1 #![allow(clippy::default_hash_types)]
4 use std::cmp::Ordering;
5 use std::collections::BTreeMap;
7 use if_chain::if_chain;
9 use rustc::hir::intravisit::{walk_body, walk_expr, walk_ty, FnKind, NestedVisitorMap, Visitor};
11 use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
12 use rustc::ty::layout::LayoutOf;
13 use rustc::ty::{self, Ty, TyCtxt, TypeckTables};
14 use rustc::{declare_tool_lint, lint_array};
15 use rustc_errors::Applicability;
16 use rustc_target::spec::abi::Abi;
17 use rustc_typeck::hir_ty_to_ty;
18 use syntax::ast::{FloatTy, IntTy, UintTy};
19 use syntax::errors::DiagnosticBuilder;
20 use syntax::source_map::Span;
22 use crate::consts::{constant, Constant};
23 use crate::utils::paths;
25 clip, comparisons, differing_macro_contexts, higher, in_constant, in_macro, int_bits, last_path_segment,
26 match_def_path, match_path, multispan_sugg, same_tys, sext, snippet, snippet_opt, snippet_with_applicability,
27 span_help_and_lint, span_lint, span_lint_and_sugg, span_lint_and_then, unsext, AbsolutePathBuffer,
30 /// Handles all the linting of funky types
33 declare_clippy_lint! {
34 /// **What it does:** Checks for use of `Box<Vec<_>>` anywhere in the code.
36 /// **Why is this bad?** `Vec` already keeps its contents in a separate area on
37 /// the heap. So if you `Box` it, you just add another level of indirection
38 /// without any benefit whatsoever.
40 /// **Known problems:** None.
45 /// values: Box<Vec<Foo>>,
58 "usage of `Box<Vec<T>>`, vector elements are already on the heap"
61 declare_clippy_lint! {
62 /// **What it does:** Checks for use of `Vec<Box<T>>` where T: Sized anywhere in the code.
64 /// **Why is this bad?** `Vec` already keeps its contents in a separate area on
65 /// the heap. So if you `Box` its contents, you just add another level of indirection.
67 /// **Known problems:** Vec<Box<T: Sized>> makes sense if T is a large type (see #3530,
73 /// values: Vec<Box<i32>>,
86 "usage of `Vec<Box<T>>` where T: Sized, vector elements are already on the heap"
89 declare_clippy_lint! {
90 /// **What it does:** Checks for use of `Option<Option<_>>` in function signatures and type
93 /// **Why is this bad?** `Option<_>` represents an optional value. `Option<Option<_>>`
94 /// represents an optional optional value which is logically the same thing as an optional
95 /// value but has an unneeded extra level of wrapping.
97 /// **Known problems:** None.
101 /// fn x() -> Option<Option<u32>> {
107 "usage of `Option<Option<T>>`"
110 declare_clippy_lint! {
111 /// **What it does:** Checks for usage of any `LinkedList`, suggesting to use a
112 /// `Vec` or a `VecDeque` (formerly called `RingBuf`).
114 /// **Why is this bad?** Gankro says:
116 /// > The TL;DR of `LinkedList` is that it's built on a massive amount of
117 /// pointers and indirection.
118 /// > It wastes memory, it has terrible cache locality, and is all-around slow.
120 /// > "only" amortized for push/pop, should be faster in the general case for
121 /// almost every possible
122 /// > workload, and isn't even amortized at all if you can predict the capacity
125 /// > `LinkedList`s are only really good if you're doing a lot of merging or
126 /// splitting of lists.
127 /// > This is because they can just mangle some pointers instead of actually
128 /// copying the data. Even
129 /// > if you're doing a lot of insertion in the middle of the list, `RingBuf`
130 /// can still be better
131 /// > because of how expensive it is to seek to the middle of a `LinkedList`.
133 /// **Known problems:** False positives – the instances where using a
134 /// `LinkedList` makes sense are few and far between, but they can still happen.
138 /// let x = LinkedList::new();
142 "usage of LinkedList, usually a vector is faster, or a more specialized data structure like a VecDeque"
145 declare_clippy_lint! {
146 /// **What it does:** Checks for use of `&Box<T>` anywhere in the code.
148 /// **Why is this bad?** Any `&Box<T>` can also be a `&T`, which is more
151 /// **Known problems:** None.
155 /// fn foo(bar: &Box<T>) { ... }
161 /// fn foo(bar: &T) { ... }
165 "a borrow of a boxed type"
168 impl LintPass for TypePass {
169 fn get_lints(&self) -> LintArray {
170 lint_array!(BOX_VEC, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX)
173 fn name(&self) -> &'static str {
178 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypePass {
179 fn check_fn(&mut self, cx: &LateContext<'_, '_>, _: FnKind<'_>, decl: &FnDecl, _: &Body, _: Span, id: HirId) {
180 // Skip trait implementations; see issue #605.
181 if let Some(hir::Node::Item(item)) = cx.tcx.hir().find_by_hir_id(cx.tcx.hir().get_parent_item(id)) {
182 if let ItemKind::Impl(_, _, _, _, Some(..), _, _) = item.node {
187 check_fn_decl(cx, decl);
190 fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, field: &hir::StructField) {
191 check_ty(cx, &field.ty, false);
194 fn check_trait_item(&mut self, cx: &LateContext<'_, '_>, item: &TraitItem) {
196 TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => check_ty(cx, ty, false),
197 TraitItemKind::Method(ref sig, _) => check_fn_decl(cx, &sig.decl),
202 fn check_local(&mut self, cx: &LateContext<'_, '_>, local: &Local) {
203 if let Some(ref ty) = local.ty {
204 check_ty(cx, ty, true);
209 fn check_fn_decl(cx: &LateContext<'_, '_>, decl: &FnDecl) {
210 for input in &decl.inputs {
211 check_ty(cx, input, false);
214 if let FunctionRetTy::Return(ref ty) = decl.output {
215 check_ty(cx, ty, false);
219 /// Checks if `qpath` has last segment with type parameter matching `path`
220 fn match_type_parameter(cx: &LateContext<'_, '_>, qpath: &QPath, path: &[&str]) -> bool {
221 let last = last_path_segment(qpath);
223 if let Some(ref params) = last.args;
224 if !params.parenthesized;
225 if let Some(ty) = params.args.iter().find_map(|arg| match arg {
226 GenericArg::Type(ty) => Some(ty),
229 if let TyKind::Path(ref qpath) = ty.node;
230 if let Some(did) = cx.tables.qpath_def(qpath, ty.hir_id).opt_def_id();
231 if match_def_path(cx.tcx, did, path);
239 /// Recursively check for `TypePass` lints in the given type. Stop at the first
242 /// The parameter `is_local` distinguishes the context of the type; types from
243 /// local bindings should only be checked for the `BORROWED_BOX` lint.
