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Commit | Line | Data |
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f20569fa XL |
1 | //! Checks for usage of `&Vec[_]` and `&String`. |
2 | ||
064997fb | 3 | use clippy_utils::diagnostics::{span_lint, span_lint_and_sugg, span_lint_and_then, span_lint_hir_and_then}; |
cdc7bbd5 | 4 | use clippy_utils::source::snippet_opt; |
5099ac24 | 5 | use clippy_utils::ty::expr_sig; |
04454e1e | 6 | use clippy_utils::visitors::contains_unsafe_block; |
5099ac24 | 7 | use clippy_utils::{get_expr_use_or_unification_node, is_lint_allowed, path_def_id, path_to_local, paths}; |
f20569fa | 8 | use if_chain::if_chain; |
04454e1e | 9 | use rustc_errors::{Applicability, MultiSpan}; |
5099ac24 FG |
10 | use rustc_hir::def_id::DefId; |
11 | use rustc_hir::hir_id::HirIdMap; | |
12 | use rustc_hir::intravisit::{walk_expr, Visitor}; | |
f20569fa | 13 | use rustc_hir::{ |
04454e1e | 14 | self as hir, AnonConst, BinOpKind, BindingAnnotation, Body, Expr, ExprKind, FnRetTy, FnSig, GenericArg, |
487cf647 FG |
15 | ImplItemKind, ItemKind, Lifetime, Mutability, Node, Param, PatKind, QPath, TraitFn, TraitItem, TraitItemKind, |
16 | TyKind, Unsafety, | |
f20569fa | 17 | }; |
2b03887a FG |
18 | use rustc_infer::infer::TyCtxtInferExt; |
19 | use rustc_infer::traits::{Obligation, ObligationCause}; | |
f20569fa | 20 | use rustc_lint::{LateContext, LateLintPass}; |
5099ac24 | 21 | use rustc_middle::hir::nested_filter; |
487cf647 | 22 | use rustc_middle::ty::{self, Binder, Clause, ExistentialPredicate, List, PredicateKind, Ty}; |
f20569fa XL |
23 | use rustc_session::{declare_lint_pass, declare_tool_lint}; |
24 | use rustc_span::source_map::Span; | |
04454e1e | 25 | use rustc_span::sym; |
cdc7bbd5 | 26 | use rustc_span::symbol::Symbol; |
2b03887a FG |
27 | use rustc_trait_selection::infer::InferCtxtExt as _; |
28 | use rustc_trait_selection::traits::query::evaluate_obligation::InferCtxtExt as _; | |
5099ac24 FG |
29 | use std::fmt; |
30 | use std::iter; | |
f20569fa XL |
31 | |
32 | declare_clippy_lint! { | |
94222f64 | 33 | /// ### What it does |
5099ac24 FG |
34 | /// This lint checks for function arguments of type `&String`, `&Vec`, |
35 | /// `&PathBuf`, and `Cow<_>`. It will also suggest you replace `.clone()` calls | |
36 | /// with the appropriate `.to_owned()`/`to_string()` calls. | |
f20569fa | 37 | /// |
94222f64 XL |
38 | /// ### Why is this bad? |
39 | /// Requiring the argument to be of the specific size | |
f20569fa XL |
40 | /// makes the function less useful for no benefit; slices in the form of `&[T]` |
41 | /// or `&str` usually suffice and can be obtained from other types, too. | |
42 | /// | |
94222f64 | 43 | /// ### Known problems |
5099ac24 | 44 | /// There may be `fn(&Vec)`-typed references pointing to your function. |
f20569fa XL |
45 | /// If you have them, you will get a compiler error after applying this lint's |
46 | /// suggestions. You then have the choice to undo your changes or change the | |
47 | /// type of the reference. | |
48 | /// | |
49 | /// Note that if the function is part of your public interface, there may be | |
50 | /// other crates referencing it, of which you may not be aware. Carefully | |
51 | /// deprecate the function before applying the lint suggestions in this case. | |
52 | /// | |
94222f64 | 53 | /// ### Example |
f20569fa | 54 | /// ```ignore |
f20569fa | 55 | /// fn foo(&Vec<u32>) { .. } |
923072b8 | 56 | /// ``` |
f20569fa | 57 | /// |
923072b8 FG |
58 | /// Use instead: |
59 | /// ```ignore | |
f20569fa XL |
60 | /// fn foo(&[u32]) { .. } |
61 | /// ``` | |
a2a8927a | 62 | #[clippy::version = "pre 1.29.0"] |
