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Auto merge of #4885 - rust-lang:mut-key-types, r=flip1995
new lint: mutable_key_type This fixes #732 – well, partly, it doesn't adress `Hash` impls, but the use of mutable types as map keys or set members changelog: add `mutable_key_type` lint r? @flip1995
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,120 @@ | ||
| use crate::utils::{match_def_path, paths, span_lint, trait_ref_of_method, walk_ptrs_ty}; | ||
| use rustc::declare_lint_pass; | ||
| use rustc::hir; | ||
| use rustc::lint::{LateContext, LateLintPass, LintArray, LintPass}; | ||
| use rustc::ty::{Adt, Dynamic, Opaque, Param, RawPtr, Ref, Ty, TypeAndMut}; | ||
| use rustc_session::declare_tool_lint; | ||
| use syntax::source_map::Span; | ||
|
|
||
| declare_clippy_lint! { | ||
| /// **What it does:** Checks for sets/maps with mutable key types. | ||
| /// | ||
| /// **Why is this bad?** All of `HashMap`, `HashSet`, `BTreeMap` and | ||
| /// `BtreeSet` rely on either the hash or the order of keys be unchanging, | ||
| /// so having types with interior mutability is a bad idea. | ||
| /// | ||
| /// **Known problems:** We don't currently account for `Rc` or `Arc`, so | ||
| /// this may yield false positives. | ||
| /// | ||
| /// **Example:** | ||
| /// ```rust | ||
| /// use std::cmp::{PartialEq, Eq}; | ||
| /// use std::collections::HashSet; | ||
| /// use std::hash::{Hash, Hasher}; | ||
| /// use std::sync::atomic::AtomicUsize; | ||
| ///# #[allow(unused)] | ||
| /// | ||
| /// struct Bad(AtomicUsize); | ||
| /// impl PartialEq for Bad { | ||
| /// fn eq(&self, rhs: &Self) -> bool { | ||
| /// .. | ||
| /// ; unimplemented!(); | ||
| /// } | ||
| /// } | ||
| /// | ||
| /// impl Eq for Bad {} | ||
| /// | ||
| /// impl Hash for Bad { | ||
| /// fn hash<H: Hasher>(&self, h: &mut H) { | ||
| /// .. | ||
| /// ; unimplemented!(); | ||
| /// } | ||
| /// } | ||
| /// | ||
| /// fn main() { | ||
| /// let _: HashSet<Bad> = HashSet::new(); | ||
| /// } | ||
| /// ``` | ||
| pub MUTABLE_KEY_TYPE, | ||
| correctness, | ||
| "Check for mutable Map/Set key type" | ||
| } | ||
|
|
||
| declare_lint_pass!(MutableKeyType => [ MUTABLE_KEY_TYPE ]); | ||
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||
| impl<'a, 'tcx> LateLintPass<'a, 'tcx> for MutableKeyType { | ||
| fn check_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::Item) { | ||
| if let hir::ItemKind::Fn(ref sig, ..) = item.kind { | ||
| check_sig(cx, item.hir_id, &sig.decl); | ||
| } | ||
| } | ||
|
|
||
| fn check_impl_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::ImplItem) { | ||
| if let hir::ImplItemKind::Method(ref sig, ..) = item.kind { | ||
| if trait_ref_of_method(cx, item.hir_id).is_none() { | ||
| check_sig(cx, item.hir_id, &sig.decl); | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn check_trait_item(&mut self, cx: &LateContext<'a, 'tcx>, item: &'tcx hir::TraitItem) { | ||
| if let hir::TraitItemKind::Method(ref sig, ..) = item.kind { | ||
| check_sig(cx, item.hir_id, &sig.decl); | ||
| } | ||
| } | ||
|
|
||
| fn check_local(&mut self, cx: &LateContext<'_, '_>, local: &hir::Local) { | ||
| if let hir::PatKind::Wild = local.pat.kind { | ||
| return; | ||
| } | ||
| check_ty(cx, local.span, cx.tables.pat_ty(&*local.pat)); | ||
| } | ||
| } | ||
|
|
||
| fn check_sig<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, item_hir_id: hir::HirId, decl: &hir::FnDecl) { | ||
| let fn_def_id = cx.tcx.hir().local_def_id(item_hir_id); | ||
| let fn_sig = cx.tcx.fn_sig(fn_def_id); | ||
| for (hir_ty, ty) in decl.inputs.iter().zip(fn_sig.inputs().skip_binder().iter()) { | ||
| check_ty(cx, hir_ty.span, ty); | ||
