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::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, 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.
45 /// fn im_too_long() {
47 /// // ... 100 more LoC
51 declare_clippy_lint! {
54 "functions with too many lines"
57 /// **What it does:** Checks for public functions that dereferences raw pointer
58 /// arguments but are not marked unsafe.
60 /// **Why is this bad?** The function should probably be marked `unsafe`, since
61 /// for an arbitrary raw pointer, there is no way of telling for sure if it is
64 /// **Known problems:**
66 /// * It does not check functions recursively so if the pointer is passed to a
67 /// private non-`unsafe` function which does the dereferencing, the lint won't
69 /// * It only checks for arguments whose type are raw pointers, not raw pointers
70 /// got from an argument in some other way (`fn foo(bar: &[*const u8])` or
71 /// `some_argument.get_raw_ptr()`).
75 /// pub fn foo(x: *const u8) {
76 /// println!("{}", unsafe { *x });
79 declare_clippy_lint! {
80 pub NOT_UNSAFE_PTR_ARG_DEREF,
82 "public functions dereferencing raw pointer arguments but not marked `unsafe`"
85 #[derive(Copy, Clone)]
86 pub struct Functions {
92 pub fn new(threshold: u64, max_lines: u64) -> Self {
93 Self { threshold, max_lines }
97 impl LintPass for Functions {
98 fn get_lints(&self) -> LintArray {
99 lint_array!(TOO_MANY_ARGUMENTS, TOO_MANY_LINES, NOT_UNSAFE_PTR_ARG_DEREF)
102 fn name(&self) -> &'static str {
107 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for Functions {
110 cx: &LateContext<'a, 'tcx>,
111 kind: intravisit::FnKind<'tcx>,
112 decl: &'tcx hir::FnDecl,
113 body: &'tcx hir::Body,
117 let is_impl = if let Some(hir::Node::Item(item)) = cx
120 .find_by_hir_id(cx.tcx.hir().get_parent_node_by_hir_id(hir_id))
122 matches!(item.node, hir::ItemKind::Impl(_, _, _, _, Some(_), _, _))
127 let unsafety = match kind {
128 hir::intravisit::FnKind::ItemFn(_, _, hir::FnHeader { unsafety, .. }, _, _) => unsafety,
129 hir::intravisit::FnKind::Method(_, sig, _, _) => sig.header.unsafety,
130 hir::intravisit::FnKind::Closure(_) => return,
133 // don't warn for implementations, it's not their fault
135 // don't lint extern functions decls, it's not their fault either
137 hir::intravisit::FnKind::Method(
140 header: hir::FnHeader { abi: Abi::Rust, .. },
146 | hir::intravisit::FnKind::ItemFn(_, _, hir::FnHeader { abi: Abi::Rust, .. }, _, _) => {
147 self.check_arg_number(cx, decl, span)
153 let nodeid = cx.tcx.hir().hir_to_node_id(hir_id);
154 self.check_raw_ptr(cx, unsafety, decl, body, nodeid);
155 self.check_line_number(cx, span, body);
158 fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) {
159 if let hir::TraitItemKind::Method(ref sig, ref eid) = item.node {
160 // don't lint extern functions decls, it's not their fault
161 if sig.header.abi == Abi::Rust {
162 self.check_arg_number(cx, &sig.decl, item.span);
165 if let hir::TraitMethod::Provided(eid) = *eid {
166 let body = cx.tcx.hir().body(eid);
167 self.check_raw_ptr(cx, sig.header.unsafety, &sig.decl, body, item.id);
173 impl<'a, 'tcx> Functions {
174 fn check_arg_number(self, cx: &LateContext<'_, '_>, decl: &hir::FnDecl, span: Span) {
175 let args = decl.inputs.len() as u64;
176 if args > self.threshold {
181 &format!("this function has too many arguments ({}/{})", args, self.threshold),
186 fn check_line_number(self, cx: &LateContext<'_, '_>, span: Span, body: &'tcx hir::Body) {
187 if in_external_macro(cx.sess(), span) {
191 let code_snippet = snippet(cx, body.value.span, "..");
192 let mut line_count: u64 = 0;
193 let mut in_comment = false;
194 let mut code_in_line;
196 // Skip the surrounding function decl.
