1 use crate::utils::{iter_input_pats, snippet, span_lint, type_is_unsafe_function};
4 use rustc::hir::def::Def;
5 use rustc::hir::intravisit;
6 use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass};
8 use rustc::{declare_tool_lint, lint_array};
9 use rustc_data_structures::fx::FxHashSet;
10 use rustc_target::spec::abi::Abi;
12 use syntax::source_map::Span;
14 /// **What it does:** Checks for functions with too many parameters.
16 /// **Why is this bad?** Functions with lots of parameters are considered bad
17 /// style and reduce readability (“what does the 5th parameter mean?”). Consider
18 /// grouping some parameters into a new type.
20 /// **Known problems:** None.
24 /// fn foo(x: u32, y: u32, name: &str, c: Color, w: f32, h: f32, a: f32, b: f32) {
28 declare_clippy_lint! {
29 pub TOO_MANY_ARGUMENTS,
31 "functions with too many arguments"
34 /// **What it does:** Checks for functions with a large amount of lines.
36 /// **Why is this bad?** Functions with a lot of lines are harder to understand
37 /// due to having to look at a larger amount of code to understand what the
38 /// function is doing. Consider splitting the body of the function into
39 /// multiple functions.
41 /// **Known problems:** None.
44 declare_clippy_lint! {
47 "functions with too many lines"
50 /// **What it does:** Checks for public functions that dereferences raw pointer
51 /// arguments but are not marked unsafe.
53 /// **Why is this bad?** The function should probably be marked `unsafe`, since
54 /// for an arbitrary raw pointer, there is no way of telling for sure if it is
57 /// **Known problems:**
59 /// * It does not check functions recursively so if the pointer is passed to a
60 /// private non-`unsafe` function which does the dereferencing, the lint won't
62 /// * It only checks for arguments whose type are raw pointers, not raw pointers
63 /// got from an argument in some other way (`fn foo(bar: &[*const u8])` or
64 /// `some_argument.get_raw_ptr()`).
68 /// pub fn foo(x: *const u8) {
69 /// println!("{}", unsafe { *x });
72 declare_clippy_lint! {
73 pub NOT_UNSAFE_PTR_ARG_DEREF,
75 "public functions dereferencing raw pointer arguments but not marked `unsafe`"
78 #[derive(Copy, Clone)]
79 pub struct Functions {
85 pub fn new(threshold: u64, max_lines: u64) -> Self {
93 impl LintPass for Functions {
94 fn get_lints(&self) -> LintArray {
95 lint_array!(TOO_MANY_ARGUMENTS, TOO_MANY_LINES, NOT_UNSAFE_PTR_ARG_DEREF)
98 fn name(&self) -> &'static str {
103 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Functions {
106 cx: &LateContext<'a, 'tcx>,
107 kind: intravisit::FnKind<'tcx>,
108 decl: &'tcx hir::FnDecl,
109 body: &'tcx hir::Body,
113 let is_impl = if let Some(hir::Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_node(nodeid)) {
114 matches!(item.node, hir::ItemKind::Impl(_, _, _, _, Some(_), _, _))
119 let unsafety = match kind {
120 hir::intravisit::FnKind::ItemFn(_, _, hir::FnHeader { unsafety, .. }, _, _) => unsafety,
121 hir::intravisit::FnKind::Method(_, sig, _, _) => sig.header.unsafety,
122 hir::intravisit::FnKind::Closure(_) => return,
125 // don't warn for implementations, it's not their fault
127 // don't lint extern functions decls, it's not their fault either
129 hir::intravisit::FnKind::Method(
132 header: hir::FnHeader { abi: Abi::Rust, .. },
138 | hir::intravisit::FnKind::ItemFn(_, _, hir::FnHeader { abi: Abi::Rust, .. }, _, _) => {
139 self.check_arg_number(cx, decl, span)
145 self.check_raw_ptr(cx, unsafety, decl, body, nodeid);
146 self.check_line_number(cx, span);
149 fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
