| #![allow(rustc::default_hash_types)] |
| |
| use std::borrow::Cow; |
| use std::cmp::Ordering; |
| use std::collections::BTreeMap; |
| |
| use if_chain::if_chain; |
| use rustc_ast::ast::{FloatTy, IntTy, LitFloatType, LitIntType, LitKind, UintTy}; |
| use rustc_errors::{Applicability, DiagnosticBuilder}; |
| use rustc_hir as hir; |
| use rustc_hir::intravisit::{walk_body, walk_expr, walk_ty, FnKind, NestedVisitorMap, Visitor}; |
| use rustc_hir::{ |
| BinOpKind, Block, Body, Expr, ExprKind, FnDecl, FnRetTy, FnSig, GenericArg, GenericParamKind, HirId, ImplItem, |
| ImplItemKind, Item, ItemKind, Lifetime, Local, MatchSource, MutTy, Mutability, QPath, Stmt, StmtKind, TraitFn, |
| TraitItem, TraitItemKind, TyKind, UnOp, |
| }; |
| use rustc_lint::{LateContext, LateLintPass, LintContext}; |
| use rustc_middle::hir::map::Map; |
| use rustc_middle::lint::in_external_macro; |
| use rustc_middle::ty::{self, InferTy, Ty, TyCtxt, TyS, TypeckTables}; |
| use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass}; |
| use rustc_span::hygiene::{ExpnKind, MacroKind}; |
| use rustc_span::source_map::Span; |
| use rustc_span::symbol::sym; |
| use rustc_target::abi::LayoutOf; |
| use rustc_target::spec::abi::Abi; |
| use rustc_typeck::hir_ty_to_ty; |
| |
| use crate::consts::{constant, Constant}; |
| use crate::utils::paths; |
| use crate::utils::{ |
| clip, comparisons, differing_macro_contexts, higher, in_constant, indent_of, int_bits, is_type_diagnostic_item, |
| last_path_segment, match_def_path, match_path, method_chain_args, multispan_sugg, numeric_literal::NumericLiteral, |
| qpath_res, sext, snippet, snippet_block_with_applicability, snippet_opt, snippet_with_applicability, |
| snippet_with_macro_callsite, span_lint, span_lint_and_help, span_lint_and_sugg, span_lint_and_then, unsext, |
| }; |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for use of `Box<Vec<_>>` anywhere in the code. |
| /// |
| /// **Why is this bad?** `Vec` already keeps its contents in a separate area on |
| /// the heap. So if you `Box` it, you just add another level of indirection |
| /// without any benefit whatsoever. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust,ignore |
| /// struct X { |
| /// values: Box<Vec<Foo>>, |
| /// } |
| /// ``` |
| /// |
| /// Better: |
| /// |
| /// ```rust,ignore |
| /// struct X { |
| /// values: Vec<Foo>, |
| /// } |
| /// ``` |
| pub BOX_VEC, |
| perf, |
| "usage of `Box<Vec<T>>`, vector elements are already on the heap" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for use of `Vec<Box<T>>` where T: Sized anywhere in the code. |
| /// |
| /// **Why is this bad?** `Vec` already keeps its contents in a separate area on |
| /// the heap. So if you `Box` its contents, you just add another level of indirection. |
| /// |
| /// **Known problems:** Vec<Box<T: Sized>> makes sense if T is a large type (see #3530, |
| /// 1st comment). |
| /// |
| /// **Example:** |
| /// ```rust |
| /// struct X { |
| /// values: Vec<Box<i32>>, |
| /// } |
| /// ``` |
| /// |
| /// Better: |
| /// |
| /// ```rust |
| /// struct X { |
| /// values: Vec<i32>, |
| /// } |
| /// ``` |
| pub VEC_BOX, |
| complexity, |
| "usage of `Vec<Box<T>>` where T: Sized, vector elements are already on the heap" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for use of `Option<Option<_>>` in function signatures and type |
| /// definitions |
| /// |
| /// **Why is this bad?** `Option<_>` represents an optional value. `Option<Option<_>>` |
| /// represents an optional optional value which is logically the same thing as an optional |
| /// value but has an unneeded extra level of wrapping. |
| /// |
| /// If you have a case where `Some(Some(_))`, `Some(None)` and `None` are distinct cases, |
| /// consider a custom `enum` instead, with clear names for each case. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example** |
| /// ```rust |
| /// fn get_data() -> Option<Option<u32>> { |
| /// None |
| /// } |
| /// ``` |
| /// |
| /// Better: |
| /// |
| /// ```rust |
| /// pub enum Contents { |
| /// Data(Vec<u8>), // Was Some(Some(Vec<u8>)) |
| /// NotYetFetched, // Was Some(None) |
| /// None, // Was None |
| /// } |
| /// |
| /// fn get_data() -> Contents { |
| /// Contents::None |
| /// } |
| /// ``` |
| pub OPTION_OPTION, |
| pedantic, |
| "usage of `Option<Option<T>>`" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for usage of any `LinkedList`, suggesting to use a |
| /// `Vec` or a `VecDeque` (formerly called `RingBuf`). |
| /// |
| /// **Why is this bad?** Gankro says: |
| /// |
| /// > The TL;DR of `LinkedList` is that it's built on a massive amount of |
| /// pointers and indirection. |
| /// > It wastes memory, it has terrible cache locality, and is all-around slow. |
| /// `RingBuf`, while |
| /// > "only" amortized for push/pop, should be faster in the general case for |
| /// almost every possible |
| /// > workload, and isn't even amortized at all if you can predict the capacity |
| /// you need. |
| /// > |
| /// > `LinkedList`s are only really good if you're doing a lot of merging or |
| /// splitting of lists. |
| /// > This is because they can just mangle some pointers instead of actually |
| /// copying the data. Even |
| /// > if you're doing a lot of insertion in the middle of the list, `RingBuf` |
| /// can still be better |
| /// > because of how expensive it is to seek to the middle of a `LinkedList`. |
| /// |
| /// **Known problems:** False positives – the instances where using a |
| /// `LinkedList` makes sense are few and far between, but they can still happen. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// # use std::collections::LinkedList; |
| /// let x: LinkedList<usize> = LinkedList::new(); |
| /// ``` |
| pub LINKEDLIST, |
| pedantic, |
| "usage of LinkedList, usually a vector is faster, or a more specialized data structure like a `VecDeque`" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for use of `&Box<T>` anywhere in the code. |
| /// |
| /// **Why is this bad?** Any `&Box<T>` can also be a `&T`, which is more |
| /// general. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust,ignore |
| /// fn foo(bar: &Box<T>) { ... } |
| /// ``` |
| /// |
| /// Better: |
| /// |
| /// ```rust,ignore |
| /// fn foo(bar: &T) { ... } |
| /// ``` |
| pub BORROWED_BOX, |
| complexity, |
| "a borrow of a boxed type" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for use of redundant allocations anywhere in the code. |
| /// |
| /// **Why is this bad?** Expressions such as `Rc<&T>`, `Rc<Rc<T>>`, `Rc<Box<T>>`, `Box<&T>` |
| /// add an unnecessary level of indirection. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// # use std::rc::Rc; |
| /// fn foo(bar: Rc<&usize>) {} |
| /// ``` |
| /// |
| /// Better: |
| /// |
| /// ```rust |
| /// fn foo(bar: &usize) {} |
| /// ``` |
| pub REDUNDANT_ALLOCATION, |
| perf, |
| "redundant allocation" |
| } |
| |
| pub struct Types { |
| vec_box_size_threshold: u64, |
| } |
| |
| impl_lint_pass!(Types => [BOX_VEC, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX, REDUNDANT_ALLOCATION]); |
| |
| impl<'tcx> LateLintPass<'tcx> for Types { |
| fn check_fn(&mut self, cx: &LateContext<'_>, _: FnKind<'_>, decl: &FnDecl<'_>, _: &Body<'_>, _: Span, id: HirId) { |
| // Skip trait implementations; see issue #605. |
| if let Some(hir::Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_item(id)) { |
| if let ItemKind::Impl { of_trait: Some(_), .. } = item.kind { |
| return; |
| } |
| } |
| |
| self.check_fn_decl(cx, decl); |
| } |
| |
| fn check_struct_field(&mut self, cx: &LateContext<'_>, field: &hir::StructField<'_>) { |
| self.check_ty(cx, &field.ty, false); |
| } |
| |
| fn check_trait_item(&mut self, cx: &LateContext<'_>, item: &TraitItem<'_>) { |
| match item.kind { |
| TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => self.check_ty(cx, ty, false), |
| TraitItemKind::Fn(ref sig, _) => self.check_fn_decl(cx, &sig.decl), |
| _ => (), |
| } |
| } |
| |
| fn check_local(&mut self, cx: &LateContext<'_>, local: &Local<'_>) { |
| if let Some(ref ty) = local.ty { |
| self.check_ty(cx, ty, true); |
| } |
| } |
| } |
| |
| /// Checks if `qpath` has last segment with type parameter matching `path` |
| fn match_type_parameter(cx: &LateContext<'_>, qpath: &QPath<'_>, path: &[&str]) -> Option<Span> { |
| let last = last_path_segment(qpath); |
| if_chain! { |
| if let Some(ref params) = last.args; |
| if !params.parenthesized; |
| if let Some(ty) = params.args.iter().find_map(|arg| match arg { |
| GenericArg::Type(ty) => Some(ty), |
| _ => None, |
| }); |
| if let TyKind::Path(ref qpath) = ty.kind; |
| if let Some(did) = qpath_res(cx, qpath, ty.hir_id).opt_def_id(); |
| if match_def_path(cx, did, path); |
| then { |
| return Some(ty.span); |
| } |
| } |
| None |
| } |
| |
| fn match_borrows_parameter(_cx: &LateContext<'_>, qpath: &QPath<'_>) -> Option<Span> { |
| let last = last_path_segment(qpath); |
| if_chain! { |
| if let Some(ref params) = last.args; |
| if !params.parenthesized; |
| if let Some(ty) = params.args.iter().find_map(|arg| match arg { |
| GenericArg::Type(ty) => Some(ty), |
| _ => None, |
| }); |
| if let TyKind::Rptr(..) = ty.kind; |
| then { |
| return Some(ty.span); |
| } |
| } |
| None |
| } |
| |
| impl Types { |
| pub fn new(vec_box_size_threshold: u64) -> Self { |
| Self { vec_box_size_threshold } |
| } |
| |
| fn check_fn_decl(&mut self, cx: &LateContext<'_>, decl: &FnDecl<'_>) { |
| for input in decl.inputs { |
| self.check_ty(cx, input, false); |
| } |
| |
| if let FnRetTy::Return(ref ty) = decl.output { |
| self.check_ty(cx, ty, false); |
