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