220 lines
8.1 KiB
Rust
220 lines
8.1 KiB
Rust
use clippy_utils::diagnostics::span_lint_and_sugg;
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use clippy_utils::is_test_module_or_function;
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use clippy_utils::source::{snippet, snippet_with_applicability};
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use rustc_data_structures::fx::FxHashSet;
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use rustc_errors::Applicability;
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use rustc_hir::def::{DefKind, Res};
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use rustc_hir::{Item, ItemKind, PathSegment, UseKind};
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use rustc_lint::{LateContext, LateLintPass, LintContext};
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use rustc_middle::ty;
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use rustc_session::impl_lint_pass;
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use rustc_span::symbol::kw;
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use rustc_span::{sym, BytePos};
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for `use Enum::*`.
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///
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/// ### Why is this bad?
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/// It is usually better style to use the prefixed name of
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/// an enumeration variant, rather than importing variants.
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///
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/// ### Known problems
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/// Old-style enumerations that prefix the variants are
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/// still around.
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///
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/// ### Example
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/// ```no_run
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/// use std::cmp::Ordering::*;
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///
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/// # fn foo(_: std::cmp::Ordering) {}
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/// foo(Less);
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/// ```
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///
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/// Use instead:
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/// ```no_run
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/// use std::cmp::Ordering;
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///
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/// # fn foo(_: Ordering) {}
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/// foo(Ordering::Less)
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/// ```
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#[clippy::version = "pre 1.29.0"]
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pub ENUM_GLOB_USE,
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pedantic,
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"use items that import all variants of an enum"
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}
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for wildcard imports `use _::*`.
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///
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/// ### Why is this bad?
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/// wildcard imports can pollute the namespace. This is especially bad if
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/// you try to import something through a wildcard, that already has been imported by name from
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/// a different source:
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///
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/// ```rust,ignore
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/// use crate1::foo; // Imports a function named foo
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/// use crate2::*; // Has a function named foo
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///
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/// foo(); // Calls crate1::foo
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/// ```
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///
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/// This can lead to confusing error messages at best and to unexpected behavior at worst.
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///
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/// ### Exceptions
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/// Wildcard imports are allowed from modules that their name contains `prelude`. Many crates
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/// (including the standard library) provide modules named "prelude" specifically designed
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/// for wildcard import.
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///
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/// `use super::*` is allowed in test modules. This is defined as any module with "test" in the name.
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///
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/// These exceptions can be disabled using the `warn-on-all-wildcard-imports` configuration flag.
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///
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/// ### Known problems
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/// If macros are imported through the wildcard, this macro is not included
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/// by the suggestion and has to be added by hand.
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///
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/// Applying the suggestion when explicit imports of the things imported with a glob import
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/// exist, may result in `unused_imports` warnings.
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///
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/// ### Example
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/// ```rust,ignore
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/// use crate1::*;
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///
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/// foo();
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/// ```
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///
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/// Use instead:
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/// ```rust,ignore
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/// use crate1::foo;
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///
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/// foo();
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/// ```
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#[clippy::version = "1.43.0"]
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pub WILDCARD_IMPORTS,
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pedantic,
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"lint `use _::*` statements"
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}
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#[derive(Default)]
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pub struct WildcardImports {
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warn_on_all: bool,
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test_modules_deep: u32,
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allowed_segments: FxHashSet<String>,
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}
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impl WildcardImports {
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pub fn new(warn_on_all: bool, allowed_wildcard_imports: FxHashSet<String>) -> Self {
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Self {
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warn_on_all,
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test_modules_deep: 0,
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allowed_segments: allowed_wildcard_imports,
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}
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}
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}
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impl_lint_pass!(WildcardImports => [ENUM_GLOB_USE, WILDCARD_IMPORTS]);
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impl LateLintPass<'_> for WildcardImports {
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fn check_item(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
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if cx.sess().is_test_crate() {
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return;
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}
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if is_test_module_or_function(cx.tcx, item) {
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self.test_modules_deep = self.test_modules_deep.saturating_add(1);
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}
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let module = cx.tcx.parent_module_from_def_id(item.owner_id.def_id);
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if cx.tcx.visibility(item.owner_id.def_id) != ty::Visibility::Restricted(module.to_def_id()) {
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return;
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}
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if let ItemKind::Use(use_path, UseKind::Glob) = &item.kind
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&& (self.warn_on_all || !self.check_exceptions(item, use_path.segments))
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&& let used_imports = cx.tcx.names_imported_by_glob_use(item.owner_id.def_id)
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&& !used_imports.is_empty() // Already handled by `unused_imports`
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&& !used_imports.contains(&kw::Underscore)
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{
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let mut applicability = Applicability::MachineApplicable;
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let import_source_snippet = snippet_with_applicability(cx, use_path.span, "..", &mut applicability);
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let (span, braced_glob) = if import_source_snippet.is_empty() {
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// This is a `_::{_, *}` import
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// In this case `use_path.span` is empty and ends directly in front of the `*`,
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// so we need to extend it by one byte.
