mirror of
https://github.com/rust-lang/rust-clippy
synced 2024-12-22 19:13:29 +00:00
717 lines
26 KiB
Rust
717 lines
26 KiB
Rust
//! checks for attributes
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use crate::utils::{
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first_line_of_span, is_present_in_source, match_panic_def_id, snippet_opt, span_lint, span_lint_and_help,
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span_lint_and_sugg, span_lint_and_then, without_block_comments,
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};
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use if_chain::if_chain;
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use rustc_ast::{AttrKind, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
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use rustc_errors::Applicability;
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use rustc_hir::{
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Block, Expr, ExprKind, ImplItem, ImplItemKind, Item, ItemKind, StmtKind, TraitFn, TraitItem, TraitItemKind,
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};
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use rustc_lint::{CheckLintNameResult, EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
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use rustc_middle::lint::in_external_macro;
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use rustc_middle::ty;
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use rustc_session::{declare_lint_pass, declare_tool_lint};
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use rustc_span::lev_distance::find_best_match_for_name;
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use rustc_span::source_map::Span;
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use rustc_span::sym;
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use rustc_span::symbol::{Symbol, SymbolStr};
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use semver::Version;
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static UNIX_SYSTEMS: &[&str] = &[
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"android",
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"dragonfly",
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"emscripten",
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"freebsd",
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"fuchsia",
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"haiku",
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"illumos",
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"ios",
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"l4re",
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"linux",
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"macos",
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"netbsd",
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"openbsd",
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"redox",
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"solaris",
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"vxworks",
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];
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// NOTE: windows is excluded from the list because it's also a valid target family.
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static NON_UNIX_SYSTEMS: &[&str] = &["hermit", "none", "wasi"];
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declare_clippy_lint! {
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/// **What it does:** Checks for items annotated with `#[inline(always)]`,
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/// unless the annotated function is empty or simply panics.
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///
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/// **Why is this bad?** While there are valid uses of this annotation (and once
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/// you know when to use it, by all means `allow` this lint), it's a common
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/// newbie-mistake to pepper one's code with it.
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///
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/// As a rule of thumb, before slapping `#[inline(always)]` on a function,
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/// measure if that additional function call really affects your runtime profile
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/// sufficiently to make up for the increase in compile time.
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///
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/// **Known problems:** False positives, big time. This lint is meant to be
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/// deactivated by everyone doing serious performance work. This means having
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/// done the measurement.
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///
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/// **Example:**
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/// ```ignore
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/// #[inline(always)]
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/// fn not_quite_hot_code(..) { ... }
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/// ```
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pub INLINE_ALWAYS,
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pedantic,
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"use of `#[inline(always)]`"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for `extern crate` and `use` items annotated with
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/// lint attributes.
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///
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/// This lint permits `#[allow(unused_imports)]`, `#[allow(deprecated)]`,
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/// `#[allow(unreachable_pub)]`, `#[allow(clippy::wildcard_imports)]` and
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/// `#[allow(clippy::enum_glob_use)]` on `use` items and `#[allow(unused_imports)]` on
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/// `extern crate` items with a `#[macro_use]` attribute.
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///
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/// **Why is this bad?** Lint attributes have no effect on crate imports. Most
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/// likely a `!` was forgotten.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```ignore
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/// // Bad
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/// #[deny(dead_code)]
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/// extern crate foo;
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/// #[forbid(dead_code)]
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/// use foo::bar;
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///
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/// // Ok
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/// #[allow(unused_imports)]
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/// use foo::baz;
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/// #[allow(unused_imports)]
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/// #[macro_use]
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/// extern crate baz;
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/// ```
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pub USELESS_ATTRIBUTE,
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correctness,
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"use of lint attributes on `extern crate` items"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for `#[deprecated]` annotations with a `since`
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/// field that is not a valid semantic version.
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///
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/// **Why is this bad?** For checking the version of the deprecation, it must be
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/// a valid semver. Failing that, the contained information is useless.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// ```rust
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/// #[deprecated(since = "forever")]
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/// fn something_else() { /* ... */ }
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/// ```
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pub DEPRECATED_SEMVER,
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correctness,
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"use of `#[deprecated(since = \"x\")]` where x is not semver"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for empty lines after outer attributes
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///
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/// **Why is this bad?**
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/// Most likely the attribute was meant to be an inner attribute using a '!'.
