1 #![allow(clippy::default_hash_types)]
3 use crate::consts::{constant, Constant};
4 use crate::utils::paths;
6 clip, comparisons, differing_macro_contexts, higher, in_constant, in_macro, int_bits, last_path_segment,
7 match_def_path, match_path, multispan_sugg, same_tys, sext, snippet, snippet_opt, snippet_with_applicability,
8 span_help_and_lint, span_lint, span_lint_and_sugg, span_lint_and_then, unsext, AbsolutePathBuffer,
10 use if_chain::if_chain;
12 use rustc::hir::intravisit::{walk_body, walk_expr, walk_ty, FnKind, NestedVisitorMap, Visitor};
14 use rustc::lint::{in_external_macro, LateContext, LateLintPass, LintArray, LintContext, LintPass};
15 use rustc::ty::layout::LayoutOf;
16 use rustc::ty::{self, Ty, TyCtxt, TypeckTables};
17 use rustc::{declare_tool_lint, lint_array};
18 use rustc_errors::Applicability;
19 use rustc_target::spec::abi::Abi;
20 use rustc_typeck::hir_ty_to_ty;
22 use std::cmp::Ordering;
23 use std::collections::BTreeMap;
24 use syntax::ast::{FloatTy, IntTy, UintTy};
25 use syntax::errors::DiagnosticBuilder;
26 use syntax::source_map::Span;
28 /// Handles all the linting of funky types
31 declare_clippy_lint! {
32 /// **What it does:** Checks for use of `Box<Vec<_>>` anywhere in the code.
34 /// **Why is this bad?** `Vec` already keeps its contents in a separate area on
35 /// the heap. So if you `Box` it, you just add another level of indirection
36 /// without any benefit whatsoever.
38 /// **Known problems:** None.
43 /// values: Box<Vec<Foo>>,
56 "usage of `Box<Vec<T>>`, vector elements are already on the heap"
59 declare_clippy_lint! {
60 /// **What it does:** Checks for use of `Vec<Box<T>>` where T: Sized anywhere in the code.
62 /// **Why is this bad?** `Vec` already keeps its contents in a separate area on
63 /// the heap. So if you `Box` its contents, you just add another level of indirection.
65 /// **Known problems:** Vec<Box<T: Sized>> makes sense if T is a large type (see #3530,
71 /// values: Vec<Box<i32>>,
84 "usage of `Vec<Box<T>>` where T: Sized, vector elements are already on the heap"
87 declare_clippy_lint! {
88 /// **What it does:** Checks for use of `Option<Option<_>>` in function signatures and type
91 /// **Why is this bad?** `Option<_>` represents an optional value. `Option<Option<_>>`
92 /// represents an optional optional value which is logically the same thing as an optional
93 /// value but has an unneeded extra level of wrapping.
95 /// **Known problems:** None.
99 /// fn x() -> Option<Option<u32>> {
104 "usage of `Option<Option<T>>`"
107 declare_clippy_lint! {
108 /// **What it does:** Checks for usage of any `LinkedList`, suggesting to use a
109 /// `Vec` or a `VecDeque` (formerly called `RingBuf`).
111 /// **Why is this bad?** Gankro says:
113 /// > The TL;DR of `LinkedList` is that it's built on a massive amount of
114 /// pointers and indirection.
115 /// > It wastes memory, it has terrible cache locality, and is all-around slow.
117 /// > "only" amortized for push/pop, should be faster in the general case for
118 /// almost every possible
119 /// > workload, and isn't even amortized at all if you can predict the capacity
122 /// > `LinkedList`s are only really good if you're doing a lot of merging or
123 /// splitting of lists.
124 /// > This is because they can just mangle some pointers instead of actually
125 /// copying the data. Even
126 /// > if you're doing a lot of insertion in the middle of the list, `RingBuf`
127 /// can still be better
128 /// > because of how expensive it is to seek to the middle of a `LinkedList`.
130 /// **Known problems:** False positives – the instances where using a
131 /// `LinkedList` makes sense are few and far between, but they can still happen.
135 /// let x = LinkedList::new();
139 "usage of LinkedList, usually a vector is faster, or a more specialized data structure like a VecDeque"
142 declare_clippy_lint! {
143 /// **What it does:** Checks for use of `&Box<T>` anywhere in the code.
145 /// **Why is this bad?** Any `&Box<T>` can also be a `&T`, which is more
148 /// **Known problems:** None.
152 /// fn foo(bar: &Box<T>) { ... }
158 /// fn foo(bar: &T) { ... }
162 "a borrow of a boxed type"
165 impl LintPass for TypePass {
166 fn get_lints(&self) -> LintArray {
167 lint_array!(BOX_VEC, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX)
170 fn name(&self) -> &'static str {
175 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypePass {
176 fn check_fn(&mut self, cx: &LateContext<'_, '_>, _: FnKind<'_>, decl: &FnDecl, _: &Body, _: Span, id: HirId) {
177 // skip trait implementations, see #605
178 if let Some(hir::Node::Item(item)) = cx.tcx.hir().find_by_hir_id(cx.tcx.hir().get_parent_item(id)) {
179 if let ItemKind::Impl(_, _, _, _, Some(..), _, _) = item.node {
184 check_fn_decl(cx, decl);
187 fn check_struct_field(&mut self, cx: &LateContext<'_, '_>, field: &hir::StructField) {
188 check_ty(cx, &field.ty, false);
191 fn check_trait_item(&mut self, cx: &LateContext<'_, '_>, item: &TraitItem) {
193 TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => check_ty(cx, ty, false),
194 TraitItemKind::Method(ref sig, _) => check_fn_decl(cx, &sig.decl),
199 fn check_local(&mut self, cx: &LateContext<'_, '_>, local: &Local) {
200 if let Some(ref ty) = local.ty {
201 check_ty(cx, ty, true);
206 fn check_fn_decl(cx: &LateContext<'_, '_>, decl: &FnDecl) {
207 for input in &decl.inputs {
208 check_ty(cx, input, false);
211 if let FunctionRetTy::Return(ref ty) = decl.output {
212 check_ty(cx, ty, false);
216 /// Check if `qpath` has last segment with type parameter matching `path`
217 fn match_type_parameter(cx: &LateContext<'_, '_>, qpath: &QPath, path: &[&str]) -> bool {
218 let last = last_path_segment(qpath);
220 if let Some(ref params) = last.args;
221 if !params.parenthesized;
222 if let Some(ty) = params.args.iter().find_map(|arg| match arg {
223 GenericArg::Type(ty) => Some(ty),
226 if let TyKind::Path(ref qpath) = ty.node;
227 if let Some(did) = cx.tables.qpath_def(qpath, ty.hir_id).opt_def_id();
228 if match_def_path(cx.tcx, did, path);
236 /// Recursively check for `TypePass` lints in the given type. Stop at the first
239 /// The parameter `is_local` distinguishes the context of the type; types from
240 /// local bindings should only be checked for the `BORROWED_BOX` lint.