| } |
| } |
| |
| /// Recursively check for `TypePass` lints in the given type. Stop at the first |
| /// lint found. |
| /// |
| /// The parameter `is_local` distinguishes the context of the type; types from |
| /// local bindings should only be checked for the `BORROWED_BOX` lint. |
| #[allow(clippy::too_many_lines)] |
| fn check_ty(&mut self, cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, is_local: bool) { |
| if hir_ty.span.from_expansion() { |
| return; |
| } |
| match hir_ty.kind { |
| TyKind::Path(ref qpath) if !is_local => { |
| let hir_id = hir_ty.hir_id; |
| let res = qpath_res(cx, qpath, hir_id); |
| if let Some(def_id) = res.opt_def_id() { |
| if Some(def_id) == cx.tcx.lang_items().owned_box() { |
| if let Some(span) = match_borrows_parameter(cx, qpath) { |
| span_lint_and_sugg( |
| cx, |
| REDUNDANT_ALLOCATION, |
| hir_ty.span, |
| "usage of `Box<&T>`", |
| "try", |
| snippet(cx, span, "..").to_string(), |
| Applicability::MachineApplicable, |
| ); |
| return; // don't recurse into the type |
| } |
| if match_type_parameter(cx, qpath, &paths::VEC).is_some() { |
| span_lint_and_help( |
| cx, |
| BOX_VEC, |
| hir_ty.span, |
| "you seem to be trying to use `Box<Vec<T>>`. Consider using just `Vec<T>`", |
| None, |
| "`Vec<T>` is already on the heap, `Box<Vec<T>>` makes an extra allocation.", |
| ); |
| return; // don't recurse into the type |
| } |
| } else if cx.tcx.is_diagnostic_item(sym::Rc, def_id) { |
| if let Some(span) = match_type_parameter(cx, qpath, &paths::RC) { |
| span_lint_and_sugg( |
| cx, |
| REDUNDANT_ALLOCATION, |
| hir_ty.span, |
| "usage of `Rc<Rc<T>>`", |
| "try", |
| snippet(cx, span, "..").to_string(), |
| Applicability::MachineApplicable, |
| ); |
| return; // don't recurse into the type |
| } |
| if let Some(span) = match_type_parameter(cx, qpath, &paths::BOX) { |
| span_lint_and_sugg( |
| cx, |
| REDUNDANT_ALLOCATION, |
| hir_ty.span, |
| "usage of `Rc<Box<T>>`", |
| "try", |
| snippet(cx, span, "..").to_string(), |
| Applicability::MachineApplicable, |
| ); |
| return; // don't recurse into the type |
| } |
| if let Some(span) = match_borrows_parameter(cx, qpath) { |
| span_lint_and_sugg( |
| cx, |
| REDUNDANT_ALLOCATION, |
| hir_ty.span, |
| "usage of `Rc<&T>`", |
| "try", |
| snippet(cx, span, "..").to_string(), |
| Applicability::MachineApplicable, |
| ); |
| return; // don't recurse into the type |
| } |
| } else if cx.tcx.is_diagnostic_item(sym!(vec_type), def_id) { |
| if_chain! { |
| // Get the _ part of Vec<_> |
| if let Some(ref last) = last_path_segment(qpath).args; |
| if let Some(ty) = last.args.iter().find_map(|arg| match arg { |
| GenericArg::Type(ty) => Some(ty), |
| _ => None, |
| }); |
| // ty is now _ at this point |
| if let TyKind::Path(ref ty_qpath) = ty.kind; |
| let res = qpath_res(cx, ty_qpath, ty.hir_id); |
| if let Some(def_id) = res.opt_def_id(); |
| if Some(def_id) == cx.tcx.lang_items().owned_box(); |
| // At this point, we know ty is Box<T>, now get T |
| if let Some(ref last) = last_path_segment(ty_qpath).args; |
| if let Some(boxed_ty) = last.args.iter().find_map(|arg| match arg { |
| GenericArg::Type(ty) => Some(ty), |
| _ => None, |
| }); |
| let ty_ty = hir_ty_to_ty(cx.tcx, boxed_ty); |
| if ty_ty.is_sized(cx.tcx.at(ty.span), cx.param_env); |
| if let Ok(ty_ty_size) = cx.layout_of(ty_ty).map(|l| l.size.bytes()); |
| if ty_ty_size <= self.vec_box_size_threshold; |
| then { |
| span_lint_and_sugg( |
| cx, |
| VEC_BOX, |
| hir_ty.span, |
| "`Vec<T>` is already on the heap, the boxing is unnecessary.", |
| "try", |
| format!("Vec<{}>", ty_ty), |
| Applicability::MachineApplicable, |
| ); |
| return; // don't recurse into the type |
| } |
| } |
| } else if cx.tcx.is_diagnostic_item(sym!(option_type), def_id) { |
| if match_type_parameter(cx, qpath, &paths::OPTION).is_some() { |
| span_lint( |
| cx, |
| OPTION_OPTION, |
| hir_ty.span, |
| "consider using `Option<T>` instead of `Option<Option<T>>` or a custom \ |
| enum if you need to distinguish all 3 cases", |
| ); |
| return; // don't recurse into the type |
| } |
| } else if match_def_path(cx, def_id, &paths::LINKED_LIST) { |
| span_lint_and_help( |
| cx, |
| LINKEDLIST, |
| hir_ty.span, |
| "I see you're using a LinkedList! Perhaps you meant some other data structure?", |
| None, |
| "a `VecDeque` might work", |
| ); |
| return; // don't recurse into the type |
| } |
| } |
| match *qpath { |
| QPath::Resolved(Some(ref ty), ref p) => { |
| self.check_ty(cx, ty, is_local); |
| for ty in p.segments.iter().flat_map(|seg| { |
| seg.args |
| .as_ref() |
| .map_or_else(|| [].iter(), |params| params.args.iter()) |
| .filter_map(|arg| match arg { |
| GenericArg::Type(ty) => Some(ty), |
| _ => None, |
| }) |
| }) { |
| self.check_ty(cx, ty, is_local); |
| } |
| }, |
| QPath::Resolved(None, ref p) => { |
| for ty in p.segments.iter().flat_map(|seg| { |
| seg.args |
| .as_ref() |
| .map_or_else(|| [].iter(), |params| params.args.iter()) |
| .filter_map(|arg| match arg { |
| GenericArg::Type(ty) => Some(ty), |
| _ => None, |
| }) |
| }) { |
| self.check_ty(cx, ty, is_local); |
| } |
| }, |
| QPath::TypeRelative(ref ty, ref seg) => { |
| self.check_ty(cx, ty, is_local); |
| if let Some(ref params) = seg.args { |
| for ty in params.args.iter().filter_map(|arg| match arg { |
| GenericArg::Type(ty) => Some(ty), |
| _ => None, |
| }) { |
| self.check_ty(cx, ty, is_local); |
| } |
| } |
| }, |
| } |
| }, |
| TyKind::Rptr(ref lt, ref mut_ty) => self.check_ty_rptr(cx, hir_ty, is_local, lt, mut_ty), |
| // recurse |
| TyKind::Slice(ref ty) | TyKind::Array(ref ty, _) | TyKind::Ptr(MutTy { ref ty, .. }) => { |
| self.check_ty(cx, ty, is_local) |
| }, |
| TyKind::Tup(tys) => { |
| for ty in tys { |
| self.check_ty(cx, ty, is_local); |
| } |
| }, |
| _ => {}, |
| } |
| } |
| |
| fn check_ty_rptr( |
| &mut self, |
| cx: &LateContext<'_>, |
| hir_ty: &hir::Ty<'_>, |
| is_local: bool, |
| lt: &Lifetime, |
| mut_ty: &MutTy<'_>, |
| ) { |
| match mut_ty.ty.kind { |
| TyKind::Path(ref qpath) => { |
| let hir_id = mut_ty.ty.hir_id; |
| let def = qpath_res(cx, qpath, hir_id); |
| if_chain! { |
| if let Some(def_id) = def.opt_def_id(); |
| if Some(def_id) == cx.tcx.lang_items().owned_box(); |
| if let QPath::Resolved(None, ref path) = *qpath; |
| if let [ref bx] = *path.segments; |
| if let Some(ref params) = bx.args; |
| if !params.parenthesized; |
| if let Some(inner) = params.args.iter().find_map(|arg| match arg { |
| GenericArg::Type(ty) => Some(ty), |
| _ => None, |
| }); |
| then { |
| if is_any_trait(inner) { |
| // Ignore `Box<Any>` types; see issue #1884 for details. |
| return; |
| } |
| |
| let ltopt = if lt.is_elided() { |
| String::new() |
| } else { |
| format!("{} ", lt.name.ident().as_str()) |
| }; |
| |
| if mut_ty.mutbl == Mutability::Mut { |
| // Ignore `&mut Box<T>` types; see issue #2907 for |
| // details. |
| return; |
| } |
| let mut applicability = Applicability::MachineApplicable; |
| span_lint_and_sugg( |
| cx, |
| BORROWED_BOX, |
| hir_ty.span, |
| "you seem to be trying to use `&Box<T>`. Consider using just `&T`", |
| "try", |
| format!( |
| "&{}{}", |
| ltopt, |
| &snippet_with_applicability(cx, inner.span, "..", &mut applicability) |
| ), |
| Applicability::Unspecified, |
| ); |
| return; // don't recurse into the type |
| } |
| }; |
| self.check_ty(cx, &mut_ty.ty, is_local); |
| }, |
| _ => self.check_ty(cx, &mut_ty.ty, is_local), |
| } |
| } |
| } |
| |
| // Returns true if given type is `Any` trait. |
| fn is_any_trait(t: &hir::Ty<'_>) -> bool { |
| if_chain! { |
| if let TyKind::TraitObject(ref traits, _) = t.kind; |
| if !traits.is_empty(); |
| // Only Send/Sync can be used as additional traits, so it is enough to |
| // check only the first trait. |
| if match_path(&traits[0].trait_ref.path, &paths::ANY_TRAIT); |
| then { |
| return true; |
| } |
| } |
| |
| false |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for binding a unit value. |
| /// |
| /// **Why is this bad?** A unit value cannot usefully be used anywhere. So |
| /// binding one is kind of pointless. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// let x = { |
| /// 1; |
| /// }; |
| /// ``` |
| pub LET_UNIT_VALUE, |
| pedantic, |
| "creating a `let` binding to a value of unit type, which usually can't be used afterwards" |
| } |
| |
| declare_lint_pass!(LetUnitValue => [LET_UNIT_VALUE]); |
| |
| impl<'tcx> LateLintPass<'tcx> for LetUnitValue { |
| fn check_stmt(&mut self, cx: &LateContext<'tcx>, stmt: &'tcx Stmt<'_>) { |
| if let StmtKind::Local(ref local) = stmt.kind { |
| if is_unit(cx.tables().pat_ty(&local.pat)) { |
| if in_external_macro(cx.sess(), stmt.span) || local.pat.span.from_expansion() { |
| return; |
| } |
| if higher::is_from_for_desugar(local) { |
| return; |
| } |
| span_lint_and_then( |
| cx, |
| LET_UNIT_VALUE, |
| stmt.span, |
| "this let-binding has unit value", |
| |diag| { |
| if let Some(expr) = &local.init { |
| let snip = snippet_with_macro_callsite(cx, expr.span, "()"); |
| diag.span_suggestion( |
| stmt.span, |
| "omit the `let` binding", |
| format!("{};", snip), |
| Applicability::MachineApplicable, // snippet |
| ); |
| } |
| }, |
| ); |
| } |
| } |
| } |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for comparisons to unit. This includes all binary |
| /// comparisons (like `==` and `<`) and asserts. |
| /// |
| /// **Why is this bad?** Unit is always equal to itself, and thus is just a |
| /// clumsily written constant. Mostly this happens when someone accidentally |
| /// adds semicolons at the end of the operands. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// # fn foo() {}; |