244 #[allow(clippy::too_many_lines)]
245 fn check_ty(cx: &LateContext<'_, '_>, hir_ty: &hir::Ty, is_local: bool) {
246 if in_macro(hir_ty.span) {
250 TyKind::Path(ref qpath) if !is_local => {
251 let hir_id = hir_ty.hir_id;
252 let def = cx.tables.qpath_def(qpath, hir_id);
253 if let Some(def_id) = def.opt_def_id() {
254 if Some(def_id) == cx.tcx.lang_items().owned_box() {
255 if match_type_parameter(cx, qpath, &paths::VEC) {
260 "you seem to be trying to use `Box<Vec<T>>`. Consider using just `Vec<T>`",
261 "`Vec<T>` is already on the heap, `Box<Vec<T>>` makes an extra allocation.",
263 return; // don't recurse into the type
265 } else if match_def_path(cx.tcx, def_id, &paths::VEC) {
267 // Get the _ part of Vec<_>
268 if let Some(ref last) = last_path_segment(qpath).args;
269 if let Some(ty) = last.args.iter().find_map(|arg| match arg {
270 GenericArg::Type(ty) => Some(ty),
273 // ty is now _ at this point
274 if let TyKind::Path(ref ty_qpath) = ty.node;
275 let def = cx.tables.qpath_def(ty_qpath, ty.hir_id);
276 if let Some(def_id) = def.opt_def_id();
277 if Some(def_id) == cx.tcx.lang_items().owned_box();
278 // At this point, we know ty is Box<T>, now get T
279 if let Some(ref last) = last_path_segment(ty_qpath).args;
280 if let Some(boxed_ty) = last.args.iter().find_map(|arg| match arg {
281 GenericArg::Type(ty) => Some(ty),
285 let ty_ty = hir_ty_to_ty(cx.tcx, boxed_ty);
286 if ty_ty.is_sized(cx.tcx.at(ty.span), cx.param_env) {
291 "`Vec<T>` is already on the heap, the boxing is unnecessary.",
293 format!("Vec<{}>", ty_ty),
294 Applicability::MachineApplicable,
296 return; // don't recurse into the type
300 } else if match_def_path(cx.tcx, def_id, &paths::OPTION) {
301 if match_type_parameter(cx, qpath, &paths::OPTION) {
306 "consider using `Option<T>` instead of `Option<Option<T>>` or a custom \
307 enum if you need to distinguish all 3 cases",
309 return; // don't recurse into the type
311 } else if match_def_path(cx.tcx, def_id, &paths::LINKED_LIST) {
316 "I see you're using a LinkedList! Perhaps you meant some other data structure?",
317 "a VecDeque might work",
319 return; // don't recurse into the type
323 QPath::Resolved(Some(ref ty), ref p) => {
324 check_ty(cx, ty, is_local);
325 for ty in p.segments.iter().flat_map(|seg| {
328 .map_or_else(|| [].iter(), |params| params.args.iter())
329 .filter_map(|arg| match arg {
330 GenericArg::Type(ty) => Some(ty),
334 check_ty(cx, ty, is_local);
337 QPath::Resolved(None, ref p) => {
338 for ty in p.segments.iter().flat_map(|seg| {
341 .map_or_else(|| [].iter(), |params| params.args.iter())
342 .filter_map(|arg| match arg {
343 GenericArg::Type(ty) => Some(ty),
347 check_ty(cx, ty, is_local);
350 QPath::TypeRelative(ref ty, ref seg) => {
351 check_ty(cx, ty, is_local);
352 if let Some(ref params) = seg.args {
353 for ty in params.args.iter().filter_map(|arg| match arg {
354 GenericArg::Type(ty) => Some(ty),
357 check_ty(cx, ty, is_local);
363 TyKind::Rptr(ref lt, ref mut_ty) => check_ty_rptr(cx, hir_ty, is_local, lt, mut_ty),
365 TyKind::Slice(ref ty) | TyKind::Array(ref ty, _) | TyKind::Ptr(MutTy { ref ty, .. }) => {
366 check_ty(cx, ty, is_local)
368 TyKind::Tup(ref tys) => {
370 check_ty(cx, ty, is_local);
377 fn check_ty_rptr(cx: &LateContext<'_, '_>, hir_ty: &hir::Ty, is_local: bool, lt: &Lifetime, mut_ty: &MutTy) {
378 match mut_ty.ty.node {
379 TyKind::Path(ref qpath) => {
380 let hir_id = mut_ty.ty.hir_id;
381 let def = cx.tables.qpath_def(qpath, hir_id);
383 if let Some(def_id) = def.opt_def_id();
384 if Some(def_id) == cx.tcx.lang_items().owned_box();
385 if let QPath::Resolved(None, ref path) = *qpath;
386 if let [ref bx] = *path.segments;
387 if let Some(ref params) = bx.args;
388 if !params.parenthesized;
389 if let Some(inner) = params.args.iter().find_map(|arg| match arg {
390 GenericArg::Type(ty) => Some(ty),
394 if is_any_trait(inner) {
395 // Ignore `Box<Any>` types; see issue #1884 for details.
399 let ltopt = if lt.is_elided() {
402 format!("{} ", lt.name.ident().as_str())
404 let mutopt = if mut_ty.mutbl == Mutability::MutMutable {
409 let mut applicability = Applicability::MachineApplicable;
414 "you seem to be trying to use `&Box<T>`. Consider using just `&T`",
420 &snippet_with_applicability(cx, inner.span, "..", &mut applicability)
422 Applicability::Unspecified,
424 return; // don't recurse into the type
427 check_ty(cx, &mut_ty.ty, is_local);
429 _ => check_ty(cx, &mut_ty.ty, is_local),
433 // Returns true if given type is `Any` trait.
434 fn is_any_trait(t: &hir::Ty) -> bool {
436 if let TyKind::TraitObject(ref traits, _) = t.node;
437 if traits.len() >= 1;
438 // Only Send/Sync can be used as additional traits, so it is enough to
439 // check only the first trait.
440 if match_path(&traits[0].trait_ref.path, &paths::ANY_TRAIT);
451 declare_clippy_lint! {
452 /// **What it does:** Checks for binding a unit value.
454 /// **Why is this bad?** A unit value cannot usefully be used anywhere. So
455 /// binding one is kind of pointless.
457 /// **Known problems:** None.
467 "creating a let binding to a value of unit type, which usually can't be used afterwards"
470 impl LintPass for LetPass {
471 fn get_lints(&self) -> LintArray {
472 lint_array!(LET_UNIT_VALUE)
475 fn name(&self) -> &'static str {
480 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LetPass {
481 fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx Stmt) {
482 if let StmtKind::Local(ref local) = stmt.node {
483 if is_unit(cx.tables.pat_ty(&local.pat)) {
484 if in_external_macro(cx.sess(), stmt.span) || in_macro(local.pat.span) {
487 if higher::is_from_for_desugar(local) {
495 "this let-binding has unit value. Consider omitting `let {} =`",
496 snippet(cx, local.pat.span, "..")
504 declare_clippy_lint! {
505 /// **What it does:** Checks for comparisons to unit.
507 /// **Why is this bad?** Unit is always equal to itself, and thus is just a
508 /// clumsily written constant. Mostly this happens when someone accidentally
509 /// adds semicolons at the end of the operands.
511 /// **Known problems:** None.
533 "comparing unit values"
538 impl LintPass for UnitCmp {
539 fn get_lints(&self) -> LintArray {
540 lint_array!(UNIT_CMP)
543 fn name(&self) -> &'static str {
548 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnitCmp {
549 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
550 if in_macro(expr.span) {
553 if let ExprKind::Binary(ref cmp, ref left, _) = expr.node {
555 if op.is_comparison() && is_unit(cx.tables.expr_ty(left)) {
556 let result = match op {
557 BinOpKind::Eq | BinOpKind::Le | BinOpKind::Ge => "true",
565 "{}-comparison of unit values detected. This will always be {}",
575 declare_clippy_lint! {
576 /// **What it does:** Checks for passing a unit value as an argument to a function without using a
577 /// unit literal (`()`).
579 /// **Why is this bad?** This is likely the result of an accidental semicolon.
581 /// **Known problems:** None.
592 "passing unit to a function"
597 impl LintPass for UnitArg {
598 fn get_lints(&self) -> LintArray {
599 lint_array!(UNIT_ARG)
602 fn name(&self) -> &'static str {
607 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnitArg {
608 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
609 if in_macro(expr.span) {
613 // apparently stuff in the desugaring of `?` can trigger this
614 // so check for that here
615 // only the calls to `Try::from_error` is marked as desugared,
616 // so we need to check both the current Expr and its parent.