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(use_path.span.with_hi(use_path.span.hi() + BytePos(1)), true)
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} else {
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// In this case, the `use_path.span` ends right before the `::*`, so we need to
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// extend it up to the `*`. Since it is hard to find the `*` in weird
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// formatting like `use _ :: *;`, we extend it up to, but not including the
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// `;`. In nested imports, like `use _::{inner::*, _}` there is no `;` and we
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// can just use the end of the item span
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let mut span = use_path.span.with_hi(item.span.hi());
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if snippet(cx, span, "").ends_with(';') {
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span = use_path.span.with_hi(item.span.hi() - BytePos(1));
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}
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(span, false)
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};
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let mut imports = used_imports.items().map(ToString::to_string).into_sorted_stable_ord();
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let imports_string = if imports.len() == 1 {
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imports.pop().unwrap()
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} else if braced_glob {
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imports.join(", ")
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} else {
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format!("{{{}}}", imports.join(", "))
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};
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let sugg = if braced_glob {
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imports_string
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} else {
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format!("{import_source_snippet}::{imports_string}")
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};
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// Glob imports always have a single resolution.
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let (lint, message) = if let Res::Def(DefKind::Enum, _) = use_path.res[0] {
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(ENUM_GLOB_USE, "usage of wildcard import for enum variants")
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} else {
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(WILDCARD_IMPORTS, "usage of wildcard import")
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};
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span_lint_and_sugg(cx, lint, span, message, "try", sugg, applicability);
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}
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}
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fn check_item_post(&mut self, cx: &LateContext<'_>, item: &Item<'_>) {
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if is_test_module_or_function(cx.tcx, item) {
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self.test_modules_deep = self.test_modules_deep.saturating_sub(1);
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}
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}
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}
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impl WildcardImports {
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fn check_exceptions(&self, item: &Item<'_>, segments: &[PathSegment<'_>]) -> bool {
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item.span.from_expansion()
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|| is_prelude_import(segments)
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|| (is_super_only_import(segments) && self.test_modules_deep > 0)
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|| is_allowed_via_config(segments, &self.allowed_segments)
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}
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}
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// Allow "...prelude::..::*" imports.
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// Many crates have a prelude, and it is imported as a glob by design.
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fn is_prelude_import(segments: &[PathSegment<'_>]) -> bool {
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segments
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.iter()
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.any(|ps| ps.ident.as_str().contains(sym::prelude.as_str()))
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}
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// Allow "super::*" imports in tests.
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fn is_super_only_import(segments: &[PathSegment<'_>]) -> bool {
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segments.len() == 1 && segments[0].ident.name == kw::Super
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}
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// Allow skipping imports containing user configured segments,
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// i.e. "...::utils::...::*" if user put `allowed-wildcard-imports = ["utils"]` in `Clippy.toml`
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fn is_allowed_via_config(segments: &[PathSegment<'_>], allowed_segments: &FxHashSet<String>) -> bool {
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// segment matching need to be exact instead of using 'contains', in case user unintentionally put
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// a single character in the config thus skipping most of the warnings.
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segments.iter().any(|seg| allowed_segments.contains(seg.ident.as_str()))
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}
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