1 use clippy_utils::diagnostics::span_lint_and_help;
2 use rustc_ast::ast::{Crate, Inline, Item, ItemKind, ModKind};
3 use rustc_errors::MultiSpan;
4 use rustc_lint::{EarlyContext, EarlyLintPass, LintContext, Level};
5 use rustc_session::{declare_tool_lint, impl_lint_pass};
6 use rustc_span::{FileName, Span};
7 use std::collections::BTreeMap;
8 use std::path::PathBuf;
10 declare_clippy_lint! {
12 /// Checks for files that are included as modules multiple times.
14 /// ### Why is this bad?
15 /// Loading a file as a module more than once causes it to be compiled
16 /// multiple times, taking longer and putting duplicate content into the
27 /// #[path = "./b.rs"]
42 #[clippy::version = "1.62.0"]
45 "file loaded as module multiple times"
48 #[derive(PartialOrd, Ord, PartialEq, Eq)]
52 lint_levels: Vec<Level>,
56 pub struct DuplicateMod {
57 /// map from the canonicalized path to `Modules`, `BTreeMap` to make the
58 /// order deterministic for tests
59 modules: BTreeMap<PathBuf, Modules>,
62 impl_lint_pass!(DuplicateMod => [DUPLICATE_MOD]);
64 impl EarlyLintPass for DuplicateMod {
65 fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
66 if let ItemKind::Mod(_, ModKind::Loaded(_, Inline::No, mod_spans)) = &item.kind
67 && let FileName::Real(real) = cx.sess().source_map().span_to_filename(mod_spans.inner_span)
68 && let Some(local_path) = real.into_local_path()
69 && let Ok(absolute_path) = local_path.canonicalize()
71 let modules = self.modules.entry(absolute_path).or_insert(Modules {
74 lint_levels: Vec::new(),
76 modules.spans.push(item.span_with_attributes());
77 modules.lint_levels.push(cx.get_lint_level(DUPLICATE_MOD));
81 fn check_crate_post(&mut self, cx: &EarlyContext<'_>, _: &Crate) {
82 for Modules { local_path, spans, lint_levels } in self.modules.values() {
87 // At this point the lint would be emitted
88 assert_eq!(spans.len(), lint_levels.len());
89 let spans: Vec<_> = spans.into_iter().zip(lint_levels).filter_map(|(span, lvl)|{
90 if let Some(id) = lvl.get_expectation_id() {
91 cx.fulfill_expectation(id);
94 (!matches!(lvl, Level::Allow | Level::Expect(_))).then_some(*span)
102 let mut multi_span = MultiSpan::from_spans(spans.clone());
103 let (&first, duplicates) = spans.split_first().unwrap();
105 multi_span.push_span_label(first, "first loaded here");
106 for &duplicate in duplicates {
107 multi_span.push_span_label(duplicate, "loaded again here");
114 &format!("file is loaded as a module multiple times: `{}`", local_path.display()),
116 "replace all but one `mod` item with `use` items",