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/// If it was meant to be an outer attribute, then the following item
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/// should not be separated by empty lines.
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///
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/// **Known problems:** Can cause false positives.
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///
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/// From the clippy side it's difficult to detect empty lines between an attributes and the
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/// following item because empty lines and comments are not part of the AST. The parsing
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/// currently works for basic cases but is not perfect.
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///
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/// **Example:**
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/// ```rust
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/// // Good (as inner attribute)
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/// #![allow(dead_code)]
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///
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/// fn this_is_fine() { }
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///
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/// // Bad
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/// #[allow(dead_code)]
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///
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/// fn not_quite_good_code() { }
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///
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/// // Good (as outer attribute)
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/// #[allow(dead_code)]
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/// fn this_is_fine_too() { }
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/// ```
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pub EMPTY_LINE_AFTER_OUTER_ATTR,
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nursery,
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"empty line after outer attribute"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for `allow`/`warn`/`deny`/`forbid` attributes with scoped clippy
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/// lints and if those lints exist in clippy. If there is an uppercase letter in the lint name
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/// (not the tool name) and a lowercase version of this lint exists, it will suggest to lowercase
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/// the lint name.
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///
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/// **Why is this bad?** A lint attribute with a mistyped lint name won't have an effect.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// Bad:
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/// ```rust
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/// #![warn(if_not_els)]
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/// #![deny(clippy::All)]
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/// ```
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///
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/// Good:
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/// ```rust
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/// #![warn(if_not_else)]
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/// #![deny(clippy::all)]
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/// ```
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pub UNKNOWN_CLIPPY_LINTS,
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style,
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"unknown_lints for scoped Clippy lints"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for `warn`/`deny`/`forbid` attributes targeting the whole clippy::restriction category.
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///
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/// **Why is this bad?** Restriction lints sometimes are in contrast with other lints or even go against idiomatic rust.
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/// These lints should only be enabled on a lint-by-lint basis and with careful consideration.
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///
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/// **Known problems:** None.
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///
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/// **Example:**
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/// Bad:
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/// ```rust
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/// #![deny(clippy::restriction)]
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/// ```
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///
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/// Good:
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/// ```rust
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/// #![deny(clippy::as_conversions)]
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/// ```
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pub BLANKET_CLIPPY_RESTRICTION_LINTS,
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style,
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"enabling the complete restriction group"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for `#[cfg_attr(rustfmt, rustfmt_skip)]` and suggests to replace it
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/// with `#[rustfmt::skip]`.
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///
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/// **Why is this bad?** Since tool_attributes ([rust-lang/rust#44690](https://github.com/rust-lang/rust/issues/44690))
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/// are stable now, they should be used instead of the old `cfg_attr(rustfmt)` attributes.
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///
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/// **Known problems:** This lint doesn't detect crate level inner attributes, because they get
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/// processed before the PreExpansionPass lints get executed. See
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/// [#3123](https://github.com/rust-lang/rust-clippy/pull/3123#issuecomment-422321765)
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///
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/// **Example:**
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///
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/// Bad:
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/// ```rust
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/// #[cfg_attr(rustfmt, rustfmt_skip)]
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/// fn main() { }
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/// ```
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///
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/// Good:
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/// ```rust
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/// #[rustfmt::skip]
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/// fn main() { }
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/// ```
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pub DEPRECATED_CFG_ATTR,
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complexity,
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"usage of `cfg_attr(rustfmt)` instead of tool attributes"
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}
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declare_clippy_lint! {
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/// **What it does:** Checks for cfg attributes having operating systems used in target family position.
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///
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/// **Why is this bad?** The configuration option will not be recognised and the related item will not be included
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/// by the conditional compilation engine.
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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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/// Bad:
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/// ```rust
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/// #[cfg(linux)]
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/// fn conditional() { }
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/// ```
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///
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/// Good:
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/// ```rust
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/// #[cfg(target_os = "linux")]
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/// fn conditional() { }
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/// ```
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///
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/// Or:
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/// ```rust
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/// #[cfg(unix)]
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/// fn conditional() { }
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/// ```
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/// Check the [Rust Reference](https://doc.rust-lang.org/reference/conditional-compilation.html#target_os) for more details.
