-#![allow(rustc::default_hash_types)]
-
mod borrowed_box;
-mod box_vec;
+mod box_collection;
mod linked_list;
mod option_option;
mod rc_buffer;
+mod rc_mutex;
mod redundant_allocation;
+mod type_complexity;
mod utils;
mod vec_box;
-use std::borrow::Cow;
-use std::collections::BTreeMap;
-
-use clippy_utils::diagnostics::{multispan_sugg, span_lint, span_lint_and_then};
-use clippy_utils::source::{snippet, snippet_opt};
-use clippy_utils::ty::is_type_diagnostic_item;
-use if_chain::if_chain;
-use rustc_errors::DiagnosticBuilder;
use rustc_hir as hir;
-use rustc_hir::intravisit::{walk_body, walk_expr, walk_ty, FnKind, NestedVisitorMap, Visitor};
+use rustc_hir::intravisit::FnKind;
use rustc_hir::{
- Body, Expr, ExprKind, FnDecl, FnRetTy, FnSig, GenericArg, GenericParamKind, HirId, ImplItem, ImplItemKind, Item,
- ItemKind, Local, MutTy, QPath, TraitFn, TraitItem, TraitItemKind, TyKind,
+ Body, FnDecl, FnRetTy, GenericArg, HirId, ImplItem, ImplItemKind, Item, ItemKind, Local, MutTy, QPath, TraitItem,
+ TraitItemKind, TyKind,
};
-use rustc_lint::{LateContext, LateLintPass, LintContext};
-use rustc_middle::hir::map::Map;
-use rustc_middle::lint::in_external_macro;
-use rustc_middle::ty::{Ty, TyS, TypeckResults};
-use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::source_map::Span;
-use rustc_span::symbol::sym;
-use rustc_target::spec::abi::Abi;
-use rustc_typeck::hir_ty_to_ty;
-
-use clippy_utils::paths;
-use clippy_utils::{differing_macro_contexts, match_path};
declare_clippy_lint! {
- /// **What it does:** Checks for use of `Box<Vec<_>>` anywhere in the code.
+ /// ### What it does
+ /// Checks for use of `Box<T>` where T is a collection such as Vec anywhere in the code.
/// Check the [Box documentation](https://doc.rust-lang.org/std/boxed/index.html) for more information.
///
- /// **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
+ /// ### Why is this bad?
+ /// Collections already keeps their contents in a separate area on
+ /// the heap. So if you `Box` them, you just add another level of indirection
/// without any benefit whatsoever.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// struct X {
/// values: Box<Vec<Foo>>,
/// values: Vec<Foo>,
/// }
/// ```
- pub BOX_VEC,
+ #[clippy::version = "1.57.0"]
+ pub BOX_COLLECTION,
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.
+ /// ### What it does
+ /// Checks for use of `Vec<Box<T>>` where T: Sized anywhere in the code.
/// Check the [Box documentation](https://doc.rust-lang.org/std/boxed/index.html) for more information.
///
- /// **Why is this bad?** `Vec` already keeps its contents in a separate area on
+ /// ### 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](https://github.com/rust-lang/rust-clippy/issues/3530),
+ /// ### Known problems
+ /// Vec<Box<T: Sized>> makes sense if T is a large type (see [#3530](https://github.com/rust-lang/rust-clippy/issues/3530),
/// 1st comment).
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// struct X {
/// values: Vec<Box<i32>>,
/// values: Vec<i32>,
/// }
/// ```
+ #[clippy::version = "1.33.0"]
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
+ /// ### 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<_>>`
+ /// ### 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**
+ /// ### Example
/// ```rust
/// fn get_data() -> Option<Option<u32>> {
/// None
/// Contents::None
/// }
/// ```
+ #[clippy::version = "pre 1.29.0"]
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
+ /// ### 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:
+ /// ### Why is this bad?
+ /// Gankro says:
///
/// > The TL;DR of `LinkedList` is that it's built on a massive amount of
/// pointers and indirection.