| /// # fn bar() {}; |
| /// # fn baz() {}; |
| /// if { |
| /// foo(); |
| /// } == { |
| /// bar(); |
| /// } { |
| /// baz(); |
| /// } |
| /// ``` |
| /// is equal to |
| /// ```rust |
| /// # fn foo() {}; |
| /// # fn bar() {}; |
| /// # fn baz() {}; |
| /// { |
| /// foo(); |
| /// bar(); |
| /// baz(); |
| /// } |
| /// ``` |
| /// |
| /// For asserts: |
| /// ```rust |
| /// # fn foo() {}; |
| /// # fn bar() {}; |
| /// assert_eq!({ foo(); }, { bar(); }); |
| /// ``` |
| /// will always succeed |
| pub UNIT_CMP, |
| correctness, |
| "comparing unit values" |
| } |
| |
| declare_lint_pass!(UnitCmp => [UNIT_CMP]); |
| |
| impl<'tcx> LateLintPass<'tcx> for UnitCmp { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) { |
| if expr.span.from_expansion() { |
| if let Some(callee) = expr.span.source_callee() { |
| if let ExpnKind::Macro(MacroKind::Bang, symbol) = callee.kind { |
| if let ExprKind::Binary(ref cmp, ref left, _) = expr.kind { |
| let op = cmp.node; |
| if op.is_comparison() && is_unit(cx.tables().expr_ty(left)) { |
| let result = match &*symbol.as_str() { |
| "assert_eq" | "debug_assert_eq" => "succeed", |
| "assert_ne" | "debug_assert_ne" => "fail", |
| _ => return, |
| }; |
| span_lint( |
| cx, |
| UNIT_CMP, |
| expr.span, |
| &format!( |
| "`{}` of unit values detected. This will always {}", |
| symbol.as_str(), |
| result |
| ), |
| ); |
| } |
| } |
| } |
| } |
| return; |
| } |
| if let ExprKind::Binary(ref cmp, ref left, _) = expr.kind { |
| let op = cmp.node; |
| if op.is_comparison() && is_unit(cx.tables().expr_ty(left)) { |
| let result = match op { |
| BinOpKind::Eq | BinOpKind::Le | BinOpKind::Ge => "true", |
| _ => "false", |
| }; |
| span_lint( |
| cx, |
| UNIT_CMP, |
| expr.span, |
| &format!( |
| "{}-comparison of unit values detected. This will always be {}", |
| op.as_str(), |
| result |
| ), |
| ); |
| } |
| } |
| } |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for passing a unit value as an argument to a function without using a |
| /// unit literal (`()`). |
| /// |
| /// **Why is this bad?** This is likely the result of an accidental semicolon. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust,ignore |
| /// foo({ |
| /// let a = bar(); |
| /// baz(a); |
| /// }) |
| /// ``` |
| pub UNIT_ARG, |
| complexity, |
| "passing unit to a function" |
| } |
| |
| declare_lint_pass!(UnitArg => [UNIT_ARG]); |
| |
| impl<'tcx> LateLintPass<'tcx> for UnitArg { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| if expr.span.from_expansion() { |
| return; |
| } |
| |
| // apparently stuff in the desugaring of `?` can trigger this |
| // so check for that here |
| // only the calls to `Try::from_error` is marked as desugared, |
| // so we need to check both the current Expr and its parent. |
| if is_questionmark_desugar_marked_call(expr) { |
| return; |
| } |
| if_chain! { |
| let map = &cx.tcx.hir(); |
| let opt_parent_node = map.find(map.get_parent_node(expr.hir_id)); |
| if let Some(hir::Node::Expr(parent_expr)) = opt_parent_node; |
| if is_questionmark_desugar_marked_call(parent_expr); |
| then { |
| return; |
| } |
| } |
| |
| match expr.kind { |
| ExprKind::Call(_, args) | ExprKind::MethodCall(_, _, args, _) => { |
| let args_to_recover = args |
| .iter() |
| .filter(|arg| { |
| if is_unit(cx.tables().expr_ty(arg)) && !is_unit_literal(arg) { |
| if let ExprKind::Match(.., MatchSource::TryDesugar) = &arg.kind { |
| false |
| } else { |
| true |
| } |
| } else { |
| false |
| } |
| }) |
| .collect::<Vec<_>>(); |
| if !args_to_recover.is_empty() { |
| lint_unit_args(cx, expr, &args_to_recover); |
| } |
| }, |
| _ => (), |
| } |
| } |
| } |
| |
| fn lint_unit_args(cx: &LateContext<'_>, expr: &Expr<'_>, args_to_recover: &[&Expr<'_>]) { |
| let mut applicability = Applicability::MachineApplicable; |
| let (singular, plural) = if args_to_recover.len() > 1 { |
| ("", "s") |
| } else { |
| ("a ", "") |
| }; |
| span_lint_and_then( |
| cx, |
| UNIT_ARG, |
| expr.span, |
| &format!("passing {}unit value{} to a function", singular, plural), |
| |db| { |
| let mut or = ""; |
| args_to_recover |
| .iter() |
| .filter_map(|arg| { |
| if_chain! { |
| if let ExprKind::Block(block, _) = arg.kind; |
| if block.expr.is_none(); |
| if let Some(last_stmt) = block.stmts.iter().last(); |
| if let StmtKind::Semi(last_expr) = last_stmt.kind; |
| if let Some(snip) = snippet_opt(cx, last_expr.span); |
| then { |
| Some(( |
| last_stmt.span, |
| snip, |
| )) |
| } |
| else { |
| None |
| } |
| } |
| }) |
| .for_each(|(span, sugg)| { |
| db.span_suggestion( |
| span, |
| "remove the semicolon from the last statement in the block", |
| sugg, |
| Applicability::MaybeIncorrect, |
| ); |
| or = "or "; |
| }); |
| let sugg = args_to_recover |
| .iter() |
| .filter(|arg| !is_empty_block(arg)) |
| .enumerate() |
| .map(|(i, arg)| { |
| let indent = if i == 0 { |
| 0 |
| } else { |
| indent_of(cx, expr.span).unwrap_or(0) |
| }; |
| format!( |
| "{}{};", |
| " ".repeat(indent), |
| snippet_block_with_applicability(cx, arg.span, "..", Some(expr.span), &mut applicability) |
| ) |
| }) |
| .collect::<Vec<String>>(); |
| let mut and = ""; |
| if !sugg.is_empty() { |
| let plural = if sugg.len() > 1 { "s" } else { "" }; |
| db.span_suggestion( |
| expr.span.with_hi(expr.span.lo()), |
| &format!("{}move the expression{} in front of the call...", or, plural), |
| format!("{}\n", sugg.join("\n")), |
| applicability, |
| ); |
| and = "...and " |
| } |
| db.multipart_suggestion( |
| &format!("{}use {}unit literal{} instead", and, singular, plural), |
| args_to_recover |
| .iter() |
| .map(|arg| (arg.span, "()".to_string())) |
| .collect::<Vec<_>>(), |
| applicability, |
| ); |
| }, |
| ); |
| } |
| |
| fn is_empty_block(expr: &Expr<'_>) -> bool { |
| matches!( |
| expr.kind, |
| ExprKind::Block( |
| Block { |
| stmts: &[], expr: None, .. |
| }, |
| _, |
| ) |
| ) |
| } |
| |
| fn is_questionmark_desugar_marked_call(expr: &Expr<'_>) -> bool { |
| use rustc_span::hygiene::DesugaringKind; |
| if let ExprKind::Call(ref callee, _) = expr.kind { |
| callee.span.is_desugaring(DesugaringKind::QuestionMark) |
| } else { |
| false |
| } |
| } |
| |
| fn is_unit(ty: Ty<'_>) -> bool { |
| match ty.kind { |
| ty::Tuple(slice) if slice.is_empty() => true, |
| _ => false, |
| } |
| } |
| |
| fn is_unit_literal(expr: &Expr<'_>) -> bool { |
| match expr.kind { |
| ExprKind::Tup(ref slice) if slice.is_empty() => true, |
| _ => false, |
| } |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for casts from any numerical to a float type where |
| /// the receiving type cannot store all values from the original type without |
| /// rounding errors. This possible rounding is to be expected, so this lint is |
| /// `Allow` by default. |
| /// |
| /// Basically, this warns on casting any integer with 32 or more bits to `f32` |
| /// or any 64-bit integer to `f64`. |
| /// |
| /// **Why is this bad?** It's not bad at all. But in some applications it can be |
| /// helpful to know where precision loss can take place. This lint can help find |
| /// those places in the code. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// let x = u64::MAX; |
| /// x as f64; |
| /// ``` |
| pub CAST_PRECISION_LOSS, |
| pedantic, |
| "casts that cause loss of precision, e.g., `x as f32` where `x: u64`" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for casts from a signed to an unsigned numerical |
| /// type. In this case, negative values wrap around to large positive values, |
| /// which can be quite surprising in practice. However, as the cast works as |
| /// defined, this lint is `Allow` by default. |
| /// |
| /// **Why is this bad?** Possibly surprising results. You can activate this lint |
| /// as a one-time check to see where numerical wrapping can arise. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// let y: i8 = -1; |
| /// y as u128; // will return 18446744073709551615 |
| /// ``` |
| pub CAST_SIGN_LOSS, |
| pedantic, |
| "casts from signed types to unsigned types, e.g., `x as u32` where `x: i32`" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for casts between numerical types that may |
| /// truncate large values. This is expected behavior, so the cast is `Allow` by |
| /// default. |
| /// |
| /// **Why is this bad?** In some problem domains, it is good practice to avoid |
| /// truncation. This lint can be activated to help assess where additional |
| /// checks could be beneficial. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// fn as_u8(x: u64) -> u8 { |
| /// x as u8 |
| /// } |
| /// ``` |
| pub CAST_POSSIBLE_TRUNCATION, |
| pedantic, |
| "casts that may cause truncation of the value, e.g., `x as u8` where `x: u32`, or `x as i32` where `x: f32`" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for casts from an unsigned type to a signed type of |
| /// the same size. Performing such a cast is a 'no-op' for the compiler, |
| /// i.e., nothing is changed at the bit level, and the binary representation of |
| /// the value is reinterpreted. This can cause wrapping if the value is too big |
| /// for the target signed type. However, the cast works as defined, so this lint |
| /// is `Allow` by default. |
| /// |
| /// **Why is this bad?** While such a cast is not bad in itself, the results can |
| /// be surprising when this is not the intended behavior, as demonstrated by the |
| /// example below. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// u32::MAX as i32; // will yield a value of `-1` |
| /// ``` |
| pub CAST_POSSIBLE_WRAP, |
| pedantic, |