617 if is_questionmark_desugar_marked_call(expr) {
621 let map = &cx.tcx.hir();
622 let opt_parent_node = map.find_by_hir_id(map.get_parent_node_by_hir_id(expr.hir_id));
623 if let Some(hir::Node::Expr(parent_expr)) = opt_parent_node;
624 if is_questionmark_desugar_marked_call(parent_expr);
631 ExprKind::Call(_, ref args) | ExprKind::MethodCall(_, _, ref args) => {
633 if is_unit(cx.tables.expr_ty(arg)) && !is_unit_literal(arg) {
634 if let ExprKind::Match(.., match_source) = &arg.node {
635 if *match_source == MatchSource::TryDesugar {
644 "passing a unit value to a function",
645 "if you intended to pass a unit value, use a unit literal instead",
647 Applicability::MachineApplicable,
657 fn is_questionmark_desugar_marked_call(expr: &Expr) -> bool {
658 use syntax_pos::hygiene::CompilerDesugaringKind;
659 if let ExprKind::Call(ref callee, _) = expr.node {
660 callee.span.is_compiler_desugaring(CompilerDesugaringKind::QuestionMark)
666 fn is_unit(ty: Ty<'_>) -> bool {
668 ty::Tuple(slice) if slice.is_empty() => true,
673 fn is_unit_literal(expr: &Expr) -> bool {
675 ExprKind::Tup(ref slice) if slice.is_empty() => true,
682 declare_clippy_lint! {
683 /// **What it does:** Checks for casts from any numerical to a float type where
684 /// the receiving type cannot store all values from the original type without
685 /// rounding errors. This possible rounding is to be expected, so this lint is
686 /// `Allow` by default.
688 /// Basically, this warns on casting any integer with 32 or more bits to `f32`
689 /// or any 64-bit integer to `f64`.
691 /// **Why is this bad?** It's not bad at all. But in some applications it can be
692 /// helpful to know where precision loss can take place. This lint can help find
693 /// those places in the code.
695 /// **Known problems:** None.
699 /// let x = u64::MAX;
702 pub CAST_PRECISION_LOSS,
704 "casts that cause loss of precision, e.g., `x as f32` where `x: u64`"
707 declare_clippy_lint! {
708 /// **What it does:** Checks for casts from a signed to an unsigned numerical
709 /// type. In this case, negative values wrap around to large positive values,
710 /// which can be quite surprising in practice. However, as the cast works as
711 /// defined, this lint is `Allow` by default.
713 /// **Why is this bad?** Possibly surprising results. You can activate this lint
714 /// as a one-time check to see where numerical wrapping can arise.
716 /// **Known problems:** None.
721 /// y as u128 // will return 18446744073709551615
725 "casts from signed types to unsigned types, e.g., `x as u32` where `x: i32`"
728 declare_clippy_lint! {
729 /// **What it does:** Checks for on casts between numerical types that may
730 /// truncate large values. This is expected behavior, so the cast is `Allow` by
733 /// **Why is this bad?** In some problem domains, it is good practice to avoid
734 /// truncation. This lint can be activated to help assess where additional
735 /// checks could be beneficial.
737 /// **Known problems:** None.
741 /// fn as_u8(x: u64) -> u8 {
745 pub CAST_POSSIBLE_TRUNCATION,
747 "casts that may cause truncation of the value, e.g., `x as u8` where `x: u32`, or `x as i32` where `x: f32`"
750 declare_clippy_lint! {
751 /// **What it does:** Checks for casts from an unsigned type to a signed type of
752 /// the same size. Performing such a cast is a 'no-op' for the compiler,
753 /// i.e., nothing is changed at the bit level, and the binary representation of
754 /// the value is reinterpreted. This can cause wrapping if the value is too big
755 /// for the target signed type. However, the cast works as defined, so this lint
756 /// is `Allow` by default.
758 /// **Why is this bad?** While such a cast is not bad in itself, the results can
759 /// be surprising when this is not the intended behavior, as demonstrated by the
762 /// **Known problems:** None.
766 /// u32::MAX as i32 // will yield a value of `-1`
768 pub CAST_POSSIBLE_WRAP,
770 "casts that may cause wrapping around the value, e.g., `x as i32` where `x: u32` and `x > i32::MAX`"
773 declare_clippy_lint! {
774 /// **What it does:** Checks for on casts between numerical types that may
775 /// be replaced by safe conversion functions.
777 /// **Why is this bad?** Rust's `as` keyword will perform many kinds of
778 /// conversions, including silently lossy conversions. Conversion functions such
779 /// as `i32::from` will only perform lossless conversions. Using the conversion
780 /// functions prevents conversions from turning into silent lossy conversions if
781 /// the types of the input expressions ever change, and make it easier for
782 /// people reading the code to know that the conversion is lossless.
784 /// **Known problems:** None.
788 /// fn as_u64(x: u8) -> u64 {
793 /// Using `::from` would look like this:
796 /// fn as_u64(x: u8) -> u64 {
802 "casts using `as` that are known to be lossless, e.g., `x as u64` where `x: u8`"
805 declare_clippy_lint! {
806 /// **What it does:** Checks for casts to the same type.
808 /// **Why is this bad?** It's just unnecessary.
810 /// **Known problems:** None.
814 /// let _ = 2i32 as i32
816 pub UNNECESSARY_CAST,
818 "cast to the same type, e.g., `x as i32` where `x: i32`"
821 declare_clippy_lint! {
822 /// **What it does:** Checks for casts from a less-strictly-aligned pointer to a
823 /// more-strictly-aligned pointer
825 /// **Why is this bad?** Dereferencing the resulting pointer may be undefined
828 /// **Known problems:** None.
832 /// let _ = (&1u8 as *const u8) as *const u16;
833 /// let _ = (&mut 1u8 as *mut u8) as *mut u16;
835 pub CAST_PTR_ALIGNMENT,
837 "cast from a pointer to a more-strictly-aligned pointer"
840 declare_clippy_lint! {
841 /// **What it does:** Checks for casts of function pointers to something other than usize
843 /// **Why is this bad?**
844 /// Casting a function pointer to anything other than usize/isize is not portable across
845 /// architectures, because you end up losing bits if the target type is too small or end up with a
846 /// bunch of extra bits that waste space and add more instructions to the final binary than
847 /// strictly necessary for the problem
849 /// Casting to isize also doesn't make sense since there are no signed addresses.
855 /// fn fun() -> i32 {}
856 /// let a = fun as i64;
859 /// fn fun2() -> i32 {}
860 /// let a = fun2 as usize;
862 pub FN_TO_NUMERIC_CAST,
864 "casting a function pointer to a numeric type other than usize"
867 declare_clippy_lint! {
868 /// **What it does:** Checks for casts of a function pointer to a numeric type not wide enough to
871 /// **Why is this bad?**
872 /// Such a cast discards some bits of the function's address. If this is intended, it would be more
873 /// clearly expressed by casting to usize first, then casting the usize to the intended type (with
874 /// a comment) to perform the truncation.
880 /// fn fn1() -> i16 {
883 /// let _ = fn1 as i32;
885 /// // Better: Cast to usize first, then comment with the reason for the truncation
886 /// fn fn2() -> i16 {
889 /// let fn_ptr = fn2 as usize;
890 /// let fn_ptr_truncated = fn_ptr as i32;
892 pub FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
894 "casting a function pointer to a numeric type not wide enough to store the address"
897 /// Returns the size in bits of an integral type.