/// 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
+ /// ### Known problems
+ /// False positives – the instances where using a
/// `LinkedList` makes sense are few and far between, but they can still happen.
///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # use std::collections::LinkedList;
/// let x: LinkedList<usize> = LinkedList::new();
/// ```
+ #[clippy::version = "pre 1.29.0"]
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.
+ /// ### What it does
+ /// Checks for use of `&Box<T>` anywhere in the code.
/// Check the [Box documentation](https://doc.rust-lang.org/std/boxed/index.html) for more information.
///
- /// **Why is this bad?** Any `&Box<T>` can also be a `&T`, which is more
+ /// ### Why is this bad?
+ /// Any `&Box<T>` can also be a `&T`, which is more
/// general.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// fn foo(bar: &Box<T>) { ... }
/// ```
/// ```rust,ignore
/// fn foo(bar: &T) { ... }
/// ```
+ #[clippy::version = "pre 1.29.0"]
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.
+ /// ### 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.
+ /// ### Why is this bad?
+ /// Expressions such as `Rc<&T>`, `Rc<Rc<T>>`, `Rc<Arc<T>>`, `Rc<Box<T>>`, `Arc<&T>`, `Arc<Rc<T>>`,
+ /// `Arc<Arc<T>>`, `Arc<Box<T>>`, `Box<&T>`, `Box<Rc<T>>`, `Box<Arc<T>>`, `Box<Box<T>>`, add an unnecessary level of indirection.
///
- /// **Known problems:** None.
- ///
- /// **Example:**
+ /// ### Example
/// ```rust
/// # use std::rc::Rc;
/// fn foo(bar: Rc<&usize>) {}
/// ```rust
/// fn foo(bar: &usize) {}
/// ```
+ #[clippy::version = "1.44.0"]
pub REDUNDANT_ALLOCATION,
perf,
"redundant allocation"
}
declare_clippy_lint! {
- /// **What it does:** Checks for `Rc<T>` and `Arc<T>` when `T` is a mutable buffer type such as `String` or `Vec`.
+ /// ### What it does
+ /// Checks for `Rc<T>` and `Arc<T>` when `T` is a mutable buffer type such as `String` or `Vec`.
///
- /// **Why is this bad?** Expressions such as `Rc<String>` usually have no advantage over `Rc<str>`, since
+ /// ### Why is this bad?
+ /// Expressions such as `Rc<String>` usually have no advantage over `Rc<str>`, since
/// it is larger and involves an extra level of indirection, and doesn't implement `Borrow<str>`.
///
/// While mutating a buffer type would still be possible with `Rc::get_mut()`, it only
/// type with an interior mutable container (such as `RefCell` or `Mutex`) would normally
/// be used.
///
- /// **Known problems:** This pattern can be desirable to avoid the overhead of a `RefCell` or `Mutex` for
+ /// ### Known problems
+ /// This pattern can be desirable to avoid the overhead of a `RefCell` or `Mutex` for
/// cases where mutation only happens before there are any additional references.
///
- /// **Example:**
+ /// ### Example
/// ```rust,ignore
/// # use std::rc::Rc;
/// fn foo(interned: Rc<String>) { ... }
/// ```rust,ignore
/// fn foo(interned: Rc<str>) { ... }
/// ```
+ #[clippy::version = "1.48.0"]
pub RC_BUFFER,
restriction,
"shared ownership of a buffer type"
}
+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.
+ ///
+ /// ### Example
+ /// ```rust
+ /// # use std::rc::Rc;
+ /// struct Foo {
+ /// inner: Rc<Vec<Vec<Box<(u32, u32, u32, u32)>>>>,
+ /// }
+ /// ```
+ #[clippy::version = "pre 1.29.0"]
+ pub TYPE_COMPLEXITY,
+ complexity,
+ "usage of very complex types that might be better factored into `type` definitions"
+}
+
+declare_clippy_lint! {
+ /// ### What it does
+ /// Checks for `Rc<Mutex<T>>`.
+ ///
+ /// ### Why is this bad?
+ /// `Rc` is used in single thread and `Mutex` is used in multi thread.