241 #[allow(clippy::too_many_lines)]
242 fn check_ty(cx: &LateContext<'_, '_>, hir_ty: &hir::Ty, is_local: bool) {
243 if in_macro(hir_ty.span) {
247 TyKind::Path(ref qpath) if !is_local => {
248 let hir_id = hir_ty.hir_id;
249 let def = cx.tables.qpath_def(qpath, hir_id);
250 if let Some(def_id) = def.opt_def_id() {
251 if Some(def_id) == cx.tcx.lang_items().owned_box() {
252 if match_type_parameter(cx, qpath, &paths::VEC) {
257 "you seem to be trying to use `Box<Vec<T>>`. Consider using just `Vec<T>`",
258 "`Vec<T>` is already on the heap, `Box<Vec<T>>` makes an extra allocation.",
260 return; // don't recurse into the type
262 } else if match_def_path(cx.tcx, def_id, &paths::VEC) {
264 // Get the _ part of Vec<_>
265 if let Some(ref last) = last_path_segment(qpath).args;
266 if let Some(ty) = last.args.iter().find_map(|arg| match arg {
267 GenericArg::Type(ty) => Some(ty),
270 // ty is now _ at this point
271 if let TyKind::Path(ref ty_qpath) = ty.node;
272 let def = cx.tables.qpath_def(ty_qpath, ty.hir_id);
273 if let Some(def_id) = def.opt_def_id();
274 if Some(def_id) == cx.tcx.lang_items().owned_box();
275 // At this point, we know ty is Box<T>, now get T
276 if let Some(ref last) = last_path_segment(ty_qpath).args;
277 if let Some(boxed_ty) = last.args.iter().find_map(|arg| match arg {
278 GenericArg::Type(ty) => Some(ty),
282 let ty_ty = hir_ty_to_ty(cx.tcx, boxed_ty);
283 if ty_ty.is_sized(cx.tcx.at(ty.span), cx.param_env) {
288 "`Vec<T>` is already on the heap, the boxing is unnecessary.",
290 format!("Vec<{}>", ty_ty),
291 Applicability::MachineApplicable,
293 return; // don't recurse into the type
297 } else if match_def_path(cx.tcx, def_id, &paths::OPTION) {
298 if match_type_parameter(cx, qpath, &paths::OPTION) {
303 "consider using `Option<T>` instead of `Option<Option<T>>` or a custom \
304 enum if you need to distinguish all 3 cases",
306 return; // don't recurse into the type
308 } else if match_def_path(cx.tcx, def_id, &paths::LINKED_LIST) {
313 "I see you're using a LinkedList! Perhaps you meant some other data structure?",
314 "a VecDeque might work",
316 return; // don't recurse into the type
320 QPath::Resolved(Some(ref ty), ref p) => {
321 check_ty(cx, ty, is_local);
322 for ty in p.segments.iter().flat_map(|seg| {
325 .map_or_else(|| [].iter(), |params| params.args.iter())
326 .filter_map(|arg| match arg {
327 GenericArg::Type(ty) => Some(ty),
331 check_ty(cx, ty, is_local);
334 QPath::Resolved(None, ref p) => {
335 for ty in p.segments.iter().flat_map(|seg| {
338 .map_or_else(|| [].iter(), |params| params.args.iter())
339 .filter_map(|arg| match arg {
340 GenericArg::Type(ty) => Some(ty),
344 check_ty(cx, ty, is_local);
347 QPath::TypeRelative(ref ty, ref seg) => {
348 check_ty(cx, ty, is_local);
349 if let Some(ref params) = seg.args {
350 for ty in params.args.iter().filter_map(|arg| match arg {
351 GenericArg::Type(ty) => Some(ty),
354 check_ty(cx, ty, is_local);
360 TyKind::Rptr(ref lt, ref mut_ty) => check_ty_rptr(cx, hir_ty, is_local, lt, mut_ty),
362 TyKind::Slice(ref ty) | TyKind::Array(ref ty, _) | TyKind::Ptr(MutTy { ref ty, .. }) => {
363 check_ty(cx, ty, is_local)
365 TyKind::Tup(ref tys) => {
367 check_ty(cx, ty, is_local);
374 fn check_ty_rptr(cx: &LateContext<'_, '_>, hir_ty: &hir::Ty, is_local: bool, lt: &Lifetime, mut_ty: &MutTy) {
375 match mut_ty.ty.node {
376 TyKind::Path(ref qpath) => {
377 let hir_id = mut_ty.ty.hir_id;
378 let def = cx.tables.qpath_def(qpath, hir_id);
380 if let Some(def_id) = def.opt_def_id();
381 if Some(def_id) == cx.tcx.lang_items().owned_box();
382 if let QPath::Resolved(None, ref path) = *qpath;
383 if let [ref bx] = *path.segments;
384 if let Some(ref params) = bx.args;
385 if !params.parenthesized;
386 if let Some(inner) = params.args.iter().find_map(|arg| match arg {
387 GenericArg::Type(ty) => Some(ty),
391 if is_any_trait(inner) {
392 // Ignore `Box<Any>` types, see #1884 for details.
396 let ltopt = if lt.is_elided() {
399 format!("{} ", lt.name.ident().as_str())
401 let mutopt = if mut_ty.mutbl == Mutability::MutMutable {
406 let mut applicability = Applicability::MachineApplicable;
411 "you seem to be trying to use `&Box<T>`. Consider using just `&T`",
417 &snippet_with_applicability(cx, inner.span, "..", &mut applicability)
419 Applicability::Unspecified,
421 return; // don't recurse into the type
424 check_ty(cx, &mut_ty.ty, is_local);
426 _ => check_ty(cx, &mut_ty.ty, is_local),
430 // Returns true if given type is `Any` trait.
431 fn is_any_trait(t: &hir::Ty) -> bool {
433 if let TyKind::TraitObject(ref traits, _) = t.node;
434 if traits.len() >= 1;
435 // Only Send/Sync can be used as additional traits, so it is enough to
436 // check only the first trait.
437 if match_path(&traits[0].trait_ref.path, &paths::ANY_TRAIT);
448 declare_clippy_lint! {
449 /// **What it does:** Checks for binding a unit value.
451 /// **Why is this bad?** A unit value cannot usefully be used anywhere. So
452 /// binding one is kind of pointless.
454 /// **Known problems:** None.
464 "creating a let binding to a value of unit type, which usually can't be used afterwards"
467 impl LintPass for LetPass {
468 fn get_lints(&self) -> LintArray {
469 lint_array!(LET_UNIT_VALUE)
472 fn name(&self) -> &'static str {
477 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for LetPass {
478 fn check_stmt(&mut self, cx: &LateContext<'a, 'tcx>, stmt: &'tcx Stmt) {
479 if let StmtKind::Local(ref local) = stmt.node {
480 if is_unit(cx.tables.pat_ty(&local.pat)) {
481 if in_external_macro(cx.sess(), stmt.span) || in_macro(local.pat.span) {
484 if higher::is_from_for_desugar(local) {
492 "this let-binding has unit value. Consider omitting `let {} =`",
493 snippet(cx, local.pat.span, "..")
501 declare_clippy_lint! {
502 /// **What it does:** Checks for comparisons to unit.
504 /// **Why is this bad?** Unit is always equal to itself, and thus is just a
505 /// clumsily written constant. Mostly this happens when someone accidentally
506 /// adds semicolons at the end of the operands.
508 /// **Known problems:** None.
530 "comparing unit values"
535 impl LintPass for UnitCmp {
536 fn get_lints(&self) -> LintArray {
537 lint_array!(UNIT_CMP)
540 fn name(&self) -> &'static str {
545 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnitCmp {
546 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
547 if in_macro(expr.span) {
550 if let ExprKind::Binary(ref cmp, ref left, _) = expr.node {
552 if op.is_comparison() && is_unit(cx.tables.expr_ty(left)) {
553 let result = match op {
554 BinOpKind::Eq | BinOpKind::Le | BinOpKind::Ge => "true",
562 "{}-comparison of unit values detected. This will always be {}",
572 declare_clippy_lint! {
573 /// **What it does:** Checks for passing a unit value as an argument to a function without using a
574 /// unit literal (`()`).
576 /// **Why is this bad?** This is likely the result of an accidental semicolon.
578 /// **Known problems:** None.
589 "passing unit to a function"
594 impl LintPass for UnitArg {
595 fn get_lints(&self) -> LintArray {
596 lint_array!(UNIT_ARG)
599 fn name(&self) -> &'static str {
604 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for UnitArg {
605 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
606 if in_macro(expr.span) {
610 // apparently stuff in the desugaring of `?` can trigger this
611 // so check for that here
612 // only the calls to `Try::from_error` is marked as desugared,
613 // so we need to check both the current Expr and its parent.