| "casts that may cause wrapping around the value, e.g., `x as i32` where `x: u32` and `x > i32::MAX`" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for casts between numerical types that may |
| /// be replaced by safe conversion functions. |
| /// |
| /// **Why is this bad?** Rust's `as` keyword will perform many kinds of |
| /// conversions, including silently lossy conversions. Conversion functions such |
| /// as `i32::from` will only perform lossless conversions. Using the conversion |
| /// functions prevents conversions from turning into silent lossy conversions if |
| /// the types of the input expressions ever change, and make it easier for |
| /// people reading the code to know that the conversion is lossless. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// fn as_u64(x: u8) -> u64 { |
| /// x as u64 |
| /// } |
| /// ``` |
| /// |
| /// Using `::from` would look like this: |
| /// |
| /// ```rust |
| /// fn as_u64(x: u8) -> u64 { |
| /// u64::from(x) |
| /// } |
| /// ``` |
| pub CAST_LOSSLESS, |
| pedantic, |
| "casts using `as` that are known to be lossless, e.g., `x as u64` where `x: u8`" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for casts to the same type. |
| /// |
| /// **Why is this bad?** It's just unnecessary. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// let _ = 2i32 as i32; |
| /// ``` |
| pub UNNECESSARY_CAST, |
| complexity, |
| "cast to the same type, e.g., `x as i32` where `x: i32`" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for casts from a less-strictly-aligned pointer to a |
| /// more-strictly-aligned pointer |
| /// |
| /// **Why is this bad?** Dereferencing the resulting pointer may be undefined |
| /// behavior. |
| /// |
| /// **Known problems:** Using `std::ptr::read_unaligned` and `std::ptr::write_unaligned` or similar |
| /// on the resulting pointer is fine. Is over-zealous: Casts with manual alignment checks or casts like |
| /// u64-> u8 -> u16 can be fine. Miri is able to do a more in-depth analysis. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// let _ = (&1u8 as *const u8) as *const u16; |
| /// let _ = (&mut 1u8 as *mut u8) as *mut u16; |
| /// ``` |
| pub CAST_PTR_ALIGNMENT, |
| pedantic, |
| "cast from a pointer to a more-strictly-aligned pointer" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for casts of function pointers to something other than usize |
| /// |
| /// **Why is this bad?** |
| /// Casting a function pointer to anything other than usize/isize is not portable across |
| /// architectures, because you end up losing bits if the target type is too small or end up with a |
| /// bunch of extra bits that waste space and add more instructions to the final binary than |
| /// strictly necessary for the problem |
| /// |
| /// Casting to isize also doesn't make sense since there are no signed addresses. |
| /// |
| /// **Example** |
| /// |
| /// ```rust |
| /// // Bad |
| /// fn fun() -> i32 { 1 } |
| /// let a = fun as i64; |
| /// |
| /// // Good |
| /// fn fun2() -> i32 { 1 } |
| /// let a = fun2 as usize; |
| /// ``` |
| pub FN_TO_NUMERIC_CAST, |
| style, |
| "casting a function pointer to a numeric type other than usize" |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for casts of a function pointer to a numeric type not wide enough to |
| /// store address. |
| /// |
| /// **Why is this bad?** |
| /// Such a cast discards some bits of the function's address. If this is intended, it would be more |
| /// clearly expressed by casting to usize first, then casting the usize to the intended type (with |
| /// a comment) to perform the truncation. |
| /// |
| /// **Example** |
| /// |
| /// ```rust |
| /// // Bad |
| /// fn fn1() -> i16 { |
| /// 1 |
| /// }; |
| /// let _ = fn1 as i32; |
| /// |
| /// // Better: Cast to usize first, then comment with the reason for the truncation |
| /// fn fn2() -> i16 { |
| /// 1 |
| /// }; |
| /// let fn_ptr = fn2 as usize; |
| /// let fn_ptr_truncated = fn_ptr as i32; |
| /// ``` |
| pub FN_TO_NUMERIC_CAST_WITH_TRUNCATION, |
| style, |
| "casting a function pointer to a numeric type not wide enough to store the address" |
| } |
| |
| /// Returns the size in bits of an integral type. |
| /// Will return 0 if the type is not an int or uint variant |
| fn int_ty_to_nbits(typ: Ty<'_>, tcx: TyCtxt<'_>) -> u64 { |
| match typ.kind { |
| ty::Int(i) => match i { |
| IntTy::Isize => tcx.data_layout.pointer_size.bits(), |
| IntTy::I8 => 8, |
| IntTy::I16 => 16, |
| IntTy::I32 => 32, |
| IntTy::I64 => 64, |
| IntTy::I128 => 128, |
| }, |
| ty::Uint(i) => match i { |
| UintTy::Usize => tcx.data_layout.pointer_size.bits(), |
| UintTy::U8 => 8, |
| UintTy::U16 => 16, |
| UintTy::U32 => 32, |
| UintTy::U64 => 64, |
| UintTy::U128 => 128, |
| }, |
| _ => 0, |
| } |
| } |
| |
| fn is_isize_or_usize(typ: Ty<'_>) -> bool { |
| match typ.kind { |
| ty::Int(IntTy::Isize) | ty::Uint(UintTy::Usize) => true, |
| _ => false, |
| } |
| } |
| |
| fn span_precision_loss_lint(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to_f64: bool) { |
| let mantissa_nbits = if cast_to_f64 { 52 } else { 23 }; |
| let arch_dependent = is_isize_or_usize(cast_from) && cast_to_f64; |
| let arch_dependent_str = "on targets with 64-bit wide pointers "; |
| let from_nbits_str = if arch_dependent { |
| "64".to_owned() |
| } else if is_isize_or_usize(cast_from) { |
| "32 or 64".to_owned() |
| } else { |
| int_ty_to_nbits(cast_from, cx.tcx).to_string() |
| }; |
| span_lint( |
| cx, |
| CAST_PRECISION_LOSS, |
| expr.span, |
| &format!( |
| "casting `{0}` to `{1}` causes a loss of precision {2}(`{0}` is {3} bits wide, \ |
| but `{1}`'s mantissa is only {4} bits wide)", |
| cast_from, |
| if cast_to_f64 { "f64" } else { "f32" }, |
| if arch_dependent { arch_dependent_str } else { "" }, |
| from_nbits_str, |
| mantissa_nbits |
| ), |
| ); |
| } |
| |
| fn should_strip_parens(op: &Expr<'_>, snip: &str) -> bool { |
| if let ExprKind::Binary(_, _, _) = op.kind { |
| if snip.starts_with('(') && snip.ends_with(')') { |
| return true; |
| } |
| } |
| false |
| } |
| |
| fn span_lossless_lint(cx: &LateContext<'_>, expr: &Expr<'_>, op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) { |
| // Do not suggest using From in consts/statics until it is valid to do so (see #2267). |
| if in_constant(cx, expr.hir_id) { |
| return; |
| } |
| // The suggestion is to use a function call, so if the original expression |
| // has parens on the outside, they are no longer needed. |
| let mut applicability = Applicability::MachineApplicable; |
| let opt = snippet_opt(cx, op.span); |
| let sugg = if let Some(ref snip) = opt { |
| if should_strip_parens(op, snip) { |
| &snip[1..snip.len() - 1] |
| } else { |
| snip.as_str() |
| } |
| } else { |
| applicability = Applicability::HasPlaceholders; |
| ".." |
| }; |
| |
| span_lint_and_sugg( |
| cx, |
| CAST_LOSSLESS, |
| expr.span, |
| &format!( |
| "casting `{}` to `{}` may become silently lossy if you later change the type", |
| cast_from, cast_to |
| ), |
| "try", |
| format!("{}::from({})", cast_to, sugg), |
| applicability, |
| ); |
| } |
| |
| enum ArchSuffix { |
| _32, |
| _64, |
| None, |
| } |
| |
| fn check_loss_of_sign(cx: &LateContext<'_>, expr: &Expr<'_>, op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) { |
| if !cast_from.is_signed() || cast_to.is_signed() { |
| return; |
| } |
| |
| // don't lint for positive constants |
| let const_val = constant(cx, &cx.tables(), op); |
| if_chain! { |
| if let Some((const_val, _)) = const_val; |
| if let Constant::Int(n) = const_val; |
| if let ty::Int(ity) = cast_from.kind; |
| if sext(cx.tcx, n, ity) >= 0; |
| then { |
| return |
| } |
| } |
| |
| // don't lint for the result of methods that always return non-negative values |
| if let ExprKind::MethodCall(ref path, _, _, _) = op.kind { |
| let mut method_name = path.ident.name.as_str(); |
| let allowed_methods = ["abs", "checked_abs", "rem_euclid", "checked_rem_euclid"]; |
| |
| if_chain! { |
| if method_name == "unwrap"; |
| if let Some(arglist) = method_chain_args(op, &["unwrap"]); |
| if let ExprKind::MethodCall(ref inner_path, _, _, _) = &arglist[0][0].kind; |
| then { |
| method_name = inner_path.ident.name.as_str(); |
| } |
| } |
| |
| if allowed_methods.iter().any(|&name| method_name == name) { |
| return; |
| } |
| } |
| |
| span_lint( |
| cx, |
| CAST_SIGN_LOSS, |
| expr.span, |
| &format!( |
| "casting `{}` to `{}` may lose the sign of the value", |
| cast_from, cast_to |
| ), |
| ); |
| } |
| |
| fn check_truncation_and_wrapping(cx: &LateContext<'_>, expr: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) { |
| let arch_64_suffix = " on targets with 64-bit wide pointers"; |
| let arch_32_suffix = " on targets with 32-bit wide pointers"; |
| let cast_unsigned_to_signed = !cast_from.is_signed() && cast_to.is_signed(); |
| let from_nbits = int_ty_to_nbits(cast_from, cx.tcx); |
| let to_nbits = int_ty_to_nbits(cast_to, cx.tcx); |
| let (span_truncation, suffix_truncation, span_wrap, suffix_wrap) = |
| match (is_isize_or_usize(cast_from), is_isize_or_usize(cast_to)) { |
| (true, true) | (false, false) => ( |
| to_nbits < from_nbits, |
| ArchSuffix::None, |
| to_nbits == from_nbits && cast_unsigned_to_signed, |
| ArchSuffix::None, |
| ), |
| (true, false) => ( |
| to_nbits <= 32, |
| if to_nbits == 32 { |
| ArchSuffix::_64 |
| } else { |
| ArchSuffix::None |
| }, |
| to_nbits <= 32 && cast_unsigned_to_signed, |
| ArchSuffix::_32, |
| ), |
| (false, true) => ( |
| from_nbits == 64, |
| ArchSuffix::_32, |
| cast_unsigned_to_signed, |
| if from_nbits == 64 { |
| ArchSuffix::_64 |
| } else { |
| ArchSuffix::_32 |
| }, |
| ), |
| }; |
| if span_truncation { |
