10cf3cb945
A check for `#[non_exhaustive]` is often done in combination with checking whether the type is local to the crate, in a variety of ways. Create a helper method and standardize on it as the way to check for this.
76 lines
2.4 KiB
Rust
76 lines
2.4 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::is_from_proc_macro;
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use rustc_errors::Applicability;
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use rustc_hir::def::{DefKind, Res};
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use rustc_hir::{Pat, PatKind, QPath};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::declare_lint_pass;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for struct patterns that match against unit variant.
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///
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/// ### Why is this bad?
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/// Struct pattern `{ }` or `{ .. }` is not needed for unit variant.
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///
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/// ### Example
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/// ```no_run
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/// match Some(42) {
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/// Some(v) => v,
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/// None { .. } => 0,
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/// };
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/// // Or
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/// match Some(42) {
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/// Some(v) => v,
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/// None { } => 0,
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/// };
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/// ```
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/// Use instead:
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/// ```no_run
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/// match Some(42) {
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/// Some(v) => v,
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/// None => 0,
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/// };
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/// ```
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#[clippy::version = "1.86.0"]
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pub UNNEEDED_STRUCT_PATTERN,
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style,
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"using struct pattern to match against unit variant"
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}
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declare_lint_pass!(UnneededStructPattern => [UNNEEDED_STRUCT_PATTERN]);
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impl LateLintPass<'_> for UnneededStructPattern {
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fn check_pat(&mut self, cx: &LateContext<'_>, pat: &Pat<'_>) {
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if !pat.span.from_expansion()
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&& let PatKind::Struct(path, [], _) = &pat.kind
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&& let QPath::Resolved(_, path) = path
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&& let Res::Def(DefKind::Variant, did) = path.res
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{
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let enum_did = cx.tcx.parent(did);
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let variant = cx.tcx.adt_def(enum_did).variant_with_id(did);
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let has_only_fields_brackets = variant.ctor.is_some() && variant.fields.is_empty();
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let non_exhaustive_activated = variant.field_list_has_applicable_non_exhaustive();
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if !has_only_fields_brackets || non_exhaustive_activated {
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return;
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}
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if is_from_proc_macro(cx, *path) {
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return;
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}
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if let Some(brackets_span) = pat.span.trim_start(path.span) {
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span_lint_and_sugg(
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cx,
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UNNEEDED_STRUCT_PATTERN,
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brackets_span,
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"struct pattern is not needed for a unit variant",
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"remove the struct pattern",
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String::new(),
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Applicability::MachineApplicable,
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);
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}
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}
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}
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}
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