614 if is_questionmark_desugar_marked_call(expr) {
618 let map = &cx.tcx.hir();
619 let opt_parent_node = map.find_by_hir_id(map.get_parent_node_by_hir_id(expr.hir_id));
620 if let Some(hir::Node::Expr(parent_expr)) = opt_parent_node;
621 if is_questionmark_desugar_marked_call(parent_expr);
628 ExprKind::Call(_, ref args) | ExprKind::MethodCall(_, _, ref args) => {
630 if is_unit(cx.tables.expr_ty(arg)) && !is_unit_literal(arg) {
631 if let ExprKind::Match(.., match_source) = &arg.node {
632 if *match_source == MatchSource::TryDesugar {
641 "passing a unit value to a function",
642 "if you intended to pass a unit value, use a unit literal instead",
644 Applicability::MachineApplicable,
654 fn is_questionmark_desugar_marked_call(expr: &Expr) -> bool {
655 use syntax_pos::hygiene::CompilerDesugaringKind;
656 if let ExprKind::Call(ref callee, _) = expr.node {
657 callee.span.is_compiler_desugaring(CompilerDesugaringKind::QuestionMark)
663 fn is_unit(ty: Ty<'_>) -> bool {
665 ty::Tuple(slice) if slice.is_empty() => true,
670 fn is_unit_literal(expr: &Expr) -> bool {
672 ExprKind::Tup(ref slice) if slice.is_empty() => true,
679 declare_clippy_lint! {
680 /// **What it does:** Checks for casts from any numerical to a float type where
681 /// the receiving type cannot store all values from the original type without
682 /// rounding errors. This possible rounding is to be expected, so this lint is
683 /// `Allow` by default.
685 /// Basically, this warns on casting any integer with 32 or more bits to `f32`
686 /// or any 64-bit integer to `f64`.
688 /// **Why is this bad?** It's not bad at all. But in some applications it can be
689 /// helpful to know where precision loss can take place. This lint can help find
690 /// those places in the code.
692 /// **Known problems:** None.
696 /// let x = u64::MAX;
699 pub CAST_PRECISION_LOSS,
701 "casts that cause loss of precision, e.g. `x as f32` where `x: u64`"
704 declare_clippy_lint! {
705 /// **What it does:** Checks for casts from a signed to an unsigned numerical
706 /// type. In this case, negative values wrap around to large positive values,
707 /// which can be quite surprising in practice. However, as the cast works as
708 /// defined, this lint is `Allow` by default.
710 /// **Why is this bad?** Possibly surprising results. You can activate this lint
711 /// as a one-time check to see where numerical wrapping can arise.
713 /// **Known problems:** None.
718 /// y as u128 // will return 18446744073709551615
722 "casts from signed types to unsigned types, e.g. `x as u32` where `x: i32`"
725 declare_clippy_lint! {
726 /// **What it does:** Checks for on casts between numerical types that may
727 /// truncate large values. This is expected behavior, so the cast is `Allow` by
730 /// **Why is this bad?** In some problem domains, it is good practice to avoid
731 /// truncation. This lint can be activated to help assess where additional
732 /// checks could be beneficial.
734 /// **Known problems:** None.
738 /// fn as_u8(x: u64) -> u8 {
742 pub CAST_POSSIBLE_TRUNCATION,
744 "casts that may cause truncation of the value, e.g. `x as u8` where `x: u32`, or `x as i32` where `x: f32`"
747 declare_clippy_lint! {
748 /// **What it does:** Checks for casts from an unsigned type to a signed type of
749 /// the same size. Performing such a cast is a 'no-op' for the compiler,
750 /// i.e. nothing is changed at the bit level, and the binary representation of
751 /// the value is reinterpreted. This can cause wrapping if the value is too big
752 /// for the target signed type. However, the cast works as defined, so this lint
753 /// is `Allow` by default.
755 /// **Why is this bad?** While such a cast is not bad in itself, the results can
756 /// be surprising when this is not the intended behavior, as demonstrated by the
759 /// **Known problems:** None.
763 /// u32::MAX as i32 // will yield a value of `-1`
765 pub CAST_POSSIBLE_WRAP,
767 "casts that may cause wrapping around the value, e.g. `x as i32` where `x: u32` and `x > i32::MAX`"
770 declare_clippy_lint! {
771 /// **What it does:** Checks for on casts between numerical types that may
772 /// be replaced by safe conversion functions.
774 /// **Why is this bad?** Rust's `as` keyword will perform many kinds of
775 /// conversions, including silently lossy conversions. Conversion functions such
776 /// as `i32::from` will only perform lossless conversions. Using the conversion
777 /// functions prevents conversions from turning into silent lossy conversions if
778 /// the types of the input expressions ever change, and make it easier for
779 /// people reading the code to know that the conversion is lossless.
781 /// **Known problems:** None.
785 /// fn as_u64(x: u8) -> u64 {
790 /// Using `::from` would look like this:
793 /// fn as_u64(x: u8) -> u64 {
799 "casts using `as` that are known to be lossless, e.g. `x as u64` where `x: u8`"
802 declare_clippy_lint! {
803 /// **What it does:** Checks for casts to the same type.
805 /// **Why is this bad?** It's just unnecessary.
807 /// **Known problems:** None.
811 /// let _ = 2i32 as i32
813 pub UNNECESSARY_CAST,
815 "cast to the same type, e.g. `x as i32` where `x: i32`"
818 declare_clippy_lint! {
819 /// **What it does:** Checks for casts from a less-strictly-aligned pointer to a
820 /// more-strictly-aligned pointer
822 /// **Why is this bad?** Dereferencing the resulting pointer may be undefined
825 /// **Known problems:** None.
829 /// let _ = (&1u8 as *const u8) as *const u16;
830 /// let _ = (&mut 1u8 as *mut u8) as *mut u16;
832 pub CAST_PTR_ALIGNMENT,
834 "cast from a pointer to a more-strictly-aligned pointer"
837 declare_clippy_lint! {
838 /// **What it does:** Checks for casts of function pointers to something other than usize
840 /// **Why is this bad?**
841 /// Casting a function pointer to anything other than usize/isize is not portable across
842 /// architectures, because you end up losing bits if the target type is too small or end up with a
843 /// bunch of extra bits that waste space and add more instructions to the final binary than
844 /// strictly necessary for the problem
846 /// Casting to isize also doesn't make sense since there are no signed addresses.
852 /// fn fun() -> i32 {}
853 /// let a = fun as i64;
856 /// fn fun2() -> i32 {}
857 /// let a = fun2 as usize;
859 pub FN_TO_NUMERIC_CAST,
861 "casting a function pointer to a numeric type other than usize"
864 declare_clippy_lint! {
865 /// **What it does:** Checks for casts of a function pointer to a numeric type not wide enough to
868 /// **Why is this bad?**
869 /// Such a cast discards some bits of the function's address. If this is intended, it would be more
870 /// clearly expressed by casting to usize first, then casting the usize to the intended type (with
871 /// a comment) to perform the truncation.
877 /// fn fn1() -> i16 {
880 /// let _ = fn1 as i32;
882 /// // Better: Cast to usize first, then comment with the reason for the truncation
883 /// fn fn2() -> i16 {
886 /// let fn_ptr = fn2 as usize;
887 /// let fn_ptr_truncated = fn_ptr as i32;
889 pub FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
891 "casting a function pointer to a numeric type not wide enough to store the address"
894 /// Returns the size in bits of an integral type.