898 /// Will return 0 if the type is not an int or uint variant
899 fn int_ty_to_nbits(typ: Ty<'_>, tcx: TyCtxt<'_, '_, '_>) -> u64 {
901 ty::Int(i) => match i {
902 IntTy::Isize => tcx.data_layout.pointer_size.bits(),
909 ty::Uint(i) => match i {
910 UintTy::Usize => tcx.data_layout.pointer_size.bits(),
921 fn is_isize_or_usize(typ: Ty<'_>) -> bool {
923 ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => true,
928 fn span_precision_loss_lint(cx: &LateContext<'_, '_>, expr: &Expr, cast_from: Ty<'_>, cast_to_f64: bool) {
929 let mantissa_nbits = if cast_to_f64 { 52 } else { 23 };
930 let arch_dependent = is_isize_or_usize(cast_from) && cast_to_f64;
931 let arch_dependent_str = "on targets with 64-bit wide pointers ";
932 let from_nbits_str = if arch_dependent {
934 } else if is_isize_or_usize(cast_from) {
935 "32 or 64".to_owned()
937 int_ty_to_nbits(cast_from, cx.tcx).to_string()
944 "casting {0} to {1} causes a loss of precision {2}({0} is {3} bits wide, but {1}'s mantissa \
945 is only {4} bits wide)",
947 if cast_to_f64 { "f64" } else { "f32" },
948 if arch_dependent { arch_dependent_str } else { "" },
955 fn should_strip_parens(op: &Expr, snip: &str) -> bool {
956 if let ExprKind::Binary(_, _, _) = op.node {
957 if snip.starts_with('(') && snip.ends_with(')') {
964 fn span_lossless_lint(cx: &LateContext<'_, '_>, expr: &Expr, op: &Expr, cast_from: Ty<'_>, cast_to: Ty<'_>) {
965 // Do not suggest using From in consts/statics until it is valid to do so (see #2267).
966 if in_constant(cx, expr.hir_id) {
969 // The suggestion is to use a function call, so if the original expression
970 // has parens on the outside, they are no longer needed.
971 let mut applicability = Applicability::MachineApplicable;
972 let opt = snippet_opt(cx, op.span);
973 let sugg = if let Some(ref snip) = opt {
974 if should_strip_parens(op, snip) {
975 &snip[1..snip.len() - 1]
980 applicability = Applicability::HasPlaceholders;
989 "casting {} to {} may become silently lossy if types change",
993 format!("{}::from({})", cast_to, sugg),
1004 fn check_loss_of_sign(cx: &LateContext<'_, '_>, expr: &Expr, op: &Expr, cast_from: Ty<'_>, cast_to: Ty<'_>) {
1005 if !cast_from.is_signed() || cast_to.is_signed() {
1009 // don't lint for positive constants
1010 let const_val = constant(cx, &cx.tables, op);
1012 if let Some((const_val, _)) = const_val;
1013 if let Constant::Int(n) = const_val;
1014 if let ty::Int(ity) = cast_from.sty;
1015 if sext(cx.tcx, n, ity) >= 0;
1025 &format!("casting {} to {} may lose the sign of the value", cast_from, cast_to),
1029 fn check_truncation_and_wrapping(cx: &LateContext<'_, '_>, expr: &Expr, cast_from: Ty<'_>, cast_to: Ty<'_>) {
1030 let arch_64_suffix = " on targets with 64-bit wide pointers";
1031 let arch_32_suffix = " on targets with 32-bit wide pointers";
1032 let cast_unsigned_to_signed = !cast_from.is_signed() && cast_to.is_signed();
1033 let from_nbits = int_ty_to_nbits(cast_from, cx.tcx);
1034 let to_nbits = int_ty_to_nbits(cast_to, cx.tcx);
1035 let (span_truncation, suffix_truncation, span_wrap, suffix_wrap) =
1036 match (is_isize_or_usize(cast_from), is_isize_or_usize(cast_to)) {
1037 (true, true) | (false, false) => (
1038 to_nbits < from_nbits,
1040 to_nbits == from_nbits && cast_unsigned_to_signed,
1050 to_nbits <= 32 && cast_unsigned_to_signed,
1056 cast_unsigned_to_signed,
1057 if from_nbits == 64 {
1064 if span_truncation {
1067 CAST_POSSIBLE_TRUNCATION,
1070 "casting {} to {} may truncate the value{}",
1073 match suffix_truncation {
1074 ArchSuffix::_32 => arch_32_suffix,
1075 ArchSuffix::_64 => arch_64_suffix,
1076 ArchSuffix::None => "",
1087 "casting {} to {} may wrap around the value{}",
1091 ArchSuffix::_32 => arch_32_suffix,
1092 ArchSuffix::_64 => arch_64_suffix,
1093 ArchSuffix::None => "",
1100 fn check_lossless(cx: &LateContext<'_, '_>, expr: &Expr, op: &Expr, cast_from: Ty<'_>, cast_to: Ty<'_>) {
1101 let cast_signed_to_unsigned = cast_from.is_signed() && !cast_to.is_signed();
1102 let from_nbits = int_ty_to_nbits(cast_from, cx.tcx);
1103 let to_nbits = int_ty_to_nbits(cast_to, cx.tcx);
1104 if !is_isize_or_usize(cast_from) && !is_isize_or_usize(cast_to) && from_nbits < to_nbits && !cast_signed_to_unsigned
1106 span_lossless_lint(cx, expr, op, cast_from, cast_to);
1110 impl LintPass for CastPass {
1111 fn get_lints(&self) -> LintArray {
1113 CAST_PRECISION_LOSS,
1115 CAST_POSSIBLE_TRUNCATION,
1121 FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
1125 fn name(&self) -> &'static str {
1130 // Check if the given type is either `core::ffi::c_void` or
1131 // one of the platform specific `libc::<platform>::c_void` of libc.
1132 fn is_c_void(tcx: TyCtxt<'_, '_, '_>, ty: Ty<'_>) -> bool {
1133 if let ty::Adt(adt, _) = ty.sty {
1134 let mut apb = AbsolutePathBuffer { names: vec![] };
1135 tcx.push_item_path(&mut apb, adt.did, false);
1137 if apb.names.is_empty() {
1140 if apb.names[0] == "libc" || apb.names[0] == "core" && *apb.names.last().unwrap() == "c_void" {
1147 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CastPass {
1148 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
1149 if let ExprKind::Cast(ref ex, _) = expr.node {
1150 let (cast_from, cast_to) = (cx.tables.expr_ty(ex), cx.tables.expr_ty(expr));
1151 lint_fn_to_numeric_cast(cx, expr, ex, cast_from, cast_to);
1152 if let ExprKind::Lit(ref lit) = ex.node {
1153 use syntax::ast::{LitIntType, LitKind};
1155 LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::FloatUnsuffixed(_) => {},
1157 if cast_from.sty == cast_to.sty && !in_external_macro(cx.sess(), expr.span) {
1163 "casting to the same type is unnecessary (`{}` -> `{}`)",
1171 if cast_from.is_numeric() && cast_to.is_numeric() && !in_external_macro(cx.sess(), expr.span) {
1172 match (cast_from.is_integral(), cast_to.is_integral()) {
1174 let from_nbits = int_ty_to_nbits(cast_from, cx.tcx);
1175 let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.sty {
1180 if is_isize_or_usize(cast_from) || from_nbits >= to_nbits {
1181 span_precision_loss_lint(cx, expr, cast_from, to_nbits == 64);
1183 if from_nbits < to_nbits {
1184 span_lossless_lint(cx, expr, ex, cast_from, cast_to);
1190 CAST_POSSIBLE_TRUNCATION,
1192 &format!("casting {} to {} may truncate the value", cast_from, cast_to),
1194 if !cast_to.is_signed() {
1199 &format!("casting {} to {} may lose the sign of the value", cast_from, cast_to),
1204 check_loss_of_sign(cx, expr, ex, cast_from, cast_to);
1205 check_truncation_and_wrapping(cx, expr, cast_from, cast_to);
1206 check_lossless(cx, expr, ex, cast_from, cast_to);
1209 if let (&ty::Float(FloatTy::F64), &ty::Float(FloatTy::F32)) = (&cast_from.sty, &cast_to.sty) {
1212 CAST_POSSIBLE_TRUNCATION,
1214 "casting f64 to f32 may truncate the value",
1217 if let (&ty::Float(FloatTy::F32), &ty::Float(FloatTy::F64)) = (&cast_from.sty, &cast_to.sty) {
1218 span_lossless_lint(cx, expr, ex, cast_from, cast_to);
1225 if let ty::RawPtr(from_ptr_ty) = &cast_from.sty;
1226 if let ty::RawPtr(to_ptr_ty) = &cast_to.sty;
1227 if let Some(from_align) = cx.layout_of(from_ptr_ty.ty).ok().map(|a| a.align.abi);
1228 if let Some(to_align) = cx.layout_of(to_ptr_ty.ty).ok().map(|a| a.align.abi);
1229 if from_align < to_align;
1230 // with c_void, we inherently need to trust the user
1231 if !is_c_void(cx.tcx, from_ptr_ty.ty);
1237 &format!("casting from `{}` to a more-strictly-aligned pointer (`{}`)", cast_from, cast_to)
1245 fn lint_fn_to_numeric_cast(
1246 cx: &LateContext<'_, '_>,
1252 // We only want to check casts to `ty::Uint` or `ty::Int`
1254 ty::Uint(_) | ty::Int(..) => { /* continue on */ },
1257 match cast_from.sty {
1258 ty::FnDef(..) | ty::FnPtr(_) => {
1259 let mut applicability = Applicability::MachineApplicable;
1260 let from_snippet = snippet_with_applicability(cx, cast_expr.span, "x", &mut applicability);
1262 let to_nbits = int_ty_to_nbits(cast_to, cx.tcx);
1263 if to_nbits < cx.tcx.data_layout.pointer_size.bits() {
1266 FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
1269 "casting function pointer `{}` to `{}`, which truncates the value",
1270 from_snippet, cast_to
1273 format!("{} as usize", from_snippet),
1276 } else if cast_to.sty != ty::Uint(UintTy::Usize) {
1281 &format!("casting function pointer `{}` to `{}`", from_snippet, cast_to),
1283 format!("{} as usize", from_snippet),
1292 declare_clippy_lint! {
1293 /// **What it does:** Checks for types used in structs, parameters and `let`
1294 /// declarations above a certain complexity threshold.
