[args_idx]; |
| let result = &mut self.results[args_idx]; |
| |
| // Helper function to handle early returns. |
| let mut set_skip_flag = || { |
| if !result.skip { |
| self.skip_count += 1; |
| } |
| result.skip = true; |
| }; |
| |
| match get_expr_use_or_unification_node(self.cx.tcx, e) { |
| Some((Node::Stmt(_), _)) => (), |
| Some((Node::Local(l), _)) => { |
| // Only trace simple bindings. e.g `let x = y;` |
| if let PatKind::Binding(BindingAnnotation::Unannotated, id, _, None) = l.pat.kind { |
| self.bindings.insert(id, args_idx); |
| } else { |
| set_skip_flag(); |
| } |
| }, |
| Some((Node::Expr(e), child_id)) => match e.kind { |
| ExprKind::Call(f, expr_args) => { |
| let i = expr_args.iter().position(|arg| arg.hir_id == child_id).unwrap_or(0); |
| if expr_sig(self.cx, f) |
| .map(|sig| sig.input(i).skip_binder().peel_refs()) |
| .map_or(true, |ty| match *ty.kind() { |
| ty::Param(_) => true, |
| ty::Adt(def, _) => def.did() == args.ty_did, |
| _ => false, |
| }) |
| { |
| // Passed to a function taking the non-dereferenced type. |
| set_skip_flag(); |
| } |
| }, |
| ExprKind::MethodCall(name, expr_args @ [self_arg, ..], _) => { |
| let i = expr_args.iter().position(|arg| arg.hir_id == child_id).unwrap_or(0); |
| if i == 0 { |
| // Check if the method can be renamed. |
| let name = name.ident.as_str(); |
| if let Some((_, replacement)) = args.method_renames.iter().find(|&&(x, _)| x == name) { |
| result.replacements.push(PtrArgReplacement { |
| expr_span: e.span, |
| self_span: self_arg.span, |
| replacement, |
| }); |
| return; |
| } |
| } |
| |
| let id = if let Some(x) = self.cx.typeck_results().type_dependent_def_id(e.hir_id) { |
| x |
| } else { |
| set_skip_flag(); |
| return; |
| }; |
| |
| match *self.cx.tcx.fn_sig(id).skip_binder().inputs()[i].peel_refs().kind() { |
| ty::Param(_) => { |
| set_skip_flag(); |
| }, |
| // If the types match check for methods which exist on both types. e.g. `Vec::len` and |
| // `slice::len` |
| ty::Adt(def, _) if def.did() == args.ty_did => { |
| set_skip_flag(); |
| }, |
| _ => (), |
| } |
| }, |
| // Indexing is fine for currently supported types. |
| ExprKind::Index(e, _) if e.hir_id == child_id => (), |
| _ => set_skip_flag(), |
| }, |
| _ => set_skip_flag(), |
| } |
| } |
| } |
| |
| let mut skip_count = 0; |
| let mut results = args.iter().map(|_| PtrArgResult::default()).collect::<Vec<_>>(); |
| let mut v = V { |
| cx, |
| bindings: args |
| .iter() |
| .enumerate() |
| .filter_map(|(i, arg)| { |
| let param = &body.params[arg.idx]; |
| match param.pat.kind { |
| PatKind::Binding(BindingAnnotation::Unannotated, id, _, None) |
| if !is_lint_allowed(cx, PTR_ARG, param.hir_id) => |
| { |
| Some((id, i)) |
| }, |
| _ => { |
| skip_count += 1; |
| results[i].skip = true; |
| None |
| }, |
| } |
| }) |
| .collect(), |
| args, |
| results, |
| skip_count, |
| }; |
| v.visit_expr(&body.value); |
| v.results |
| } |
| |
| fn get_rptr_lm<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> Option<(&'tcx Lifetime, Mutability, Span)> { |
| if let TyKind::Rptr(ref lt, ref m) = ty.kind { |
| Some((lt, m.mutbl, ty.span)) |
| } else { |
| None |
| } |
| } |
| |
| fn is_null_path(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool { |
| if let ExprKind::Call(pathexp, []) = expr.kind { |
| path_def_id(cx, pathexp).map_or(false, |id| { |
| matches!(cx.tcx.get_diagnostic_name(id), Some(sym::ptr_null | sym::ptr_null_mut)) |
| }) |
| } else { |
| false |
| } |
| } |
