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