1296 /// **Why is this bad?** Too complex types make the code less readable. Consider
1297 /// using a `type` definition to simplify them.
1299 /// **Known problems:** None.
1304 /// inner: Rc<Vec<Vec<Box<(u32, u32, u32, u32)>>>>,
1307 pub TYPE_COMPLEXITY,
1309 "usage of very complex types that might be better factored into `type` definitions"
1312 pub struct TypeComplexityPass {
1316 impl TypeComplexityPass {
1317 pub fn new(threshold: u64) -> Self {
1322 impl LintPass for TypeComplexityPass {
1323 fn get_lints(&self) -> LintArray {
1324 lint_array!(TYPE_COMPLEXITY)
1327 fn name(&self) -> &'static str {
1328 "TypeComplexityPass"
1332 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeComplexityPass {
1335 cx: &LateContext<'a, 'tcx>,
1342 self.check_fndecl(cx, decl);
1345 fn check_struct_field(&mut self, cx: &LateContext<'a, 'tcx>, field: &'tcx hir::StructField) {
1346 // enum variants are also struct fields now
1347 self.check_type(cx, &field.ty);
1350 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
1352 ItemKind::Static(ref ty, _, _) | ItemKind::Const(ref ty, _) => self.check_type(cx, ty),
1353 // functions, enums, structs, impls and traits are covered
1358 fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx TraitItem) {
1360 TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => self.check_type(cx, ty),
1361 TraitItemKind::Method(MethodSig { ref decl, .. }, TraitMethod::Required(_)) => self.check_fndecl(cx, decl),
1362 // methods with default impl are covered by check_fn
1367 fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx ImplItem) {
1369 ImplItemKind::Const(ref ty, _) | ImplItemKind::Type(ref ty) => self.check_type(cx, ty),
1370 // methods are covered by check_fn
1375 fn check_local(&mut self, cx: &LateContext<'a, 'tcx>, local: &'tcx Local) {
1376 if let Some(ref ty) = local.ty {
1377 self.check_type(cx, ty);
1382 impl<'a, 'tcx> TypeComplexityPass {
1383 fn check_fndecl(&self, cx: &LateContext<'a, 'tcx>, decl: &'tcx FnDecl) {
1384 for arg in &decl.inputs {
1385 self.check_type(cx, arg);
1387 if let Return(ref ty) = decl.output {
1388 self.check_type(cx, ty);
1392 fn check_type(&self, cx: &LateContext<'_, '_>, ty: &hir::Ty) {
1393 if in_macro(ty.span) {
1397 let mut visitor = TypeComplexityVisitor { score: 0, nest: 1 };
1398 visitor.visit_ty(ty);
1402 if score > self.threshold {
1407 "very complex type used. Consider factoring parts into `type` definitions",
1413 /// Walks a type and assigns a complexity score to it.
1414 struct TypeComplexityVisitor {
1415 /// total complexity score of the type
1417 /// current nesting level
1421 impl<'tcx> Visitor<'tcx> for TypeComplexityVisitor {
1422 fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
1423 let (add_score, sub_nest) = match ty.node {
1424 // _, &x and *x have only small overhead; don't mess with nesting level
1425 TyKind::Infer | TyKind::Ptr(..) | TyKind::Rptr(..) => (1, 0),
1427 // the "normal" components of a type: named types, arrays/tuples
1428 TyKind::Path(..) | TyKind::Slice(..) | TyKind::Tup(..) | TyKind::Array(..) => (10 * self.nest, 1),
1430 // function types bring a lot of overhead
1431 TyKind::BareFn(ref bare) if bare.abi == Abi::Rust => (50 * self.nest, 1),
1433 TyKind::TraitObject(ref param_bounds, _) => {
1434 let has_lifetime_parameters = param_bounds.iter().any(|bound| {
1435 bound.bound_generic_params.iter().any(|gen| match gen.kind {
1436 GenericParamKind::Lifetime { .. } => true,
1440 if has_lifetime_parameters {
1441 // complex trait bounds like A<'a, 'b>
1444 // simple trait bounds like A + B
1451 self.score += add_score;
1452 self.nest += sub_nest;
1454 self.nest -= sub_nest;
1456 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
1457 NestedVisitorMap::None
1461 declare_clippy_lint! {
1462 /// **What it does:** Checks for expressions where a character literal is cast
1463 /// to `u8` and suggests using a byte literal instead.
1465 /// **Why is this bad?** In general, casting values to smaller types is
1466 /// error-prone and should be avoided where possible. In the particular case of
1467 /// converting a character literal to u8, it is easy to avoid by just using a
1468 /// byte literal instead. As an added bonus, `b'a'` is even slightly shorter
1469 /// than `'a' as u8`.
1471 /// **Known problems:** None.
1478 /// A better version, using the byte literal:
1485 "casting a character literal to u8"
1488 pub struct CharLitAsU8;
1490 impl LintPass for CharLitAsU8 {
1491 fn get_lints(&self) -> LintArray {
1492 lint_array!(CHAR_LIT_AS_U8)
1495 fn name(&self) -> &'static str {
1500 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CharLitAsU8 {
1501 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
1502 use syntax::ast::{LitKind, UintTy};
1504 if let ExprKind::Cast(ref e, _) = expr.node {
1505 if let ExprKind::Lit(ref l) = e.node {
1506 if let LitKind::Char(_) = l.node {
1507 if ty::Uint(UintTy::U8) == cx.tables.expr_ty(expr).sty && !in_macro(expr.span) {
1508 let msg = "casting character literal to u8. `char`s \
1509 are 4 bytes wide in rust, so casting to u8 \
1512 "Consider using a byte literal instead:\nb{}",
1513 snippet(cx, e.span, "'x'")
1515 span_help_and_lint(cx, CHAR_LIT_AS_U8, expr.span, msg, &help);
1523 declare_clippy_lint! {
1524 /// **What it does:** Checks for comparisons where one side of the relation is
1525 /// either the minimum or maximum value for its type and warns if it involves a
1526 /// case that is always true or always false. Only integer and boolean types are
1529 /// **Why is this bad?** An expression like `min <= x` may misleadingly imply
1530 /// that is is possible for `x` to be less than the minimum. Expressions like
1531 /// `max < x` are probably mistakes.