| span_lint( |
| cx, |
| CAST_POSSIBLE_TRUNCATION, |
| expr.span, |
| &format!( |
| "casting `{}` to `{}` may truncate the value{}", |
| cast_from, |
| cast_to, |
| match suffix_truncation { |
| ArchSuffix::_32 => arch_32_suffix, |
| ArchSuffix::_64 => arch_64_suffix, |
| ArchSuffix::None => "", |
| } |
| ), |
| ); |
| } |
| if span_wrap { |
| span_lint( |
| cx, |
| CAST_POSSIBLE_WRAP, |
| expr.span, |
| &format!( |
| "casting `{}` to `{}` may wrap around the value{}", |
| cast_from, |
| cast_to, |
| match suffix_wrap { |
| ArchSuffix::_32 => arch_32_suffix, |
| ArchSuffix::_64 => arch_64_suffix, |
| ArchSuffix::None => "", |
| } |
| ), |
| ); |
| } |
| } |
| |
| fn check_lossless(cx: &LateContext<'_>, expr: &Expr<'_>, op: &Expr<'_>, cast_from: Ty<'_>, cast_to: Ty<'_>) { |
| let cast_signed_to_unsigned = cast_from.is_signed() && !cast_to.is_signed(); |
| let from_nbits = int_ty_to_nbits(cast_from, cx.tcx); |
| let to_nbits = int_ty_to_nbits(cast_to, cx.tcx); |
| if !is_isize_or_usize(cast_from) && !is_isize_or_usize(cast_to) && from_nbits < to_nbits && !cast_signed_to_unsigned |
| { |
| span_lossless_lint(cx, expr, op, cast_from, cast_to); |
| } |
| } |
| |
| declare_lint_pass!(Casts => [ |
| CAST_PRECISION_LOSS, |
| CAST_SIGN_LOSS, |
| CAST_POSSIBLE_TRUNCATION, |
| CAST_POSSIBLE_WRAP, |
| CAST_LOSSLESS, |
| UNNECESSARY_CAST, |
| CAST_PTR_ALIGNMENT, |
| FN_TO_NUMERIC_CAST, |
| FN_TO_NUMERIC_CAST_WITH_TRUNCATION, |
| ]); |
| |
| // Check if the given type is either `core::ffi::c_void` or |
| // one of the platform specific `libc::<platform>::c_void` of libc. |
| fn is_c_void(cx: &LateContext<'_>, ty: Ty<'_>) -> bool { |
| if let ty::Adt(adt, _) = ty.kind { |
| let names = cx.get_def_path(adt.did); |
| |
| if names.is_empty() { |
| return false; |
| } |
| if names[0] == sym!(libc) || names[0] == sym::core && *names.last().unwrap() == sym!(c_void) { |
| return true; |
| } |
| } |
| false |
| } |
| |
| /// Returns the mantissa bits wide of a fp type. |
| /// Will return 0 if the type is not a fp |
| fn fp_ty_mantissa_nbits(typ: Ty<'_>) -> u32 { |
| match typ.kind { |
| ty::Float(FloatTy::F32) => 23, |
| ty::Float(FloatTy::F64) | ty::Infer(InferTy::FloatVar(_)) => 52, |
| _ => 0, |
| } |
| } |
| |
| impl<'tcx> LateLintPass<'tcx> for Casts { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| if expr.span.from_expansion() { |
| return; |
| } |
| if let ExprKind::Cast(ref ex, _) = expr.kind { |
| let (cast_from, cast_to) = (cx.tables().expr_ty(ex), cx.tables().expr_ty(expr)); |
| lint_fn_to_numeric_cast(cx, expr, ex, cast_from, cast_to); |
| if let ExprKind::Lit(ref lit) = ex.kind { |
| if_chain! { |
| if let LitKind::Int(n, _) = lit.node; |
| if let Some(src) = snippet_opt(cx, lit.span); |
| if cast_to.is_floating_point(); |
| if let Some(num_lit) = NumericLiteral::from_lit_kind(&src, &lit.node); |
| let from_nbits = 128 - n.leading_zeros(); |
| let to_nbits = fp_ty_mantissa_nbits(cast_to); |
| if from_nbits != 0 && to_nbits != 0 && from_nbits <= to_nbits && num_lit.is_decimal(); |
| then { |
| span_lint_and_sugg( |
| cx, |
| UNNECESSARY_CAST, |
| expr.span, |
| &format!("casting integer literal to `{}` is unnecessary", cast_to), |
| "try", |
| format!("{}_{}", n, cast_to), |
| Applicability::MachineApplicable, |
| ); |
| return; |
| } |
| } |
| match lit.node { |
| LitKind::Int(_, LitIntType::Unsuffixed) | LitKind::Float(_, LitFloatType::Unsuffixed) => {}, |
| _ => { |
| if cast_from.kind == cast_to.kind && !in_external_macro(cx.sess(), expr.span) { |
| span_lint( |
| cx, |
| UNNECESSARY_CAST, |
| expr.span, |
| &format!( |
| "casting to the same type is unnecessary (`{}` -> `{}`)", |
| cast_from, cast_to |
| ), |
| ); |
| } |
| }, |
| } |
| } |
| if cast_from.is_numeric() && cast_to.is_numeric() && !in_external_macro(cx.sess(), expr.span) { |
| lint_numeric_casts(cx, expr, ex, cast_from, cast_to); |
| } |
| |
| lint_cast_ptr_alignment(cx, expr, cast_from, cast_to); |
| } |
| } |
| } |
| |
| fn lint_numeric_casts<'tcx>( |
| cx: &LateContext<'tcx>, |
| expr: &Expr<'tcx>, |
| cast_expr: &Expr<'_>, |
| cast_from: Ty<'tcx>, |
| cast_to: Ty<'tcx>, |
| ) { |
| match (cast_from.is_integral(), cast_to.is_integral()) { |
| (true, false) => { |
| let from_nbits = int_ty_to_nbits(cast_from, cx.tcx); |
| let to_nbits = if let ty::Float(FloatTy::F32) = cast_to.kind { |
| 32 |
| } else { |
| 64 |
| }; |
| if is_isize_or_usize(cast_from) || from_nbits >= to_nbits { |
| span_precision_loss_lint(cx, expr, cast_from, to_nbits == 64); |
| } |
| if from_nbits < to_nbits { |
| span_lossless_lint(cx, expr, cast_expr, cast_from, cast_to); |
| } |
| }, |
| (false, true) => { |
| span_lint( |
| cx, |
| CAST_POSSIBLE_TRUNCATION, |
| expr.span, |
| &format!("casting `{}` to `{}` may truncate the value", cast_from, cast_to), |
| ); |
| if !cast_to.is_signed() { |
| span_lint( |
| cx, |
| CAST_SIGN_LOSS, |
| expr.span, |
| &format!( |
| "casting `{}` to `{}` may lose the sign of the value", |
| cast_from, cast_to |
| ), |
| ); |
| } |
| }, |
| (true, true) => { |
| check_loss_of_sign(cx, expr, cast_expr, cast_from, cast_to); |
| check_truncation_and_wrapping(cx, expr, cast_from, cast_to); |
| check_lossless(cx, expr, cast_expr, cast_from, cast_to); |
| }, |
| (false, false) => { |
| if let (&ty::Float(FloatTy::F64), &ty::Float(FloatTy::F32)) = (&cast_from.kind, &cast_to.kind) { |
| span_lint( |
| cx, |
| CAST_POSSIBLE_TRUNCATION, |
| expr.span, |
| "casting `f64` to `f32` may truncate the value", |
| ); |
| } |
| if let (&ty::Float(FloatTy::F32), &ty::Float(FloatTy::F64)) = (&cast_from.kind, &cast_to.kind) { |
| span_lossless_lint(cx, expr, cast_expr, cast_from, cast_to); |
| } |
| }, |
| } |
| } |
| |
| fn lint_cast_ptr_alignment<'tcx>(cx: &LateContext<'tcx>, expr: &Expr<'_>, cast_from: Ty<'tcx>, cast_to: Ty<'tcx>) { |
| if_chain! { |
| if let ty::RawPtr(from_ptr_ty) = &cast_from.kind; |
| if let ty::RawPtr(to_ptr_ty) = &cast_to.kind; |
| if let Ok(from_layout) = cx.layout_of(from_ptr_ty.ty); |
| if let Ok(to_layout) = cx.layout_of(to_ptr_ty.ty); |
| if from_layout.align.abi < to_layout.align.abi; |
| // with c_void, we inherently need to trust the user |
| if !is_c_void(cx, from_ptr_ty.ty); |
| // when casting from a ZST, we don't know enough to properly lint |
| if !from_layout.is_zst(); |
| then { |
| span_lint( |
| cx, |
| CAST_PTR_ALIGNMENT, |
| expr.span, |
| &format!( |
| "casting from `{}` to a more-strictly-aligned pointer (`{}`) ({} < {} bytes)", |
| cast_from, |
| cast_to, |
| from_layout.align.abi.bytes(), |
| to_layout.align.abi.bytes(), |
| ), |
| ); |
| } |
| } |
| } |
| |
| fn lint_fn_to_numeric_cast( |
| cx: &LateContext<'_>, |
| expr: &Expr<'_>, |
| cast_expr: &Expr<'_>, |
| cast_from: Ty<'_>, |
| cast_to: Ty<'_>, |
| ) { |
| // We only want to check casts to `ty::Uint` or `ty::Int` |
| match cast_to.kind { |
| ty::Uint(_) | ty::Int(..) => { /* continue on */ }, |
| _ => return, |
| } |
| match cast_from.kind { |
| ty::FnDef(..) | ty::FnPtr(_) => { |
| let mut applicability = Applicability::MaybeIncorrect; |
| let from_snippet = snippet_with_applicability(cx, cast_expr.span, "x", &mut applicability); |
| |
| let to_nbits = int_ty_to_nbits(cast_to, cx.tcx); |
| if to_nbits < cx.tcx.data_layout.pointer_size.bits() { |
| span_lint_and_sugg( |
| cx, |
| FN_TO_NUMERIC_CAST_WITH_TRUNCATION, |
| expr.span, |
| &format!( |
| "casting function pointer `{}` to `{}`, which truncates the value", |
| from_snippet, cast_to |
| ), |
| "try", |
| format!("{} as usize", from_snippet), |
| applicability, |
| ); |
| } else if cast_to.kind != ty::Uint(UintTy::Usize) { |
| span_lint_and_sugg( |
| cx, |
| FN_TO_NUMERIC_CAST, |
| expr.span, |
| &format!("casting function pointer `{}` to `{}`", from_snippet, cast_to), |
| "try", |
| format!("{} as usize", from_snippet), |
| applicability, |
| ); |
| } |
| }, |
| _ => {}, |
| } |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for types used in structs, parameters and `let` |
| /// declarations above a certain complexity threshold. |
| /// |
| /// **Why is this bad?** Too complex types make the code less readable. Consider |
| /// using a `type` definition to simplify them. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// # use std::rc::Rc; |
| /// struct Foo { |
| /// inner: Rc<Vec<Vec<Box<(u32, u32, u32, u32)>>>>, |
| /// } |
| /// ``` |
| pub TYPE_COMPLEXITY, |
| complexity, |
| "usage of very complex types that might be better factored into `type` definitions" |
| } |
| |
| pub struct TypeComplexity { |
| threshold: u64, |
| } |
| |
| impl TypeComplexity { |
| #[must_use] |
| pub fn new(threshold: u64) -> Self { |
| Self { threshold } |
| } |
| } |
| |
| impl_lint_pass!(TypeComplexity => [TYPE_COMPLEXITY]); |
| |
| impl<'tcx> LateLintPass<'tcx> for TypeComplexity { |
| fn check_fn( |
| &mut self, |
| cx: &LateContext<'tcx>, |
| _: FnKind<'tcx>, |
| decl: &'tcx FnDecl<'_>, |
| _: &'tcx Body<'_>, |
| _: Span, |
| _: HirId, |
| ) { |
| self.check_fndecl(cx, decl); |
| } |
| |
| fn check_struct_field(&mut self, cx: &LateContext<'tcx>, field: &'tcx hir::StructField<'_>) { |
| // enum variants are also struct fields now |
| self.check_type(cx, &field.ty); |
| } |
| |
| fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) { |
| match item.kind { |
| ItemKind::Static(ref ty, _, _) | ItemKind::Const(ref ty, _) => self.check_type(cx, ty), |
| // functions, enums, structs, impls and traits are covered |
| _ => (), |
| } |
| } |
| |
| fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) { |
| match item.kind { |
| TraitItemKind::Const(ref ty, _) | TraitItemKind::Type(_, Some(ref ty)) => self.check_type(cx, ty), |
