5101c8e87f
`ast::Item` has an `ident` field. - It's always non-empty for these item kinds: `ExternCrate`, `Static`, `Const`, `Fn`, `Mod`, `TyAlias`, `Enum`, `Struct`, `Union`, `Trait`, `TraitAlias`, `MacroDef`, `Delegation`. - It's always empty for these item kinds: `Use`, `ForeignMod`, `GlobalAsm`, `Impl`, `MacCall`, `DelegationMac`. There is a similar story for `AssocItemKind` and `ForeignItemKind`. Some sites that handle items check for an empty ident, some don't. This is a very C-like way of doing things, but this is Rust, we have sum types, we can do this properly and never forget to check for the exceptional case and never YOLO possibly empty identifiers (or possibly dummy spans) around and hope that things will work out. The commit is large but it's mostly obvious plumbing work. Some notable things. - `ast::Item` got 8 bytes bigger. This could be avoided by boxing the fields within some of the `ast::ItemKind` variants (specifically: `Struct`, `Union`, `Enum`). I might do that in a follow-up; this commit is big enough already. - For the visitors: `FnKind` no longer needs an `ident` field because the `Fn` within how has one. - In the parser, the `ItemInfo` typedef is no longer needed. It was used in various places to return an `Ident` alongside an `ItemKind`, but now the `Ident` (if present) is within the `ItemKind`. - In a few places I renamed identifier variables called `name` (or `foo_name`) as `ident` (or `foo_ident`), to better match the type, and because `name` is normally used for `Symbol`s. It's confusing to see something like `foo_name.name`.
86 lines
3 KiB
Rust
86 lines
3 KiB
Rust
use rustc_ast::visit::FnKind;
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use rustc_ast::{Fn, NodeId, WherePredicateKind};
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use rustc_data_structures::fx::FxHashMap;
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use rustc_lint::{EarlyContext, EarlyLintPass};
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use rustc_session::declare_lint_pass;
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use rustc_span::Span;
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use clippy_utils::diagnostics::span_lint;
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use clippy_utils::source::SpanRangeExt;
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declare_clippy_lint! {
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/// ### What it does
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/// Check if a generic is defined both in the bound predicate and in the `where` clause.
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///
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/// ### Why is this bad?
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/// It can be confusing for developers when seeing bounds for a generic in multiple places.
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///
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/// ### Example
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/// ```no_run
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/// fn ty<F: std::fmt::Debug>(a: F)
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/// where
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/// F: Sized,
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/// {}
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/// ```
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/// Use instead:
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/// ```no_run
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/// fn ty<F>(a: F)
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/// where
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/// F: Sized + std::fmt::Debug,
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/// {}
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/// ```
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#[clippy::version = "1.78.0"]
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pub MULTIPLE_BOUND_LOCATIONS,
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suspicious,
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"defining generic bounds in multiple locations"
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}
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declare_lint_pass!(MultipleBoundLocations => [MULTIPLE_BOUND_LOCATIONS]);
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impl EarlyLintPass for MultipleBoundLocations {
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fn check_fn(&mut self, cx: &EarlyContext<'_>, kind: FnKind<'_>, _: Span, _: NodeId) {
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if let FnKind::Fn(_, _, Fn { generics, .. }) = kind
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&& !generics.params.is_empty()
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&& !generics.where_clause.predicates.is_empty()
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{
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let mut generic_params_with_bounds = FxHashMap::default();
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for param in &generics.params {
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if !param.bounds.is_empty() {
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generic_params_with_bounds.insert(param.ident.name.as_str(), param.ident.span);
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}
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}
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for clause in &generics.where_clause.predicates {
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match &clause.kind {
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WherePredicateKind::BoundPredicate(pred) => {
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if (!pred.bound_generic_params.is_empty() || !pred.bounds.is_empty())
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&& let Some(Some(bound_span)) = pred
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.bounded_ty
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.span
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.with_source_text(cx, |src| generic_params_with_bounds.get(src))
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{
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emit_lint(cx, *bound_span, pred.bounded_ty.span);
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}
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},
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WherePredicateKind::RegionPredicate(pred) => {
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if !pred.bounds.is_empty()
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&& let Some(bound_span) = generic_params_with_bounds.get(&pred.lifetime.ident.name.as_str())
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{
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emit_lint(cx, *bound_span, pred.lifetime.ident.span);
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}
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},
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WherePredicateKind::EqPredicate(_) => {},
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}
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}
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}
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}
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}
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fn emit_lint(cx: &EarlyContext<'_>, bound_span: Span, where_span: Span) {
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span_lint(
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cx,
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MULTIPLE_BOUND_LOCATIONS,
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vec![bound_span, where_span],
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"bound is defined in more than one place",
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);
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}
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