f20569fa XL |
63 | pub PTR_ARG, |
64 | style, | |
65 | "fn arguments of the type `&Vec<...>` or `&String`, suggesting to use `&[...]` or `&str` instead, respectively" | |
66 | } | |
67 | ||
68 | declare_clippy_lint! { | |
94222f64 XL |
69 | /// ### What it does |
70 | /// This lint checks for equality comparisons with `ptr::null` | |
f20569fa | 71 | /// |
94222f64 XL |
72 | /// ### Why is this bad? |
73 | /// It's easier and more readable to use the inherent | |
f20569fa XL |
74 | /// `.is_null()` |
75 | /// method instead | |
76 | /// | |
94222f64 | 77 | /// ### Example |
923072b8 FG |
78 | /// ```rust,ignore |
79 | /// use std::ptr; | |
80 | /// | |
f20569fa | 81 | /// if x == ptr::null { |
923072b8 | 82 | /// // .. |
f20569fa | 83 | /// } |
923072b8 | 84 | /// ``` |
f20569fa | 85 | /// |
923072b8 FG |
86 | /// Use instead: |
87 | /// ```rust,ignore | |
f20569fa | 88 | /// if x.is_null() { |
923072b8 | 89 | /// // .. |
f20569fa XL |
90 | /// } |
91 | /// ``` | |
a2a8927a | 92 | #[clippy::version = "pre 1.29.0"] |
f20569fa XL |
93 | pub CMP_NULL, |
94 | style, | |
cdc7bbd5 | 95 | "comparing a pointer to a null pointer, suggesting to use `.is_null()` instead" |
f20569fa XL |
96 | } |
97 | ||
98 | declare_clippy_lint! { | |
94222f64 | 99 | /// ### What it does |
04454e1e FG |
100 | /// This lint checks for functions that take immutable references and return |
101 | /// mutable ones. This will not trigger if no unsafe code exists as there | |
102 | /// are multiple safe functions which will do this transformation | |
103 | /// | |
104 | /// To be on the conservative side, if there's at least one mutable | |
105 | /// reference with the output lifetime, this lint will not trigger. | |
f20569fa | 106 | /// |
94222f64 | 107 | /// ### Why is this bad? |
04454e1e FG |
108 | /// Creating a mutable reference which can be repeatably derived from an |
109 | /// immutable reference is unsound as it allows creating multiple live | |
110 | /// mutable references to the same object. | |
111 | /// | |
112 | /// This [error](https://github.com/rust-lang/rust/issues/39465) actually | |
113 | /// lead to an interim Rust release 1.15.1. | |
f20569fa | 114 | /// |
94222f64 | 115 | /// ### Known problems |
04454e1e FG |
116 | /// This pattern is used by memory allocators to allow allocating multiple |
117 | /// objects while returning mutable references to each one. So long as | |
118 | /// different mutable references are returned each time such a function may | |
119 | /// be safe. | |
f20569fa | 120 | /// |
94222f64 | 121 | /// ### Example |
f20569fa XL |
122 | /// ```ignore |
123 | /// fn foo(&Foo) -> &mut Bar { .. } | |
124 | /// ``` | |
a2a8927a | 125 | #[clippy::version = "pre 1.29.0"] |
f20569fa XL |
126 | pub MUT_FROM_REF, |
127 | correctness, | |
128 | "fns that create mutable refs from immutable ref args" | |
129 | } | |
130 | ||
cdc7bbd5 | 131 | declare_clippy_lint! { |
94222f64 XL |
132 | /// ### What it does |
133 | /// This lint checks for invalid usages of `ptr::null`. | |
cdc7bbd5 | 134 | /// |
94222f64 XL |
135 | /// ### Why is this bad? |
136 | /// This causes undefined behavior. | |
cdc7bbd5 | 137 | /// |
94222f64 | 138 | /// ### Example |
cdc7bbd5 | 139 | /// ```ignore |
923072b8 | 140 | /// // Undefined behavior |
cdc7bbd5 XL |
141 | /// unsafe { std::slice::from_raw_parts(ptr::null(), 0); } |
142 | /// ``` | |
143 | /// | |
923072b8 | 144 | /// Use instead: |
3c0e092e | 145 | /// ```ignore |
cdc7bbd5 XL |
146 | /// unsafe { std::slice::from_raw_parts(NonNull::dangling().as_ptr(), 0); } |
147 | /// ``` | |
a2a8927a | 148 | #[clippy::version = "1.53.0"] |