| } | ||
| check_ty( | ||
| cx, | ||
| decl.output.span(), | ||
| cx.tcx.erase_late_bound_regions(&fn_sig.output()), | ||
| ); | ||
| } | ||
|
|
||
| // We want to lint 1. sets or maps with 2. not immutable key types and 3. no unerased | ||
| // generics (because the compiler cannot ensure immutability for unknown types). | ||
| fn check_ty<'a, 'tcx>(cx: &LateContext<'a, 'tcx>, span: Span, ty: Ty<'tcx>) { | ||
| let ty = walk_ptrs_ty(ty); | ||
| if let Adt(def, substs) = ty.kind { | ||
| if [&paths::HASHMAP, &paths::BTREEMAP, &paths::HASHSET, &paths::BTREESET] | ||
| .iter() | ||
| .any(|path| match_def_path(cx, def.did, &**path)) | ||
| { | ||
| let key_type = substs.type_at(0); | ||
| if is_concrete_type(key_type) && !key_type.is_freeze(cx.tcx, cx.param_env, span) { | ||
| span_lint(cx, MUTABLE_KEY_TYPE, span, "mutable key type"); | ||
| } | ||
| } | ||
| } | ||
| } | ||
|
|
||
| fn is_concrete_type(ty: Ty<'_>) -> bool { | ||
| match ty.kind { | ||
| RawPtr(TypeAndMut { ty: inner_ty, .. }) | Ref(_, inner_ty, _) => is_concrete_type(inner_ty), | ||
| Dynamic(..) | Opaque(..) | Param(..) => false, | ||
| _ => true, | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,37 @@ | ||
| use std::collections::{HashMap, HashSet}; | ||
| use std::hash::{Hash, Hasher}; | ||
| use std::sync::atomic::{AtomicUsize, Ordering::Relaxed}; | ||
|
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| struct Key(AtomicUsize); | ||
|
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| impl Clone for Key { | ||
| fn clone(&self) -> Self { | ||
| Key(AtomicUsize::new(self.0.load(Relaxed))) | ||
| } | ||
| } | ||
|
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||
| impl PartialEq for Key { | ||
| fn eq(&self, other: &Self) -> bool { | ||
| self.0.load(Relaxed) == other.0.load(Relaxed) | ||
| } | ||
| } | ||
|
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| impl Eq for Key {} | ||
|
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| impl Hash for Key { | ||
| fn hash<H: Hasher>(&self, h: &mut H) { | ||
| self.0.load(Relaxed).hash(h); | ||
| } | ||
| } | ||
|
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||
| fn should_not_take_this_arg(m: &mut HashMap<Key, usize>, _n: usize) -> HashSet<Key> { | ||
| let _other: HashMap<Key, bool> = HashMap::new(); | ||
| m.keys().cloned().collect() | ||
| } | ||
|
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| fn this_is_ok(m: &mut HashMap<usize, Key>) {} | ||
|
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||
| fn main() { | ||
| let _ = should_not_take_this_arg(&mut HashMap::new(), 1); | ||
| this_is_ok(&mut HashMap::new()); | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,22 @@ | ||
| error: mutable key type | ||
| --> $DIR/mut_key.rs:27:32 | ||
| | | ||
| LL | fn should_not_take_this_arg(m: &mut HashMap<Key, usize>, _n: usize) -> HashSet<Key> { | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^ | ||
| | | ||
| = note: `#[deny(clippy::mutable_key_type)]` on by default | ||
|
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||
| error: mutable key type | ||
| --> $DIR/mut_key.rs:27:72 | ||
| | | ||
| LL | fn should_not_take_this_arg(m: &mut HashMap<Key, usize>, _n: usize) -> HashSet<Key> { | ||
| | ^^^^^^^^^^^^ | ||
|
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| error: mutable key type | ||
| --> $DIR/mut_key.rs:28:5 | ||
| | | ||
| LL | let _other: HashMap<Key, bool> = HashMap::new(); | ||
| | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ | ||
|
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| error: aborting due to 3 previous errors | ||
|
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