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| 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}; |
| 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; |
| 9 | + |
| 10 | +declare_clippy_lint! { |
| 11 | + /// ### What it does |
| 12 | + /// Checks for files that are included as modules multiple times. |
| 13 | + /// |
| 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 |
| 17 | + /// module tree. |
| 18 | + /// |
| 19 | + /// ### Example |
| 20 | + /// ```rust,ignore |
| 21 | + /// // lib.rs |
| 22 | + /// mod a; |
| 23 | + /// mod b; |
| 24 | + /// ``` |
| 25 | + /// ```rust,ignore |
| 26 | + /// // a.rs |
| 27 | + /// #[path = "./b.rs"] |
| 28 | + /// mod b; |
| 29 | + /// ``` |
| 30 | + /// |
| 31 | + /// Use instead: |
| 32 | + /// |
| 33 | + /// ```rust,ignore |
| 34 | + /// // lib.rs |
| 35 | + /// mod a; |
| 36 | + /// mod b; |
| 37 | + /// ``` |
| 38 | + /// ```rust,ignore |
| 39 | + /// // a.rs |
| 40 | + /// use crate::b; |
| 41 | + /// ``` |
| 42 | + #[clippy::version = "1.62.0"] |
| 43 | + pub DUPLICATE_MOD, |
| 44 | + suspicious, |
| 45 | + "file loaded as module multiple times" |
| 46 | +} |
| 47 | + |
| 48 | +#[derive(PartialOrd, Ord, PartialEq, Eq)] |
| 49 | +struct Modules { |
| 50 | + local_path: PathBuf, |
| 51 | + spans: Vec<Span>, |
| 52 | +} |
| 53 | + |
| 54 | +#[derive(Default)] |
| 55 | +pub struct DuplicateMod { |
| 56 | + /// map from the canonicalized path to `Modules`, `BTreeMap` to make the |
| 57 | + /// order deterministic for tests |
| 58 | + modules: BTreeMap<PathBuf, Modules>, |
| 59 | +} |
| 60 | + |
| 61 | +impl_lint_pass!(DuplicateMod => [DUPLICATE_MOD]); |
| 62 | + |
| 63 | +impl EarlyLintPass for DuplicateMod { |
| 64 | + fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) { |
| 65 | + if let ItemKind::Mod(_, ModKind::Loaded(_, Inline::No, mod_spans)) = &item.kind |
| 66 | + && let FileName::Real(real) = cx.sess().source_map().span_to_filename(mod_spans.inner_span) |
| 67 | + && let Some(local_path) = real.into_local_path() |
| 68 | + && let Ok(absolute_path) = local_path.canonicalize() |
| 69 | + { |
| 70 | + let modules = self.modules.entry(absolute_path).or_insert(Modules { |
| 71 | + local_path, |
| 72 | + spans: Vec::new(), |
| 73 | + }); |
| 74 | + modules.spans.push(item.span_with_attributes()); |
| 75 | + } |
| 76 | + } |
| 77 | + |
| 78 | + fn check_crate_post(&mut self, cx: &EarlyContext<'_>, _: &Crate) { |
| 79 | + for Modules { local_path, spans } in self.modules.values() { |
| 80 | + if spans.len() < 2 { |
| 81 | + continue; |
| 82 | + } |
| 83 | + |
| 84 | + let mut multi_span = MultiSpan::from_spans(spans.clone()); |
| 85 | + let (&first, duplicates) = spans.split_first().unwrap(); |
| 86 | + |
| 87 | + multi_span.push_span_label(first, "first loaded here"); |
| 88 | + for &duplicate in duplicates { |
| 89 | + multi_span.push_span_label(duplicate, "loaded again here"); |
| 90 | + } |
| 91 | + |
| 92 | + span_lint_and_help( |
| 93 | + cx, |
| 94 | + DUPLICATE_MOD, |
| 95 | + multi_span, |
| 96 | + &format!("file is loaded as a module multiple times: `{}`", local_path.display()), |
| 97 | + None, |
| 98 | + "replace all but one `mod` item with `use` items", |
| 99 | + ); |
| 100 | + } |
| 101 | + } |
| 102 | +} |
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