cdc7bbd5 XL |
149 | pub INVALID_NULL_PTR_USAGE, |
150 | correctness, | |
151 | "invalid usage of a null pointer, suggesting `NonNull::dangling()` instead" | |
152 | } | |
153 | ||
154 | declare_lint_pass!(Ptr => [PTR_ARG, CMP_NULL, MUT_FROM_REF, INVALID_NULL_PTR_USAGE]); | |
f20569fa XL |
155 | |
156 | impl<'tcx> LateLintPass<'tcx> for Ptr { | |
5099ac24 FG |
157 | fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) { |
158 | if let TraitItemKind::Fn(sig, trait_method) = &item.kind { | |
159 | if matches!(trait_method, TraitFn::Provided(_)) { | |
160 | // Handled by check body. | |
161 | return; | |
162 | } | |
f20569fa | 163 | |
04454e1e | 164 | check_mut_from_ref(cx, sig, None); |
5099ac24 FG |
165 | for arg in check_fn_args( |
166 | cx, | |
9ffffee4 | 167 | cx.tcx.fn_sig(item.owner_id).subst_identity().skip_binder().inputs(), |
5099ac24 FG |
168 | sig.decl.inputs, |
169 | &[], | |
170 | ) | |
171 | .filter(|arg| arg.mutability() == Mutability::Not) | |
172 | { | |
064997fb FG |
173 | span_lint_hir_and_then(cx, PTR_ARG, arg.emission_id, arg.span, &arg.build_msg(), |diag| { |
174 | diag.span_suggestion( | |
175 | arg.span, | |
176 | "change this to", | |
177 | format!("{}{}", arg.ref_prefix, arg.deref_ty.display(cx)), | |
178 | Applicability::Unspecified, | |
179 | ); | |
180 | }); | |
f20569fa | 181 | } |
f20569fa XL |
182 | } |
183 | } | |
184 | ||
5099ac24 FG |
185 | fn check_body(&mut self, cx: &LateContext<'tcx>, body: &'tcx Body<'_>) { |
186 | let hir = cx.tcx.hir(); | |
187 | let mut parents = hir.parent_iter(body.value.hir_id); | |
04454e1e | 188 | let (item_id, sig, is_trait_item) = match parents.next() { |
5099ac24 FG |
189 | Some((_, Node::Item(i))) => { |
190 | if let ItemKind::Fn(sig, ..) = &i.kind { | |
2b03887a | 191 | (i.owner_id, sig, false) |
5099ac24 FG |
192 | } else { |
193 | return; | |
194 | } | |
195 | }, | |
196 | Some((_, Node::ImplItem(i))) => { | |
197 | if !matches!(parents.next(), | |
198 | Some((_, Node::Item(i))) if matches!(&i.kind, ItemKind::Impl(i) if i.of_trait.is_none()) | |
199 | ) { | |
200 | return; | |
201 | } | |
202 | if let ImplItemKind::Fn(sig, _) = &i.kind { | |
2b03887a | 203 | (i.owner_id, sig, false) |
5099ac24 FG |
204 | } else { |
205 | return; | |
206 | } | |
207 | }, | |
208 | Some((_, Node::TraitItem(i))) => { | |
209 | if let TraitItemKind::Fn(sig, _) = &i.kind { | |
2b03887a | 210 | (i.owner_id, sig, true) |
5099ac24 FG |
211 | } else { |
212 | return; | |
213 | } | |
214 | }, | |
215 | _ => return, | |
216 | }; | |
217 | ||
04454e1e FG |
218 | check_mut_from_ref(cx, sig, Some(body)); |
219 | let decl = sig.decl; | |
9ffffee4 | 220 | let sig = cx.tcx.fn_sig(item_id).subst_identity().skip_binder(); |
5099ac24 FG |
221 | let lint_args: Vec<_> = check_fn_args(cx, sig.inputs(), decl.inputs, body.params) |
222 | .filter(|arg| !is_trait_item || arg.mutability() == Mutability::Not) | |
223 | .collect(); | |
224 | let results = check_ptr_arg_usage(cx, body, &lint_args); | |
225 | ||
226 | for (result, args) in results.iter().zip(lint_args.iter()).filter(|(r, _)| !r.skip) { | |
064997fb | 227 | span_lint_hir_and_then(cx, PTR_ARG, args.emission_id, args.span, &args.build_msg(), |diag| { |
5099ac24 FG |
228 | diag.multipart_suggestion( |
229 | "change this to", | |
230 | iter::once((args.span, format!("{}{}", args.ref_prefix, args.deref_ty.display(cx)))) | |
231 | .chain(result.replacements.iter().map(|r| { | |
232 | ( | |
233 | r.expr_span, | |
234 | format!("{}{}", snippet_opt(cx, r.self_span).unwrap(), r.replacement), | |
235 | ) | |
236 | })) | |
237 | .collect(), | |
238 | Applicability::Unspecified, | |
