[`zero_divided_by_zero`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_divided_by_zero
[`zero_prefixed_literal`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_prefixed_literal
[`zero_ptr`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_ptr
+[`zero_sized_map_values`]: https://rust-lang.github.io/rust-clippy/master/index.html#zero_sized_map_values
[`zst_offset`]: https://rust-lang.github.io/rust-clippy/master/index.html#zst_offset
<!-- end autogenerated links to lint list -->
mod wildcard_imports;
mod write;
mod zero_div_zero;
+mod zero_sized_map_values;
// end lints modules, do not remove this comment, it’s used in `update_lints`
pub use crate::utils::conf::Conf;
&write::WRITE_LITERAL,
&write::WRITE_WITH_NEWLINE,
&zero_div_zero::ZERO_DIVIDED_BY_ZERO,
+ &zero_sized_map_values::ZERO_SIZED_MAP_VALUES,
]);
// end register lints, do not remove this comment, it’s used in `update_lints`
store.register_late_pass(|| box undropped_manually_drops::UndroppedManuallyDrops);
store.register_late_pass(|| box strings::StrToString);
store.register_late_pass(|| box strings::StringToString);
+ store.register_late_pass(|| box zero_sized_map_values::ZeroSizedMapValues);
store.register_group(true, "clippy::restriction", Some("clippy_restriction"), vec![
LintId::of(&arithmetic::FLOAT_ARITHMETIC),
LintId::of(&unused_self::UNUSED_SELF),
LintId::of(&wildcard_imports::ENUM_GLOB_USE),
LintId::of(&wildcard_imports::WILDCARD_IMPORTS),
+ LintId::of(&zero_sized_map_values::ZERO_SIZED_MAP_VALUES),
]);
#[cfg(feature = "internal-lints")]
--- /dev/null
+use if_chain::if_chain;
+use rustc_hir::{self as hir, HirId, ItemKind, Node};
+use rustc_lint::{LateContext, LateLintPass};
+use rustc_middle::ty::{Adt, Ty};
+use rustc_session::{declare_lint_pass, declare_tool_lint};
+use rustc_target::abi::LayoutOf as _;
+use rustc_typeck::hir_ty_to_ty;
+
+use crate::utils::{is_type_diagnostic_item, match_type, paths, span_lint_and_help};
+
+declare_clippy_lint! {
+ /// **What it does:** Checks for maps with zero-sized value types anywhere in the code.
+ ///
+ /// **Why is this bad?** Since there is only a single value for a zero-sized type, a map
+ /// containing zero sized values is effectively a set. Using a set in that case improves
+ /// readability and communicates intent more clearly.
+ ///
+ /// **Known problems:**
+ /// * A zero-sized type cannot be recovered later if it contains private fields.
+ /// * This lints the signature of public items
+ ///
+ /// **Example:**
+ ///
+ /// ```rust
+ /// # use std::collections::HashMap;
+ /// fn unique_words(text: &str) -> HashMap<&str, ()> {
+ /// todo!();
+ /// }
+ /// ```
+ /// Use instead:
+ /// ```rust
+ /// # use std::collections::HashSet;
+ /// fn unique_words(text: &str) -> HashSet<&str> {
+ /// todo!();
+ /// }
+ /// ```
+ pub ZERO_SIZED_MAP_VALUES,
+ pedantic,
+ "usage of map with zero-sized value type"
+}
+
+declare_lint_pass!(ZeroSizedMapValues => [ZERO_SIZED_MAP_VALUES]);
+
+impl LateLintPass<'_> for ZeroSizedMapValues {
+ fn check_ty(&mut self, cx: &LateContext<'_>, hir_ty: &hir::Ty<'_>) {
+ if_chain! {
+ if !hir_ty.span.from_expansion();
+ if !in_trait_impl(cx, hir_ty.hir_id);
+ let ty = ty_from_hir_ty(cx, hir_ty);
+ if is_type_diagnostic_item(cx, ty, sym!(hashmap_type)) || match_type(cx, ty, &paths::BTREEMAP);
+ if let Adt(_, ref substs) = ty.kind();
+ let ty = substs.type_at(1);
+ if let Ok(layout) = cx.layout_of(ty);
+ if layout.is_zst();
+ then {
+ span_lint_and_help(cx, ZERO_SIZED_MAP_VALUES, hir_ty.span, "map with zero-sized value type", None, "consider using a set instead");
+ }
+ }
+ }
+}
+
