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Auto merge of #6617 - Manishearth:exhaustive_enums, r=camsteffen
New lint: exhaustive_enums, exhaustive_structs Fixes #6616 changelog: Added restriction lint: `exhaustive_enums`, `exhaustive_structs`
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‎CHANGELOG.md

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@@ -1938,6 +1938,8 @@ Released 2018-09-13
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[`erasing_op`]: https://rust-lang.github.io/rust-clippy/master/index.html#erasing_op
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[`eval_order_dependence`]: https://rust-lang.github.io/rust-clippy/master/index.html#eval_order_dependence
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[`excessive_precision`]: https://rust-lang.github.io/rust-clippy/master/index.html#excessive_precision
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[`exhaustive_enums`]: https://rust-lang.github.io/rust-clippy/master/index.html#exhaustive_enums
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[`exhaustive_structs`]: https://rust-lang.github.io/rust-clippy/master/index.html#exhaustive_structs
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[`exit`]: https://rust-lang.github.io/rust-clippy/master/index.html#exit
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[`expect_fun_call`]: https://rust-lang.github.io/rust-clippy/master/index.html#expect_fun_call
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[`expect_used`]: https://rust-lang.github.io/rust-clippy/master/index.html#expect_used

‎clippy_lints/src/exhaustive_items.rs

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use crate::utils::{indent_of, span_lint_and_then};
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use if_chain::if_chain;
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use rustc_errors::Applicability;
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use rustc_hir::{Item, ItemKind};
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use rustc_lint::{LateContext, LateLintPass};
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::sym;
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declare_clippy_lint! {
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/// **What it does:** Warns on any exported `enum`s that are not tagged `#[non_exhaustive]`
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///
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/// **Why is this bad?** Exhaustive enums are typically fine, but a project which does
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/// not wish to make a stability commitment around exported enums may wish to
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/// disable them by default.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// enum Foo {
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/// Bar,
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/// Baz
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/// }
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/// ```
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/// Use instead:
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/// ```rust
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/// #[non_exhaustive]
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/// enum Foo {
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/// Bar,
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/// Baz
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/// }
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/// ```
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pub EXHAUSTIVE_ENUMS,
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restriction,
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"detects exported enums that have not been marked #[non_exhaustive]"
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}
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declare_clippy_lint! {
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/// **What it does:** Warns on any exported `structs`s that are not tagged `#[non_exhaustive]`
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///
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/// **Why is this bad?** Exhaustive structs are typically fine, but a project which does
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/// not wish to make a stability commitment around exported structs may wish to
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/// disable them by default.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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///
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/// ```rust
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/// struct Foo {
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/// bar: u8,
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/// baz: String,
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/// }
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/// ```
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/// Use instead:
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/// ```rust
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/// #[non_exhaustive]
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/// struct Foo {
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/// bar: u8,
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/// baz: String,
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/// }
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/// ```
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pub EXHAUSTIVE_STRUCTS,
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restriction,
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"detects exported structs that have not been marked #[non_exhaustive]"
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}
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declare_lint_pass!(ExhaustiveItems => [EXHAUSTIVE_ENUMS, EXHAUSTIVE_STRUCTS]);
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impl LateLintPass<'_> for ExhaustiveItems {
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fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
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if_chain! {
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if let ItemKind::Enum(..) | ItemKind::Struct(..) = item.kind;
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if cx.access_levels.is_exported(item.hir_id);
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if !item.attrs.iter().any(|a| a.has_name(sym::non_exhaustive));
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then {
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let (lint, msg) = if let ItemKind::Enum(..) = item.kind {
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(EXHAUSTIVE_ENUMS, "exported enums should not be exhaustive")
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} else {
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(EXHAUSTIVE_STRUCTS, "exported structs should not be exhaustive")
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};
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let suggestion_span = item.span.shrink_to_lo();
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let indent = " ".repeat(indent_of(cx, item.span).unwrap_or(0));
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span_lint_and_then(
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cx,
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lint,
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item.span,
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msg,
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|diag| {
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let sugg = format!("#[non_exhaustive]\n{}", indent);
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diag.span_suggestion(suggestion_span,
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"try adding #[non_exhaustive]",
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sugg,
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Applicability::MaybeIncorrect);
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}
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);
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}
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}
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}
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}

‎clippy_lints/src/lib.rs

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@@ -200,6 +200,7 @@ mod escape;
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mod eta_reduction;
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mod eval_order_dependence;
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mod excessive_bools;
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mod exhaustive_items;
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mod exit;
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mod explicit_write;
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mod fallible_impl_from;
@@ -615,6 +616,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
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&eval_order_dependence::EVAL_ORDER_DEPENDENCE,
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&excessive_bools::FN_PARAMS_EXCESSIVE_BOOLS,
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&excessive_bools::STRUCT_EXCESSIVE_BOOLS,
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&exhaustive_items::EXHAUSTIVE_ENUMS,
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&exhaustive_items::EXHAUSTIVE_STRUCTS,
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&exit::EXIT,
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&explicit_write::EXPLICIT_WRITE,
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&fallible_impl_from::FALLIBLE_IMPL_FROM,
@@ -1101,6 +1104,7 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
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store.register_late_pass(|| box eval_order_dependence::EvalOrderDependence);
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store.register_late_pass(|| box missing_doc::MissingDoc::new());
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store.register_late_pass(|| box missing_inline::MissingInline);
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store.register_late_pass(move || box exhaustive_items::ExhaustiveItems);
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store.register_late_pass(|| box if_let_some_result::OkIfLet);
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store.register_late_pass(|| box partialeq_ne_impl::PartialEqNeImpl);
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store.register_late_pass(|| box unused_io_amount::UnusedIoAmount);
@@ -1251,6 +1255,8 @@ pub fn register_plugins(store: &mut rustc_lint::LintStore, sess: &Session, conf:
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LintId::of(&create_dir::CREATE_DIR),
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LintId::of(&dbg_macro::DBG_MACRO),
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LintId::of(&else_if_without_else::ELSE_IF_WITHOUT_ELSE),
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LintId::of(&exhaustive_items::EXHAUSTIVE_ENUMS),
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LintId::of(&exhaustive_items::EXHAUSTIVE_STRUCTS),
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LintId::of(&exit::EXIT),
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LintId::of(&float_literal::LOSSY_FLOAT_LITERAL),
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LintId::of(&implicit_return::IMPLICIT_RETURN),