895 /// Will return 0 if the type is not an int or uint variant
896 fn int_ty_to_nbits(typ: Ty<'_>, tcx: TyCtxt<'_, '_, '_>) -> u64 {
898 ty::Int(i) => match i {
899 IntTy::Isize => tcx.data_layout.pointer_size.bits(),
906 ty::Uint(i) => match i {
907 UintTy::Usize => tcx.data_layout.pointer_size.bits(),
918 fn is_isize_or_usize(typ: Ty<'_>) -> bool {
920 ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => true,
925 fn span_precision_loss_lint(cx: &LateContext<'_, '_>, expr: &Expr, cast_from: Ty<'_>, cast_to_f64: bool) {
926 let mantissa_nbits = if cast_to_f64 { 52 } else { 23 };
927 let arch_dependent = is_isize_or_usize(cast_from) && cast_to_f64;
928 let arch_dependent_str = "on targets with 64-bit wide pointers ";
929 let from_nbits_str = if arch_dependent {
931 } else if is_isize_or_usize(cast_from) {
932 "32 or 64".to_owned()
934 int_ty_to_nbits(cast_from, cx.tcx).to_string()
941 "casting {0} to {1} causes a loss of precision {2}({0} is {3} bits wide, but {1}'s mantissa \
942 is only {4} bits wide)",
944 if cast_to_f64 { "f64" } else { "f32" },
945 if arch_dependent { arch_dependent_str } else { "" },
952 fn should_strip_parens(op: &Expr, snip: &str) -> bool {
953 if let ExprKind::Binary(_, _, _) = op.node {
954 if snip.starts_with('(') && snip.ends_with(')') {
961 fn span_lossless_lint(cx: &LateContext<'_, '_>, expr: &Expr, op: &Expr, cast_from: Ty<'_>, cast_to: Ty<'_>) {
962 // Do not suggest using From in consts/statics until it is valid to do so (see #2267).
963 if in_constant(cx, expr.hir_id) {
966 // The suggestion is to use a function call, so if the original expression
967 // has parens on the outside, they are no longer needed.
968 let mut applicability = Applicability::MachineApplicable;
969 let opt = snippet_opt(cx, op.span);
970 let sugg = if let Some(ref snip) = opt {
971 if should_strip_parens(op, snip) {
972 &snip[1..snip.len() - 1]
977 applicability = Applicability::HasPlaceholders;
986 "casting {} to {} may become silently lossy if types change",
990 format!("{}::from({})", cast_to, sugg),
1001 fn check_loss_of_sign(cx: &LateContext<'_, '_>, expr: &Expr, op: &Expr, cast_from: Ty<'_>, cast_to: Ty<'_>) {
1002 if !cast_from.is_signed() || cast_to.is_signed() {
1006 // don't lint for positive constants
1007 let const_val = constant(cx, &cx.tables, op);
1009 if let Some((const_val, _)) = const_val;
1010 if let Constant::Int(n) = const_val;
1011 if let ty::Int(ity) = cast_from.sty;
1012 if sext(cx.tcx, n, ity) >= 0;
1022 &format!("casting {} to {} may lose the sign of the value", cast_from, cast_to),
1026 fn check_truncation_and_wrapping(cx: &LateContext<'_, '_>, expr: &Expr, cast_from: Ty<'_>, cast_to: Ty<'_>) {
1027 let arch_64_suffix = " on targets with 64-bit wide pointers";
1028 let arch_32_suffix = " on targets with 32-bit wide pointers";
1029 let cast_unsigned_to_signed = !cast_from.is_signed() && cast_to.is_signed();
1030 let from_nbits = int_ty_to_nbits(cast_from, cx.tcx);
1031 let to_nbits = int_ty_to_nbits(cast_to, cx.tcx);
1032 let (span_truncation, suffix_truncation, span_wrap, suffix_wrap) =
1033 match (is_isize_or_usize(cast_from), is_isize_or_usize(cast_to)) {
1034 (true, true) | (false, false) => (
1035 to_nbits < from_nbits,
1037 to_nbits == from_nbits && cast_unsigned_to_signed,
1047 to_nbits <= 32 && cast_unsigned_to_signed,
1053 cast_unsigned_to_signed,
1054 if from_nbits == 64 {
1061 if span_truncation {
1064 CAST_POSSIBLE_TRUNCATION,
1067 "casting {} to {} may truncate the value{}",
1070 match suffix_truncation {
1071 ArchSuffix::_32 => arch_32_suffix,
1072 ArchSuffix::_64 => arch_64_suffix,
1073 ArchSuffix::None => "",
1084 "casting {} to {} may wrap around the value{}",
1088 ArchSuffix::_32 => arch_32_suffix,
1089 ArchSuffix::_64 => arch_64_suffix,
1090 ArchSuffix::None => "",
1097 fn check_lossless(cx: &LateContext<'_, '_>, expr: &Expr, op: &Expr, cast_from: Ty<'_>, cast_to: Ty<'_>) {
1098 let cast_signed_to_unsigned = cast_from.is_signed() && !cast_to.is_signed();
1099 let from_nbits = int_ty_to_nbits(cast_from, cx.tcx);
1100 let to_nbits = int_ty_to_nbits(cast_to, cx.tcx);
1101 if !is_isize_or_usize(cast_from) && !is_isize_or_usize(cast_to) && from_nbits < to_nbits && !cast_signed_to_unsigned
1103 span_lossless_lint(cx, expr, op, cast_from, cast_to);
1107 impl LintPass for CastPass {
1108 fn get_lints(&self) -> LintArray {
1110 CAST_PRECISION_LOSS,
1112 CAST_POSSIBLE_TRUNCATION,
1118 FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
1122 fn name(&self) -> &'static str {
1127 // Check if the given type is either `core::ffi::c_void` or
1128 // one of the platform specific `libc::<platform>::c_void` of libc.
1129 fn is_c_void(tcx: TyCtxt<'_, '_, '_>, ty: Ty<'_>) -> bool {
1130 if let ty::Adt(adt, _) = ty.sty {
1131 let mut apb = AbsolutePathBuffer { names: vec![] };
1132 tcx.push_item_path(&mut apb, adt.did, false);
1134 if apb.names.is_empty() {
1137 if apb.names[0] == "libc" || apb.names[0] == "core" && *apb.names.last().unwrap() == "c_void" {
1144 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CastPass {
1145 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
1146 if let ExprKind::Cast(ref ex, _) = expr.node {
1147 let (cast_from, cast_to) = (cx.tables.expr_ty(ex), cx.tables.expr_ty(expr));
1148 lint_fn_to_numeric_cast(cx, expr, ex, cast_from, cast_to);
1149 if let ExprKind::Lit(ref lit) = ex.node {
1150 use syntax::ast::{LitIntType, LitKind};
1152 LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::FloatUnsuffixed(_) => {},
1154 if cast_from.sty == cast_to.sty && !in_external_macro(cx.sess(), expr.span) {
1160 "casting to the same type is unnecessary (`{}` -> `{}`)",
1168 if cast_from.is_numeric() && cast_to.is_numeric() && !in_external_macro(cx.sess(), expr.span) {
1169 match (cast_from.is_integral(), cast_to.is_integral()) {
1171 let from_nbits = int_ty_to_nbits(cast_from, cx.tcx);
1172 let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.sty {
1177 if is_isize_or_usize(cast_from) || from_nbits >= to_nbits {
1178 span_precision_loss_lint(cx, expr, cast_from, to_nbits == 64);
1180 if from_nbits < to_nbits {
1181 span_lossless_lint(cx, expr, ex, cast_from, cast_to);
1187 CAST_POSSIBLE_TRUNCATION,
1189 &format!("casting {} to {} may truncate the value", cast_from, cast_to),
1191 if !cast_to.is_signed() {
1196 &format!("casting {} to {} may lose the sign of the value", cast_from, cast_to),
1201 check_loss_of_sign(cx, expr, ex, cast_from, cast_to);
1202 check_truncation_and_wrapping(cx, expr, cast_from, cast_to);
1203 check_lossless(cx, expr, ex, cast_from, cast_to);
1206 if let (&ty::Float(FloatTy::F64), &ty::Float(FloatTy::F32)) = (&cast_from.sty, &cast_to.sty) {
1209 CAST_POSSIBLE_TRUNCATION,
1211 "casting f64 to f32 may truncate the value",
1214 if let (&ty::Float(FloatTy::F32), &ty::Float(FloatTy::F64)) = (&cast_from.sty, &cast_to.sty) {
1215 span_lossless_lint(cx, expr, ex, cast_from, cast_to);
1222 if let ty::RawPtr(from_ptr_ty) = &cast_from.sty;
1223 if let ty::RawPtr(to_ptr_ty) = &cast_to.sty;
1224 if let Some(from_align) = cx.layout_of(from_ptr_ty.ty).ok().map(|a| a.align.abi);
1225 if let Some(to_align) = cx.layout_of(to_ptr_ty.ty).ok().map(|a| a.align.abi);
1226 if from_align < to_align;
1227 // with c_void, we inherently need to trust the user
1228 if !is_c_void(cx.tcx, from_ptr_ty.ty);
1234 &format!("casting from `{}` to a more-strictly-aligned pointer (`{}`)", cast_from, cast_to)
1242 fn lint_fn_to_numeric_cast(
1243 cx: &LateContext<'_, '_>,
1249 // We only want to check casts to `ty::Uint` or `ty::Int`
1251 ty::Uint(_) | ty::Int(..) => { /* continue on */ },
1254 match cast_from.sty {
1255 ty::FnDef(..) | ty::FnPtr(_) => {
1256 let mut applicability = Applicability::MachineApplicable;
1257 let from_snippet = snippet_with_applicability(cx, cast_expr.span, "x", &mut applicability);
1259 let to_nbits = int_ty_to_nbits(cast_to, cx.tcx);
1260 if to_nbits < cx.tcx.data_layout.pointer_size.bits() {
1263 FN_TO_NUMERIC_CAST_WITH_TRUNCATION,
1266 "casting function pointer `{}` to `{}`, which truncates the value",
1267 from_snippet, cast_to
1270 format!("{} as usize", from_snippet),
1273 } else if cast_to.sty != ty::Uint(UintTy::Usize) {
1278 &format!("casting function pointer `{}` to `{}`", from_snippet, cast_to),
1280 format!("{} as usize", from_snippet),
1289 declare_clippy_lint! {
1290 /// **What it does:** Checks for types used in structs, parameters and `let`
1291 /// declarations above a certain complexity threshold.