+fn in_trait_impl(cx: &LateContext<'_>, hir_id: HirId) -> bool {
+ let parent_id = cx.tcx.hir().get_parent_item(hir_id);
+ if let Some(Node::Item(item)) = cx.tcx.hir().find(cx.tcx.hir().get_parent_item(parent_id)) {
+ if let ItemKind::Impl { of_trait: Some(_), .. } = item.kind {
+ return true;
+ }
+ }
+ false
+}
+
+fn ty_from_hir_ty<'tcx>(cx: &LateContext<'tcx>, hir_ty: &hir::Ty<'_>) -> Ty<'tcx> {
+ cx.maybe_typeck_results()
+ .and_then(|results| {
+ if results.hir_owner == hir_ty.hir_id.owner {
+ results.node_type_opt(hir_ty.hir_id)
+ } else {
+ None
+ }
+ })
+ .unwrap_or_else(|| hir_ty_to_ty(cx.tcx, hir_ty))
+}
--- /dev/null
+#![warn(clippy::zero_sized_map_values)]
+use std::collections::BTreeMap;
+
+const CONST_OK: Option<BTreeMap<String, usize>> = None;
+const CONST_NOT_OK: Option<BTreeMap<String, ()>> = None;
+
+static STATIC_OK: Option<BTreeMap<String, usize>> = None;
+static STATIC_NOT_OK: Option<BTreeMap<String, ()>> = None;
+
+type OkMap = BTreeMap<String, usize>;
+type NotOkMap = BTreeMap<String, ()>;
+
+enum TestEnum {
+ Ok(BTreeMap<String, usize>),
+ NotOk(BTreeMap<String, ()>),
+}
+
+struct Test {
+ ok: BTreeMap<String, usize>,
+ not_ok: BTreeMap<String, ()>,
+
+ also_not_ok: Vec<BTreeMap<usize, ()>>,
+}
+
+trait TestTrait {
+ type Output;
+
+ fn produce_output() -> Self::Output;
+
+ fn weird_map(&self, map: BTreeMap<usize, ()>);
+}
+
+impl Test {
+ fn ok(&self) -> BTreeMap<String, usize> {
+ todo!()
+ }
+
+ fn not_ok(&self) -> BTreeMap<String, ()> {
+ todo!()
+ }
+}
+
+impl TestTrait for Test {
+ type Output = BTreeMap<String, ()>;
+
+ fn produce_output() -> Self::Output {
+ todo!();
+ }
+
+ fn weird_map(&self, map: BTreeMap<usize, ()>) {
+ todo!();
+ }
+}
+
+fn test(map: BTreeMap<String, ()>, key: &str) -> BTreeMap<String, ()> {
+ todo!();
+}
+
+fn test2(map: BTreeMap<String, usize>, key: &str) -> BTreeMap<String, usize> {
+ todo!();
+}
+
+fn main() {
+ let _: BTreeMap<String, ()> = BTreeMap::new();
+ let _: BTreeMap<String, usize> = BTreeMap::new();
+
+ let _: BTreeMap<_, _> = std::iter::empty::<(String, ())>().collect();
+}
--- /dev/null
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:5:28
+ |
+LL | const CONST_NOT_OK: Option<BTreeMap<String, ()>> = None;
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = note: `-D clippy::zero-sized-map-values` implied by `-D warnings`
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:8:30
+ |
+LL | static STATIC_NOT_OK: Option<BTreeMap<String, ()>> = None;
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:11:17
+ |
+LL | type NotOkMap = BTreeMap<String, ()>;
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:15:11
+ |
+LL | NotOk(BTreeMap<String, ()>),
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:20:13
+ |
+LL | not_ok: BTreeMap<String, ()>,
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:22:22
+ |
+LL | also_not_ok: Vec<BTreeMap<usize, ()>>,
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:30:30
+ |
+LL | fn weird_map(&self, map: BTreeMap<usize, ()>);
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:38:25
+ |
+LL | fn not_ok(&self) -> BTreeMap<String, ()> {
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:55:14
+ |
+LL | fn test(map: BTreeMap<String, ()>, key: &str) -> BTreeMap<String, ()> {
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:55:50
+ |
+LL | fn test(map: BTreeMap<String, ()>, key: &str) -> BTreeMap<String, ()> {
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:64:35
+ |
+LL | let _: BTreeMap<String, ()> = BTreeMap::new();
+ | ^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:64:12
+ |
+LL | let _: BTreeMap<String, ()> = BTreeMap::new();