+ /// Consider using `Rc<RefCell<T>>` in single thread or `Arc<Mutex<T>>` in multi thread.
+ ///
+ /// ### Known problems
+ /// Sometimes combining generic types can lead to the requirement that a
+ /// type use Rc in conjunction with Mutex. We must consider those cases false positives, but
+ /// alas they are quite hard to rule out. Luckily they are also rare.
+ ///
+ /// ### Example
+ /// ```rust,ignore
+ /// use std::rc::Rc;
+ /// use std::sync::Mutex;
+ /// fn foo(interned: Rc<Mutex<i32>>) { ... }
+ /// ```
+ ///
+ /// Better:
+ ///
+ /// ```rust,ignore
+ /// use std::rc::Rc;
+ /// use std::cell::RefCell
+ /// fn foo(interned: Rc<RefCell<i32>>) { ... }
+ /// ```
+ #[clippy::version = "1.55.0"]
+ pub RC_MUTEX,
+ restriction,
+ "usage of `Rc<Mutex<T>>`"
+}
+
pub struct Types {
vec_box_size_threshold: u64,
+ type_complexity_threshold: u64,
+ avoid_breaking_exported_api: bool,
}
-impl_lint_pass!(Types => [BOX_VEC, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX, REDUNDANT_ALLOCATION, RC_BUFFER]);
+impl_lint_pass!(Types => [BOX_COLLECTION, VEC_BOX, OPTION_OPTION, LINKEDLIST, BORROWED_BOX, REDUNDANT_ALLOCATION, RC_BUFFER, RC_MUTEX, TYPE_COMPLEXITY]);
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(hir::Impl { of_trait: Some(_), .. }) = item.kind {
- return;
- }
+ let is_in_trait_impl = if let Some(hir::Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_item(id))
+ {
+ matches!(item.kind, ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }))
+ } else {
+ false
+ };
+
+ let is_exported = cx.access_levels.is_exported(cx.tcx.hir().local_def_id(id));
+
+ self.check_fn_decl(
+ cx,
+ decl,
+ CheckTyContext {
+ is_in_trait_impl,
+ is_exported,
+ ..CheckTyContext::default()
+ },
+ );
+ }
+
+ fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
+ let is_exported = cx.access_levels.is_exported(item.def_id);
+
+ match item.kind {
+ ItemKind::Static(ty, _, _) | ItemKind::Const(ty, _) => self.check_ty(
+ cx,
+ ty,
+ CheckTyContext {
+ is_exported,
+ ..CheckTyContext::default()
+ },
+ ),
+ // functions, enums, structs, impls and traits are covered
+ _ => (),
}
+ }
- self.check_fn_decl(cx, decl);
+ fn check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'_>) {
+ match item.kind {
+ ImplItemKind::Const(ty, _) => self.check_ty(
+ cx,
+ ty,
+ CheckTyContext {
+ is_in_trait_impl: true,
+ ..CheckTyContext::default()
+ },
+ ),
+ // Methods are covered by check_fn.