1293 /// **Why is this bad?** Too complex types make the code less readable. Consider
1294 /// using a `type` definition to simplify them.
1296 /// **Known problems:** None.
1301 /// inner: Rc<Vec<Vec<Box<(u32, u32, u32, u32)>>>>,
1304 pub TYPE_COMPLEXITY,
1306 "usage of very complex types that might be better factored into `type` definitions"
1309 pub struct TypeComplexityPass {
1313 impl TypeComplexityPass {
1314 pub fn new(threshold: u64) -> Self {
1319 impl LintPass for TypeComplexityPass {
1320 fn get_lints(&self) -> LintArray {
1321 lint_array!(TYPE_COMPLEXITY)
1324 fn name(&self) -> &'static str {
1325 "TypeComplexityPass"
1329 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for TypeComplexityPass {
1332 cx: &LateContext<'a, 'tcx>,
1339 self.check_fndecl(cx, decl);
1342 fn check_struct_field(&mut self, cx: &LateContext<'a, 'tcx>, field: &'tcx hir::StructField) {
1343 // enum variants are also struct fields now
1344 self.check_type(cx, &field.ty);
1347 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
1349 ItemKind::Static(ref ty, _, _) | ItemKind::Const(ref ty, _) => self.check_type(cx, ty),
1350 // functions, enums, structs, impls and traits are covered
1355 fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx TraitItem) {
1357 TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => self.check_type(cx, ty),
1358 TraitItemKind::Method(MethodSig { ref decl, .. }, TraitMethod::Required(_)) => self.check_fndecl(cx, decl),
1359 // methods with default impl are covered by check_fn
1364 fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx ImplItem) {
1366 ImplItemKind::Const(ref ty, _) | ImplItemKind::Type(ref ty) => self.check_type(cx, ty),
1367 // methods are covered by check_fn
1372 fn check_local(&mut self, cx: &LateContext<'a, 'tcx>, local: &'tcx Local) {
1373 if let Some(ref ty) = local.ty {
1374 self.check_type(cx, ty);
1379 impl<'a, 'tcx> TypeComplexityPass {
1380 fn check_fndecl(&self, cx: &LateContext<'a, 'tcx>, decl: &'tcx FnDecl) {
1381 for arg in &decl.inputs {
1382 self.check_type(cx, arg);
1384 if let Return(ref ty) = decl.output {
1385 self.check_type(cx, ty);
1389 fn check_type(&self, cx: &LateContext<'_, '_>, ty: &hir::Ty) {
1390 if in_macro(ty.span) {
1394 let mut visitor = TypeComplexityVisitor { score: 0, nest: 1 };
1395 visitor.visit_ty(ty);
1399 if score > self.threshold {
1404 "very complex type used. Consider factoring parts into `type` definitions",
1410 /// Walks a type and assigns a complexity score to it.
1411 struct TypeComplexityVisitor {
1412 /// total complexity score of the type
1414 /// current nesting level
1418 impl<'tcx> Visitor<'tcx> for TypeComplexityVisitor {
1419 fn visit_ty(&mut self, ty: &'tcx hir::Ty) {
1420 let (add_score, sub_nest) = match ty.node {
1421 // _, &x and *x have only small overhead; don't mess with nesting level
1422 TyKind::Infer | TyKind::Ptr(..) | TyKind::Rptr(..) => (1, 0),
1424 // the "normal" components of a type: named types, arrays/tuples
1425 TyKind::Path(..) | TyKind::Slice(..) | TyKind::Tup(..) | TyKind::Array(..) => (10 * self.nest, 1),
1427 // function types bring a lot of overhead
1428 TyKind::BareFn(ref bare) if bare.abi == Abi::Rust => (50 * self.nest, 1),
1430 TyKind::TraitObject(ref param_bounds, _) => {
1431 let has_lifetime_parameters = param_bounds.iter().any(|bound| {
1432 bound.bound_generic_params.iter().any(|gen| match gen.kind {
1433 GenericParamKind::Lifetime { .. } => true,
1437 if has_lifetime_parameters {
1438 // complex trait bounds like A<'a, 'b>
1441 // simple trait bounds like A + B
1448 self.score += add_score;
1449 self.nest += sub_nest;
1451 self.nest -= sub_nest;
1453 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
1454 NestedVisitorMap::None
1458 declare_clippy_lint! {
1459 /// **What it does:** Checks for expressions where a character literal is cast
1460 /// to `u8` and suggests using a byte literal instead.
1462 /// **Why is this bad?** In general, casting values to smaller types is
1463 /// error-prone and should be avoided where possible. In the particular case of
1464 /// converting a character literal to u8, it is easy to avoid by just using a
1465 /// byte literal instead. As an added bonus, `b'a'` is even slightly shorter
1466 /// than `'a' as u8`.
1468 /// **Known problems:** None.
1475 /// A better version, using the byte literal:
1482 "casting a character literal to u8"
1485 pub struct CharLitAsU8;
1487 impl LintPass for CharLitAsU8 {
1488 fn get_lints(&self) -> LintArray {
1489 lint_array!(CHAR_LIT_AS_U8)
1492 fn name(&self) -> &'static str {
1497 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for CharLitAsU8 {
1498 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
1499 use syntax::ast::{LitKind, UintTy};
1501 if let ExprKind::Cast(ref e, _) = expr.node {
1502 if let ExprKind::Lit(ref l) = e.node {
1503 if let LitKind::Char(_) = l.node {
1504 if ty::Uint(UintTy::U8) == cx.tables.expr_ty(expr).sty && !in_macro(expr.span) {
1505 let msg = "casting character literal to u8. `char`s \
1506 are 4 bytes wide in rust, so casting to u8 \
1509 "Consider using a byte literal instead:\nb{}",
1510 snippet(cx, e.span, "'x'")
1512 span_help_and_lint(cx, CHAR_LIT_AS_U8, expr.span, msg, &help);
1520 declare_clippy_lint! {
1521 /// **What it does:** Checks for comparisons where one side of the relation is
1522 /// either the minimum or maximum value for its type and warns if it involves a
1523 /// case that is always true or always false. Only integer and boolean types are
1526 /// **Why is this bad?** An expression like `min <= x` may misleadingly imply
1527 /// that is is possible for `x` to be less than the minimum. Expressions like
1528 /// `max < x` are probably mistakes.