239 | ); | |
240 | }); | |
f20569fa XL |
241 | } |
242 | } | |
243 | ||
244 | fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { | |
cdc7bbd5 XL |
245 | if let ExprKind::Binary(ref op, l, r) = expr.kind { |
246 | if (op.node == BinOpKind::Eq || op.node == BinOpKind::Ne) && (is_null_path(cx, l) || is_null_path(cx, r)) { | |
f20569fa XL |
247 | span_lint( |
248 | cx, | |
249 | CMP_NULL, | |
250 | expr.span, | |
251 | "comparing with null is better expressed by the `.is_null()` method", | |
252 | ); | |
253 | } | |
cdc7bbd5 XL |
254 | } else { |
255 | check_invalid_ptr_usage(cx, expr); | |
256 | } | |
257 | } | |
258 | } | |
259 | ||
260 | fn check_invalid_ptr_usage<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { | |
261 | // (fn_path, arg_indices) - `arg_indices` are the `arg` positions where null would cause U.B. | |
262 | const INVALID_NULL_PTR_USAGE_TABLE: [(&[&str], &[usize]); 16] = [ | |
263 | (&paths::SLICE_FROM_RAW_PARTS, &[0]), | |
264 | (&paths::SLICE_FROM_RAW_PARTS_MUT, &[0]), | |
265 | (&paths::PTR_COPY, &[0, 1]), | |
266 | (&paths::PTR_COPY_NONOVERLAPPING, &[0, 1]), | |
267 | (&paths::PTR_READ, &[0]), | |
268 | (&paths::PTR_READ_UNALIGNED, &[0]), | |
269 | (&paths::PTR_READ_VOLATILE, &[0]), | |
270 | (&paths::PTR_REPLACE, &[0]), | |
271 | (&paths::PTR_SLICE_FROM_RAW_PARTS, &[0]), | |
272 | (&paths::PTR_SLICE_FROM_RAW_PARTS_MUT, &[0]), | |
273 | (&paths::PTR_SWAP, &[0, 1]), | |
274 | (&paths::PTR_SWAP_NONOVERLAPPING, &[0, 1]), | |
275 | (&paths::PTR_WRITE, &[0]), | |
276 | (&paths::PTR_WRITE_UNALIGNED, &[0]), | |
277 | (&paths::PTR_WRITE_VOLATILE, &[0]), | |
278 | (&paths::PTR_WRITE_BYTES, &[0]), | |
279 | ]; | |
280 | ||
281 | if_chain! { | |
17df50a5 | 282 | if let ExprKind::Call(fun, args) = expr.kind; |
cdc7bbd5 XL |
283 | if let ExprKind::Path(ref qpath) = fun.kind; |
284 | if let Some(fun_def_id) = cx.qpath_res(qpath, fun.hir_id).opt_def_id(); | |
285 | let fun_def_path = cx.get_def_path(fun_def_id).into_iter().map(Symbol::to_ident_string).collect::<Vec<_>>(); | |
286 | if let Some(&(_, arg_indices)) = INVALID_NULL_PTR_USAGE_TABLE | |
287 | .iter() | |
288 | .find(|&&(fn_path, _)| fn_path == fun_def_path); | |
289 | then { | |
290 | for &arg_idx in arg_indices { | |
291 | if let Some(arg) = args.get(arg_idx).filter(|arg| is_null_path(cx, arg)) { | |
292 | span_lint_and_sugg( | |
293 | cx, | |
294 | INVALID_NULL_PTR_USAGE, | |
295 | arg.span, | |
296 | "pointer must be non-null", | |
297 | "change this to", | |
298 | "core::ptr::NonNull::dangling().as_ptr()".to_string(), | |
299 | Applicability::MachineApplicable, | |
300 | ); | |
301 | } | |
302 | } | |
f20569fa XL |
303 | } |
304 | } | |
305 | } | |
306 | ||
5099ac24 FG |
307 | #[derive(Default)] |
308 | struct PtrArgResult { | |
309 | skip: bool, | |
310 | replacements: Vec<PtrArgReplacement>, | |
311 | } | |
f20569fa | 312 | |
5099ac24 FG |
313 | struct PtrArgReplacement { |
314 | expr_span: Span, | |
315 | self_span: Span, | |
316 | replacement: &'static str, | |
317 | } | |
3c0e092e | 318 | |
5099ac24 FG |
319 | struct PtrArg<'tcx> { |
320 | idx: usize, | |
064997fb | 321 | emission_id: hir::HirId, |
5099ac24 FG |
322 | span: Span, |
323 | ty_did: DefId, | |
324 | ty_name: Symbol, | |
325 | method_renames: &'static [(&'static str, &'static str)], | |
326 | ref_prefix: RefPrefix, | |
327 | deref_ty: DerefTy<'tcx>, | |
5099ac24 FG |
328 | } |
329 | impl PtrArg<'_> { | |
330 | fn build_msg(&self) -> String { | |
331 | format!( | |
332 | "writing `&{}{}` instead of `&{}{}` involves a new object where a slice will do", | |
333 | self.ref_prefix.mutability.prefix_str(), | |
334 | self.ty_name, | |