+ // Type aliases are ignored because oftentimes it's impossible to
+ // make type alias declaration in trait simpler, see #1013
+ ImplItemKind::Fn(..) | ImplItemKind::TyAlias(..) => (),
+ }
}
fn check_field_def(&mut self, cx: &LateContext<'_>, field: &hir::FieldDef<'_>) {
- self.check_ty(cx, &field.ty, false);
+ let is_exported = cx.access_levels.is_exported(cx.tcx.hir().local_def_id(field.hir_id));
+
+ self.check_ty(
+ cx,
+ field.ty,
+ CheckTyContext {
+ is_exported,
+ ..CheckTyContext::default()
+ },
+ );
}
- fn check_trait_item(&mut self, cx: &LateContext<'_>, item: &TraitItem<'_>) {
+ fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &TraitItem<'_>) {
+ let is_exported = cx.access_levels.is_exported(item.def_id);
+
+ let context = CheckTyContext {
+ is_exported,
+ ..CheckTyContext::default()
+ };
+
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),
+ TraitItemKind::Const(ty, _) | TraitItemKind::Type(_, Some(ty)) => {
+ self.check_ty(cx, ty, context);
+ },
+ TraitItemKind::Fn(ref sig, _) => self.check_fn_decl(cx, sig.decl, context),
TraitItemKind::Type(..) => (),
}
}
fn check_local(&mut self, cx: &LateContext<'_>, local: &Local<'_>) {
- if let Some(ref ty) = local.ty {
- self.check_ty(cx, ty, true);
+ if let Some(ty) = local.ty {
+ self.check_ty(
+ cx,
+ ty,
+ CheckTyContext {
+ is_local: true,
+ ..CheckTyContext::default()
+ },
+ );
}
}
}
impl Types {
- pub fn new(vec_box_size_threshold: u64) -> Self {
- Self { vec_box_size_threshold }
+ pub fn new(vec_box_size_threshold: u64, type_complexity_threshold: u64, avoid_breaking_exported_api: bool) -> Self {
+ Self {
+ vec_box_size_threshold,
+ type_complexity_threshold,
+ avoid_breaking_exported_api,
+ }
}
- fn check_fn_decl(&mut self, cx: &LateContext<'_>, decl: &FnDecl<'_>) {
+ fn check_fn_decl(&mut self, cx: &LateContext<'_>, decl: &FnDecl<'_>, context: CheckTyContext) {
for input in decl.inputs {
- self.check_ty(cx, input, false);
+ self.check_ty(cx, input, context);
}
- if let FnRetTy::Return(ref ty) = decl.output {
- self.check_ty(cx, ty, false);
+ if let FnRetTy::Return(ty) = decl.output {
+ self.check_ty(cx, ty, context);
}
}
/// lint found.
///
/// The parameter `is_local` distinguishes the context of the type.
- fn check_ty(&mut self, cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, is_local: bool) {
+ fn check_ty(&mut self, cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>, mut context: CheckTyContext) {
if hir_ty.span.from_expansion() {
return;
}
+
+ if !context.is_nested_call && type_complexity::check(cx, hir_ty, self.type_complexity_threshold) {
+ return;
+ }
+
+ // Skip trait implementations; see issue #605.
+ if context.is_in_trait_impl {
+ return;
+ }
+
match hir_ty.kind {
- TyKind::Path(ref qpath) if !is_local => {
+ TyKind::Path(ref qpath) if !context.is_local => {
let hir_id = hir_ty.hir_id;
let res = cx.qpath_res(qpath, hir_id);
if let Some(def_id) = res.opt_def_id() {
- let mut triggered = false;
- triggered |= box_vec::check(cx, hir_ty, qpath, def_id);
- triggered |= redundant_allocation::check(cx, hir_ty, qpath, def_id);
- triggered |= rc_buffer::check(cx, hir_ty, qpath, def_id);
- triggered |= vec_box::check(cx, hir_ty, qpath, def_id, self.vec_box_size_threshold);
- triggered |= option_option::check(cx, hir_ty, qpath, def_id);
- triggered |= linked_list::check(cx, hir_ty, def_id);
-
- if triggered {
- return;
+ if self.is_type_change_allowed(context) {
+ // All lints that are being checked in this block are guarded by
+ // the `avoid_breaking_exported_api` configuration. When adding a
+ // new lint, please also add the name to the configuration documentation
+ // in `clippy_lints::utils::conf.rs`
+
+ let mut triggered = false;
+ triggered |= box_collection::check(cx, hir_ty, qpath, def_id);
+ triggered |= redundant_allocation::check(cx, hir_ty, qpath, def_id);
+ triggered |= rc_buffer::check(cx, hir_ty, qpath, def_id);
+ triggered |= vec_box::check(cx, hir_ty, qpath, def_id, self.vec_box_size_threshold);
+ triggered |= option_option::check(cx, hir_ty, qpath, def_id);