1530 /// **Known problems:** For `usize` the size of the current compile target will
1531 /// be assumed (e.g. 64 bits on 64 bit systems). This means code that uses such
1532 /// a comparison to detect target pointer width will trigger this lint. One can
1533 /// use `mem::sizeof` and compare its value or conditional compilation
1535 /// like `#[cfg(target_pointer_width = "64")] ..` instead.
1540 /// 100 > std::i32::MAX
1542 pub ABSURD_EXTREME_COMPARISONS,
1544 "a comparison with a maximum or minimum value that is always true or false"
1547 pub struct AbsurdExtremeComparisons;
1549 impl LintPass for AbsurdExtremeComparisons {
1550 fn get_lints(&self) -> LintArray {
1551 lint_array!(ABSURD_EXTREME_COMPARISONS)
1554 fn name(&self) -> &'static str {
1555 "AbsurdExtremeComparisons"
1564 struct ExtremeExpr<'a> {
1569 enum AbsurdComparisonResult {
1572 InequalityImpossible,
1575 fn is_cast_between_fixed_and_target<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> bool {
1576 if let ExprKind::Cast(ref cast_exp, _) = expr.node {
1577 let precast_ty = cx.tables.expr_ty(cast_exp);
1578 let cast_ty = cx.tables.expr_ty(expr);
1580 return is_isize_or_usize(precast_ty) != is_isize_or_usize(cast_ty);
1586 fn detect_absurd_comparison<'a, 'tcx>(
1587 cx: &LateContext<'a, 'tcx>,
1591 ) -> Option<(ExtremeExpr<'tcx>, AbsurdComparisonResult)> {
1592 use crate::types::AbsurdComparisonResult::*;
1593 use crate::types::ExtremeType::*;
1594 use crate::utils::comparisons::*;
1596 // absurd comparison only makes sense on primitive types
1597 // primitive types don't implement comparison operators with each other
1598 if cx.tables.expr_ty(lhs) != cx.tables.expr_ty(rhs) {
1602 // comparisons between fix sized types and target sized types are considered unanalyzable
1603 if is_cast_between_fixed_and_target(cx, lhs) || is_cast_between_fixed_and_target(cx, rhs) {
1607 let normalized = normalize_comparison(op, lhs, rhs);
1608 let (rel, normalized_lhs, normalized_rhs) = if let Some(val) = normalized {
1614 let lx = detect_extreme_expr(cx, normalized_lhs);
1615 let rx = detect_extreme_expr(cx, normalized_rhs);
1620 (Some(l @ ExtremeExpr { which: Maximum, .. }), _) => (l, AlwaysFalse), // max < x
1621 (_, Some(r @ ExtremeExpr { which: Minimum, .. })) => (r, AlwaysFalse), // x < min
1627 (Some(l @ ExtremeExpr { which: Minimum, .. }), _) => (l, AlwaysTrue), // min <= x
1628 (Some(l @ ExtremeExpr { which: Maximum, .. }), _) => (l, InequalityImpossible), // max <= x
1629 (_, Some(r @ ExtremeExpr { which: Minimum, .. })) => (r, InequalityImpossible), // x <= min
1630 (_, Some(r @ ExtremeExpr { which: Maximum, .. })) => (r, AlwaysTrue), // x <= max
1634 Rel::Ne | Rel::Eq => return None,
1638 fn detect_extreme_expr<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<ExtremeExpr<'tcx>> {
1639 use crate::types::ExtremeType::*;
1641 let ty = cx.tables.expr_ty(expr);
1643 let cv = constant(cx, cx.tables, expr)?.0;
1645 let which = match (&ty.sty, cv) {
1646 (&ty::Bool, Constant::Bool(false)) | (&ty::Uint(_), Constant::Int(0)) => Minimum,
1647 (&ty::Int(ity), Constant::Int(i))
1648 if i == unsext(cx.tcx, i128::min_value() >> (128 - int_bits(cx.tcx, ity)), ity) =>
1653 (&ty::Bool, Constant::Bool(true)) => Maximum,
1654 (&ty::Int(ity), Constant::Int(i))
1655 if i == unsext(cx.tcx, i128::max_value() >> (128 - int_bits(cx.tcx, ity)), ity) =>
1659 (&ty::Uint(uty), Constant::Int(i)) if clip(cx.tcx, u128::max_value(), uty) == i => Maximum,
1663 Some(ExtremeExpr { which, expr })
1666 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for AbsurdExtremeComparisons {
1667 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
1668 use crate::types::AbsurdComparisonResult::*;
1669 use crate::types::ExtremeType::*;
1671 if let ExprKind::Binary(ref cmp, ref lhs, ref rhs) = expr.node {
1672 if let Some((culprit, result)) = detect_absurd_comparison(cx, cmp.node, lhs, rhs) {
1673 if !in_macro(expr.span) {
1674 let msg = "this comparison involving the minimum or maximum element for this \
1675 type contains a case that is always true or always false";
1677 let conclusion = match result {
1678 AlwaysFalse => "this comparison is always false".to_owned(),
1679 AlwaysTrue => "this comparison is always true".to_owned(),
1680 InequalityImpossible => format!(
1681 "the case where the two sides are not equal never occurs, consider using {} == {} \
1683 snippet(cx, lhs.span, "lhs"),
1684 snippet(cx, rhs.span, "rhs")
1689 "because {} is the {} value for this type, {}",
1690 snippet(cx, culprit.expr.span, "x"),
1691 match culprit.which {
1692 Minimum => "minimum",
1693 Maximum => "maximum",
1698 span_help_and_lint(cx, ABSURD_EXTREME_COMPARISONS, expr.span, msg, &help);
1705 declare_clippy_lint! {
1706 /// **What it does:** Checks for comparisons where the relation is always either
1707 /// true or false, but where one side has been upcast so that the comparison is
1708 /// necessary. Only integer types are checked.
