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rust/compiler/rustc_passes/src/check_attr.rs
Michael Goulet ca68cf0d46 Merge attrs, better validation
2023-06-20 04:38:55 +00:00

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//! This module implements some validity checks for attributes.
//! In particular it verifies that `#[inline]` and `#[repr]` attributes are
//! attached to items that actually support them and if there are
//! conflicts between multiple such attributes attached to the same
//! item.
use crate::{errors, fluent_generated as fluent};
use rustc_ast::{ast, AttrStyle, Attribute, LitKind, MetaItemKind, MetaItemLit, NestedMetaItem};
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::{Applicability, IntoDiagnosticArg, MultiSpan};
use rustc_feature::{AttributeDuplicates, AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
use rustc_hir as hir;
use rustc_hir::def_id::LocalDefId;
use rustc_hir::intravisit::{self, Visitor};
use rustc_hir::{
self, FnSig, ForeignItem, HirId, Item, ItemKind, TraitItem, CRATE_HIR_ID, CRATE_OWNER_ID,
};
use rustc_hir::{MethodKind, Target, Unsafety};
use rustc_middle::hir::nested_filter;
use rustc_middle::middle::resolve_bound_vars::ObjectLifetimeDefault;
use rustc_middle::query::Providers;
use rustc_middle::traits::ObligationCause;
use rustc_middle::ty::error::{ExpectedFound, TypeError};
use rustc_middle::ty::{self, TyCtxt};
use rustc_session::lint::builtin::{
CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, INVALID_MACRO_EXPORT_ARGUMENTS,
UNUSED_ATTRIBUTES,
};
use rustc_session::parse::feature_err;
use rustc_span::symbol::{kw, sym, Symbol};
use rustc_span::{BytePos, Span, DUMMY_SP};
use rustc_target::spec::abi::Abi;
use rustc_trait_selection::infer::{TyCtxtInferExt, ValuePairs};
use rustc_trait_selection::traits::error_reporting::TypeErrCtxtExt;
use rustc_trait_selection::traits::ObligationCtxt;
use std::cell::Cell;
use std::collections::hash_map::Entry;
pub(crate) fn target_from_impl_item<'tcx>(
tcx: TyCtxt<'tcx>,
impl_item: &hir::ImplItem<'_>,
) -> Target {
match impl_item.kind {
hir::ImplItemKind::Const(..) => Target::AssocConst,
hir::ImplItemKind::Fn(..) => {
let parent_def_id = tcx.hir().get_parent_item(impl_item.hir_id()).def_id;
let containing_item = tcx.hir().expect_item(parent_def_id);
let containing_impl_is_for_trait = match &containing_item.kind {
hir::ItemKind::Impl(impl_) => impl_.of_trait.is_some(),
_ => bug!("parent of an ImplItem must be an Impl"),
};
if containing_impl_is_for_trait {
Target::Method(MethodKind::Trait { body: true })
} else {
Target::Method(MethodKind::Inherent)
}
}
hir::ImplItemKind::Type(..) => Target::AssocTy,
}
}
#[derive(Clone, Copy)]
enum ItemLike<'tcx> {
Item(&'tcx Item<'tcx>),
ForeignItem,
}
#[derive(Copy, Clone)]
pub(crate) enum ProcMacroKind {
FunctionLike,
Derive,
Attribute,
}
impl IntoDiagnosticArg for ProcMacroKind {
fn into_diagnostic_arg(self) -> rustc_errors::DiagnosticArgValue<'static> {
match self {
ProcMacroKind::Attribute => "attribute proc macro",
ProcMacroKind::Derive => "derive proc macro",
ProcMacroKind::FunctionLike => "function-like proc macro",
}
.into_diagnostic_arg()
}
}
struct CheckAttrVisitor<'tcx> {
tcx: TyCtxt<'tcx>,
// Whether or not this visitor should abort after finding errors
abort: Cell<bool>,
}
impl CheckAttrVisitor<'_> {
/// Checks any attribute.
