1 use rustc::hir::intravisit;
5 use std::collections::HashSet;
8 use syntax::codemap::Span;
9 use utils::{iter_input_pats, span_lint, type_is_unsafe_function};
11 /// **What it does:** Checks for functions with too many parameters.
13 /// **Why is this bad?** Functions with lots of parameters are considered bad
14 /// style and reduce readability (“what does the 5th parameter mean?”). Consider
15 /// grouping some parameters into a new type.
17 /// **Known problems:** None.
21 /// fn foo(x: u32, y: u32, name: &str, c: Color, w: f32, h: f32, a: f32, b:
25 pub TOO_MANY_ARGUMENTS,
27 "functions with too many arguments"
30 /// **What it does:** Checks for public functions that dereferences raw pointer
31 /// arguments but are not marked unsafe.
33 /// **Why is this bad?** The function should probably be marked `unsafe`, since
34 /// for an arbitrary raw pointer, there is no way of telling for sure if it is
37 /// **Known problems:**
39 /// * It does not check functions recursively so if the pointer is passed to a
40 /// private non-`unsafe` function which does the dereferencing, the lint won't
42 /// * It only checks for arguments whose type are raw pointers, not raw pointers
43 /// got from an argument in some other way (`fn foo(bar: &[*const u8])` or
44 /// `some_argument.get_raw_ptr()`).
48 /// pub fn foo(x: *const u8) { println!("{}", unsafe { *x }); }
51 pub NOT_UNSAFE_PTR_ARG_DEREF,
53 "public functions dereferencing raw pointer arguments but not marked `unsafe`"
56 #[derive(Copy, Clone)]
57 pub struct Functions {
62 pub fn new(threshold: u64) -> Self {
69 impl LintPass for Functions {
70 fn get_lints(&self) -> LintArray {
71 lint_array!(TOO_MANY_ARGUMENTS, NOT_UNSAFE_PTR_ARG_DEREF)
75 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Functions {
78 cx: &LateContext<'a, 'tcx>,
79 kind: intravisit::FnKind<'tcx>,
80 decl: &'tcx hir::FnDecl,
81 body: &'tcx hir::Body,
85 use rustc::hir::map::Node::*;
87 let is_impl = if let Some(NodeItem(item)) = cx.tcx.hir.find(cx.tcx.hir.get_parent_node(nodeid)) {
88 matches!(item.node, hir::ItemImpl(_, _, _, _, Some(_), _, _) | hir::ItemDefaultImpl(..))
93 let unsafety = match kind {
94 hir::intravisit::FnKind::ItemFn(_, _, unsafety, _, _, _, _) => unsafety,
95 hir::intravisit::FnKind::Method(_, sig, _, _) => sig.unsafety,
96 hir::intravisit::FnKind::Closure(_) => return,
99 // don't warn for implementations, it's not their fault
101 // don't lint extern functions decls, it's not their fault either
103 hir::intravisit::FnKind::Method(_, &hir::MethodSig { abi: Abi::Rust, .. }, _, _) |
104 hir::intravisit::FnKind::ItemFn(_, _, _, _, Abi::Rust, _, _) => self.check_arg_number(cx, decl, span),
109 self.check_raw_ptr(cx, unsafety, decl, body, nodeid);
112 fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
113 if let hir::TraitItemKind::Method(ref sig, ref eid) = item.node {
114 // don't lint extern functions decls, it's not their fault
115 if sig.abi == Abi::Rust {
116 self.check_arg_number(cx, &sig.decl, item.span);
119 if let hir::TraitMethod::Provided(eid) = *eid {
120 let body = cx.tcx.hir.body(eid);
121 self.check_raw_ptr(cx, sig.unsafety, &sig.decl, body, item.id);
127 impl<'a, 'tcx> Functions {
128 fn check_arg_number(&self, cx: &LateContext, decl: &hir::FnDecl, span: Span) {
129 let args = decl.inputs.len() as u64;
130 if args > self.threshold {
135 &format!("this function has too many arguments ({}/{})", args, self.threshold),
142 cx: &LateContext<'a, 'tcx>,
143 unsafety: hir::Unsafety,
144 decl: &'tcx hir::FnDecl,
145 body: &'tcx hir::Body,
148 let expr = &body.value;
149 if unsafety == hir::Unsafety::Normal && cx.access_levels.is_exported(nodeid) {
150 let raw_ptrs = iter_input_pats(decl, body)
151 .zip(decl.inputs.iter())
152 .filter_map(|(arg, ty)| raw_ptr_arg(arg, ty))
153 .collect::<HashSet<_>>();
155 if !raw_ptrs.is_empty() {
156 let tables = cx.tcx.body_tables(body.id());
157 let mut v = DerefVisitor {
163 hir::intravisit::walk_expr(&mut v, expr);
169 fn raw_ptr_arg(arg: &hir::Arg, ty: &hir::Ty) -> Option<hir::def_id::DefId> {
170 if let (&hir::PatKind::Binding(_, def_id, _, _), &hir::TyPtr(_)) = (&arg.pat.node, &ty.node) {
177 struct DerefVisitor<'a, 'tcx: 'a> {
178 cx: &'a LateContext<'a, 'tcx>,
179 ptrs: HashSet<hir::def_id::DefId>,
180 tables: &'a ty::TypeckTables<'tcx>,
183 impl<'a, 'tcx> hir::intravisit::Visitor<'tcx> for DerefVisitor<'a, 'tcx> {
184 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
186 hir::ExprCall(ref f, ref args) => {
187 let ty = self.tables.expr_ty(f);
189 if type_is_unsafe_function(self.cx, ty) {
195 hir::ExprMethodCall(_, _, ref args) => {
196 let def_id = self.tables.type_dependent_defs()[expr.hir_id].def_id();
197 let base_type = self.cx.tcx.type_of(def_id);
199 if type_is_unsafe_function(self.cx, base_type) {
205 hir::ExprUnary(hir::UnDeref, ref ptr) => self.check_arg(ptr),
209 hir::intravisit::walk_expr(self, expr);
211 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
212 intravisit::NestedVisitorMap::None
216 impl<'a, 'tcx: 'a> DerefVisitor<'a, 'tcx> {
217 fn check_arg(&self, ptr: &hir::Expr) {
218 if let hir::ExprPath(ref qpath) = ptr.node {
219 let def = self.cx.tables.qpath_def(qpath, ptr.hir_id);
220 if self.ptrs.contains(&def.def_id()) {
223 NOT_UNSAFE_PTR_ARG_DEREF,
225 "this public function dereferences a raw pointer but is not marked `unsafe`",