| TraitItemKind::Fn(FnSig { ref decl, .. }, TraitFn::Required(_)) => self.check_fndecl(cx, decl), |
| // methods with default impl are covered by check_fn |
| _ => (), |
| } |
| } |
| |
| fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'_>) { |
| match item.kind { |
| ImplItemKind::Const(ref ty, _) | ImplItemKind::TyAlias(ref ty) => self.check_type(cx, ty), |
| // methods are covered by check_fn |
| _ => (), |
| } |
| } |
| |
| fn check_local(&mut self, cx: &LateContext<'tcx>, local: &'tcx Local<'_>) { |
| if let Some(ref ty) = local.ty { |
| self.check_type(cx, ty); |
| } |
| } |
| } |
| |
| impl<'tcx> TypeComplexity { |
| fn check_fndecl(&self, cx: &LateContext<'tcx>, decl: &'tcx FnDecl<'_>) { |
| for arg in decl.inputs { |
| self.check_type(cx, arg); |
| } |
| if let FnRetTy::Return(ref ty) = decl.output { |
| self.check_type(cx, ty); |
| } |
| } |
| |
| fn check_type(&self, cx: &LateContext<'_>, ty: &hir::Ty<'_>) { |
| if ty.span.from_expansion() { |
| return; |
| } |
| let score = { |
| let mut visitor = TypeComplexityVisitor { score: 0, nest: 1 }; |
| visitor.visit_ty(ty); |
| visitor.score |
| }; |
| |
| if score > self.threshold { |
| span_lint( |
| cx, |
| TYPE_COMPLEXITY, |
| ty.span, |
| "very complex type used. Consider factoring parts into `type` definitions", |
| ); |
| } |
| } |
| } |
| |
| /// Walks a type and assigns a complexity score to it. |
| struct TypeComplexityVisitor { |
| /// total complexity score of the type |
| score: u64, |
| /// current nesting level |
| nest: u64, |
| } |
| |
| impl<'tcx> Visitor<'tcx> for TypeComplexityVisitor { |
| type Map = Map<'tcx>; |
| |
| fn visit_ty(&mut self, ty: &'tcx hir::Ty<'_>) { |
| let (add_score, sub_nest) = match ty.kind { |
| // _, &x and *x have only small overhead; don't mess with nesting level |
| TyKind::Infer | TyKind::Ptr(..) | TyKind::Rptr(..) => (1, 0), |
| |
| // the "normal" components of a type: named types, arrays/tuples |
| TyKind::Path(..) | TyKind::Slice(..) | TyKind::Tup(..) | TyKind::Array(..) => (10 * self.nest, 1), |
| |
| // function types bring a lot of overhead |
| TyKind::BareFn(ref bare) if bare.abi == Abi::Rust => (50 * self.nest, 1), |
| |
| TyKind::TraitObject(ref param_bounds, _) => { |
| let has_lifetime_parameters = param_bounds.iter().any(|bound| { |
| bound.bound_generic_params.iter().any(|gen| match gen.kind { |
| GenericParamKind::Lifetime { .. } => true, |
| _ => false, |
| }) |
| }); |
| if has_lifetime_parameters { |
| // complex trait bounds like A<'a, 'b> |
| (50 * self.nest, 1) |
| } else { |
| // simple trait bounds like A + B |
| (20 * self.nest, 0) |
| } |
| }, |
| |
| _ => (0, 0), |
| }; |
| self.score += add_score; |
| self.nest += sub_nest; |
| walk_ty(self, ty); |
| self.nest -= sub_nest; |
| } |
| fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { |
| NestedVisitorMap::None |
| } |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for expressions where a character literal is cast |
| /// to `u8` and suggests using a byte literal instead. |
| /// |
| /// **Why is this bad?** In general, casting values to smaller types is |
| /// error-prone and should be avoided where possible. In the particular case of |
| /// converting a character literal to u8, it is easy to avoid by just using a |
| /// byte literal instead. As an added bonus, `b'a'` is even slightly shorter |
| /// than `'a' as u8`. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust,ignore |
| /// 'x' as u8 |
| /// ``` |
| /// |
| /// A better version, using the byte literal: |
| /// |
| /// ```rust,ignore |
| /// b'x' |
| /// ``` |
| pub CHAR_LIT_AS_U8, |
| complexity, |
| "casting a character literal to `u8` truncates" |
| } |
| |
| declare_lint_pass!(CharLitAsU8 => [CHAR_LIT_AS_U8]); |
| |
| impl<'tcx> LateLintPass<'tcx> for CharLitAsU8 { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| if_chain! { |
| if !expr.span.from_expansion(); |
| if let ExprKind::Cast(e, _) = &expr.kind; |
| if let ExprKind::Lit(l) = &e.kind; |
| if let LitKind::Char(c) = l.node; |
| if ty::Uint(UintTy::U8) == cx.tables().expr_ty(expr).kind; |
| then { |
| let mut applicability = Applicability::MachineApplicable; |
| let snippet = snippet_with_applicability(cx, e.span, "'x'", &mut applicability); |
| |
| span_lint_and_then( |
| cx, |
| CHAR_LIT_AS_U8, |
| expr.span, |
| "casting a character literal to `u8` truncates", |
| |diag| { |
| diag.note("`char` is four bytes wide, but `u8` is a single byte"); |
| |
| if c.is_ascii() { |
| diag.span_suggestion( |
| expr.span, |
| "use a byte literal instead", |
| format!("b{}", snippet), |
| applicability, |
| ); |
| } |
| }); |
| } |
| } |
| } |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for comparisons where one side of the relation is |
| /// either the minimum or maximum value for its type and warns if it involves a |
| /// case that is always true or always false. Only integer and boolean types are |
| /// checked. |
| /// |
| /// **Why is this bad?** An expression like `min <= x` may misleadingly imply |
| /// that it is possible for `x` to be less than the minimum. Expressions like |
| /// `max < x` are probably mistakes. |
| /// |
| /// **Known problems:** For `usize` the size of the current compile target will |
| /// be assumed (e.g., 64 bits on 64 bit systems). This means code that uses such |
| /// a comparison to detect target pointer width will trigger this lint. One can |
| /// use `mem::sizeof` and compare its value or conditional compilation |
| /// attributes |
| /// like `#[cfg(target_pointer_width = "64")] ..` instead. |
| /// |
| /// **Example:** |
| /// |
| /// ```rust |
| /// let vec: Vec<isize> = Vec::new(); |
| /// if vec.len() <= 0 {} |
| /// if 100 > i32::MAX {} |
| /// ``` |
| pub ABSURD_EXTREME_COMPARISONS, |
| correctness, |
| "a comparison with a maximum or minimum value that is always true or false" |
| } |
| |
| declare_lint_pass!(AbsurdExtremeComparisons => [ABSURD_EXTREME_COMPARISONS]); |
| |
| enum ExtremeType { |
| Minimum, |
| Maximum, |
| } |
| |
| struct ExtremeExpr<'a> { |
| which: ExtremeType, |
| expr: &'a Expr<'a>, |
| } |
| |
| enum AbsurdComparisonResult { |
| AlwaysFalse, |
| AlwaysTrue, |
| InequalityImpossible, |
| } |
| |
| fn is_cast_between_fixed_and_target<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'tcx>) -> bool { |
| if let ExprKind::Cast(ref cast_exp, _) = expr.kind { |
| let precast_ty = cx.tables().expr_ty(cast_exp); |
| let cast_ty = cx.tables().expr_ty(expr); |
| |
| return is_isize_or_usize(precast_ty) != is_isize_or_usize(cast_ty); |
| } |
| |
| false |
| } |
| |
| fn detect_absurd_comparison<'tcx>( |
| cx: &LateContext<'tcx>, |
| op: BinOpKind, |
| lhs: &'tcx Expr<'_>, |
| rhs: &'tcx Expr<'_>, |
| ) -> Option<(ExtremeExpr<'tcx>, AbsurdComparisonResult)> { |
| use crate::types::AbsurdComparisonResult::{AlwaysFalse, AlwaysTrue, InequalityImpossible}; |
| use crate::types::ExtremeType::{Maximum, Minimum}; |
| use crate::utils::comparisons::{normalize_comparison, Rel}; |
| |
| // absurd comparison only makes sense on primitive types |
| // primitive types don't implement comparison operators with each other |
| if cx.tables().expr_ty(lhs) != cx.tables().expr_ty(rhs) { |
| return None; |
| } |
| |
| // comparisons between fix sized types and target sized types are considered unanalyzable |
| if is_cast_between_fixed_and_target(cx, lhs) || is_cast_between_fixed_and_target(cx, rhs) { |
| return None; |
| } |
| |
| let (rel, normalized_lhs, normalized_rhs) = normalize_comparison(op, lhs, rhs)?; |
| |
| let lx = detect_extreme_expr(cx, normalized_lhs); |
| let rx = detect_extreme_expr(cx, normalized_rhs); |
| |
| Some(match rel { |
| Rel::Lt => { |
| match (lx, rx) { |
| (Some(l @ ExtremeExpr { which: Maximum, .. }), _) => (l, AlwaysFalse), // max < x |
| (_, Some(r @ ExtremeExpr { which: Minimum, .. })) => (r, AlwaysFalse), // x < min |
| _ => return None, |
| } |
| }, |
| Rel::Le => { |
| match (lx, rx) { |
| (Some(l @ ExtremeExpr { which: Minimum, .. }), _) => (l, AlwaysTrue), // min <= x |
| (Some(l @ ExtremeExpr { which: Maximum, .. }), _) => (l, InequalityImpossible), // max <= x |
| (_, Some(r @ ExtremeExpr { which: Minimum, .. })) => (r, InequalityImpossible), // x <= min |
| (_, Some(r @ ExtremeExpr { which: Maximum, .. })) => (r, AlwaysTrue), // x <= max |
| _ => return None, |
| } |
| }, |
| Rel::Ne | Rel::Eq => return None, |
| }) |
| } |
| |
| fn detect_extreme_expr<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<ExtremeExpr<'tcx>> { |
| use crate::types::ExtremeType::{Maximum, Minimum}; |
| |
| let ty = cx.tables().expr_ty(expr); |
| |
| let cv = constant(cx, cx.tables(), expr)?.0; |
| |
| let which = match (&ty.kind, cv) { |
| (&ty::Bool, Constant::Bool(false)) | (&ty::Uint(_), Constant::Int(0)) => Minimum, |
| (&ty::Int(ity), Constant::Int(i)) if i == unsext(cx.tcx, i128::MIN >> (128 - int_bits(cx.tcx, ity)), ity) => { |
| Minimum |
| }, |
| |
| (&ty::Bool, Constant::Bool(true)) => Maximum, |
| (&ty::Int(ity), Constant::Int(i)) if i == unsext(cx.tcx, i128::MAX >> (128 - int_bits(cx.tcx, ity)), ity) => { |
| Maximum |
| }, |
| (&ty::Uint(uty), Constant::Int(i)) if clip(cx.tcx, u128::MAX, uty) == i => Maximum, |
| |
| _ => return None, |
| }; |
| Some(ExtremeExpr { which, expr }) |
| } |
| |
| impl<'tcx> LateLintPass<'tcx> for AbsurdExtremeComparisons { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| use crate::types::AbsurdComparisonResult::{AlwaysFalse, AlwaysTrue, InequalityImpossible}; |
| use crate::types::ExtremeType::{Maximum, Minimum}; |
| |
| if let ExprKind::Binary(ref cmp, ref lhs, ref rhs) = expr.kind { |