335 | self.ref_prefix.mutability.prefix_str(), | |
336 | self.deref_ty.argless_str(), | |
337 | ) | |
338 | } | |
339 | ||
340 | fn mutability(&self) -> Mutability { | |
341 | self.ref_prefix.mutability | |
342 | } | |
343 | } | |
344 | ||
345 | struct RefPrefix { | |
487cf647 | 346 | lt: Lifetime, |
5099ac24 FG |
347 | mutability: Mutability, |
348 | } | |
349 | impl fmt::Display for RefPrefix { | |
350 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { | |
351 | use fmt::Write; | |
352 | f.write_char('&')?; | |
487cf647 FG |
353 | if !self.lt.is_anonymous() { |
354 | self.lt.ident.fmt(f)?; | |
355 | f.write_char(' ')?; | |
5099ac24 FG |
356 | } |
357 | f.write_str(self.mutability.prefix_str()) | |
358 | } | |
359 | } | |
360 | ||
361 | struct DerefTyDisplay<'a, 'tcx>(&'a LateContext<'tcx>, &'a DerefTy<'tcx>); | |
362 | impl fmt::Display for DerefTyDisplay<'_, '_> { | |
363 | fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { | |
364 | use std::fmt::Write; | |
365 | match self.1 { | |
366 | DerefTy::Str => f.write_str("str"), | |
367 | DerefTy::Path => f.write_str("Path"), | |
368 | DerefTy::Slice(hir_ty, ty) => { | |
369 | f.write_char('[')?; | |
370 | match hir_ty.and_then(|s| snippet_opt(self.0, s)) { | |
371 | Some(s) => f.write_str(&s)?, | |
372 | None => ty.fmt(f)?, | |
f20569fa | 373 | } |
5099ac24 | 374 | f.write_char(']') |
3c0e092e | 375 | }, |
5099ac24 FG |
376 | } |
377 | } | |
378 | } | |
379 | ||
380 | enum DerefTy<'tcx> { | |
381 | Str, | |
382 | Path, | |
383 | Slice(Option<Span>, Ty<'tcx>), | |
384 | } | |
385 | impl<'tcx> DerefTy<'tcx> { | |
2b03887a FG |
386 | fn ty(&self, cx: &LateContext<'tcx>) -> Ty<'tcx> { |
387 | match *self { | |
388 | Self::Str => cx.tcx.types.str_, | |
389 | Self::Path => cx.tcx.mk_adt( | |
390 | cx.tcx.adt_def(cx.tcx.get_diagnostic_item(sym::Path).unwrap()), | |
391 | List::empty(), | |
392 | ), | |
393 | Self::Slice(_, ty) => cx.tcx.mk_slice(ty), | |
394 | } | |
395 | } | |
396 | ||
5099ac24 FG |
397 | fn argless_str(&self) -> &'static str { |
398 | match *self { | |
399 | Self::Str => "str", | |
400 | Self::Path => "Path", | |
401 | Self::Slice(..) => "[_]", | |
402 | } | |
403 | } | |
404 | ||
405 | fn display<'a>(&'a self, cx: &'a LateContext<'tcx>) -> DerefTyDisplay<'a, 'tcx> { | |
406 | DerefTyDisplay(cx, self) | |
407 | } | |
408 | } | |
409 | ||
410 | fn check_fn_args<'cx, 'tcx: 'cx>( | |
411 | cx: &'cx LateContext<'tcx>, | |
923072b8 FG |
412 | tys: &'tcx [Ty<'tcx>], |
413 | hir_tys: &'tcx [hir::Ty<'tcx>], | |
414 | params: &'tcx [Param<'tcx>], | |
5099ac24 FG |
415 | ) -> impl Iterator<Item = PtrArg<'tcx>> + 'cx { |
416 | tys.iter() | |
417 | .zip(hir_tys.iter()) | |
418 | .enumerate() | |
419 | .filter_map(|(i, (ty, hir_ty))| { | |
420 | if_chain! { | |
421 | if let ty::Ref(_, ty, mutability) = *ty.kind(); | |
422 | if let ty::Adt(adt, substs) = *ty.kind(); | |
423 | ||
9c376795 | 424 | if let TyKind::Ref(lt, ref ty) = hir_ty.kind; |
5099ac24 FG |
425 | if let TyKind::Path(QPath::Resolved(None, path)) = ty.ty.kind; |
426 | ||
427 | // Check that the name as typed matches the actual name of the type. | |
428 | // e.g. `fn foo(_: &Foo)` shouldn't trigger the lint when `Foo` is an alias for `Vec` | |
429 | if let [.., name] = path.segments; | |
5e7ed085 | 430 | if cx.tcx.item_name(adt.did()) == name.ident.name; |
5099ac24 | 431 | |
5099ac24 | 432 | then { |
064997fb | 433 | let emission_id = params.get(i).map_or(hir_ty.hir_id, |param| param.hir_id); |
5e7ed085 | 434 | let (method_renames, deref_ty) = match cx.tcx.get_diagnostic_name(adt.did()) { |
5099ac24 FG |
435 | Some(sym::Vec) => ( |