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pub MISMATCHED_TARGET_OS,
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correctness,
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"usage of `cfg(operating_system)` instead of `cfg(target_os = \"operating_system\")`"
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}
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declare_lint_pass!(Attributes => [
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INLINE_ALWAYS,
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DEPRECATED_SEMVER,
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USELESS_ATTRIBUTE,
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UNKNOWN_CLIPPY_LINTS,
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BLANKET_CLIPPY_RESTRICTION_LINTS,
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]);
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impl<'tcx> LateLintPass<'tcx> for Attributes {
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fn check_attribute(&mut self, cx: &LateContext<'tcx>, attr: &'tcx Attribute) {
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if let Some(items) = &attr.meta_item_list() {
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if let Some(ident) = attr.ident() {
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let ident = &*ident.as_str();
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match ident {
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"allow" | "warn" | "deny" | "forbid" => {
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check_clippy_lint_names(cx, ident, items);
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},
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_ => {},
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}
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if items.is_empty() || !attr.has_name(sym::deprecated) {
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return;
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}
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for item in items {
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if_chain! {
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if let NestedMetaItem::MetaItem(mi) = &item;
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if let MetaItemKind::NameValue(lit) = &mi.kind;
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if mi.has_name(sym::since);
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then {
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check_semver(cx, item.span(), lit);
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}
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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 check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
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if is_relevant_item(cx, item) {
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check_attrs(cx, item.span, item.ident.name, &item.attrs)
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}
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match item.kind {
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ItemKind::ExternCrate(..) | ItemKind::Use(..) => {
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let skip_unused_imports = item.attrs.iter().any(|attr| attr.has_name(sym::macro_use));
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for attr in item.attrs {
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if in_external_macro(cx.sess(), attr.span) {
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return;
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}
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if let Some(lint_list) = &attr.meta_item_list() {
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if let Some(ident) = attr.ident() {
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match &*ident.as_str() {
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"allow" | "warn" | "deny" | "forbid" => {
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// permit `unused_imports`, `deprecated`, `unreachable_pub`,
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// `clippy::wildcard_imports`, and `clippy::enum_glob_use` for `use` items
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// and `unused_imports` for `extern crate` items with `macro_use`
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for lint in lint_list {
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match item.kind {
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ItemKind::Use(..) => {
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if is_word(lint, sym!(unused_imports))
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|| is_word(lint, sym::deprecated)
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|| is_word(lint, sym!(unreachable_pub))
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|| is_word(lint, sym!(unused))
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|| extract_clippy_lint(lint)
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.map_or(false, |s| s == "wildcard_imports")
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|| extract_clippy_lint(lint).map_or(false, |s| s == "enum_glob_use")
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{
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return;
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}
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},
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ItemKind::ExternCrate(..) => {
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if is_word(lint, sym!(unused_imports)) && skip_unused_imports {
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return;
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}
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if is_word(lint, sym!(unused_extern_crates)) {
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return;
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}
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},
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_ => {},
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}
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}
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let line_span = first_line_of_span(cx, attr.span);
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if let Some(mut sugg) = snippet_opt(cx, line_span) {
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if sugg.contains("#[") {
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span_lint_and_then(
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cx,
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USELESS_ATTRIBUTE,
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line_span,
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"useless lint attribute",
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|diag| {
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sugg = sugg.replacen("#[", "#![", 1);
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diag.span_suggestion(
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line_span,
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"if you just forgot a `!`, use",
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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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},
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_ => {},
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}
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}
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}
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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 check_impl_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx ImplItem<'_>) {
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if is_relevant_impl(cx, item) {
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check_attrs(cx, item.span, item.ident.name, &item.attrs)
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}
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}
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fn check_trait_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx TraitItem<'_>) {
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if is_relevant_trait(cx, item) {
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check_attrs(cx, item.span, item.ident.name, &item.attrs)
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}
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}
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}
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/// Returns the lint name if it is clippy lint.
