1 use clippy_utils::diagnostics::span_lint;
4 use rustc_lint::{self, LateContext, LateLintPass, LintContext};
5 use rustc_session::{declare_lint_pass, declare_tool_lint};
6 use rustc_span::source_map::Span;
11 /// It lints if an exported function, method, trait method with default impl,
12 /// or trait method impl is not `#[inline]`.
14 /// ### Why is this bad?
15 /// In general, it is not. Functions can be inlined across
16 /// crates when that's profitable as long as any form of LTO is used. When LTO is disabled,
17 /// functions that are not `#[inline]` cannot be inlined across crates. Certain types of crates
18 /// might intend for most of the methods in their public API to be able to be inlined across
19 /// crates even when LTO is disabled. For these types of crates, enabling this lint might make
20 /// sense. It allows the crate to require all exported methods to be `#[inline]` by default, and
21 /// then opt out for specific methods where this might not make sense.
25 /// pub fn foo() {} // missing #[inline]
27 /// #[inline] pub fn bar() {} // ok
28 /// #[inline(always)] pub fn baz() {} // ok
32 /// fn def_bar() {} // missing #[inline]
37 /// fn private() {} // ok
40 /// impl Bar for Baz {
41 /// fn bar() {} // ok - Baz is not exported
44 /// pub struct PubBaz;
46 /// fn private() {} // ok
47 /// pub fn not_ptrivate() {} // missing #[inline]
50 /// impl Bar for PubBaz {
51 /// fn bar() {} // missing #[inline]
52 /// fn def_bar() {} // missing #[inline]
55 #[clippy::version = "pre 1.29.0"]
56 pub MISSING_INLINE_IN_PUBLIC_ITEMS,
58 "detects missing `#[inline]` attribute for public callables (functions, trait methods, methods...)"
61 fn check_missing_inline_attrs(cx: &LateContext<'_>, attrs: &[ast::Attribute], sp: Span, desc: &'static str) {
62 let has_inline = attrs.iter().any(|a| a.has_name(sym::inline));
66 MISSING_INLINE_IN_PUBLIC_ITEMS,
68 &format!("missing `#[inline]` for {}", desc),
73 fn is_executable_or_proc_macro(cx: &LateContext<'_>) -> bool {
74 use rustc_session::config::CrateType;
80 .any(|t: &CrateType| matches!(t, CrateType::Executable | CrateType::ProcMacro))
83 declare_lint_pass!(MissingInline => [MISSING_INLINE_IN_PUBLIC_ITEMS]);
85 impl<'tcx> LateLintPass<'tcx> for MissingInline {
86 fn check_item(&mut self, cx: &LateContext<'tcx>, it: &'tcx hir::Item<'_>) {
87 if rustc_middle::lint::in_external_macro(cx.sess(), it.span) || is_executable_or_proc_macro(cx) {
91 if !cx.access_levels.is_exported(it.def_id) {
95 hir::ItemKind::Fn(..) => {
96 let desc = "a function";
97 let attrs = cx.tcx.hir().attrs(it.hir_id());
98 check_missing_inline_attrs(cx, attrs, it.span, desc);
100 hir::ItemKind::Trait(ref _is_auto, ref _unsafe, ref _generics, _bounds, trait_items) => {
101 // note: we need to check if the trait is exported so we can't use
102 // `LateLintPass::check_trait_item` here.
103 for tit in trait_items {
104 let tit_ = cx.tcx.hir().trait_item(tit.id);
106 hir::TraitItemKind::Const(..) | hir::TraitItemKind::Type(..) => {},
107 hir::TraitItemKind::Fn(..) => {
108 if tit.defaultness.has_value() {
109 // trait method with default body needs inline in case
110 // an impl is not provided
111 let desc = "a default trait method";
112 let item = cx.tcx.hir().trait_item(tit.id);
113 let attrs = cx.tcx.hir().attrs(item.hir_id());
114 check_missing_inline_attrs(cx, attrs, item.span, desc);
120 hir::ItemKind::Const(..)
121 | hir::ItemKind::Enum(..)
122 | hir::ItemKind::Macro(..)
123 | hir::ItemKind::Mod(..)
124 | hir::ItemKind::Static(..)
125 | hir::ItemKind::Struct(..)
126 | hir::ItemKind::TraitAlias(..)
127 | hir::ItemKind::GlobalAsm(..)
128 | hir::ItemKind::TyAlias(..)
129 | hir::ItemKind::Union(..)
130 | hir::ItemKind::OpaqueTy(..)
131 | hir::ItemKind::ExternCrate(..)
132 | hir::ItemKind::ForeignMod { .. }
133 | hir::ItemKind::Impl { .. }
134 | hir::ItemKind::Use(..) => {},
138 fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx hir::ImplItem<'_>) {
139 use rustc_middle::ty::{ImplContainer, TraitContainer};
140 if rustc_middle::lint::in_external_macro(cx.sess(), impl_item.span) || is_executable_or_proc_macro(cx) {
144 // If the item being implemented is not exported, then we don't need #[inline]
145 if !cx.access_levels.is_exported(impl_item.def_id) {
149 let desc = match impl_item.kind {
150 hir::ImplItemKind::Fn(..) => "a method",
151 hir::ImplItemKind::Const(..) | hir::ImplItemKind::TyAlias(_) => return,
154 let trait_def_id = match cx.tcx.associated_item(impl_item.def_id).container {
155 TraitContainer(cid) => Some(cid),
156 ImplContainer(cid) => cx.tcx.impl_trait_ref(cid).map(|t| t.def_id),
159 if let Some(trait_def_id) = trait_def_id {
160 if trait_def_id.is_local() && !cx.access_levels.is_exported(impl_item.def_id) {
161 // If a trait is being implemented for an item, and the
162 // trait is not exported, we don't need #[inline]
167 let attrs = cx.tcx.hir().attrs(impl_item.hir_id());
168 check_missing_inline_attrs(cx, attrs, impl_item.span, desc);