1 use rustc::hir::intravisit;
5 use rustc::hir::def::Def;
6 use std::collections::HashSet;
9 use syntax::codemap::Span;
10 use utils::{iter_input_pats, span_lint, type_is_unsafe_function};
12 /// **What it does:** Checks for functions with too many parameters.
14 /// **Why is this bad?** Functions with lots of parameters are considered bad
15 /// style and reduce readability (“what does the 5th parameter mean?”). Consider
16 /// grouping some parameters into a new type.
18 /// **Known problems:** None.
22 /// fn foo(x: u32, y: u32, name: &str, c: Color, w: f32, h: f32, a: f32, b:
26 pub TOO_MANY_ARGUMENTS,
28 "functions with too many arguments"
31 /// **What it does:** Checks for public functions that dereferences raw pointer
32 /// arguments but are not marked unsafe.
34 /// **Why is this bad?** The function should probably be marked `unsafe`, since
35 /// for an arbitrary raw pointer, there is no way of telling for sure if it is
38 /// **Known problems:**
40 /// * It does not check functions recursively so if the pointer is passed to a
41 /// private non-`unsafe` function which does the dereferencing, the lint won't
43 /// * It only checks for arguments whose type are raw pointers, not raw pointers
44 /// got from an argument in some other way (`fn foo(bar: &[*const u8])` or
45 /// `some_argument.get_raw_ptr()`).
49 /// pub fn foo(x: *const u8) { println!("{}", unsafe { *x }); }
52 pub NOT_UNSAFE_PTR_ARG_DEREF,
54 "public functions dereferencing raw pointer arguments but not marked `unsafe`"
57 #[derive(Copy, Clone)]
58 pub struct Functions {
63 pub fn new(threshold: u64) -> Self {
70 impl LintPass for Functions {
71 fn get_lints(&self) -> LintArray {
72 lint_array!(TOO_MANY_ARGUMENTS, NOT_UNSAFE_PTR_ARG_DEREF)
76 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Functions {
79 cx: &LateContext<'a, 'tcx>,
80 kind: intravisit::FnKind<'tcx>,
81 decl: &'tcx hir::FnDecl,
82 body: &'tcx hir::Body,
86 use rustc::hir::map::Node::*;
88 let is_impl = if let Some(NodeItem(item)) = cx.tcx.hir.find(cx.tcx.hir.get_parent_node(nodeid)) {
89 matches!(item.node, hir::ItemImpl(_, _, _, _, Some(_), _, _))
94 let unsafety = match kind {
95 hir::intravisit::FnKind::ItemFn(_, _, unsafety, _, _, _, _) => unsafety,
96 hir::intravisit::FnKind::Method(_, sig, _, _) => sig.unsafety,
97 hir::intravisit::FnKind::Closure(_) => return,
100 // don't warn for implementations, it's not their fault
102 // don't lint extern functions decls, it's not their fault either
104 hir::intravisit::FnKind::Method(_, &hir::MethodSig { abi: Abi::Rust, .. }, _, _) |
105 hir::intravisit::FnKind::ItemFn(_, _, _, _, Abi::Rust, _, _) => self.check_arg_number(cx, decl, span),
110 self.check_raw_ptr(cx, unsafety, decl, body, nodeid);
113 fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
114 if let hir::TraitItemKind::Method(ref sig, ref eid) = item.node {
115 // don't lint extern functions decls, it's not their fault
116 if sig.abi == Abi::Rust {
117 self.check_arg_number(cx, &sig.decl, item.span);
120 if let hir::TraitMethod::Provided(eid) = *eid {
121 let body = cx.tcx.hir.body(eid);
122 self.check_raw_ptr(cx, sig.unsafety, &sig.decl, body, item.id);
128 impl<'a, 'tcx> Functions {
129 fn check_arg_number(&self, cx: &LateContext, decl: &hir::FnDecl, span: Span) {
130 let args = decl.inputs.len() as u64;
131 if args > self.threshold {
136 &format!("this function has too many arguments ({}/{})", args, self.threshold),
143 cx: &LateContext<'a, 'tcx>,
144 unsafety: hir::Unsafety,
145 decl: &'tcx hir::FnDecl,
146 body: &'tcx hir::Body,
149 let expr = &body.value;
150 if unsafety == hir::Unsafety::Normal && cx.access_levels.is_exported(nodeid) {
151 let raw_ptrs = iter_input_pats(decl, body)
152 .zip(decl.inputs.iter())
153 .filter_map(|(arg, ty)| raw_ptr_arg(arg, ty))
154 .collect::<HashSet<_>>();
156 if !raw_ptrs.is_empty() {
157 let tables = cx.tcx.body_tables(body.id());
158 let mut v = DerefVisitor {
164 hir::intravisit::walk_expr(&mut v, expr);
170 fn raw_ptr_arg(arg: &hir::Arg, ty: &hir::Ty) -> Option<ast::NodeId> {
171 if let (&hir::PatKind::Binding(_, id, _, _), &hir::TyPtr(_)) = (&arg.pat.node, &ty.node) {
178 struct DerefVisitor<'a, 'tcx: 'a> {
179 cx: &'a LateContext<'a, 'tcx>,
180 ptrs: HashSet<ast::NodeId>,
181 tables: &'a ty::TypeckTables<'tcx>,
184 impl<'a, 'tcx> hir::intravisit::Visitor<'tcx> for DerefVisitor<'a, 'tcx> {
185 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
187 hir::ExprCall(ref f, ref args) => {
188 let ty = self.tables.expr_ty(f);
190 if type_is_unsafe_function(self.cx, ty) {
196 hir::ExprMethodCall(_, _, ref args) => {
197 let def_id = self.tables.type_dependent_defs()[expr.hir_id].def_id();
198 let base_type = self.cx.tcx.type_of(def_id);
200 if type_is_unsafe_function(self.cx, base_type) {
206 hir::ExprUnary(hir::UnDeref, ref ptr) => self.check_arg(ptr),
210 hir::intravisit::walk_expr(self, expr);
212 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
213 intravisit::NestedVisitorMap::None
217 impl<'a, 'tcx: 'a> DerefVisitor<'a, 'tcx> {
218 fn check_arg(&self, ptr: &hir::Expr) {
219 if let hir::ExprPath(ref qpath) = ptr.node {
220 if let Def::Local(id) = self.cx.tables.qpath_def(qpath, ptr.hir_id) {
221 if self.ptrs.contains(&id) {
224 NOT_UNSAFE_PTR_ARG_DEREF,
226 "this public function dereferences a raw pointer but is not marked `unsafe`",