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fn extract_clippy_lint(lint: &NestedMetaItem) -> Option<SymbolStr> {
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if_chain! {
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if let Some(meta_item) = lint.meta_item();
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if meta_item.path.segments.len() > 1;
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if let tool_name = meta_item.path.segments[0].ident;
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if tool_name.name == sym::clippy;
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let lint_name = meta_item.path.segments.last().unwrap().ident.name;
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then {
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return Some(lint_name.as_str());
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}
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}
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None
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}
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fn check_clippy_lint_names(cx: &LateContext<'_>, ident: &str, items: &[NestedMetaItem]) {
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let lint_store = cx.lints();
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for lint in items {
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if let Some(lint_name) = extract_clippy_lint(lint) {
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if let CheckLintNameResult::Tool(Err((None, _))) = lint_store.check_lint_name(&lint_name, Some(sym::clippy))
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{
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span_lint_and_then(
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cx,
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UNKNOWN_CLIPPY_LINTS,
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lint.span(),
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&format!("unknown clippy lint: clippy::{}", lint_name),
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|diag| {
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let name_lower = lint_name.to_lowercase();
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let symbols = lint_store
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.get_lints()
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.iter()
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.map(|l| Symbol::intern(&l.name_lower()))
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.collect::<Vec<_>>();
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let sugg = find_best_match_for_name(
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&symbols,
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Symbol::intern(&format!("clippy::{}", name_lower)),
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None,
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);
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if lint_name.chars().any(char::is_uppercase)
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&& lint_store.find_lints(&format!("clippy::{}", name_lower)).is_ok()
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{
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diag.span_suggestion(
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lint.span(),
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"lowercase the lint name",
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format!("clippy::{}", name_lower),
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Applicability::MachineApplicable,
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);
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} else if let Some(sugg) = sugg {
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diag.span_suggestion(
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lint.span(),
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"did you mean",
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sugg.to_string(),
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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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} else if lint_name == "restriction" && ident != "allow" {
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span_lint_and_help(
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cx,
