};
use rustc::hir::*;
use rustc::lint::*;
+use rustc::{declare_lint, lint_array};
+use if_chain::if_chain;
use rustc::ty::{self, TyCtxt};
use semver::Version;
use syntax::ast::{AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem, NestedMetaItemKind};
}
/// **What it does:** Checks for `extern crate` and `use` items annotated with
-/// lint attributes
+/// lint attributes.
+///
+/// This lint whitelists `#[allow(unused_imports)]` and `#[allow(deprecated)]` on
+/// `use` items and `#[allow(unused_imports)]` on `extern crate` items with a
+/// `#[macro_use]` attribute.
///
/// **Why is this bad?** Lint attributes have no effect on crate imports. Most
-/// likely a `!` was
-/// forgotten
+/// likely a `!` was forgotten.
///
-/// **Known problems:** Technically one might allow `unused_import` on a `use`
-/// item,
-/// but it's easier to remove the unused item.
+/// **Known problems:** None.
///
/// **Example:**
/// ```rust
+/// // Bad
/// #[deny(dead_code)]
/// extern crate foo;
-/// #[allow(unused_import)]
+/// #[forbid(dead_code)]
/// use foo::bar;
+///
+/// // Ok
+/// #[allow(unused_imports)]
+/// use foo::baz;
+/// #[allow(unused_imports)]
+/// #[macro_use]
+/// extern crate baz;
/// ```
declare_clippy_lint! {
pub USELESS_ATTRIBUTE,
check_attrs(cx, item.span, item.name, &item.attrs)
}
match item.node {
- ItemKind::ExternCrate(_) | ItemKind::Use(_, _) => {
+ ItemKind::ExternCrate(..) | ItemKind::Use(..) => {
+ let skip_unused_imports = item.attrs.iter().any(|attr| attr.name() == "macro_use");
+
for attr in &item.attrs {
if let Some(ref lint_list) = attr.meta_item_list() {
match &*attr.name().as_str() {
"allow" | "warn" | "deny" | "forbid" => {
- // whitelist `unused_imports` and `deprecated`
+ // whitelist `unused_imports` and `deprecated` for `use` items
+ // and `unused_imports` for `extern crate` items with `macro_use`
for lint in lint_list {
- if is_word(lint, "unused_imports") || is_word(lint, "deprecated") {
- if let ItemKind::Use(_, _) = item.node {
- return;
- }
+ match item.node {
+ ItemKind::Use(..) => if is_word(lint, "unused_imports")
+ || is_word(lint, "deprecated") {
+ return
+ },
+ ItemKind::ExternCrate(..) => if is_word(lint, "unused_imports")
+ && skip_unused_imports {
+ return
+ },
+ _ => {},
}
}
let line_span = last_line_of_span(cx, attr.span);