1710 /// **Why is this bad?** An expression like `let x : u8 = ...; (x as u32) > 300`
1711 /// will mistakenly imply that it is possible for `x` to be outside the range of
1714 /// **Known problems:**
1715 /// https://github.com/rust-lang/rust-clippy/issues/886
1719 /// let x : u8 = ...; (x as u32) > 300
1721 pub INVALID_UPCAST_COMPARISONS,
1723 "a comparison involving an upcast which is always true or false"
1726 pub struct InvalidUpcastComparisons;
1728 impl LintPass for InvalidUpcastComparisons {
1729 fn get_lints(&self) -> LintArray {
1730 lint_array!(INVALID_UPCAST_COMPARISONS)
1733 fn name(&self) -> &'static str {
1734 "InvalidUpcastComparisons"
1738 #[derive(Copy, Clone, Debug, Eq)]
1745 #[allow(clippy::cast_sign_loss)]
1746 fn cmp_s_u(s: i128, u: u128) -> Ordering {
1749 } else if u > (i128::max_value() as u128) {
1757 impl PartialEq for FullInt {
1758 fn eq(&self, other: &Self) -> bool {
1759 self.partial_cmp(other).expect("partial_cmp only returns Some(_)") == Ordering::Equal
1763 impl PartialOrd for FullInt {
1764 fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
1765 Some(match (self, other) {
1766 (&FullInt::S(s), &FullInt::S(o)) => s.cmp(&o),
1767 (&FullInt::U(s), &FullInt::U(o)) => s.cmp(&o),
1768 (&FullInt::S(s), &FullInt::U(o)) => Self::cmp_s_u(s, o),
1769 (&FullInt::U(s), &FullInt::S(o)) => Self::cmp_s_u(o, s).reverse(),
1773 impl Ord for FullInt {
1774 fn cmp(&self, other: &Self) -> Ordering {
1775 self.partial_cmp(other)
1776 .expect("partial_cmp for FullInt can never return None")
1780 fn numeric_cast_precast_bounds<'a>(cx: &LateContext<'_, '_>, expr: &'a Expr) -> Option<(FullInt, FullInt)> {
1782 use syntax::ast::{IntTy, UintTy};
1784 if let ExprKind::Cast(ref cast_exp, _) = expr.node {
1785 let pre_cast_ty = cx.tables.expr_ty(cast_exp);
1786 let cast_ty = cx.tables.expr_ty(expr);
1787 // if it's a cast from i32 to u32 wrapping will invalidate all these checks
1788 if cx.layout_of(pre_cast_ty).ok().map(|l| l.size) == cx.layout_of(cast_ty).ok().map(|l| l.size) {
1791 match pre_cast_ty.sty {
1792 ty::Int(int_ty) => Some(match int_ty {
1794 FullInt::S(i128::from(i8::min_value())),
1795 FullInt::S(i128::from(i8::max_value())),
1798 FullInt::S(i128::from(i16::min_value())),
1799 FullInt::S(i128::from(i16::max_value())),
1802 FullInt::S(i128::from(i32::min_value())),
1803 FullInt::S(i128::from(i32::max_value())),
1806 FullInt::S(i128::from(i64::min_value())),
1807 FullInt::S(i128::from(i64::max_value())),
1809 IntTy::I128 => (FullInt::S(i128::min_value()), FullInt::S(i128::max_value())),
1811 FullInt::S(isize::min_value() as i128),
1812 FullInt::S(isize::max_value() as i128),
1815 ty::Uint(uint_ty) => Some(match uint_ty {
1817 FullInt::U(u128::from(u8::min_value())),
1818 FullInt::U(u128::from(u8::max_value())),
1821 FullInt::U(u128::from(u16::min_value())),
1822 FullInt::U(u128::from(u16::max_value())),
1825 FullInt::U(u128::from(u32::min_value())),
1826 FullInt::U(u128::from(u32::max_value())),
1829 FullInt::U(u128::from(u64::min_value())),
1830 FullInt::U(u128::from(u64::max_value())),
1832 UintTy::U128 => (FullInt::U(u128::min_value()), FullInt::U(u128::max_value())),
1834 FullInt::U(usize::min_value() as u128),
1835 FullInt::U(usize::max_value() as u128),
1845 fn node_as_const_fullint<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) -> Option<FullInt> {
1846 let val = constant(cx, cx.tables, expr)?.0;
1847 if let Constant::Int(const_int) = val {
1848 match cx.tables.expr_ty(expr).sty {
1849 ty::Int(ity) => Some(FullInt::S(sext(cx.tcx, const_int, ity))),
1850 ty::Uint(_) => Some(FullInt::U(const_int)),
1858 fn err_upcast_comparison(cx: &LateContext<'_, '_>, span: Span, expr: &Expr, always: bool) {
1859 if let ExprKind::Cast(ref cast_val, _) = expr.node {
1862 INVALID_UPCAST_COMPARISONS,
1865 "because of the numeric bounds on `{}` prior to casting, this expression is always {}",
1866 snippet(cx, cast_val.span, "the expression"),
1867 if always { "true" } else { "false" },
1873 fn upcast_comparison_bounds_err<'a, 'tcx>(
1874 cx: &LateContext<'a, 'tcx>,
1876 rel: comparisons::Rel,
1877 lhs_bounds: Option<(FullInt, FullInt)>,
1882 use crate::utils::comparisons::*;
1884 if let Some((lb, ub)) = lhs_bounds {
1885 if let Some(norm_rhs_val) = node_as_const_fullint(cx, rhs) {
1886 if rel == Rel::Eq || rel == Rel::Ne {
1887 if norm_rhs_val < lb || norm_rhs_val > ub {
1888 err_upcast_comparison(cx, span, lhs, rel == Rel::Ne);
1890 } else if match rel {
1905 Rel::Eq | Rel::Ne => unreachable!(),
1907 err_upcast_comparison(cx, span, lhs, true)
1908 } else if match rel {
1923 Rel::Eq | Rel::Ne => unreachable!(),
1925 err_upcast_comparison(cx, span, lhs, false)
1931 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for InvalidUpcastComparisons {
1932 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
1933 if let ExprKind::Binary(ref cmp, ref lhs, ref rhs) = expr.node {
1934 let normalized = comparisons::normalize_comparison(cmp.node, lhs, rhs);
1935 let (rel, normalized_lhs, normalized_rhs) = if let Some(val) = normalized {
1941 let lhs_bounds = numeric_cast_precast_bounds(cx, normalized_lhs);
1942 let rhs_bounds = numeric_cast_precast_bounds(cx, normalized_rhs);
1944 upcast_comparison_bounds_err(cx, expr.span, rel, lhs_bounds, normalized_lhs, normalized_rhs, false);
1945 upcast_comparison_bounds_err(cx, expr.span, rel, rhs_bounds, normalized_rhs, normalized_lhs, true);
1950 declare_clippy_lint! {
1951 /// **What it does:** Checks for public `impl` or `fn` missing generalization
1952 /// over different hashers and implicitly defaulting to the default hashing
1953 /// algorithm (SipHash).
1955 /// **Why is this bad?** `HashMap` or `HashSet` with custom hashers cannot be
1958 /// **Known problems:** Suggestions for replacing constructors can contain
1959 /// false-positives. Also applying suggestions can require modification of other
1960 /// pieces of code, possibly including external crates.
1964 /// impl<K: Hash + Eq, V> Serialize for HashMap<K, V> { ... }
1966 /// pub foo(map: &mut HashMap<i32, i32>) { .. }
1968 pub IMPLICIT_HASHER,
1970 "missing generalization over different hashers"
1973 pub struct ImplicitHasher;
1975 impl LintPass for ImplicitHasher {
1976 fn get_lints(&self) -> LintArray {
1977 lint_array!(IMPLICIT_HASHER)
1980 fn name(&self) -> &'static str {
1985 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for ImplicitHasher {
1986 #[allow(clippy::cast_possible_truncation, clippy::too_many_lines)]
1987 fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx Item) {
1988 use syntax_pos::BytePos;
1990 fn suggestion<'a, 'tcx>(
1991 cx: &LateContext<'a, 'tcx>,
1992 db: &mut DiagnosticBuilder<'_>,
1993 generics_span: Span,
1994 generics_suggestion_span: Span,
1995 target: &ImplicitHasherType<'_>,
1996 vis: ImplicitHasherConstructorVisitor<'_, '_, '_>,
1998 let generics_snip = snippet(cx, generics_span, "");
2000 let generics_snip = if generics_snip.is_empty() {
2003 &generics_snip[1..generics_snip.len() - 1]
2008 "consider adding a type parameter".to_string(),
2011 generics_suggestion_span,
2013 "<{}{}S: ::std::hash::BuildHasher{}>",
2015 if generics_snip.is_empty() { "" } else { ", " },
2016 if vis.suggestions.is_empty() {
2019 // request users to add `Default` bound so that generic constructors can be used
2026 format!("{}<{}, S>", target.type_name(), target.type_arguments(),),
2031 if !vis.suggestions.is_empty() {
2032 multispan_sugg(db, "...and use generic constructor".into(), vis.suggestions);
2036 if !cx.access_levels.is_exported(cx.tcx.hir().hir_to_node_id(item.hir_id)) {
2041 ItemKind::Impl(_, _, _, ref generics, _, ref ty, ref items) => {
2042 let mut vis = ImplicitHasherTypeVisitor::new(cx);
2045 for target in &vis.found {
2046 if differing_macro_contexts(item.span, target.span()) {
2050 let generics_suggestion_span = generics.span.substitute_dummy({
2051 let pos = snippet_opt(cx, item.span.until(target.span()))
2052 .and_then(|snip| Some(item.span.lo() + BytePos(snip.find("impl")? as u32 + 4)));
2053 if let Some(pos) = pos {
2054 Span::new(pos, pos, item.span.data().ctxt)
2060 let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target);
2061 for item in items.iter().map(|item| cx.tcx.hir().impl_item(item.id)) {
2062 ctr_vis.visit_impl_item(item);
2070 "impl for `{}` should be generalized over different hashers",
2074 suggestion(cx, db, generics.span, generics_suggestion_span, target, ctr_vis);
2079 ItemKind::Fn(ref decl, .., ref generics, body_id) => {
2080 let body = cx.tcx.hir().body(body_id);
2082 for ty in &decl.inputs {
2083 let mut vis = ImplicitHasherTypeVisitor::new(cx);
2086 for target in &vis.found {
2087 let generics_suggestion_span = generics.span.substitute_dummy({
2088 let pos = snippet_opt(cx, item.span.until(body.arguments[0].pat.span))
2090 let i = snip.find("fn")?;
2091 Some(item.span.lo() + BytePos((i + (&snip[i..]).find('(')?) as u32))
2093 .expect("failed to create span for type parameters");
2094 Span::new(pos, pos, item.span.data().ctxt)
2097 let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target);
2098 ctr_vis.visit_body(body);
2105 "parameter of type `{}` should be generalized over different hashers",
2109 suggestion(cx, db, generics.span, generics_suggestion_span, target, ctr_vis);
2120 enum ImplicitHasherType<'tcx> {
2121 HashMap(Span, Ty<'tcx>, Cow<'static, str>, Cow<'static, str>),
2122 HashSet(Span, Ty<'tcx>, Cow<'static, str>),
2125 impl<'tcx> ImplicitHasherType<'tcx> {
2126 /// Checks that `ty` is a target type without a BuildHasher.