1533 /// **Known problems:** For `usize` the size of the current compile target will
1534 /// be assumed (e.g., 64 bits on 64 bit systems). This means code that uses such
1535 /// a comparison to detect target pointer width will trigger this lint. One can
1536 /// use `mem::sizeof` and compare its value or conditional compilation
1538 /// like `#[cfg(target_pointer_width = "64")] ..` instead.
1543 /// 100 > std::i32::MAX
1545 pub ABSURD_EXTREME_COMPARISONS,
1547 "a comparison with a maximum or minimum value that is always true or false"
1550 pub struct AbsurdExtremeComparisons;
1552 impl LintPass for AbsurdExtremeComparisons {
1553 fn get_lints(&self) -> LintArray {
1554 lint_array!(ABSURD_EXTREME_COMPARISONS)
1557 fn name(&self) -> &'static str {
1558 "AbsurdExtremeComparisons"
1567 struct ExtremeExpr<'a> {
1572 enum AbsurdComparisonResult {
1575 InequalityImpossible,
1578 fn is_cast_between_fixed_and_target<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> bool {
1579 if let ExprKind::Cast(ref cast_exp, _) = expr.node {
1580 let precast_ty = cx.tables.expr_ty(cast_exp);
1581 let cast_ty = cx.tables.expr_ty(expr);
1583 return is_isize_or_usize(precast_ty) != is_isize_or_usize(cast_ty);
1589 fn detect_absurd_comparison<'a, 'tcx>(
1590 cx: &LateContext<'a, 'tcx>,
1594 ) -> Option<(ExtremeExpr<'tcx>, AbsurdComparisonResult)> {
1595 use crate::types::AbsurdComparisonResult::*;
1596 use crate::types::ExtremeType::*;
1597 use crate::utils::comparisons::*;
1599 // absurd comparison only makes sense on primitive types
1600 // primitive types don't implement comparison operators with each other
1601 if cx.tables.expr_ty(lhs) != cx.tables.expr_ty(rhs) {
1605 // comparisons between fix sized types and target sized types are considered unanalyzable
1606 if is_cast_between_fixed_and_target(cx, lhs) || is_cast_between_fixed_and_target(cx, rhs) {
1610 let normalized = normalize_comparison(op, lhs, rhs);
1611 let (rel, normalized_lhs, normalized_rhs) = if let Some(val) = normalized {
1617 let lx = detect_extreme_expr(cx, normalized_lhs);
1618 let rx = detect_extreme_expr(cx, normalized_rhs);
1623 (Some(l @ ExtremeExpr { which: Maximum, .. }), _) => (l, AlwaysFalse), // max < x
1624 (_, Some(r @ ExtremeExpr { which: Minimum, .. })) => (r, AlwaysFalse), // x < min
1630 (Some(l @ ExtremeExpr { which: Minimum, .. }), _) => (l, AlwaysTrue), // min <= x
1631 (Some(l @ ExtremeExpr { which: Maximum, .. }), _) => (l, InequalityImpossible), // max <= x
1632 (_, Some(r @ ExtremeExpr { which: Minimum, .. })) => (r, InequalityImpossible), // x <= min
1633 (_, Some(r @ ExtremeExpr { which: Maximum, .. })) => (r, AlwaysTrue), // x <= max
1637 Rel::Ne | Rel::Eq => return None,
1641 fn detect_extreme_expr<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<ExtremeExpr<'tcx>> {
1642 use crate::types::ExtremeType::*;
1644 let ty = cx.tables.expr_ty(expr);
1646 let cv = constant(cx, cx.tables, expr)?.0;
1648 let which = match (&ty.sty, cv) {
1649 (&ty::Bool, Constant::Bool(false)) | (&ty::Uint(_), Constant::Int(0)) => Minimum,
1650 (&ty::Int(ity), Constant::Int(i))
1651 if i == unsext(cx.tcx, i128::min_value() >> (128 - int_bits(cx.tcx, ity)), ity) =>
1656 (&ty::Bool, Constant::Bool(true)) => Maximum,
1657 (&ty::Int(ity), Constant::Int(i))
1658 if i == unsext(cx.tcx, i128::max_value() >> (128 - int_bits(cx.tcx, ity)), ity) =>
1662 (&ty::Uint(uty), Constant::Int(i)) if clip(cx.tcx, u128::max_value(), uty) == i => Maximum,
1666 Some(ExtremeExpr { which, expr })
1669 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AbsurdExtremeComparisons {
1670 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
1671 use crate::types::AbsurdComparisonResult::*;
1672 use crate::types::ExtremeType::*;
1674 if let ExprKind::Binary(ref cmp, ref lhs, ref rhs) = expr.node {
1675 if let Some((culprit, result)) = detect_absurd_comparison(cx, cmp.node, lhs, rhs) {
1676 if !in_macro(expr.span) {
1677 let msg = "this comparison involving the minimum or maximum element for this \
1678 type contains a case that is always true or always false";
1680 let conclusion = match result {
1681 AlwaysFalse => "this comparison is always false".to_owned(),
1682 AlwaysTrue => "this comparison is always true".to_owned(),
1683 InequalityImpossible => format!(
1684 "the case where the two sides are not equal never occurs, consider using {} == {} \
1686 snippet(cx, lhs.span, "lhs"),
1687 snippet(cx, rhs.span, "rhs")
1692 "because {} is the {} value for this type, {}",
1693 snippet(cx, culprit.expr.span, "x"),
1694 match culprit.which {
1695 Minimum => "minimum",
1696 Maximum => "maximum",
1701 span_help_and_lint(cx, ABSURD_EXTREME_COMPARISONS, expr.span, msg, &help);
1708 declare_clippy_lint! {
1709 /// **What it does:** Checks for comparisons where the relation is always either
1710 /// true or false, but where one side has been upcast so that the comparison is
1711 /// necessary. Only integer types are checked.