197 let start_brace_idx = match code_snippet.find('{') {
201 let end_brace_idx = match code_snippet.find('}') {
203 None => code_snippet.len(),
205 let function_lines = code_snippet[start_brace_idx..end_brace_idx].lines();
207 for mut line in function_lines {
208 code_in_line = false;
210 line = line.trim_start();
215 match line.find("*/") {
217 line = &line[i + 2..];
224 let multi_idx = match line.find("/*") {
228 let single_idx = match line.find("//") {
232 code_in_line |= multi_idx > 0 && single_idx > 0;
233 // Implies multi_idx is below line.len()
234 if multi_idx < single_idx {
235 line = &line[multi_idx + 2..];
247 if line_count > self.max_lines {
248 span_lint(cx, TOO_MANY_LINES, span, "This function has a large number of lines.")
254 cx: &LateContext<'a, 'tcx>,
255 unsafety: hir::Unsafety,
256 decl: &'tcx hir::FnDecl,
257 body: &'tcx hir::Body,
260 let expr = &body.value;
261 if unsafety == hir::Unsafety::Normal && cx.access_levels.is_exported(nodeid) {
262 let raw_ptrs = iter_input_pats(decl, body)
263 .zip(decl.inputs.iter())
264 .filter_map(|(arg, ty)| raw_ptr_arg(arg, ty))
265 .collect::<FxHashSet<_>>();
267 if !raw_ptrs.is_empty() {
268 let tables = cx.tcx.body_tables(body.id());
269 let mut v = DerefVisitor {
275 hir::intravisit::walk_expr(&mut v, expr);
281 fn raw_ptr_arg(arg: &hir::Arg, ty: &hir::Ty) -> Option<ast::NodeId> {
282 if let (&hir::PatKind::Binding(_, id, _, _, _), &hir::TyKind::Ptr(_)) = (&arg.pat.node, &ty.node) {
289 struct DerefVisitor<'a, 'tcx: 'a> {
290 cx: &'a LateContext<'a, 'tcx>,
291 ptrs: FxHashSet<ast::NodeId>,
292 tables: &'a ty::TypeckTables<'tcx>,
295 impl<'a, 'tcx> hir::intravisit::Visitor<'tcx> for DerefVisitor<'a, 'tcx> {
296 fn visit_expr(&mut self, expr: &'tcx hir::Expr) {
298 hir::ExprKind::Call(ref f, ref args) => {
299 let ty = self.tables.expr_ty(f);
301 if type_is_unsafe_function(self.cx, ty) {
307 hir::ExprKind::MethodCall(_, _, ref args) => {
308 let def_id = self.tables.type_dependent_defs()[expr.hir_id].def_id();
309 let base_type = self.cx.tcx.type_of(def_id);
311 if type_is_unsafe_function(self.cx, base_type) {
317 hir::ExprKind::Unary(hir::UnDeref, ref ptr) => self.check_arg(ptr),
321 hir::intravisit::walk_expr(self, expr);
323 fn nested_visit_map<'this>(&'this mut self) -> intravisit::NestedVisitorMap<'this, 'tcx> {
324 intravisit::NestedVisitorMap::None
328 impl<'a, 'tcx: 'a> DerefVisitor<'a, 'tcx> {
329 fn check_arg(&self, ptr: &hir::Expr) {
330 if let hir::ExprKind::Path(ref qpath) = ptr.node {
331 if let Def::Local(id) = self.cx.tables.qpath_def(qpath, ptr.hir_id) {
332 if self.ptrs.contains(&id) {
335 NOT_UNSAFE_PTR_ARG_DEREF,
337 "this public function dereferences a raw pointer but is not marked `unsafe`",