+ | ^^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_btreemap_values.rs:67:12
+ |
+LL | let _: BTreeMap<_, _> = std::iter::empty::<(String, ())>().collect();
+ | ^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: aborting due to 13 previous errors
+
--- /dev/null
+#![warn(clippy::zero_sized_map_values)]
+use std::collections::HashMap;
+
+const CONST_OK: Option<HashMap<String, usize>> = None;
+const CONST_NOT_OK: Option<HashMap<String, ()>> = None;
+
+static STATIC_OK: Option<HashMap<String, usize>> = None;
+static STATIC_NOT_OK: Option<HashMap<String, ()>> = None;
+
+type OkMap = HashMap<String, usize>;
+type NotOkMap = HashMap<String, ()>;
+
+enum TestEnum {
+ Ok(HashMap<String, usize>),
+ NotOk(HashMap<String, ()>),
+}
+
+struct Test {
+ ok: HashMap<String, usize>,
+ not_ok: HashMap<String, ()>,
+
+ also_not_ok: Vec<HashMap<usize, ()>>,
+}
+
+trait TestTrait {
+ type Output;
+
+ fn produce_output() -> Self::Output;
+
+ fn weird_map(&self, map: HashMap<usize, ()>);
+}
+
+impl Test {
+ fn ok(&self) -> HashMap<String, usize> {
+ todo!()
+ }
+
+ fn not_ok(&self) -> HashMap<String, ()> {
+ todo!()
+ }
+}
+
+impl TestTrait for Test {
+ type Output = HashMap<String, ()>;
+
+ fn produce_output() -> Self::Output {
+ todo!();
+ }
+
+ fn weird_map(&self, map: HashMap<usize, ()>) {
+ todo!();
+ }
+}
+
+fn test(map: HashMap<String, ()>, key: &str) -> HashMap<String, ()> {
+ todo!();
+}
+
+fn test2(map: HashMap<String, usize>, key: &str) -> HashMap<String, usize> {
+ todo!();
+}
+
+fn main() {
+ let _: HashMap<String, ()> = HashMap::new();
+ let _: HashMap<String, usize> = HashMap::new();
+
+ let _: HashMap<_, _> = std::iter::empty::<(String, ())>().collect();
+}
--- /dev/null
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:5:28
+ |
+LL | const CONST_NOT_OK: Option<HashMap<String, ()>> = None;
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = note: `-D clippy::zero-sized-map-values` implied by `-D warnings`
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:8:30
+ |
+LL | static STATIC_NOT_OK: Option<HashMap<String, ()>> = None;
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:11:17
+ |
+LL | type NotOkMap = HashMap<String, ()>;
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:15:11
+ |
+LL | NotOk(HashMap<String, ()>),
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:20:13
+ |
+LL | not_ok: HashMap<String, ()>,
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:22:22
+ |
+LL | also_not_ok: Vec<HashMap<usize, ()>>,
+ | ^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:30:30
+ |
+LL | fn weird_map(&self, map: HashMap<usize, ()>);
+ | ^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:38:25
+ |
+LL | fn not_ok(&self) -> HashMap<String, ()> {
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:55:14
+ |
+LL | fn test(map: HashMap<String, ()>, key: &str) -> HashMap<String, ()> {
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:55:49
+ |
+LL | fn test(map: HashMap<String, ()>, key: &str) -> HashMap<String, ()> {
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:64:34
+ |
+LL | let _: HashMap<String, ()> = HashMap::new();
+ | ^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:64:12
+ |
+LL | let _: HashMap<String, ()> = HashMap::new();
+ | ^^^^^^^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: map with zero-sized value type
+ --> $DIR/zero_sized_hashmap_values.rs:67:12
+ |
+LL | let _: HashMap<_, _> = std::iter::empty::<(String, ())>().collect();
+ | ^^^^^^^^^^^^^
+ |
+ = help: consider using a set instead
+
+error: aborting due to 13 previous errors
+
projects / rust.git / commitdiff