+ triggered |= linked_list::check(cx, hir_ty, def_id);
+ triggered |= rc_mutex::check(cx, hir_ty, qpath, def_id);
+
+ if triggered {
+ return;
+ }
}
}
match *qpath {
- QPath::Resolved(Some(ref ty), ref p) => {
- self.check_ty(cx, ty, is_local);
+ QPath::Resolved(Some(ty), p) => {
+ context.is_nested_call = true;
+ self.check_ty(cx, ty, context);
for ty in p.segments.iter().flat_map(|seg| {
seg.args
.as_ref()
_ => None,
})
}) {
- self.check_ty(cx, ty, is_local);
+ self.check_ty(cx, ty, context);
}
},
- QPath::Resolved(None, ref p) => {
+ QPath::Resolved(None, p) => {
+ context.is_nested_call = true;
for ty in p.segments.iter().flat_map(|seg| {
seg.args
.as_ref()
_ => None,
})
}) {
- self.check_ty(cx, ty, is_local);
+ self.check_ty(cx, ty, context);
}
},
- QPath::TypeRelative(ref ty, ref seg) => {
- self.check_ty(cx, ty, is_local);
- if let Some(ref params) = seg.args {
+ QPath::TypeRelative(ty, seg) => {
+ context.is_nested_call = true;
+ self.check_ty(cx, ty, context);
+ if let Some(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);
+ self.check_ty(cx, ty, context);
}
}
},
}
},
TyKind::Rptr(ref lt, ref mut_ty) => {
+ context.is_nested_call = true;
if !borrowed_box::check(cx, hir_ty, lt, mut_ty) {
- self.check_ty(cx, &mut_ty.ty, is_local);
+ self.check_ty(cx, mut_ty.ty, context);
}
},
- TyKind::Slice(ref ty) | TyKind::Array(ref ty, _) | TyKind::Ptr(MutTy { ref ty, .. }) => {
- self.check_ty(cx, ty, is_local)
+ TyKind::Slice(ty) | TyKind::Array(ty, _) | TyKind::Ptr(MutTy { ty, .. }) => {
+ context.is_nested_call = true;
+ self.check_ty(cx, ty, context);
},
TyKind::Tup(tys) => {
+ context.is_nested_call = true;
for ty in tys {
- self.check_ty(cx, ty, is_local);
- }
- },
- _ => {},
- }
- }
-}
-
-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_field_def(&mut self, cx: &LateContext<'tcx>, field: &'tcx hir::FieldDef<'_>) {
- // 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
- TraitItemKind::Type(..) | TraitItemKind::Fn(_, TraitFn::Provided(_)) => (),
- }
- }
-
- 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
- ImplItemKind::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| matches!(gen.kind, GenericParamKind::Lifetime { .. }))
- });
- 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 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 impl_) => {
- let mut vis = ImplicitHasherTypeVisitor::new(cx);
- vis.visit_ty(impl_.self_ty);
-
- for target in &vis.found {
- if differing_macro_contexts(item.span, target.span()) {
- return;
- }
-
- let generics_suggestion_span = impl_.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 impl_.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, impl_.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);
- },
- );
- }
+ self.check_ty(cx, ty, context);
}
},
_ => {},
}
}
-}
-
-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,
- }
+ /// This function checks if the type is allowed to change in the current context
+ /// based on the `avoid_breaking_exported_api` configuration
+ fn is_type_change_allowed(&self, context: CheckTyContext) -> bool {
+ !(context.is_exported && self.avoid_breaking_exported_api)
}
}
-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_results: Option<&'tcx TypeckResults<'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_results: cx.maybe_typeck_results(),
- 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_results = self.maybe_typeck_results.replace(self.cx.tcx.typeck_body(body.id()));
- walk_body(self, body);
- self.maybe_typeck_results = old_maybe_typeck_results;
- }
-
- 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_results.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())
- }
+#[allow(clippy::struct_excessive_bools)]
+#[derive(Clone, Copy, Default)]
+struct CheckTyContext {
+ is_in_trait_impl: bool,
+ /// `true` for types on local variables.
+ is_local: bool,
+ /// `true` for types that are part of the public API.
+ is_exported: bool,
+ is_nested_call: bool,
}
projects / rust.git / blobdiff