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use clippy_utils::diagnostics::span_lint_and_then;
use if_chain::if_chain;
use rustc_ast::{Item, ItemKind, UseTreeKind};
use rustc_errors::Applicability;
use rustc_lint::{EarlyContext, EarlyLintPass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::symbol::kw;
declare_clippy_lint! {
/// ### What it does
/// Checks for imports ending in `::{self}`.
///
/// ### Why is this bad?
/// In most cases, this can be written much more cleanly by omitting `::{self}`.
///
/// ### Known problems
/// Removing `::{self}` will cause any non-module items at the same path to also be imported.
/// This might cause a naming conflict (https://github.com/rust-lang/rustfmt/issues/3568). This lint makes no attempt
/// to detect this scenario and that is why it is a restriction lint.
///
/// ### Example
/// ```rust
/// use std::io::{self};
/// ```
/// Use instead:
/// ```rust
/// use std::io;
/// ```
#[clippy::version = "1.53.0"]
pub UNNECESSARY_SELF_IMPORTS,
restriction,
"imports ending in `::{self}`, which can be omitted"
}
declare_lint_pass!(UnnecessarySelfImports => [UNNECESSARY_SELF_IMPORTS]);
impl EarlyLintPass for UnnecessarySelfImports {
fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
if_chain! {
if let ItemKind::Use(use_tree) = &item.kind;
if let UseTreeKind::Nested(nodes) = &use_tree.kind;
if let [(self_tree, _)] = &**nodes;
if let [self_seg] = &*self_tree.prefix.segments;
if self_seg.ident.name == kw::SelfLower;
if let Some(last_segment) = use_tree.prefix.segments.last();
then {
span_lint_and_then(
cx,
UNNECESSARY_SELF_IMPORTS,
item.span,
"import ending with `::{self}`",
|diag| {
diag.span_suggestion(
last_segment.span().with_hi(item.span.hi()),
"consider omitting `::{self}`",
format!(
"{}{};",
last_segment.ident,
if let UseTreeKind::Simple(Some(alias), ..) = self_tree.kind { format!(" as {}", alias) } else { String::new() },
),
Applicability::MaybeIncorrect,
);
diag.note("this will slightly change semantics; any non-module items at the same path will also be imported");
},
);
}
}
}
}
|