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BLANKET_CLIPPY_RESTRICTION_LINTS,
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lint.span(),
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"restriction lints are not meant to be all enabled",
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None,
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"try enabling only the lints you really need",
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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 is_relevant_item(cx: &LateContext<'_>, item: &Item<'_>) -> bool {
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if let ItemKind::Fn(_, _, eid) = item.kind {
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is_relevant_expr(cx, cx.tcx.typeck_body(eid), &cx.tcx.hir().body(eid).value)
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} else {
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true
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}
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}
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fn is_relevant_impl(cx: &LateContext<'_>, item: &ImplItem<'_>) -> bool {
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match item.kind {
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ImplItemKind::Fn(_, eid) => is_relevant_expr(cx, cx.tcx.typeck_body(eid), &cx.tcx.hir().body(eid).value),
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_ => false,
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}
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}
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fn is_relevant_trait(cx: &LateContext<'_>, item: &TraitItem<'_>) -> bool {
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match item.kind {
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TraitItemKind::Fn(_, TraitFn::Required(_)) => true,
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TraitItemKind::Fn(_, TraitFn::Provided(eid)) => {
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is_relevant_expr(cx, cx.tcx.typeck_body(eid), &cx.tcx.hir().body(eid).value)
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},
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_ => false,
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}
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}
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|
|
fn is_relevant_block(cx: &LateContext<'_>, typeck_results: &ty::TypeckResults<'_>, block: &Block<'_>) -> bool {
|
|
block.stmts.first().map_or(
|
|
block
|
|
.expr
|
|
.as_ref()
|
|
.map_or(false, |e| is_relevant_expr(cx, typeck_results, e)),
|
|
|stmt| match &stmt.kind {
|
|
StmtKind::Local(_) => true,
|
|
StmtKind::Expr(expr) | StmtKind::Semi(expr) => is_relevant_expr(cx, typeck_results, expr),
|
|
_ => false,
|
|
},
|
|
)
|
|
}
|
|
|
|
fn is_relevant_expr(cx: &LateContext<'_>, typeck_results: &ty::TypeckResults<'_>, expr: &Expr<'_>) -> bool {
|
|
match &expr.kind {
|
|
ExprKind::Block(block, _) => is_relevant_block(cx, typeck_results, block),
|
|
ExprKind::Ret(Some(e)) => is_relevant_expr(cx, typeck_results, e),
|
|
ExprKind::Ret(None) | ExprKind::Break(_, None) => false,
|
|
ExprKind::Call(path_expr, _) => {
|
|
if let ExprKind::Path(qpath) = &path_expr.kind {
|
|
typeck_results
|
|
.qpath_res(qpath, path_expr.hir_id)
|
|
.opt_def_id()
|
|
.map_or(true, |fun_id| !match_panic_def_id(cx, fun_id))
|
|
} else {
|
|
true
|
|
}
|
|
},
|
|
_ => true,
|
|
}
|
|
}
|
|
|
|
fn check_attrs(cx: &LateContext<'_>, span: Span, name: Symbol, attrs: &[Attribute]) {
|
|
if span.from_expansion() {
|
|
return;
|
|
}
|
|
|
|
for attr in attrs {
|
|
if let Some(values) = attr.meta_item_list() {
|
|
if values.len() != 1 || !attr.has_name(sym::inline) {
|
|
continue;
|
|
}
|
|
if is_word(&values[0], sym::always) {
|
|
span_lint(
|
|
cx,
|
|
INLINE_ALWAYS,
|
|
attr.span,
|
|
&format!(
|
|
"you have declared `#[inline(always)]` on `{}`. This is usually a bad idea",
|
|
name
|
|
),
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_semver(cx: &LateContext<'_>, span: Span, lit: &Lit) {
|
|
if let LitKind::Str(is, _) = lit.kind {
|
|
if Version::parse(&is.as_str()).is_ok() {
|
|
return;
|
|
}
|
|
}
|
|
span_lint(
|
|
cx,
|
|
DEPRECATED_SEMVER,
|
|
span,
|
|
"the since field must contain a semver-compliant version",
|
|
);
|
|
}
|
|
|
|
fn is_word(nmi: &NestedMetaItem, expected: Symbol) -> bool {
|
|
if let NestedMetaItem::MetaItem(mi) = &nmi {
|
|
mi.is_word() && mi.has_name(expected)
