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|
use clippy_utils::diagnostics::span_lint_hir_and_then;
use clippy_utils::source::snippet;
use hir::def::{DefKind, Res};
use if_chain::if_chain;
use rustc_ast::ast;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_errors::Applicability;
use rustc_hir as hir;
use rustc_lint::{LateContext, LateLintPass, LintContext};
use rustc_session::{declare_tool_lint, impl_lint_pass};
use rustc_span::{edition::Edition, sym, Span};
declare_clippy_lint! {
/// ### What it does
/// Checks for `#[macro_use] use...`.
///
/// ### Why is this bad?
/// Since the Rust 2018 edition you can import
/// macro's directly, this is considered idiomatic.
///
/// ### Example
/// ```rust,ignore
/// #[macro_use]
/// use some_macro;
/// ```
#[clippy::version = "1.44.0"]
pub MACRO_USE_IMPORTS,
pedantic,
"#[macro_use] is no longer needed"
}
#[derive(Clone, Debug, PartialEq, Eq)]
struct PathAndSpan {
path: String,
span: Span,
}
/// `MacroRefData` includes the name of the macro.
#[derive(Debug, Clone)]
pub struct MacroRefData {
name: String,
}
impl MacroRefData {
pub fn new(name: String) -> Self {
Self { name }
}
}
#[derive(Default)]
#[expect(clippy::module_name_repetitions)]
pub struct MacroUseImports {
/// the actual import path used and the span of the attribute above it. The value is
/// the location, where the lint should be emitted.
imports: Vec<(String, Span, hir::HirId)>,
/// the span of the macro reference, kept to ensure only one reference is used per macro call.
collected: FxHashSet<Span>,
mac_refs: Vec<MacroRefData>,
}
impl_lint_pass!(MacroUseImports => [MACRO_USE_IMPORTS]);
impl MacroUseImports {
fn push_unique_macro(&mut self, cx: &LateContext<'_>, span: Span) {
let call_site = span.source_callsite();
let name = snippet(cx, cx.sess().source_map().span_until_char(call_site, '!'), "_");
if span.source_callee().is_some() && !self.collected.contains(&call_site) {
let name = if name.contains("::") {
name.split("::").last().unwrap().to_string()
} else {
name.to_string()
};
self.mac_refs.push(MacroRefData::new(name));
self.collected.insert(call_site);
}
}
fn push_unique_macro_pat_ty(&mut self, cx: &LateContext<'_>, span: Span) {
let call_site = span.source_callsite();
let name = snippet(cx, cx.sess().source_map().span_until_char(call_site, '!'), "_");
if span.source_callee().is_some() && !self.collected.contains(&call_site) {
self.mac_refs.push(MacroRefData::new(name.to_string()));
self.collected.insert(call_site);
}
}
}
impl<'tcx> LateLintPass<'tcx> for MacroUseImports {
fn check_item(&mut self, cx: &LateContext<'_>, item: &hir::Item<'_>) {
if_chain! {
if cx.sess().opts.edition >= Edition::Edition2018;
if let hir::ItemKind::Use(path, _kind) = &item.kind;
let hir_id = item.hir_id();
let attrs = cx.tcx.hir().attrs(hir_id);
if let Some(mac_attr) = attrs.iter().find(|attr| attr.has_name(sym::macro_use));
if let Res::Def(DefKind::Mod, id) = path.res;
if !id.is_local();
then {
for kid in cx.tcx.module_children(id).iter() {
if let Res::Def(DefKind::Macro(_mac_type), mac_id) = kid.res {
let span = mac_attr.span;
let def_path = cx.tcx.def_path_str(mac_id);
self.imports.push((def_path, span, hir_id));
}
}
} else {
if item.span.from_expansion() {
self.push_unique_macro_pat_ty(cx, item.span);
}
}
}
}
fn check_attribute(&mut self, cx: &LateContext<'_>, attr: &ast::Attribute) {
if attr.span.from_expansion() {
self.push_unique_macro(cx, attr.span);
}
}
fn check_expr(&mut self, cx: &LateContext<'_>, expr: &hir::Expr<'_>) {
if expr.span.from_expansion() {
self.push_unique_macro(cx, expr.span);
}
}
fn check_stmt(&mut self, cx: &LateContext<'_>, stmt: &hir::Stmt<'_>) {
if stmt.span.from_expansion() {
self.push_unique_macro(cx, stmt.span);
}
}
fn check_pat(&mut self, cx: &LateContext<'_>, pat: &hir::Pat<'_>) {
if pat.span.from_expansion() {
self.push_unique_macro_pat_ty(cx, pat.span);
}
}
fn check_ty(&mut self, cx: &LateContext<'_>, ty: &hir::Ty<'_>) {
if ty.span.from_expansion() {
self.push_unique_macro_pat_ty(cx, ty.span);
}
}
fn check_crate_post(&mut self, cx: &LateContext<'_>) {
let mut used = FxHashMap::default();
let mut check_dup = vec![];
for (import, span, hir_id) in &self.imports {
let found_idx = self.mac_refs.iter().position(|mac| import.ends_with(&mac.name));
if let Some(idx) = found_idx {
self.mac_refs.remove(idx);
let seg = import.split("::").collect::<Vec<_>>();
match seg.as_slice() {
// an empty path is impossible
// a path should always consist of 2 or more segments
[] | [_] => return,
[root, item] => {
if !check_dup.contains(&(*item).to_string()) {
used.entry(((*root).to_string(), span, hir_id))
.or_insert_with(Vec::new)
.push((*item).to_string());
check_dup.push((*item).to_string());
}
},
[root, rest @ ..] => {
if rest.iter().all(|item| !check_dup.contains(&(*item).to_string())) {
let filtered = rest
.iter()
.filter_map(|item| {
if check_dup.contains(&(*item).to_string()) {
None
} else {
Some((*item).to_string())
}
})
.collect::<Vec<_>>();
used.entry(((*root).to_string(), span, hir_id))
.or_insert_with(Vec::new)
.push(filtered.join("::"));
check_dup.extend(filtered);
} else {
let rest = rest.to_vec();
used.entry(((*root).to_string(), span, hir_id))
.or_insert_with(Vec::new)
.push(rest.join("::"));
check_dup.extend(rest.iter().map(ToString::to_string));
}
},
}
}
}
let mut suggestions = vec![];
for ((root, span, hir_id), path) in used {
if path.len() == 1 {
suggestions.push((span, format!("{root}::{}", path[0]), hir_id));
} else {
suggestions.push((span, format!("{root}::{{{}}}", path.join(", ")), hir_id));
}
}
// If mac_refs is not empty we have encountered an import we could not handle
// such as `std::prelude::v1::foo` or some other macro that expands to an import.
if self.mac_refs.is_empty() {
for (span, import, hir_id) in suggestions {
let help = format!("use {import};");
span_lint_hir_and_then(
cx,
MACRO_USE_IMPORTS,
*hir_id,
*span,
"`macro_use` attributes are no longer needed in the Rust 2018 edition",
|diag| {
diag.span_suggestion(
*span,
"remove the attribute and import the macro directly, try",
help,
Applicability::MaybeIncorrect,
);
},
);
}
}
}
}
|