1713 /// **Why is this bad?** An expression like `let x : u8 = ...; (x as u32) > 300`
1714 /// will mistakenly imply that it is possible for `x` to be outside the range of
1717 /// **Known problems:**
1718 /// https://github.com/rust-lang/rust-clippy/issues/886
1722 /// let x : u8 = ...; (x as u32) > 300
1724 pub INVALID_UPCAST_COMPARISONS,
1726 "a comparison involving an upcast which is always true or false"
1729 pub struct InvalidUpcastComparisons;
1731 impl LintPass for InvalidUpcastComparisons {
1732 fn get_lints(&self) -> LintArray {
1733 lint_array!(INVALID_UPCAST_COMPARISONS)
1736 fn name(&self) -> &'static str {
1737 "InvalidUpcastComparisons"
1741 #[derive(Copy, Clone, Debug, Eq)]
1748 #[allow(clippy::cast_sign_loss)]
1749 fn cmp_s_u(s: i128, u: u128) -> Ordering {
1752 } else if u > (i128::max_value() as u128) {
1760 impl PartialEq for FullInt {
1761 fn eq(&self, other: &Self) -> bool {
1762 self.partial_cmp(other).expect("partial_cmp only returns Some(_)") == Ordering::Equal
1766 impl PartialOrd for FullInt {
1767 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
1768 Some(match (self, other) {
1769 (&FullInt::S(s), &FullInt::S(o)) => s.cmp(&o),
1770 (&FullInt::U(s), &FullInt::U(o)) => s.cmp(&o),
1771 (&FullInt::S(s), &FullInt::U(o)) => Self::cmp_s_u(s, o),
1772 (&FullInt::U(s), &FullInt::S(o)) => Self::cmp_s_u(o, s).reverse(),
1776 impl Ord for FullInt {
1777 fn cmp(&self, other: &Self) -> Ordering {
1778 self.partial_cmp(other)
1779 .expect("partial_cmp for FullInt can never return None")
1783 fn numeric_cast_precast_bounds<'a>(cx: &LateContext<'_, '_>, expr: &'a Expr) -> Option<(FullInt, FullInt)> {
1785 use syntax::ast::{IntTy, UintTy};
1787 if let ExprKind::Cast(ref cast_exp, _) = expr.node {
1788 let pre_cast_ty = cx.tables.expr_ty(cast_exp);
1789 let cast_ty = cx.tables.expr_ty(expr);
1790 // if it's a cast from i32 to u32 wrapping will invalidate all these checks
1791 if cx.layout_of(pre_cast_ty).ok().map(|l| l.size) == cx.layout_of(cast_ty).ok().map(|l| l.size) {
1794 match pre_cast_ty.sty {
1795 ty::Int(int_ty) => Some(match int_ty {
1797 FullInt::S(i128::from(i8::min_value())),
1798 FullInt::S(i128::from(i8::max_value())),
1801 FullInt::S(i128::from(i16::min_value())),
1802 FullInt::S(i128::from(i16::max_value())),
1805 FullInt::S(i128::from(i32::min_value())),
1806 FullInt::S(i128::from(i32::max_value())),
1809 FullInt::S(i128::from(i64::min_value())),
1810 FullInt::S(i128::from(i64::max_value())),
1812 IntTy::I128 => (FullInt::S(i128::min_value()), FullInt::S(i128::max_value())),
1814 FullInt::S(isize::min_value() as i128),
1815 FullInt::S(isize::max_value() as i128),
1818 ty::Uint(uint_ty) => Some(match uint_ty {
1820 FullInt::U(u128::from(u8::min_value())),
1821 FullInt::U(u128::from(u8::max_value())),
1824 FullInt::U(u128::from(u16::min_value())),
1825 FullInt::U(u128::from(u16::max_value())),
1828 FullInt::U(u128::from(u32::min_value())),
1829 FullInt::U(u128::from(u32::max_value())),
1832 FullInt::U(u128::from(u64::min_value())),
1833 FullInt::U(u128::from(u64::max_value())),
1835 UintTy::U128 => (FullInt::U(u128::min_value()), FullInt::U(u128::max_value())),
1837 FullInt::U(usize::min_value() as u128),
1838 FullInt::U(usize::max_value() as u128),
1848 fn node_as_const_fullint<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<FullInt> {
1849 let val = constant(cx, cx.tables, expr)?.0;
1850 if let Constant::Int(const_int) = val {
1851 match cx.tables.expr_ty(expr).sty {
1852 ty::Int(ity) => Some(FullInt::S(sext(cx.tcx, const_int, ity))),
1853 ty::Uint(_) => Some(FullInt::U(const_int)),
1861 fn err_upcast_comparison(cx: &LateContext<'_, '_>, span: Span, expr: &Expr, always: bool) {
1862 if let ExprKind::Cast(ref cast_val, _) = expr.node {
1865 INVALID_UPCAST_COMPARISONS,
1868 "because of the numeric bounds on `{}` prior to casting, this expression is always {}",
1869 snippet(cx, cast_val.span, "the expression"),
1870 if always { "true" } else { "false" },
1876 fn upcast_comparison_bounds_err<'a, 'tcx>(
1877 cx: &LateContext<'a, 'tcx>,
1879 rel: comparisons::Rel,
1880 lhs_bounds: Option<(FullInt, FullInt)>,
1885 use crate::utils::comparisons::*;
1887 if let Some((lb, ub)) = lhs_bounds {
1888 if let Some(norm_rhs_val) = node_as_const_fullint(cx, rhs) {
1889 if rel == Rel::Eq || rel == Rel::Ne {
1890 if norm_rhs_val < lb || norm_rhs_val > ub {
1891 err_upcast_comparison(cx, span, lhs, rel == Rel::Ne);
1893 } else if match rel {
1908 Rel::Eq | Rel::Ne => unreachable!(),
1910 err_upcast_comparison(cx, span, lhs, true)
1911 } else if match rel {
1926 Rel::Eq | Rel::Ne => unreachable!(),
1928 err_upcast_comparison(cx, span, lhs, false)
1934 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidUpcastComparisons {
1935 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
1936 if let ExprKind::Binary(ref cmp, ref lhs, ref rhs) = expr.node {
1937 let normalized = comparisons::normalize_comparison(cmp.node, lhs, rhs);
1938 let (rel, normalized_lhs, normalized_rhs) = if let Some(val) = normalized {
1944 let lhs_bounds = numeric_cast_precast_bounds(cx, normalized_lhs);
1945 let rhs_bounds = numeric_cast_precast_bounds(cx, normalized_rhs);
1947 upcast_comparison_bounds_err(cx, expr.span, rel, lhs_bounds, normalized_lhs, normalized_rhs, false);
1948 upcast_comparison_bounds_err(cx, expr.span, rel, rhs_bounds, normalized_rhs, normalized_lhs, true);
1953 declare_clippy_lint! {
1954 /// **What it does:** Checks for public `impl` or `fn` missing generalization
1955 /// over different hashers and implicitly defaulting to the default hashing
1956 /// algorithm (SipHash).
1958 /// **Why is this bad?** `HashMap` or `HashSet` with custom hashers cannot be
1961 /// **Known problems:** Suggestions for replacing constructors can contain
1962 /// false-positives. Also applying suggestions can require modification of other
1963 /// pieces of code, possibly including external crates.
1967 /// impl<K: Hash + Eq, V> Serialize for HashMap<K, V> { ... }
1969 /// pub foo(map: &mut HashMap<i32, i32>) { .. }
1971 pub IMPLICIT_HASHER,
1973 "missing generalization over different hashers"
1976 pub struct ImplicitHasher;
1978 impl LintPass for ImplicitHasher {
1979 fn get_lints(&self) -> LintArray {
1980 lint_array!(IMPLICIT_HASHER)
1983 fn name(&self) -> &'static str {
1988 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ImplicitHasher {
1989 #[allow(clippy::cast_possible_truncation, clippy::too_many_lines)]
1990 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
1991 use syntax_pos::BytePos;
1993 fn suggestion<'a, 'tcx>(
1994 cx: &LateContext<'a, 'tcx>,
1995 db: &mut DiagnosticBuilder<'_>,
1996 generics_span: Span,
1997 generics_suggestion_span: Span,
1998 target: &ImplicitHasherType<'_>,
1999 vis: ImplicitHasherConstructorVisitor<'_, '_, '_>,
2001 let generics_snip = snippet(cx, generics_span, "");
2003 let generics_snip = if generics_snip.is_empty() {
2006 &generics_snip[1..generics_snip.len() - 1]
2011 "consider adding a type parameter".to_string(),
2014 generics_suggestion_span,
2016 "<{}{}S: ::std::hash::BuildHasher{}>",
2018 if generics_snip.is_empty() { "" } else { ", " },
2019 if vis.suggestions.is_empty() {
2022 // request users to add `Default` bound so that generic constructors can be used
2029 format!("{}<{}, S>", target.type_name(), target.type_arguments(),),
2034 if !vis.suggestions.is_empty() {
2035 multispan_sugg(db, "...and use generic constructor".into(), vis.suggestions);
2039 if !cx.access_levels.is_exported(cx.tcx.hir().hir_to_node_id(item.hir_id)) {
2044 ItemKind::Impl(_, _, _, ref generics, _, ref ty, ref items) => {
2045 let mut vis = ImplicitHasherTypeVisitor::new(cx);
2048 for target in &vis.found {
2049 if differing_macro_contexts(item.span, target.span()) {
2053 let generics_suggestion_span = generics.span.substitute_dummy({
2054 let pos = snippet_opt(cx, item.span.until(target.span()))
2055 .and_then(|snip| Some(item.span.lo() + BytePos(snip.find("impl")? as u32 + 4)));
2056 if let Some(pos) = pos {
2057 Span::new(pos, pos, item.span.data().ctxt)
2063 let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target);
2064 for item in items.iter().map(|item| cx.tcx.hir().impl_item(item.id)) {
2065 ctr_vis.visit_impl_item(item);
2073 "impl for `{}` should be generalized over different hashers",
2077 suggestion(cx, db, generics.span, generics_suggestion_span, target, ctr_vis);
2082 ItemKind::Fn(ref decl, .., ref generics, body_id) => {
2083 let body = cx.tcx.hir().body(body_id);
2085 for ty in &decl.inputs {
2086 let mut vis = ImplicitHasherTypeVisitor::new(cx);
2089 for target in &vis.found {
2090 let generics_suggestion_span = generics.span.substitute_dummy({
2091 let pos = snippet_opt(cx, item.span.until(body.arguments[0].pat.span))
2093 let i = snip.find("fn")?;
2094 Some(item.span.lo() + BytePos((i + (&snip[i..]).find('(')?) as u32))
2096 .expect("failed to create span for type parameters");
2097 Span::new(pos, pos, item.span.data().ctxt)
2100 let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target);
2101 ctr_vis.visit_body(body);
2108 "parameter of type `{}` should be generalized over different hashers",
2112 suggestion(cx, db, generics.span, generics_suggestion_span, target, ctr_vis);
2123 enum ImplicitHasherType<'tcx> {
2124 HashMap(Span, Ty<'tcx>, Cow<'static, str>, Cow<'static, str>),
2125 HashSet(Span, Ty<'tcx>, Cow<'static, str>),
2128 impl<'tcx> ImplicitHasherType<'tcx> {
2129 /// Checks that `ty` is a target type without a BuildHasher.