|
|
} else {
|
|
false
|
|
}
|
|
}
|
|
|
|
declare_lint_pass!(EarlyAttributes => [
|
|
DEPRECATED_CFG_ATTR,
|
|
MISMATCHED_TARGET_OS,
|
|
EMPTY_LINE_AFTER_OUTER_ATTR,
|
|
]);
|
|
|
|
impl EarlyLintPass for EarlyAttributes {
|
|
fn check_item(&mut self, cx: &EarlyContext<'_>, item: &rustc_ast::Item) {
|
|
check_empty_line_after_outer_attr(cx, item);
|
|
}
|
|
|
|
fn check_attribute(&mut self, cx: &EarlyContext<'_>, attr: &Attribute) {
|
|
check_deprecated_cfg_attr(cx, attr);
|
|
check_mismatched_target_os(cx, attr);
|
|
}
|
|
}
|
|
|
|
fn check_empty_line_after_outer_attr(cx: &EarlyContext<'_>, item: &rustc_ast::Item) {
|
|
for attr in &item.attrs {
|
|
let attr_item = if let AttrKind::Normal(ref attr, _) = attr.kind {
|
|
attr
|
|
} else {
|
|
return;
|
|
};
|
|
|
|
if attr.style == AttrStyle::Outer {
|
|
if attr_item.args.inner_tokens().is_empty() || !is_present_in_source(cx, attr.span) {
|
|
return;
|
|
}
|
|
|
|
let begin_of_attr_to_item = Span::new(attr.span.lo(), item.span.lo(), item.span.ctxt());
|
|
let end_of_attr_to_item = Span::new(attr.span.hi(), item.span.lo(), item.span.ctxt());
|
|
|
|
if let Some(snippet) = snippet_opt(cx, end_of_attr_to_item) {
|
|
let lines = snippet.split('\n').collect::<Vec<_>>();
|
|
let lines = without_block_comments(lines);
|
|
|
|
if lines.iter().filter(|l| l.trim().is_empty()).count() > 2 {
|
|
span_lint(
|
|
cx,
|
|
EMPTY_LINE_AFTER_OUTER_ATTR,
|
|
begin_of_attr_to_item,
|
|
"found an empty line after an outer attribute. \
|
|
Perhaps you forgot to add a `!` to make it an inner attribute?",
|
|
);
|
|
}
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_deprecated_cfg_attr(cx: &EarlyContext<'_>, attr: &Attribute) {
|
|
if_chain! {
|
|
// check cfg_attr
|
|
if attr.has_name(sym::cfg_attr);
|
|
if let Some(items) = attr.meta_item_list();
|
|
if items.len() == 2;
|
|
// check for `rustfmt`
|
|
if let Some(feature_item) = items[0].meta_item();
|
|
if feature_item.has_name(sym::rustfmt);
|
|
// check for `rustfmt_skip` and `rustfmt::skip`
|
|
if let Some(skip_item) = &items[1].meta_item();
|
|
if skip_item.has_name(sym!(rustfmt_skip)) ||
|
|
skip_item.path.segments.last().expect("empty path in attribute").ident.name == sym!(skip);
|
|
// Only lint outer attributes, because custom inner attributes are unstable
|
|
// Tracking issue: https://github.com/rust-lang/rust/issues/54726
|
|
if let AttrStyle::Outer = attr.style;
|
|
then {
|
|
span_lint_and_sugg(
|
|
cx,
|
|
DEPRECATED_CFG_ATTR,
|
|
attr.span,
|
|
"`cfg_attr` is deprecated for rustfmt and got replaced by tool attributes",
|
|
"use",
|
|
"#[rustfmt::skip]".to_string(),
|
|
Applicability::MachineApplicable,
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
fn check_mismatched_target_os(cx: &EarlyContext<'_>, attr: &Attribute) {
|
|
fn find_os(name: &str) -> Option<&'static str> {
|
|
UNIX_SYSTEMS
|
|
.iter()
|
|
.chain(NON_UNIX_SYSTEMS.iter())
|
|
.find(|&&os| os == name)
|
|
.copied()
|
|
}
|
|
|
|
fn is_unix(name: &str) -> bool {
|
|
UNIX_SYSTEMS.iter().any(|&os| os == name)
|
|
}
|
|
|
|
fn find_mismatched_target_os(items: &[NestedMetaItem]) -> Vec<(&str, Span)> {
|
|
let mut mismatched = Vec::new();
|
|
|
|
for item in items {
|
|
if let NestedMetaItem::MetaItem(meta) = item {
|
|
match &meta.kind {
|
|
MetaItemKind::List(list) => {
|
|
mismatched.extend(find_mismatched_target_os(&list));
|
|
},
|
|
MetaItemKind::Word => {
|
|
if_chain! {
|
|
if let Some(ident) = meta.ident();
|
|
if let Some(os) = find_os(&*ident.name.as_str());
|
|
then {
|
|
mismatched.push((os, ident.span));
|
|
}
|
|
}
|
|
},
|
|
_ => {},
|
|
}
|
|
}
|
|
}
|
|
|
|
mismatched
|
|
}
|
|
|
|
if_chain! {
|
|
if attr.has_name(sym::cfg);
|
|
if let Some(list) = attr.meta_item_list();
|
|
let mismatched = find_mismatched_target_os(&list);
|
|
if !mismatched.is_empty();
|
|
then {
|
|
let mess = "operating system used in target family position";
|
|
|
|
span_lint_and_then(cx, MISMATCHED_TARGET_OS, attr.span, &mess, |diag| {
|
|
// Avoid showing the unix suggestion multiple times in case
|
|
// we have more than one mismatch for unix-like systems
|
|
let mut unix_suggested = false;
|
|
|
|
for (os, span) in mismatched {
|
|
let sugg = format!("target_os = \"{}\"", os);
|
|
diag.span_suggestion(span, "try", sugg, Applicability::MaybeIncorrect);
|
|
|
|
if !unix_suggested && is_unix(os) {
|
|
diag.help("Did you mean `unix`?");
|
|
unix_suggested = true;
|
|
}
|
|
}
|
|
});
|
|
}
|
|
}
|
|
}
|