1 use rustc::hir::intravisit;
4 use std::collections::HashSet;
7 use syntax::codemap::Span;
8 use utils::{span_lint, type_is_unsafe_function, iter_input_pats};
10 /// **What it does:** Checks for functions with too many parameters.
12 /// **Why is this bad?** Functions with lots of parameters are considered bad
13 /// style and reduce readability (“what does the 5th parameter mean?”). Consider
14 /// grouping some parameters into a new type.
16 /// **Known problems:** None.
20 /// fn foo(x: u32, y: u32, name: &str, c: Color, w: f32, h: f32, a: f32, b: f32) { .. }
23 pub TOO_MANY_ARGUMENTS,
25 "functions with too many arguments"
28 /// **What it does:** Checks for public functions that dereferences raw pointer
29 /// arguments but are not marked unsafe.
31 /// **Why is this bad?** The function should probably be marked `unsafe`, since
32 /// for an arbitrary raw pointer, there is no way of telling for sure if it is
35 /// **Known problems:**
37 /// * It does not check functions recursively so if the pointer is passed to a
38 /// private non-`unsafe` function which does the dereferencing, the lint won't trigger.
39 /// * It only checks for arguments whose type are raw pointers, not raw pointers
40 /// got from an argument in some other way (`fn foo(bar: &[*const u8])` or
41 /// `some_argument.get_raw_ptr()`).
45 /// pub fn foo(x: *const u8) { println!("{}", unsafe { *x }); }
48 pub NOT_UNSAFE_PTR_ARG_DEREF,
50 "public functions dereferencing raw pointer arguments but not marked `unsafe`"
54 pub struct Functions {
59 pub fn new(threshold: u64) -> Functions {
60 Functions { threshold: threshold }
64 impl LintPass for Functions {
65 fn get_lints(&self) -> LintArray {
66 lint_array!(TOO_MANY_ARGUMENTS, NOT_UNSAFE_PTR_ARG_DEREF)
70 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Functions {
73 cx: &LateContext<'a, 'tcx>,
74 kind: intravisit::FnKind<'tcx>,
75 decl: &'tcx hir::FnDecl,
76 body: &'tcx hir::Body,
80 use rustc::hir::map::Node::*;
82 let is_impl = if let Some(NodeItem(item)) = cx.tcx.hir.find(cx.tcx.hir.get_parent_node(nodeid)) {
83 matches!(item.node, hir::ItemImpl(_, _, _, _, Some(_), _, _) | hir::ItemDefaultImpl(..))
88 let unsafety = match kind {
89 hir::intravisit::FnKind::ItemFn(_, _, unsafety, _, _, _, _) => unsafety,
90 hir::intravisit::FnKind::Method(_, sig, _, _) => sig.unsafety,
91 hir::intravisit::FnKind::Closure(_) => return,
94 // don't warn for implementations, it's not their fault
96 // don't lint extern functions decls, it's not their fault either
98 hir::intravisit::FnKind::Method(_, &hir::MethodSig { abi: Abi::Rust, .. }, _, _) |
99 hir::intravisit::FnKind::ItemFn(_, _, _, _, Abi::Rust, _, _) => self.check_arg_number(cx, decl, span),
104 self.check_raw_ptr(cx, unsafety, decl, body, nodeid);
107 fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
108 if let hir::TraitItemKind::Method(ref sig, ref eid) = item.node {
109 // don't lint extern functions decls, it's not their fault
110 if sig.abi == Abi::Rust {
111 self.check_arg_number(cx, &sig.decl, item.span);
114 if let hir::TraitMethod::Provided(eid) = *eid {
115 let body = cx.tcx.hir.body(eid);
116 self.check_raw_ptr(cx, sig.unsafety, &sig.decl, body, item.id);
122 impl<'a, 'tcx> Functions {
123 fn check_arg_number(&self, cx: &LateContext, decl: &hir::FnDecl, span: Span) {
124 let args = decl.inputs.len() as u64;
125 if args > self.threshold {
129 &format!("this function has too many arguments ({}/{})", args, self.threshold));
135 cx: &LateContext<'a, 'tcx>,
136 unsafety: hir::Unsafety,
137 decl: &'tcx hir::FnDecl,
138 body: &'tcx hir::Body,
141 let expr = &body.value;
142 if unsafety == hir::Unsafety::Normal && cx.access_levels.is_exported(nodeid) {
143 let raw_ptrs = iter_input_pats(decl, body)
144 .zip(decl.inputs.iter())
145 .filter_map(|(arg, ty)| raw_ptr_arg(arg, ty))
146 .collect::<HashSet<_>>();
148 if !raw_ptrs.is_empty() {
149 let mut v = DerefVisitor {
154 hir::intravisit::walk_expr(&mut v, expr);
160 fn raw_ptr_arg(arg: &hir::Arg, ty: &hir::Ty) -> Option<hir::def_id::DefId> {
161 if let (&hir::PatKind::Binding(_, def_id, _, _), &hir::TyPtr(_)) = (&arg.pat.node, &ty.node) {
168 struct DerefVisitor<'a, 'tcx: 'a> {
169 cx: &'a LateContext<'a, 'tcx>,
170 ptrs: HashSet<hir::def_id::DefId>,
173 impl<'a, 'tcx> hir::intravisit::Visitor<'tcx> for DerefVisitor<'a, 'tcx> {
174 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
176 hir::ExprCall(ref f, ref args) => {
177 let ty = self.cx.tables.expr_ty(f);
179 if type_is_unsafe_function(ty) {
185 hir::ExprMethodCall(_, _, ref args) => {
186 let def_id = self.cx.tables.type_dependent_defs[&expr.id].def_id();
187 let base_type = self.cx.tcx.type_of(def_id);
189 if type_is_unsafe_function(base_type) {
195 hir::ExprUnary(hir::UnDeref, ref ptr) => self.check_arg(ptr),
199 hir::intravisit::walk_expr(self, expr);
201 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
202 intravisit::NestedVisitorMap::None
206 impl<'a, 'tcx: 'a> DerefVisitor<'a, 'tcx> {
207 fn check_arg(&self, ptr: &hir::Expr) {
208 if let hir::ExprPath(ref qpath) = ptr.node {
209 let def = self.cx.tables.qpath_def(qpath, ptr.id);
210 if self.ptrs.contains(&def.def_id()) {
212 NOT_UNSAFE_PTR_ARG_DEREF,
214 "this public function dereferences a raw pointer but is not marked `unsafe`");