436 | [("clone", ".to_owned()")].as_slice(), | |
437 | DerefTy::Slice( | |
438 | name.args | |
439 | .and_then(|args| args.args.first()) | |
440 | .and_then(|arg| if let GenericArg::Type(ty) = arg { | |
441 | Some(ty.span) | |
442 | } else { | |
443 | None | |
444 | }), | |
445 | substs.type_at(0), | |
446 | ), | |
5099ac24 | 447 | ), |
487cf647 | 448 | _ if Some(adt.did()) == cx.tcx.lang_items().string() => ( |
5099ac24 FG |
449 | [("clone", ".to_owned()"), ("as_str", "")].as_slice(), |
450 | DerefTy::Str, | |
5099ac24 FG |
451 | ), |
452 | Some(sym::PathBuf) => ( | |
453 | [("clone", ".to_path_buf()"), ("as_path", "")].as_slice(), | |
454 | DerefTy::Path, | |
5099ac24 | 455 | ), |
5e7ed085 | 456 | Some(sym::Cow) if mutability == Mutability::Not => { |
5099ac24 FG |
457 | let ty_name = name.args |
458 | .and_then(|args| { | |
459 | args.args.iter().find_map(|a| match a { | |
460 | GenericArg::Type(x) => Some(x), | |
461 | _ => None, | |
462 | }) | |
463 | }) | |
464 | .and_then(|arg| snippet_opt(cx, arg.span)) | |
465 | .unwrap_or_else(|| substs.type_at(1).to_string()); | |
064997fb | 466 | span_lint_hir_and_then( |
5099ac24 FG |
467 | cx, |
468 | PTR_ARG, | |
064997fb | 469 | emission_id, |
5099ac24 FG |
470 | hir_ty.span, |
471 | "using a reference to `Cow` is not recommended", | |
064997fb FG |
472 | |diag| { |
473 | diag.span_suggestion( | |
474 | hir_ty.span, | |
475 | "change this to", | |
2b03887a | 476 | format!("&{}{ty_name}", mutability.prefix_str()), |
064997fb FG |
477 | Applicability::Unspecified, |
478 | ); | |
479 | } | |
f20569fa | 480 | ); |
5099ac24 | 481 | return None; |
f20569fa | 482 | }, |
5099ac24 FG |
483 | _ => return None, |
484 | }; | |
485 | return Some(PtrArg { | |
486 | idx: i, | |
064997fb | 487 | emission_id, |
5099ac24 | 488 | span: hir_ty.span, |
5e7ed085 | 489 | ty_did: adt.did(), |
5099ac24 FG |
490 | ty_name: name.ident.name, |
491 | method_renames, | |
492 | ref_prefix: RefPrefix { | |
487cf647 | 493 | lt: *lt, |
5099ac24 FG |
494 | mutability, |
495 | }, | |
496 | deref_ty, | |
f20569fa | 497 | }); |
f20569fa | 498 | } |
5099ac24 FG |
499 | } |
500 | None | |
501 | }) | |
502 | } | |
f20569fa | 503 | |
04454e1e FG |
504 | fn check_mut_from_ref<'tcx>(cx: &LateContext<'tcx>, sig: &FnSig<'_>, body: Option<&'tcx Body<'_>>) { |
505 | if let FnRetTy::Return(ty) = sig.decl.output | |
9c376795 | 506 | && let Some((out, Mutability::Mut, _)) = get_ref_lm(ty) |
04454e1e | 507 | { |
9ffffee4 | 508 | let out_region = cx.tcx.named_bound_var(out.hir_id); |
04454e1e FG |
509 | let args: Option<Vec<_>> = sig |
510 | .decl | |
511 | .inputs | |
512 | .iter() | |
9c376795 | 513 | .filter_map(get_ref_lm) |
9ffffee4 | 514 | .filter(|&(lt, _, _)| cx.tcx.named_bound_var(lt.hir_id) == out_region) |
064997fb | 515 | .map(|(_, mutability, span)| (mutability == Mutability::Not).then_some(span)) |
04454e1e FG |
516 | .collect(); |
517 | if let Some(args) = args | |
518 | && !args.is_empty() | |
519 | && body.map_or(true, |body| { | |
f2b60f7d | 520 | sig.header.unsafety == Unsafety::Unsafe || contains_unsafe_block(cx, body.value) |
04454e1e FG |
521 | }) |
522 | { | |
f20569fa XL |
523 | span_lint_and_then( |
524 | cx, | |
525 | MUT_FROM_REF, | |
526 | ty.span, | |
527 | "mutable borrow from immutable input(s)", | |
528 | |diag| { | |
04454e1e | 529 | let ms = MultiSpan::from_spans(args); |
f20569fa XL |
530 | diag.span_note(ms, "immutable borrow here"); |
531 | }, | |
532 | ); | |
533 | } | |
534 | } | |
535 | } | |
536 | ||
923072b8 | 537 | #[expect(clippy::too_many_lines)] |
5099ac24 FG |
538 | fn check_ptr_arg_usage<'tcx>(cx: &LateContext<'tcx>, body: &'tcx Body<'_>, args: &[PtrArg<'tcx>]) -> Vec<PtrArgResult> { |
