103 lines
3.0 KiB
Rust
103 lines
3.0 KiB
Rust
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use clippy_utils::diagnostics::span_lint_and_help;
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use rustc_ast::ast::{Crate, Inline, Item, ItemKind, ModKind};
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use rustc_errors::MultiSpan;
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use rustc_lint::{EarlyContext, EarlyLintPass, LintContext};
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use rustc_session::{declare_tool_lint, impl_lint_pass};
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use rustc_span::{FileName, Span};
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use std::collections::BTreeMap;
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use std::path::PathBuf;
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declare_clippy_lint! {
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/// ### What it does
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/// Checks for files that are included as modules multiple times.
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///
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/// ### Why is this bad?
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/// Loading a file as a module more than once causes it to be compiled
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/// multiple times, taking longer and putting duplicate content into the
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/// module tree.
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///
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/// ### Example
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/// ```rust,ignore
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/// // lib.rs
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/// mod a;
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/// mod b;
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/// ```
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/// ```rust,ignore
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/// // a.rs
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/// #[path = "./b.rs"]
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/// mod b;
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/// ```
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///
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/// Use instead:
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///
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/// ```rust,ignore
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/// // lib.rs
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/// mod a;
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/// mod b;
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/// ```
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/// ```rust,ignore
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/// // a.rs
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/// use crate::b;
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/// ```
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#[clippy::version = "1.62.0"]
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pub DUPLICATE_MOD,
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suspicious,
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"file loaded as module multiple times"
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}
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#[derive(PartialOrd, Ord, PartialEq, Eq)]
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struct Modules {
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local_path: PathBuf,
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spans: Vec<Span>,
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}
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#[derive(Default)]
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pub struct DuplicateMod {
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/// map from the canonicalized path to `Modules`, `BTreeMap` to make the
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/// order deterministic for tests
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modules: BTreeMap<PathBuf, Modules>,
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}
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impl_lint_pass!(DuplicateMod => [DUPLICATE_MOD]);
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impl EarlyLintPass for DuplicateMod {
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fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
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if let ItemKind::Mod(_, ModKind::Loaded(_, Inline::No, mod_spans)) = &item.kind
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&& let FileName::Real(real) = cx.sess().source_map().span_to_filename(mod_spans.inner_span)
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&& let Some(local_path) = real.into_local_path()
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&& let Ok(absolute_path) = local_path.canonicalize()
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{
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let modules = self.modules.entry(absolute_path).or_insert(Modules {
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local_path,
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spans: Vec::new(),
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});
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modules.spans.push(item.span_with_attributes());
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}
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}
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fn check_crate_post(&mut self, cx: &EarlyContext<'_>, _: &Crate) {
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for Modules { local_path, spans } in self.modules.values() {
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if spans.len() < 2 {
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continue;
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}
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let mut multi_span = MultiSpan::from_spans(spans.clone());
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let (&first, duplicates) = spans.split_first().unwrap();
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multi_span.push_span_label(first, "first loaded here");
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for &duplicate in duplicates {
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multi_span.push_span_label(duplicate, "loaded again here");
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}
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span_lint_and_help(
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cx,
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DUPLICATE_MOD,
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multi_span,
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&format!("file is loaded as a module multiple times: `{}`", local_path.display()),
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None,
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"replace all but one `mod` item with `use` items",
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);
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}
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}
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}
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