| if let Some((culprit, result)) = detect_absurd_comparison(cx, cmp.node, lhs, rhs) { |
| if !expr.span.from_expansion() { |
| let msg = "this comparison involving the minimum or maximum element for this \ |
| type contains a case that is always true or always false"; |
| |
| let conclusion = match result { |
| AlwaysFalse => "this comparison is always false".to_owned(), |
| AlwaysTrue => "this comparison is always true".to_owned(), |
| InequalityImpossible => format!( |
| "the case where the two sides are not equal never occurs, consider using `{} == {}` \ |
| instead", |
| snippet(cx, lhs.span, "lhs"), |
| snippet(cx, rhs.span, "rhs") |
| ), |
| }; |
| |
| let help = format!( |
| "because `{}` is the {} value for this type, {}", |
| snippet(cx, culprit.expr.span, "x"), |
| match culprit.which { |
| Minimum => "minimum", |
| Maximum => "maximum", |
| }, |
| conclusion |
| ); |
| |
| span_lint_and_help(cx, ABSURD_EXTREME_COMPARISONS, expr.span, msg, None, &help); |
| } |
| } |
| } |
| } |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for comparisons where the relation is always either |
| /// true or false, but where one side has been upcast so that the comparison is |
| /// necessary. Only integer types are checked. |
| /// |
| /// **Why is this bad?** An expression like `let x : u8 = ...; (x as u32) > 300` |
| /// will mistakenly imply that it is possible for `x` to be outside the range of |
| /// `u8`. |
| /// |
| /// **Known problems:** |
| /// https://github.com/rust-lang/rust-clippy/issues/886 |
| /// |
| /// **Example:** |
| /// ```rust |
| /// let x: u8 = 1; |
| /// (x as u32) > 300; |
| /// ``` |
| pub INVALID_UPCAST_COMPARISONS, |
| pedantic, |
| "a comparison involving an upcast which is always true or false" |
| } |
| |
| declare_lint_pass!(InvalidUpcastComparisons => [INVALID_UPCAST_COMPARISONS]); |
| |
| #[derive(Copy, Clone, Debug, Eq)] |
| enum FullInt { |
| S(i128), |
| U(u128), |
| } |
| |
| impl FullInt { |
| #[allow(clippy::cast_sign_loss)] |
| #[must_use] |
| fn cmp_s_u(s: i128, u: u128) -> Ordering { |
| if s < 0 { |
| Ordering::Less |
| } else if u > (i128::MAX as u128) { |
| Ordering::Greater |
| } else { |
| (s as u128).cmp(&u) |
| } |
| } |
| } |
| |
| impl PartialEq for FullInt { |
| #[must_use] |
| fn eq(&self, other: &Self) -> bool { |
| self.partial_cmp(other).expect("`partial_cmp` only returns `Some(_)`") == Ordering::Equal |
| } |
| } |
| |
| impl PartialOrd for FullInt { |
| #[must_use] |
| fn partial_cmp(&self, other: &Self) -> Option<Ordering> { |
| Some(match (self, other) { |
| (&Self::S(s), &Self::S(o)) => s.cmp(&o), |
| (&Self::U(s), &Self::U(o)) => s.cmp(&o), |
| (&Self::S(s), &Self::U(o)) => Self::cmp_s_u(s, o), |
| (&Self::U(s), &Self::S(o)) => Self::cmp_s_u(o, s).reverse(), |
| }) |
| } |
| } |
| impl Ord for FullInt { |
| #[must_use] |
| fn cmp(&self, other: &Self) -> Ordering { |
| self.partial_cmp(other) |
| .expect("`partial_cmp` for FullInt can never return `None`") |
| } |
| } |
| |
| fn numeric_cast_precast_bounds<'a>(cx: &LateContext<'_>, expr: &'a Expr<'_>) -> Option<(FullInt, FullInt)> { |
| if let ExprKind::Cast(ref cast_exp, _) = expr.kind { |
| let pre_cast_ty = cx.tables().expr_ty(cast_exp); |
| let cast_ty = cx.tables().expr_ty(expr); |
| // if it's a cast from i32 to u32 wrapping will invalidate all these checks |
| if cx.layout_of(pre_cast_ty).ok().map(|l| l.size) == cx.layout_of(cast_ty).ok().map(|l| l.size) { |
| return None; |
| } |
| match pre_cast_ty.kind { |
| ty::Int(int_ty) => Some(match int_ty { |
| IntTy::I8 => (FullInt::S(i128::from(i8::MIN)), FullInt::S(i128::from(i8::MAX))), |
| IntTy::I16 => (FullInt::S(i128::from(i16::MIN)), FullInt::S(i128::from(i16::MAX))), |
| IntTy::I32 => (FullInt::S(i128::from(i32::MIN)), FullInt::S(i128::from(i32::MAX))), |
| IntTy::I64 => (FullInt::S(i128::from(i64::MIN)), FullInt::S(i128::from(i64::MAX))), |
| IntTy::I128 => (FullInt::S(i128::MIN), FullInt::S(i128::MAX)), |
| IntTy::Isize => (FullInt::S(isize::MIN as i128), FullInt::S(isize::MAX as i128)), |
| }), |
| ty::Uint(uint_ty) => Some(match uint_ty { |
| UintTy::U8 => (FullInt::U(u128::from(u8::MIN)), FullInt::U(u128::from(u8::MAX))), |
| UintTy::U16 => (FullInt::U(u128::from(u16::MIN)), FullInt::U(u128::from(u16::MAX))), |
| UintTy::U32 => (FullInt::U(u128::from(u32::MIN)), FullInt::U(u128::from(u32::MAX))), |
| UintTy::U64 => (FullInt::U(u128::from(u64::MIN)), FullInt::U(u128::from(u64::MAX))), |
| UintTy::U128 => (FullInt::U(u128::MIN), FullInt::U(u128::MAX)), |
| UintTy::Usize => (FullInt::U(usize::MIN as u128), FullInt::U(usize::MAX as u128)), |
| }), |
| _ => None, |
| } |
| } else { |
| None |
| } |
| } |
| |
| fn node_as_const_fullint<'tcx>(cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) -> Option<FullInt> { |
| let val = constant(cx, cx.tables(), expr)?.0; |
| if let Constant::Int(const_int) = val { |
| match cx.tables().expr_ty(expr).kind { |
| ty::Int(ity) => Some(FullInt::S(sext(cx.tcx, const_int, ity))), |
| ty::Uint(_) => Some(FullInt::U(const_int)), |
| _ => None, |
| } |
| } else { |
| None |
| } |
| } |
| |
| fn err_upcast_comparison(cx: &LateContext<'_>, span: Span, expr: &Expr<'_>, always: bool) { |
| if let ExprKind::Cast(ref cast_val, _) = expr.kind { |
| span_lint( |
| cx, |
| INVALID_UPCAST_COMPARISONS, |
| span, |
| &format!( |
| "because of the numeric bounds on `{}` prior to casting, this expression is always {}", |
| snippet(cx, cast_val.span, "the expression"), |
| if always { "true" } else { "false" }, |
| ), |
| ); |
| } |
| } |
| |
| fn upcast_comparison_bounds_err<'tcx>( |
| cx: &LateContext<'tcx>, |
| span: Span, |
| rel: comparisons::Rel, |
| lhs_bounds: Option<(FullInt, FullInt)>, |
| lhs: &'tcx Expr<'_>, |
| rhs: &'tcx Expr<'_>, |
| invert: bool, |
| ) { |
| use crate::utils::comparisons::Rel; |
| |
| if let Some((lb, ub)) = lhs_bounds { |
| if let Some(norm_rhs_val) = node_as_const_fullint(cx, rhs) { |
| if rel == Rel::Eq || rel == Rel::Ne { |
| if norm_rhs_val < lb || norm_rhs_val > ub { |
| err_upcast_comparison(cx, span, lhs, rel == Rel::Ne); |
| } |
| } else if match rel { |
| Rel::Lt => { |
| if invert { |
| norm_rhs_val < lb |
| } else { |
| ub < norm_rhs_val |
| } |
| }, |
| Rel::Le => { |
| if invert { |
| norm_rhs_val <= lb |
| } else { |
| ub <= norm_rhs_val |
| } |
| }, |
| Rel::Eq | Rel::Ne => unreachable!(), |
| } { |
| err_upcast_comparison(cx, span, lhs, true) |
| } else if match rel { |
| Rel::Lt => { |
| if invert { |
| norm_rhs_val >= ub |
| } else { |
| lb >= norm_rhs_val |
| } |
| }, |
| Rel::Le => { |
| if invert { |
| norm_rhs_val > ub |
| } else { |
| lb > norm_rhs_val |
| } |
| }, |
| Rel::Eq | Rel::Ne => unreachable!(), |
| } { |
| err_upcast_comparison(cx, span, lhs, false) |
| } |
| } |
| } |
| } |
| |
| impl<'tcx> LateLintPass<'tcx> for InvalidUpcastComparisons { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| if let ExprKind::Binary(ref cmp, ref lhs, ref rhs) = expr.kind { |
| let normalized = comparisons::normalize_comparison(cmp.node, lhs, rhs); |
| let (rel, normalized_lhs, normalized_rhs) = if let Some(val) = normalized { |
| val |
| } else { |
| return; |
| }; |
| |
| let lhs_bounds = numeric_cast_precast_bounds(cx, normalized_lhs); |
| let rhs_bounds = numeric_cast_precast_bounds(cx, normalized_rhs); |
| |
| upcast_comparison_bounds_err(cx, expr.span, rel, lhs_bounds, normalized_lhs, normalized_rhs, false); |
| upcast_comparison_bounds_err(cx, expr.span, rel, rhs_bounds, normalized_rhs, normalized_lhs, true); |
| } |
| } |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for public `impl` or `fn` missing generalization |
| /// over different hashers and implicitly defaulting to the default hashing |
| /// algorithm (`SipHash`). |
| /// |
| /// **Why is this bad?** `HashMap` or `HashSet` with custom hashers cannot be |
| /// used with them. |
| /// |
| /// **Known problems:** Suggestions for replacing constructors can contain |
| /// false-positives. Also applying suggestions can require modification of other |
| /// pieces of code, possibly including external crates. |
| /// |
| /// **Example:** |
| /// ```rust |
| /// # use std::collections::HashMap; |
| /// # use std::hash::{Hash, BuildHasher}; |
| /// # trait Serialize {}; |
| /// impl<K: Hash + Eq, V> Serialize for HashMap<K, V> { } |
| /// |
| /// pub fn foo(map: &mut HashMap<i32, i32>) { } |
| /// ``` |
| /// could be rewritten as |
| /// ```rust |
| /// # use std::collections::HashMap; |
| /// # use std::hash::{Hash, BuildHasher}; |
| /// # trait Serialize {}; |
| /// impl<K: Hash + Eq, V, S: BuildHasher> Serialize for HashMap<K, V, S> { } |
| /// |
| /// pub fn foo<S: BuildHasher>(map: &mut HashMap<i32, i32, S>) { } |
| /// ``` |
| pub IMPLICIT_HASHER, |
| pedantic, |
| "missing generalization over different hashers" |
| } |
| |
| declare_lint_pass!(ImplicitHasher => [IMPLICIT_HASHER]); |
| |
| impl<'tcx> LateLintPass<'tcx> for ImplicitHasher { |
| #[allow(clippy::cast_possible_truncation, clippy::too_many_lines)] |
| fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) { |
| use rustc_span::BytePos; |
| |
| fn suggestion<'tcx>( |
| cx: &LateContext<'tcx>, |
| diag: &mut DiagnosticBuilder<'_>, |
| generics_span: Span, |
| generics_suggestion_span: Span, |
| target: &ImplicitHasherType<'_>, |
| vis: ImplicitHasherConstructorVisitor<'_, '_, '_>, |
| ) { |
| let generics_snip = snippet(cx, generics_span, ""); |
| // trim `<` `>` |
| let generics_snip = if generics_snip.is_empty() { |
| "" |
| } else { |
| &generics_snip[1..generics_snip.len() - 1] |
| }; |
| |
| multispan_sugg( |
| diag, |