539 | struct V<'cx, 'tcx> { | |
540 | cx: &'cx LateContext<'tcx>, | |
541 | /// Map from a local id to which argument it came from (index into `Self::args` and | |
542 | /// `Self::results`) | |
543 | bindings: HirIdMap<usize>, | |
544 | /// The arguments being checked. | |
545 | args: &'cx [PtrArg<'tcx>], | |
546 | /// The results for each argument (len should match args.len) | |
547 | results: Vec<PtrArgResult>, | |
548 | /// The number of arguments which can't be linted. Used to return early. | |
549 | skip_count: usize, | |
550 | } | |
551 | impl<'tcx> Visitor<'tcx> for V<'_, 'tcx> { | |
552 | type NestedFilter = nested_filter::OnlyBodies; | |
553 | fn nested_visit_map(&mut self) -> Self::Map { | |
554 | self.cx.tcx.hir() | |
555 | } | |
556 | ||
557 | fn visit_anon_const(&mut self, _: &'tcx AnonConst) {} | |
558 | ||
559 | fn visit_expr(&mut self, e: &'tcx Expr<'_>) { | |
560 | if self.skip_count == self.args.len() { | |
561 | return; | |
562 | } | |
563 | ||
564 | // Check if this is local we care about | |
2b03887a FG |
565 | let Some(&args_idx) = path_to_local(e).and_then(|id| self.bindings.get(&id)) else { |
566 | return walk_expr(self, e); | |
5099ac24 FG |
567 | }; |
568 | let args = &self.args[args_idx]; | |
569 | let result = &mut self.results[args_idx]; | |
570 | ||
571 | // Helper function to handle early returns. | |
572 | let mut set_skip_flag = || { | |
5e7ed085 | 573 | if !result.skip { |
5099ac24 FG |
574 | self.skip_count += 1; |
575 | } | |
576 | result.skip = true; | |
577 | }; | |
578 | ||
579 | match get_expr_use_or_unification_node(self.cx.tcx, e) { | |
580 | Some((Node::Stmt(_), _)) => (), | |
581 | Some((Node::Local(l), _)) => { | |
582 | // Only trace simple bindings. e.g `let x = y;` | |
f2b60f7d | 583 | if let PatKind::Binding(BindingAnnotation::NONE, id, _, None) = l.pat.kind { |
5099ac24 FG |
584 | self.bindings.insert(id, args_idx); |
585 | } else { | |
586 | set_skip_flag(); | |
587 | } | |
588 | }, | |
589 | Some((Node::Expr(e), child_id)) => match e.kind { | |
590 | ExprKind::Call(f, expr_args) => { | |
591 | let i = expr_args.iter().position(|arg| arg.hir_id == child_id).unwrap_or(0); | |
064997fb FG |
592 | if expr_sig(self.cx, f).and_then(|sig| sig.input(i)).map_or(true, |ty| { |
593 | match *ty.skip_binder().peel_refs().kind() { | |
2b03887a | 594 | ty::Dynamic(preds, _, _) => !matches_preds(self.cx, args.deref_ty.ty(self.cx), preds), |
5099ac24 | 595 | ty::Param(_) => true, |
5e7ed085 | 596 | ty::Adt(def, _) => def.did() == args.ty_did, |
5099ac24 | 597 | _ => false, |
064997fb FG |
598 | } |
599 | }) { | |
5099ac24 FG |
600 | // Passed to a function taking the non-dereferenced type. |
601 | set_skip_flag(); | |
602 | } | |
603 | }, | |
f2b60f7d FG |
604 | ExprKind::MethodCall(name, self_arg, expr_args, _) => { |
605 | let i = std::iter::once(self_arg) | |
606 | .chain(expr_args.iter()) | |
607 | .position(|arg| arg.hir_id == child_id) | |
608 | .unwrap_or(0); | |
5099ac24 FG |
609 | if i == 0 { |
610 | // Check if the method can be renamed. | |
611 | let name = name.ident.as_str(); | |
612 | if let Some((_, replacement)) = args.method_renames.iter().find(|&&(x, _)| x == name) { | |
613 | result.replacements.push(PtrArgReplacement { | |
614 | expr_span: e.span, | |
615 | self_span: self_arg.span, | |
616 | replacement, | |
617 | }); | |
618 | return; | |
619 | } | |
620 | } | |
621 | ||
2b03887a | 622 | let Some(id) = self.cx.typeck_results().type_dependent_def_id(e.hir_id) else { |
5099ac24 FG |
623 | set_skip_flag(); |
624 | return; | |
625 | }; | |
626 | ||
9ffffee4 FG |