2130 fn new<'a>(cx: &LateContext<'a, 'tcx>, hir_ty: &hir::Ty) -> Option<Self> {
2131 if let TyKind::Path(QPath::Resolved(None, ref path)) = hir_ty.node {
2132 let params: Vec<_> = path
2140 .filter_map(|arg| match arg {
2141 GenericArg::Type(ty) => Some(ty),
2145 let params_len = params.len();
2147 let ty = hir_ty_to_ty(cx.tcx, hir_ty);
2149 if match_path(path, &paths::HASHMAP) && params_len == 2 {
2150 Some(ImplicitHasherType::HashMap(
2153 snippet(cx, params[0].span, "K"),
2154 snippet(cx, params[1].span, "V"),
2156 } else if match_path(path, &paths::HASHSET) && params_len == 1 {
2157 Some(ImplicitHasherType::HashSet(
2160 snippet(cx, params[0].span, "T"),
2170 fn type_name(&self) -> &'static str {
2172 ImplicitHasherType::HashMap(..) => "HashMap",
2173 ImplicitHasherType::HashSet(..) => "HashSet",
2177 fn type_arguments(&self) -> String {
2179 ImplicitHasherType::HashMap(.., ref k, ref v) => format!("{}, {}", k, v),
2180 ImplicitHasherType::HashSet(.., ref t) => format!("{}", t),
2184 fn ty(&self) -> Ty<'tcx> {
2186 ImplicitHasherType::HashMap(_, ty, ..) | ImplicitHasherType::HashSet(_, ty, ..) => ty,
2190 fn span(&self) -> Span {
2192 ImplicitHasherType::HashMap(span, ..) | ImplicitHasherType::HashSet(span, ..) => span,
2197 struct ImplicitHasherTypeVisitor<'a, 'tcx: 'a> {
2198 cx: &'a LateContext<'a, 'tcx>,
2199 found: Vec<ImplicitHasherType<'tcx>>,
2202 impl<'a, 'tcx: 'a> ImplicitHasherTypeVisitor<'a, 'tcx> {
2203 fn new(cx: &'a LateContext<'a, 'tcx>) -> Self {
2204 Self { cx, found: vec![] }
2208 impl<'a, 'tcx: 'a> Visitor<'tcx> for ImplicitHasherTypeVisitor<'a, 'tcx> {
2209 fn visit_ty(&mut self, t: &'tcx hir::Ty) {
2210 if let Some(target) = ImplicitHasherType::new(self.cx, t) {
2211 self.found.push(target);
2217 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
2218 NestedVisitorMap::None
2222 /// Looks for default-hasher-dependent constructors like `HashMap::new`.
2223 struct ImplicitHasherConstructorVisitor<'a, 'b, 'tcx: 'a + 'b> {
2224 cx: &'a LateContext<'a, 'tcx>,
2225 body: &'a TypeckTables<'tcx>,
2226 target: &'b ImplicitHasherType<'tcx>,
2227 suggestions: BTreeMap<Span, String>,
2230 impl<'a, 'b, 'tcx: 'a + 'b> ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> {
2231 fn new(cx: &'a LateContext<'a, 'tcx>, target: &'b ImplicitHasherType<'tcx>) -> Self {
2236 suggestions: BTreeMap::new(),
2241 impl<'a, 'b, 'tcx: 'a + 'b> Visitor<'tcx> for ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> {
2242 fn visit_body(&mut self, body: &'tcx Body) {
2243 let prev_body = self.body;
2244 self.body = self.cx.tcx.body_tables(body.id());
2245 walk_body(self, body);
2246 self.body = prev_body;
2249 fn visit_expr(&mut self, e: &'tcx Expr) {
2251 if let ExprKind::Call(ref fun, ref args) = e.node;
2252 if let ExprKind::Path(QPath::TypeRelative(ref ty, ref method)) = fun.node;
2253 if let TyKind::Path(QPath::Resolved(None, ref ty_path)) = ty.node;
2255 if !same_tys(self.cx, self.target.ty(), self.body.expr_ty(e)) {
2259 if match_path(ty_path, &paths::HASHMAP) {
2260 if method.ident.name == "new" {
2262 .insert(e.span, "HashMap::default()".to_string());
2263 } else if method.ident.name == "with_capacity" {
2264 self.suggestions.insert(
2267 "HashMap::with_capacity_and_hasher({}, Default::default())",
2268 snippet(self.cx, args[0].span, "capacity"),
2272 } else if match_path(ty_path, &paths::HASHSET) {
2273 if method.ident.name == "new" {
2275 .insert(e.span, "HashSet::default()".to_string());
2276 } else if method.ident.name == "with_capacity" {
2277 self.suggestions.insert(
2280 "HashSet::with_capacity_and_hasher({}, Default::default())",
2281 snippet(self.cx, args[0].span, "capacity"),
2292 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
2293 NestedVisitorMap::OnlyBodies(&self.cx.tcx.hir())
2297 declare_clippy_lint! {
2298 /// **What it does:** Checks for casts of `&T` to `&mut T` anywhere in the code.
2300 /// **Why is this bad?** It’s basically guaranteed to be undefined behaviour.
2301 /// `UnsafeCell` is the only way to obtain aliasable data that is considered
2304 /// **Known problems:** None.
2310 /// *(r as *const _ as *mut _) += 1;
2315 /// Instead consider using interior mutability types.
2318 /// fn x(r: &UnsafeCell<i32>) {
2324 pub CAST_REF_TO_MUT,
2326 "a cast of reference to a mutable pointer"
2329 pub struct RefToMut;
2331 impl LintPass for RefToMut {
2332 fn get_lints(&self) -> LintArray {
2333 lint_array!(CAST_REF_TO_MUT)
2336 fn name(&self) -> &'static str {
2341 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for RefToMut {
2342 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
2344 if let ExprKind::Unary(UnOp::UnDeref, e) = &expr.node;
2345 if let ExprKind::Cast(e, t) = &e.node;
2346 if let TyKind::Ptr(MutTy { mutbl: Mutability::MutMutable, .. }) = t.node;
2347 if let ExprKind::Cast(e, t) = &e.node;
2348 if let TyKind::Ptr(MutTy { mutbl: Mutability::MutImmutable, .. }) = t.node;
2349 if let ty::Ref(..) = cx.tables.node_type(e.hir_id).sty;
2355 "casting &T to &mut T may cause undefined behaviour, consider instead using an UnsafeCell",