| "consider adding a type parameter", |
| vec![ |
| ( |
| generics_suggestion_span, |
| format!( |
| "<{}{}S: ::std::hash::BuildHasher{}>", |
| generics_snip, |
| if generics_snip.is_empty() { "" } else { ", " }, |
| if vis.suggestions.is_empty() { |
| "" |
| } else { |
| // request users to add `Default` bound so that generic constructors can be used |
| " + Default" |
| }, |
| ), |
| ), |
| ( |
| target.span(), |
| format!("{}<{}, S>", target.type_name(), target.type_arguments(),), |
| ), |
| ], |
| ); |
| |
| if !vis.suggestions.is_empty() { |
| multispan_sugg(diag, "...and use generic constructor", vis.suggestions); |
| } |
| } |
| |
| if !cx.access_levels.is_exported(item.hir_id) { |
| return; |
| } |
| |
| match item.kind { |
| ItemKind::Impl { |
| ref generics, |
| self_ty: ref ty, |
| ref items, |
| .. |
| } => { |
| let mut vis = ImplicitHasherTypeVisitor::new(cx); |
| vis.visit_ty(ty); |
| |
| for target in &vis.found { |
| if differing_macro_contexts(item.span, target.span()) { |
| return; |
| } |
| |
| let generics_suggestion_span = generics.span.substitute_dummy({ |
| let pos = snippet_opt(cx, item.span.until(target.span())) |
| .and_then(|snip| Some(item.span.lo() + BytePos(snip.find("impl")? as u32 + 4))); |
| if let Some(pos) = pos { |
| Span::new(pos, pos, item.span.data().ctxt) |
| } else { |
| return; |
| } |
| }); |
| |
| let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target); |
| for item in items.iter().map(|item| cx.tcx.hir().impl_item(item.id)) { |
| ctr_vis.visit_impl_item(item); |
| } |
| |
| span_lint_and_then( |
| cx, |
| IMPLICIT_HASHER, |
| target.span(), |
| &format!( |
| "impl for `{}` should be generalized over different hashers", |
| target.type_name() |
| ), |
| move |diag| { |
| suggestion(cx, diag, generics.span, generics_suggestion_span, target, ctr_vis); |
| }, |
| ); |
| } |
| }, |
| ItemKind::Fn(ref sig, ref generics, body_id) => { |
| let body = cx.tcx.hir().body(body_id); |
| |
| for ty in sig.decl.inputs { |
| let mut vis = ImplicitHasherTypeVisitor::new(cx); |
| vis.visit_ty(ty); |
| |
| for target in &vis.found { |
| if in_external_macro(cx.sess(), generics.span) { |
| continue; |
| } |
| let generics_suggestion_span = generics.span.substitute_dummy({ |
| let pos = snippet_opt(cx, item.span.until(body.params[0].pat.span)) |
| .and_then(|snip| { |
| let i = snip.find("fn")?; |
| Some(item.span.lo() + BytePos((i + (&snip[i..]).find('(')?) as u32)) |
| }) |
| .expect("failed to create span for type parameters"); |
| Span::new(pos, pos, item.span.data().ctxt) |
| }); |
| |
| let mut ctr_vis = ImplicitHasherConstructorVisitor::new(cx, target); |
| ctr_vis.visit_body(body); |
| |
| span_lint_and_then( |
| cx, |
| IMPLICIT_HASHER, |
| target.span(), |
| &format!( |
| "parameter of type `{}` should be generalized over different hashers", |
| target.type_name() |
| ), |
| move |diag| { |
| suggestion(cx, diag, generics.span, generics_suggestion_span, target, ctr_vis); |
| }, |
| ); |
| } |
| } |
| }, |
| _ => {}, |
| } |
| } |
| } |
| |
| enum ImplicitHasherType<'tcx> { |
| HashMap(Span, Ty<'tcx>, Cow<'static, str>, Cow<'static, str>), |
| HashSet(Span, Ty<'tcx>, Cow<'static, str>), |
| } |
| |
| impl<'tcx> ImplicitHasherType<'tcx> { |
| /// Checks that `ty` is a target type without a `BuildHasher`. |
| fn new(cx: &LateContext<'tcx>, hir_ty: &hir::Ty<'_>) -> Option<Self> { |
| if let TyKind::Path(QPath::Resolved(None, ref path)) = hir_ty.kind { |
| let params: Vec<_> = path |
| .segments |
| .last() |
| .as_ref()? |
| .args |
| .as_ref()? |
| .args |
| .iter() |
| .filter_map(|arg| match arg { |
| GenericArg::Type(ty) => Some(ty), |
| _ => None, |
| }) |
| .collect(); |
| let params_len = params.len(); |
| |
| let ty = hir_ty_to_ty(cx.tcx, hir_ty); |
| |
| if is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) && params_len == 2 { |
| Some(ImplicitHasherType::HashMap( |
| hir_ty.span, |
| ty, |
| snippet(cx, params[0].span, "K"), |
| snippet(cx, params[1].span, "V"), |
| )) |
| } else if is_type_diagnostic_item(cx, ty, sym!(hashset_type)) && params_len == 1 { |
| Some(ImplicitHasherType::HashSet( |
| hir_ty.span, |
| ty, |
| snippet(cx, params[0].span, "T"), |
| )) |
| } else { |
| None |
| } |
| } else { |
| None |
| } |
| } |
| |
| fn type_name(&self) -> &'static str { |
| match *self { |
| ImplicitHasherType::HashMap(..) => "HashMap", |
| ImplicitHasherType::HashSet(..) => "HashSet", |
| } |
| } |
| |
| fn type_arguments(&self) -> String { |
| match *self { |
| ImplicitHasherType::HashMap(.., ref k, ref v) => format!("{}, {}", k, v), |
| ImplicitHasherType::HashSet(.., ref t) => format!("{}", t), |
| } |
| } |
| |
| fn ty(&self) -> Ty<'tcx> { |
| match *self { |
| ImplicitHasherType::HashMap(_, ty, ..) | ImplicitHasherType::HashSet(_, ty, ..) => ty, |
| } |
| } |
| |
| fn span(&self) -> Span { |
| match *self { |
| ImplicitHasherType::HashMap(span, ..) | ImplicitHasherType::HashSet(span, ..) => span, |
| } |
| } |
| } |
| |
| struct ImplicitHasherTypeVisitor<'a, 'tcx> { |
| cx: &'a LateContext<'tcx>, |
| found: Vec<ImplicitHasherType<'tcx>>, |
| } |
| |
| impl<'a, 'tcx> ImplicitHasherTypeVisitor<'a, 'tcx> { |
| fn new(cx: &'a LateContext<'tcx>) -> Self { |
| Self { cx, found: vec![] } |
| } |
| } |
| |
| impl<'a, 'tcx> Visitor<'tcx> for ImplicitHasherTypeVisitor<'a, 'tcx> { |
| type Map = Map<'tcx>; |
| |
| fn visit_ty(&mut self, t: &'tcx hir::Ty<'_>) { |
| if let Some(target) = ImplicitHasherType::new(self.cx, t) { |
| self.found.push(target); |
| } |
| |
| walk_ty(self, t); |
| } |
| |
| fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { |
| NestedVisitorMap::None |
| } |
| } |
| |
| /// Looks for default-hasher-dependent constructors like `HashMap::new`. |
| struct ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> { |
| cx: &'a LateContext<'tcx>, |
| maybe_typeck_tables: Option<&'tcx TypeckTables<'tcx>>, |
| target: &'b ImplicitHasherType<'tcx>, |
| suggestions: BTreeMap<Span, String>, |
| } |
| |
| impl<'a, 'b, 'tcx> ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> { |
| fn new(cx: &'a LateContext<'tcx>, target: &'b ImplicitHasherType<'tcx>) -> Self { |
| Self { |
| cx, |
| maybe_typeck_tables: cx.maybe_typeck_tables(), |
| target, |
| suggestions: BTreeMap::new(), |
| } |
| } |
| } |
| |
| impl<'a, 'b, 'tcx> Visitor<'tcx> for ImplicitHasherConstructorVisitor<'a, 'b, 'tcx> { |
| type Map = Map<'tcx>; |
| |
| fn visit_body(&mut self, body: &'tcx Body<'_>) { |
| let old_maybe_typeck_tables = self.maybe_typeck_tables.replace(self.cx.tcx.body_tables(body.id())); |
| walk_body(self, body); |
| self.maybe_typeck_tables = old_maybe_typeck_tables; |
| } |
| |
| fn visit_expr(&mut self, e: &'tcx Expr<'_>) { |
| if_chain! { |
| if let ExprKind::Call(ref fun, ref args) = e.kind; |
| if let ExprKind::Path(QPath::TypeRelative(ref ty, ref method)) = fun.kind; |
| if let TyKind::Path(QPath::Resolved(None, ty_path)) = ty.kind; |
| then { |
| if !TyS::same_type(self.target.ty(), self.maybe_typeck_tables.unwrap().expr_ty(e)) { |
| return; |
| } |
| |
| if match_path(ty_path, &paths::HASHMAP) { |
| if method.ident.name == sym!(new) { |
| self.suggestions |
| .insert(e.span, "HashMap::default()".to_string()); |
| } else if method.ident.name == sym!(with_capacity) { |
| self.suggestions.insert( |
| e.span, |
| format!( |
| "HashMap::with_capacity_and_hasher({}, Default::default())", |
| snippet(self.cx, args[0].span, "capacity"), |
| ), |
| ); |
| } |
| } else if match_path(ty_path, &paths::HASHSET) { |
| if method.ident.name == sym!(new) { |
| self.suggestions |
| .insert(e.span, "HashSet::default()".to_string()); |
| } else if method.ident.name == sym!(with_capacity) { |
| self.suggestions.insert( |
| e.span, |
| format!( |
| "HashSet::with_capacity_and_hasher({}, Default::default())", |
| snippet(self.cx, args[0].span, "capacity"), |
| ), |
| ); |
| } |
| } |
| } |
| } |
| |
| walk_expr(self, e); |
| } |
| |
| fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> { |
| NestedVisitorMap::OnlyBodies(self.cx.tcx.hir()) |
| } |
| } |
| |
| declare_clippy_lint! { |
| /// **What it does:** Checks for casts of `&T` to `&mut T` anywhere in the code. |
| /// |
| /// **Why is this bad?** It’s basically guaranteed to be undefined behaviour. |
| /// `UnsafeCell` is the only way to obtain aliasable data that is considered |
| /// mutable. |
| /// |
| /// **Known problems:** None. |
| /// |
| /// **Example:** |
| /// ```rust,ignore |
| /// fn x(r: &i32) { |
| /// unsafe { |
| /// *(r as *const _ as *mut _) += 1; |
| /// } |
| /// } |
| /// ``` |
| /// |
| /// Instead consider using interior mutability types. |
| /// |
| /// ```rust |
| /// use std::cell::UnsafeCell; |
| /// |
| /// fn x(r: &UnsafeCell<i32>) { |
| /// unsafe { |
| /// *r.get() += 1; |
| /// } |
| /// } |
| /// ``` |
| pub CAST_REF_TO_MUT, |
| correctness, |
| "a cast of reference to a mutable pointer" |
| } |
| |
| declare_lint_pass!(RefToMut => [CAST_REF_TO_MUT]); |
| |
| impl<'tcx> LateLintPass<'tcx> for RefToMut { |
| fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) { |
| if_chain! { |
| if let ExprKind::Unary(UnOp::UnDeref, e) = &expr.kind; |
| if let ExprKind::Cast(e, t) = &e.kind; |
| if let TyKind::Ptr(MutTy { mutbl: Mutability::Mut, .. }) = t.kind; |
| if let ExprKind::Cast(e, t) = &e.kind; |
| if let TyKind::Ptr(MutTy { mutbl: Mutability::Not, .. }) = t.kind; |
| if let ty::Ref(..) = cx.tables().node_type(e.hir_id).kind; |
| then { |
| span_lint( |
| cx, |
| CAST_REF_TO_MUT, |
| expr.span, |
| "casting `&T` to `&mut T` may cause undefined behavior, consider instead using an `UnsafeCell`", |
| ); |
| } |
| } |
| } |
| } |