627 | match *self.cx.tcx.fn_sig(id).subst_identity().skip_binder().inputs()[i] |
628 | .peel_refs() | |
629 | .kind() | |
630 | { | |
2b03887a FG |
631 | ty::Dynamic(preds, _, _) if !matches_preds(self.cx, args.deref_ty.ty(self.cx), preds) => { |
632 | set_skip_flag(); | |
633 | }, | |
5099ac24 FG |
634 | ty::Param(_) => { |
635 | set_skip_flag(); | |
636 | }, | |
637 | // If the types match check for methods which exist on both types. e.g. `Vec::len` and | |
638 | // `slice::len` | |
04454e1e | 639 | ty::Adt(def, _) if def.did() == args.ty_did => { |
5099ac24 FG |
640 | set_skip_flag(); |
641 | }, | |
642 | _ => (), | |
643 | } | |
644 | }, | |
645 | // Indexing is fine for currently supported types. | |
646 | ExprKind::Index(e, _) if e.hir_id == child_id => (), | |
647 | _ => set_skip_flag(), | |
648 | }, | |
649 | _ => set_skip_flag(), | |
650 | } | |
f20569fa XL |
651 | } |
652 | } | |
5099ac24 FG |
653 | |
654 | let mut skip_count = 0; | |
655 | let mut results = args.iter().map(|_| PtrArgResult::default()).collect::<Vec<_>>(); | |
656 | let mut v = V { | |
657 | cx, | |
658 | bindings: args | |
659 | .iter() | |
660 | .enumerate() | |
661 | .filter_map(|(i, arg)| { | |
662 | let param = &body.params[arg.idx]; | |
663 | match param.pat.kind { | |
f2b60f7d | 664 | PatKind::Binding(BindingAnnotation::NONE, id, _, None) |
5099ac24 FG |
665 | if !is_lint_allowed(cx, PTR_ARG, param.hir_id) => |
666 | { | |
667 | Some((id, i)) | |
668 | }, | |
669 | _ => { | |
670 | skip_count += 1; | |
671 | results[i].skip = true; | |
672 | None | |
673 | }, | |
674 | } | |
675 | }) | |
676 | .collect(), | |
677 | args, | |
678 | results, | |
679 | skip_count, | |
680 | }; | |
f2b60f7d | 681 | v.visit_expr(body.value); |
5099ac24 | 682 | v.results |
f20569fa XL |
683 | } |
684 | ||
2b03887a FG |
685 | fn matches_preds<'tcx>( |
686 | cx: &LateContext<'tcx>, | |
687 | ty: Ty<'tcx>, | |
487cf647 | 688 | preds: &'tcx [ty::PolyExistentialPredicate<'tcx>], |
2b03887a FG |
689 | ) -> bool { |
690 | let infcx = cx.tcx.infer_ctxt().build(); | |
691 | preds.iter().all(|&p| match cx.tcx.erase_late_bound_regions(p) { | |
692 | ExistentialPredicate::Trait(p) => infcx | |
487cf647 | 693 | .type_implements_trait(p.def_id, [ty.into()].into_iter().chain(p.substs.iter()), cx.param_env) |
2b03887a FG |
694 | .must_apply_modulo_regions(), |
695 | ExistentialPredicate::Projection(p) => infcx.predicate_must_hold_modulo_regions(&Obligation::new( | |
487cf647 | 696 | cx.tcx, |
2b03887a FG |
697 | ObligationCause::dummy(), |
698 | cx.param_env, | |
487cf647 FG |
699 | cx.tcx |
700 | .mk_predicate(Binder::dummy(PredicateKind::Clause(Clause::Projection( | |
701 | p.with_self_ty(cx.tcx, ty), | |
702 | )))), | |
2b03887a FG |
703 | )), |
704 | ExistentialPredicate::AutoTrait(p) => infcx | |
487cf647 | 705 | .type_implements_trait(p, [ty], cx.param_env) |
2b03887a FG |
706 | .must_apply_modulo_regions(), |
707 | }) | |
708 | } | |
709 | ||
9c376795 FG |
710 | fn get_ref_lm<'tcx>(ty: &'tcx hir::Ty<'tcx>) -> Option<(&'tcx Lifetime, Mutability, Span)> { |
711 | if let TyKind::Ref(lt, ref m) = ty.kind { | |
f20569fa XL |
712 | Some((lt, m.mutbl, ty.span)) |
713 | } else { | |
714 | None | |
715 | } | |
716 | } | |
717 | ||
cdc7bbd5 XL |
718 | fn is_null_path(cx: &LateContext<'_>, expr: &Expr<'_>) -> bool { |
719 | if let ExprKind::Call(pathexp, []) = expr.kind { | |
5099ac24 FG |
720 | path_def_id(cx, pathexp).map_or(false, |id| { |
721 | matches!(cx.tcx.get_diagnostic_name(id), Some(sym::ptr_null | sym::ptr_null_mut)) | |
cdc7bbd5 XL |
722 | }) |
723 | } else { | |
724 | false | |
f20569fa | 725 | } |
f20569fa | 726 | } |