2127 fn new<'a>(cx: &LateContext<'a, 'tcx>, hir_ty: &hir::Ty) -> Option<Self> {
2128 if let TyKind::Path(QPath::Resolved(None, ref path)) = hir_ty.node {
2129 let params: Vec<_> = path
2137 .filter_map(|arg| match arg {
2138 GenericArg::Type(ty) => Some(ty),
2142 let params_len = params.len();
2144 let ty = hir_ty_to_ty(cx.tcx, hir_ty);
2146 if match_path(path, &paths::HASHMAP) && params_len == 2 {
2147 Some(ImplicitHasherType::HashMap(
2150 snippet(cx, params[0].span, "K"),
2151 snippet(cx, params[1].span, "V"),
2153 } else if match_path(path, &paths::HASHSET) && params_len == 1 {
2154 Some(ImplicitHasherType::HashSet(
2157 snippet(cx, params[0].span, "T"),
2167 fn type_name(&self) -> &'static str {
2169 ImplicitHasherType::HashMap(..) => "HashMap",
2170 ImplicitHasherType::HashSet(..) => "HashSet",
2174 fn type_arguments(&self) -> String {
2176 ImplicitHasherType::HashMap(.., ref k, ref v) => format!("{}, {}", k, v),
2177 ImplicitHasherType::HashSet(.., ref t) => format!("{}", t),
2181 fn ty(&self) -> Ty<'tcx> {
2183 ImplicitHasherType::HashMap(_, ty, ..) | ImplicitHasherType::HashSet(_, ty, ..) => ty,
2187 fn span(&self) -> Span {
2189 ImplicitHasherType::HashMap(span, ..) | ImplicitHasherType::HashSet(span, ..) => span,
2194 struct ImplicitHasherTypeVisitor<'a, 'tcx: 'a> {
2195 cx: &'a LateContext<'a, 'tcx>,
2196 found: Vec<ImplicitHasherType<'tcx>>,
2199 impl<'a, 'tcx: 'a> ImplicitHasherTypeVisitor<'a, 'tcx> {
2200 fn new(cx: &'a LateContext<'a, 'tcx>) -> Self {
2201 Self { cx, found: vec![] }
2205 impl<'a, 'tcx: 'a> Visitor<'tcx> for ImplicitHasherTypeVisitor<'a, 'tcx> {
2206 fn visit_ty(&mut self, t: &'tcx hir::Ty) {
2207 if let Some(target) = ImplicitHasherType::new(self.cx, t) {
2208 self.found.push(target);
2214 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
2215 NestedVisitorMap::None
2219 /// Looks for default-hasher-dependent constructors like `HashMap::new`.
2220 struct ImplicitHasherConstructorVisitor<'a, 'b, 'tcx: 'a + 'b> {
2221 cx: &'a LateContext<'a, 'tcx>,
2222 body: &'a TypeckTables<'tcx>,
2223 target: &'b ImplicitHasherType<'tcx>,
2224 suggestions: BTreeMap<Span, String>,
2227 impl<'a, 'b, 'tcx: 'a + 'b> ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> {
2228 fn new(cx: &'a LateContext<'a, 'tcx>, target: &'b ImplicitHasherType<'tcx>) -> Self {
2233 suggestions: BTreeMap::new(),
2238 impl<'a, 'b, 'tcx: 'a + 'b> Visitor<'tcx> for ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> {
2239 fn visit_body(&mut self, body: &'tcx Body) {
2240 let prev_body = self.body;
2241 self.body = self.cx.tcx.body_tables(body.id());
2242 walk_body(self, body);
2243 self.body = prev_body;
2246 fn visit_expr(&mut self, e: &'tcx Expr) {
2248 if let ExprKind::Call(ref fun, ref args) = e.node;
2249 if let ExprKind::Path(QPath::TypeRelative(ref ty, ref method)) = fun.node;
2250 if let TyKind::Path(QPath::Resolved(None, ref ty_path)) = ty.node;
2252 if !same_tys(self.cx, self.target.ty(), self.body.expr_ty(e)) {
2256 if match_path(ty_path, &paths::HASHMAP) {
2257 if method.ident.name == "new" {
2259 .insert(e.span, "HashMap::default()".to_string());
2260 } else if method.ident.name == "with_capacity" {
2261 self.suggestions.insert(
2264 "HashMap::with_capacity_and_hasher({}, Default::default())",
2265 snippet(self.cx, args[0].span, "capacity"),
2269 } else if match_path(ty_path, &paths::HASHSET) {
2270 if method.ident.name == "new" {
2272 .insert(e.span, "HashSet::default()".to_string());
2273 } else if method.ident.name == "with_capacity" {
2274 self.suggestions.insert(
2277 "HashSet::with_capacity_and_hasher({}, Default::default())",
2278 snippet(self.cx, args[0].span, "capacity"),
2289 fn nested_visit_map<'this>(&'this mut self) -> NestedVisitorMap<'this, 'tcx> {
2290 NestedVisitorMap::OnlyBodies(&self.cx.tcx.hir())
2294 declare_clippy_lint! {
2295 /// **What it does:** Checks for casts of `&T` to `&mut T` anywhere in the code.
2297 /// **Why is this bad?** It’s basically guaranteed to be undefined behaviour.
2298 /// `UnsafeCell` is the only way to obtain aliasable data that is considered
2301 /// **Known problems:** None.
2307 /// *(r as *const _ as *mut _) += 1;
2312 /// Instead consider using interior mutability types.
2315 /// fn x(r: &UnsafeCell<i32>) {
2321 pub CAST_REF_TO_MUT,
2323 "a cast of reference to a mutable pointer"
2326 pub struct RefToMut;
2328 impl LintPass for RefToMut {
2329 fn get_lints(&self) -> LintArray {
2330 lint_array!(CAST_REF_TO_MUT)
2333 fn name(&self) -> &'static str {
2338 impl<'a, 'tcx> LateLintPass<'a, 'tcx> for RefToMut {
2339 fn check_expr(&mut self, cx: &LateContext<'a, 'tcx>, expr: &'tcx Expr) {
2341 if let ExprKind::Unary(UnOp::UnDeref, e) = &expr.node;
2342 if let ExprKind::Cast(e, t) = &e.node;
2343 if let TyKind::Ptr(MutTy { mutbl: Mutability::MutMutable, .. }) = t.node;
2344 if let ExprKind::Cast(e, t) = &e.node;
2345 if let TyKind::Ptr(MutTy { mutbl: Mutability::MutImmutable, .. }) = t.node;
2346 if let ty::Ref(..) = cx.tables.node_type(e.hir_id).sty;
2352 "casting &T to &mut T may cause undefined behaviour, consider instead using an UnsafeCell",