‎tests/ui/exhaustive_items.fixed

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// run-rustfix
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#![deny(clippy::exhaustive_enums, clippy::exhaustive_structs)]
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#![allow(unused)]
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fn main() {
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// nop
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}
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pub mod enums {
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#[non_exhaustive]
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pub enum Exhaustive {
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Foo,
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Bar,
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Baz,
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Quux(String),
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}
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/// Some docs
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#[repr(C)]
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#[non_exhaustive]
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pub enum ExhaustiveWithAttrs {
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Foo,
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Bar,
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Baz,
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Quux(String),
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}
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// no warning, already non_exhaustive
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#[non_exhaustive]
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pub enum NonExhaustive {
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Foo,
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Bar,
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Baz,
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Quux(String),
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}
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// no warning, private
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enum ExhaustivePrivate {
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Foo,
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Bar,
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Baz,
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Quux(String),
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}
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// no warning, private
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#[non_exhaustive]
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enum NonExhaustivePrivate {
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Foo,
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Bar,
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Baz,
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Quux(String),
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}
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}
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pub mod structs {
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#[non_exhaustive]
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pub struct Exhaustive {
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foo: u8,
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bar: String,
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}
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// no warning, already non_exhaustive
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#[non_exhaustive]
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pub struct NonExhaustive {
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foo: u8,
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bar: String,
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}
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// no warning, private
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struct ExhaustivePrivate {
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foo: u8,
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bar: String,
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}
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// no warning, private
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#[non_exhaustive]
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struct NonExhaustivePrivate {
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foo: u8,
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bar: String,
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}
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}

‎tests/ui/exhaustive_items.rs

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// run-rustfix
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#![deny(clippy::exhaustive_enums, clippy::exhaustive_structs)]
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#![allow(unused)]
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fn main() {
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// nop
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}
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pub mod enums {
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pub enum Exhaustive {
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Foo,
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Bar,
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Baz,
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Quux(String),
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}
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/// Some docs
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#[repr(C)]
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pub enum ExhaustiveWithAttrs {
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Foo,
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Bar,
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Baz,
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Quux(String),
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}
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// no warning, already non_exhaustive
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#[non_exhaustive]
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pub enum NonExhaustive {
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Foo,
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Bar,
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Baz,
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Quux(String),
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}
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// no warning, private
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enum ExhaustivePrivate {
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Foo,
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Bar,
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Baz,
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Quux(String),
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}
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// no warning, private
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#[non_exhaustive]
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enum NonExhaustivePrivate {
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Foo,
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Bar,
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Baz,
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Quux(String),
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}
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}
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pub mod structs {
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pub struct Exhaustive {
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foo: u8,
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bar: String,
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}
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// no warning, already non_exhaustive
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#[non_exhaustive]
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pub struct NonExhaustive {
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foo: u8,
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bar: String,
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}
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// no warning, private
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struct ExhaustivePrivate {
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foo: u8,
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bar: String,
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}
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// no warning, private
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#[non_exhaustive]
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struct NonExhaustivePrivate {
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foo: u8,
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bar: String,
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}
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}

‎tests/ui/exhaustive_items.stderr

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error: exported enums should not be exhaustive
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--> $DIR/exhaustive_items.rs:11:5
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|
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LL | / pub enum Exhaustive {
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LL | | Foo,
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LL | | Bar,
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LL | | Baz,
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LL | | Quux(String),
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LL | | }
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| |_____^
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|
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note: the lint level is defined here
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--> $DIR/exhaustive_items.rs:3:9
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|
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LL | #![deny(clippy::exhaustive_enums, clippy::exhaustive_structs)]
16+
| ^^^^^^^^^^^^^^^^^^^^^^^^
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help: try adding #[non_exhaustive]
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|
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LL | #[non_exhaustive]
20+
LL | pub enum Exhaustive {
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|
22+
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error: exported enums should not be exhaustive
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--> $DIR/exhaustive_items.rs:20:5
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|
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LL | / pub enum ExhaustiveWithAttrs {
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LL | | Foo,
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LL | | Bar,
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LL | | Baz,
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LL | | Quux(String),
31+
LL | | }
32+
| |_____^
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|
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help: try adding #[non_exhaustive]
35+
|
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LL | #[non_exhaustive]
37+
LL | pub enum ExhaustiveWithAttrs {
38+
|
39+
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error: exported structs should not be exhaustive
41+
--> $DIR/exhaustive_items.rs:55:5
42+
|
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LL | / pub struct Exhaustive {
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LL | | foo: u8,
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LL | | bar: String,
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LL | | }
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| |_____^
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|
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note: the lint level is defined here
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--> $DIR/exhaustive_items.rs:3:35
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|
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LL | #![deny(clippy::exhaustive_enums, clippy::exhaustive_structs)]
53+
| ^^^^^^^^^^^^^^^^^^^^^^^^^^
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help: try adding #[non_exhaustive]
55+
|
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LL | #[non_exhaustive]
57+
LL | pub struct Exhaustive {
58+
|
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error: aborting due to 3 previous errors
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