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|
use clippy_utils::diagnostics::span_lint;
use rustc_ast::ast;
use rustc_hir as hir;
use rustc_lint::{self, LateContext, LateLintPass, LintContext};
use rustc_session::{declare_lint_pass, declare_tool_lint};
use rustc_span::source_map::Span;
use rustc_span::sym;
declare_clippy_lint! {
/// ### What it does
/// It lints if an exported function, method, trait method with default impl,
/// or trait method impl is not `#[inline]`.
///
/// ### Why is this bad?
/// In general, it is not. Functions can be inlined across
/// crates when that's profitable as long as any form of LTO is used. When LTO is disabled,
/// functions that are not `#[inline]` cannot be inlined across crates. Certain types of crates
/// might intend for most of the methods in their public API to be able to be inlined across
/// crates even when LTO is disabled. For these types of crates, enabling this lint might make
/// sense. It allows the crate to require all exported methods to be `#[inline]` by default, and
/// then opt out for specific methods where this might not make sense.
///
/// ### Example
/// ```rust
/// pub fn foo() {} // missing #[inline]
/// fn ok() {} // ok
/// #[inline] pub fn bar() {} // ok
/// #[inline(always)] pub fn baz() {} // ok
///
/// pub trait Bar {
/// fn bar(); // ok
/// fn def_bar() {} // missing #[inline]
/// }
///
/// struct Baz;
/// impl Baz {
/// fn private() {} // ok
/// }
///
/// impl Bar for Baz {
/// fn bar() {} // ok - Baz is not exported
/// }
///
/// pub struct PubBaz;
/// impl PubBaz {
/// fn private() {} // ok
/// pub fn not_private() {} // missing #[inline]
/// }
///
/// impl Bar for PubBaz {
/// fn bar() {} // missing #[inline]
/// fn def_bar() {} // missing #[inline]
/// }
/// ```
#[clippy::version = "pre 1.29.0"]
pub MISSING_INLINE_IN_PUBLIC_ITEMS,
restriction,
"detects missing `#[inline]` attribute for public callables (functions, trait methods, methods...)"
}
fn check_missing_inline_attrs(cx: &LateContext<'_>, attrs: &[ast::Attribute], sp: Span, desc: &'static str) {
let has_inline = attrs.iter().any(|a| a.has_name(sym::inline));
if !has_inline {
span_lint(
cx,
MISSING_INLINE_IN_PUBLIC_ITEMS,
sp,
&format!("missing `#[inline]` for {}", desc),
);
}
}
fn is_executable_or_proc_macro(cx: &LateContext<'_>) -> bool {
use rustc_session::config::CrateType;
cx.tcx
.sess
.crate_types()
.iter()
.any(|t: &CrateType| matches!(t, CrateType::Executable | CrateType::ProcMacro))
}
declare_lint_pass!(MissingInline => [MISSING_INLINE_IN_PUBLIC_ITEMS]);
impl<'tcx> LateLintPass<'tcx> for MissingInline {
fn check_item(&mut self, cx: &LateContext<'tcx>, it: &'tcx hir::Item<'_>) {
if rustc_middle::lint::in_external_macro(cx.sess(), it.span) || is_executable_or_proc_macro(cx) {
return;
}
if !cx.access_levels.is_exported(it.def_id) {
return;
}
match it.kind {
hir::ItemKind::Fn(..) => {
let desc = "a function";
let attrs = cx.tcx.hir().attrs(it.hir_id());
check_missing_inline_attrs(cx, attrs, it.span, desc);
},
hir::ItemKind::Trait(ref _is_auto, ref _unsafe, _generics, _bounds, trait_items) => {
// note: we need to check if the trait is exported so we can't use
// `LateLintPass::check_trait_item` here.
for tit in trait_items {
let tit_ = cx.tcx.hir().trait_item(tit.id);
match tit_.kind {
hir::TraitItemKind::Const(..) | hir::TraitItemKind::Type(..) => {},
hir::TraitItemKind::Fn(..) => {
if cx.tcx.impl_defaultness(tit.id.def_id).has_value() {
// trait method with default body needs inline in case
// an impl is not provided
let desc = "a default trait method";
let item = cx.tcx.hir().trait_item(tit.id);
let attrs = cx.tcx.hir().attrs(item.hir_id());
check_missing_inline_attrs(cx, attrs, item.span, desc);
}
},
}
}
},
hir::ItemKind::Const(..)
| hir::ItemKind::Enum(..)
| hir::ItemKind::Macro(..)
| hir::ItemKind::Mod(..)
| hir::ItemKind::Static(..)
| hir::ItemKind::Struct(..)
| hir::ItemKind::TraitAlias(..)
| hir::ItemKind::GlobalAsm(..)
| hir::ItemKind::TyAlias(..)
| hir::ItemKind::Union(..)
| hir::ItemKind::OpaqueTy(..)
| hir::ItemKind::ExternCrate(..)
| hir::ItemKind::ForeignMod { .. }
| hir::ItemKind::Impl { .. }
| hir::ItemKind::Use(..) => {},
};
}
fn check_impl_item(&mut self, cx: &LateContext<'tcx>, impl_item: &'tcx hir::ImplItem<'_>) {
use rustc_middle::ty::{ImplContainer, TraitContainer};
if rustc_middle::lint::in_external_macro(cx.sess(), impl_item.span) || is_executable_or_proc_macro(cx) {
return;
}
// If the item being implemented is not exported, then we don't need #[inline]
if !cx.access_levels.is_exported(impl_item.def_id) {
return;
}
let desc = match impl_item.kind {
hir::ImplItemKind::Fn(..) => "a method",
hir::ImplItemKind::Const(..) | hir::ImplItemKind::TyAlias(_) => return,
};
let assoc_item = cx.tcx.associated_item(impl_item.def_id);
let container_id = assoc_item.container_id(cx.tcx);
let trait_def_id = match assoc_item.container {
TraitContainer => Some(container_id),
ImplContainer => cx.tcx.impl_trait_ref(container_id).map(|t| t.def_id),
};
if let Some(trait_def_id) = trait_def_id {
if trait_def_id.is_local() && !cx.access_levels.is_exported(impl_item.def_id) {
// If a trait is being implemented for an item, and the
// trait is not exported, we don't need #[inline]
return;
}
}
let attrs = cx.tcx.hir().attrs(impl_item.hir_id());
check_missing_inline_attrs(cx, attrs, impl_item.span, desc);
}
}
|