150 if let hir::TraitItemKind::Method(ref sig, ref eid) = item.node {
151 // don't lint extern functions decls, it's not their fault
152 if sig.header.abi == Abi::Rust {
153 self.check_arg_number(cx, &sig.decl, item.span);
156 if let hir::TraitMethod::Provided(eid) = *eid {
157 let body = cx.tcx.hir().body(eid);
158 self.check_raw_ptr(cx, sig.header.unsafety, &sig.decl, body, item.id);
164 impl<'a, 'tcx> Functions {
165 fn check_arg_number(self, cx: &LateContext<'_, '_>, decl: &hir::FnDecl, span: Span) {
166 let args = decl.inputs.len() as u64;
167 if args > self.threshold {
172 &format!("this function has too many arguments ({}/{})", args, self.threshold),
177 fn check_line_number(self, cx: &LateContext, span: Span) {
178 let code_snippet = snippet(cx, span, "..");
179 let mut line_count = 0;
180 let mut in_comment = false;
181 for mut line in code_snippet.lines() {
183 let end_comment_loc = match line.find("*/") {
188 line = &line[end_comment_loc..];
190 line = line.trim_left();
191 if line.is_empty() || line.starts_with("//") { continue; }
192 if line.contains("/*") {
193 let mut count_line: bool = !line.starts_with("/*");
194 let close_counts = line.match_indices("*/").count();
195 let open_counts = line.match_indices("/*").count();
197 if close_counts > 1 || open_counts > 1 {
199 } else if close_counts == 1 {
200 match line.find("*/") {
202 line = line[i..].trim_left();
203 if !line.is_empty() && !line.starts_with("//") {
212 if count_line { line_count += 1; }
214 // No multipart comment, no single comment, non-empty string.
219 if line_count > self.max_lines {
220 span_lint(cx, TOO_MANY_LINES, span,
221 "This function has a large number of lines.")
227 cx: &LateContext<'a, 'tcx>,
228 unsafety: hir::Unsafety,
229 decl: &'tcx hir::FnDecl,
230 body: &'tcx hir::Body,
233 let expr = &body.value;
234 if unsafety == hir::Unsafety::Normal && cx.access_levels.is_exported(nodeid) {
235 let raw_ptrs = iter_input_pats(decl, body)
236 .zip(decl.inputs.iter())
237 .filter_map(|(arg, ty)| raw_ptr_arg(arg, ty))
238 .collect::<FxHashSet<_>>();
240 if !raw_ptrs.is_empty() {
241 let tables = cx.tcx.body_tables(body.id());
242 let mut v = DerefVisitor {
248 hir::intravisit::walk_expr(&mut v, expr);
254 fn raw_ptr_arg(arg: &hir::Arg, ty: &hir::Ty) -> Option<ast::NodeId> {
255 if let (&hir::PatKind::Binding(_, id, _, _), &hir::TyKind::Ptr(_)) = (&arg.pat.node, &ty.node) {
262 struct DerefVisitor<'a, 'tcx: 'a> {
263 cx: &'a LateContext<'a, 'tcx>,
264 ptrs: FxHashSet<ast::NodeId>,
265 tables: &'a ty::TypeckTables<'tcx>,
268 impl<'a, 'tcx> hir::intravisit::Visitor<'tcx> for DerefVisitor<'a, 'tcx> {
269 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
271 hir::ExprKind::Call(ref f, ref args) => {
272 let ty = self.tables.expr_ty(f);
274 if type_is_unsafe_function(self.cx, ty) {
280 hir::ExprKind::MethodCall(_, _, ref args) => {
281 let def_id = self.tables.type_dependent_defs()[expr.hir_id].def_id();
282 let base_type = self.cx.tcx.type_of(def_id);
284 if type_is_unsafe_function(self.cx, base_type) {
290 hir::ExprKind::Unary(hir::UnDeref, ref ptr) => self.check_arg(ptr),
294 hir::intravisit::walk_expr(self, expr);
296 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
297 intravisit::NestedVisitorMap::None
301 impl<'a, 'tcx: 'a> DerefVisitor<'a, 'tcx> {
302 fn check_arg(&self, ptr: &hir::Expr) {
303 if let hir::ExprKind::Path(ref qpath) = ptr.node {
304 if let Def::Local(id) = self.cx.tables.qpath_def(qpath, ptr.hir_id) {
305 if self.ptrs.contains(&id) {
308 NOT_UNSAFE_PTR_ARG_DEREF,
310 "this public function dereferences a raw pointer but is not marked `unsafe`",