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Auto merge of #86827 - camsteffen:hash-lint-resolved, r=oli-obk

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Fix internal `default_hash_types` lint to use resolved path

I run into false positives now and then (mostly in Clippy) when I want to name some util after HashMap.
This commit is contained in:
bors 2021-07-13 15:06:10 +00:00
commit 3e1c75c6e2
8 changed files with 72 additions and 71 deletions
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79
compiler/rustc_lint/src/internal.rs
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@ -2,15 +2,17 @@
//! Clippy.
use crate::{EarlyContext, EarlyLintPass, LateContext, LateLintPass, LintContext};
use rustc_ast::{ImplKind, Item, ItemKind};
use rustc_data_structures::fx::FxHashMap;
use rustc_ast as ast;
use rustc_errors::Applicability;
use rustc_hir::def::Res;
use rustc_hir::{GenericArg, HirId, MutTy, Mutability, Path, PathSegment, QPath, Ty, TyKind};
use rustc_hir::{
GenericArg, HirId, Item, ItemKind, MutTy, Mutability, Node, Path, PathSegment, QPath, Ty,
TyKind,
};
use rustc_middle::ty;
use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::hygiene::{ExpnKind, MacroKind};
use rustc_span::symbol::{kw, sym, Ident, Symbol};
use rustc_span::symbol::{kw, sym, Symbol};
declare_tool_lint! {
pub rustc::DEFAULT_HASH_TYPES,
@ -19,43 +21,35 @@ declare_tool_lint! {
report_in_external_macro: true
}
pub struct DefaultHashTypes {
map: FxHashMap<Symbol, Symbol>,
}
declare_lint_pass!(DefaultHashTypes => [DEFAULT_HASH_TYPES]);
impl DefaultHashTypes {
// we are allowed to use `HashMap` and `HashSet` as identifiers for implementing the lint itself
#[allow(rustc::default_hash_types)]
pub fn new() -> Self {
let mut map = FxHashMap::default();
map.insert(sym::HashMap, sym::FxHashMap);
map.insert(sym::HashSet, sym::FxHashSet);
Self { map }
}
}
impl_lint_pass!(DefaultHashTypes => [DEFAULT_HASH_TYPES]);
impl EarlyLintPass for DefaultHashTypes {
fn check_ident(&mut self, cx: &EarlyContext<'_>, ident: Ident) {
if let Some(replace) = self.map.get(&ident.name) {
cx.struct_span_lint(DEFAULT_HASH_TYPES, ident.span, |lint| {
// FIXME: We can avoid a copy here. Would require us to take String instead of &str.
let msg = format!("Prefer {} over {}, it has better performance", replace, ident);
lint.build(&msg)
.span_suggestion(
ident.span,
"use",
replace.to_string(),
Applicability::MaybeIncorrect, // FxHashMap, ... needs another import
)
.note(&format!(
"a `use rustc_data_structures::fx::{}` may be necessary",
replace
))
.emit();
});
impl LateLintPass<'_> for DefaultHashTypes {
fn check_path(&mut self, cx: &LateContext<'_>, path: &Path<'_>, hir_id: HirId) {
let def_id = match path.res {
Res::Def(rustc_hir::def::DefKind::Struct, id) => id,
_ => return,
};
if matches!(cx.tcx.hir().get(hir_id), Node::Item(Item { kind: ItemKind::Use(..), .. })) {
// don't lint imports, only actual usages
return;
}
let replace = if cx.tcx.is_diagnostic_item(sym::hashmap_type, def_id) {
"FxHashMap"
} else if cx.tcx.is_diagnostic_item(sym::hashset_type, def_id) {
"FxHashSet"
} else {
return;
};
cx.struct_span_lint(DEFAULT_HASH_TYPES, path.span, |lint| {
let msg = format!(
"prefer `{}` over `{}`, it has better performance",
replace,
cx.tcx.item_name(def_id)
);
lint.build(&msg)
.note(&format!("a `use rustc_data_structures::fx::{}` may be necessary", replace))
.emit();
});
}
}
@ -242,8 +236,9 @@ declare_tool_lint! {
declare_lint_pass!(LintPassImpl => [LINT_PASS_IMPL_WITHOUT_MACRO]);
impl EarlyLintPass for LintPassImpl {
fn check_item(&mut self, cx: &EarlyContext<'_>, item: &Item) {
if let ItemKind::Impl(box ImplKind { of_trait: Some(lint_pass), .. }) = &item.kind {
fn check_item(&mut self, cx: &EarlyContext<'_>, item: &ast::Item) {
if let ast::ItemKind::Impl(box ast::ImplKind { of_trait: Some(lint_pass), .. }) = &item.kind
{
if let Some(last) = lint_pass.path.segments.last() {
if last.ident.name == sym::LintPass {
let expn_data = lint_pass.path.span.ctxt().outer_expn_data();