fn check_attributes(
&self,
hir_id: HirId,
span: Span,
target: Target,
item: Option<ItemLike<'_>>,
) {
let mut doc_aliases = FxHashMap::default();
let mut specified_inline = None;
let mut seen = FxHashMap::default();
let attrs = self.tcx.hir().attrs(hir_id);
for attr in attrs {
match attr.name_or_empty() {
sym::do_not_recommend => self.check_do_not_recommend(attr.span, target),
sym::inline => self.check_inline(hir_id, attr, span, target),
sym::no_coverage => self.check_no_coverage(hir_id, attr, span, target),
sym::non_exhaustive => self.check_non_exhaustive(hir_id, attr, span, target),
sym::marker => self.check_marker(hir_id, attr, span, target),
sym::target_feature => self.check_target_feature(hir_id, attr, span, target),
sym::thread_local => self.check_thread_local(attr, span, target),
sym::track_caller => {
self.check_track_caller(hir_id, attr.span, attrs, span, target)
}
sym::doc => self.check_doc_attrs(
attr,
hir_id,
target,
&mut specified_inline,
&mut doc_aliases,
),
sym::no_link => self.check_no_link(hir_id, &attr, span, target),
sym::export_name => self.check_export_name(hir_id, &attr, span, target),
sym::rustc_layout_scalar_valid_range_start
| sym::rustc_layout_scalar_valid_range_end => {
self.check_rustc_layout_scalar_valid_range(&attr, span, target)
}
sym::allow_internal_unstable => {
self.check_allow_internal_unstable(hir_id, &attr, span, target, &attrs)
}
sym::debugger_visualizer => self.check_debugger_visualizer(&attr, target),
sym::rustc_allow_const_fn_unstable => {
self.check_rustc_allow_const_fn_unstable(hir_id, &attr, span, target)
}
sym::rustc_std_internal_symbol => {
self.check_rustc_std_internal_symbol(&attr, span, target)
}
sym::naked => self.check_naked(hir_id, attr, span, target),
sym::rustc_legacy_const_generics => {
self.check_rustc_legacy_const_generics(hir_id, &attr, span, target, item)
}
sym::rustc_lint_query_instability => {
self.check_rustc_lint_query_instability(hir_id, &attr, span, target)
}
sym::rustc_lint_diagnostics => {
self.check_rustc_lint_diagnostics(hir_id, &attr, span, target)
}
sym::rustc_lint_opt_ty => self.check_rustc_lint_opt_ty(&attr, span, target),
sym::rustc_lint_opt_deny_field_access => {
self.check_rustc_lint_opt_deny_field_access(&attr, span, target)
}
sym::rustc_clean
| sym::rustc_dirty
| sym::rustc_if_this_changed
| sym::rustc_then_this_would_need => self.check_rustc_dirty_clean(&attr),
sym::rustc_coinductive
| sym::rustc_must_implement_one_of
| sym::rustc_deny_explicit_impl
| sym::const_trait => self.check_must_be_applied_to_trait(&attr, span, target),
sym::cmse_nonsecure_entry => {
self.check_cmse_nonsecure_entry(hir_id, attr, span, target)
}
sym::collapse_debuginfo => self.check_collapse_debuginfo(attr, span, target),
sym::must_not_suspend => self.check_must_not_suspend(&attr, span, target),
sym::must_use => self.check_must_use(hir_id, &attr, target),
sym::rustc_pass_by_value => self.check_pass_by_value(&attr, span, target),
sym::rustc_allow_incoherent_impl => {
self.check_allow_incoherent_impl(&attr, span, target)
}
sym::rustc_has_incoherent_inherent_impls => {
self.check_has_incoherent_inherent_impls(&attr, span, target)
}
sym::ffi_pure => self.check_ffi_pure(attr.span, attrs, target),
sym::ffi_const => self.check_ffi_const(attr.span, target),
sym::ffi_returns_twice => self.check_ffi_returns_twice(attr.span, target),
sym::rustc_const_unstable
| sym::rustc_const_stable
| sym::unstable
| sym::stable
| sym::rustc_allowed_through_unstable_modules
| sym::rustc_promotable => self.check_stability_promotable(&attr, span, target),
sym::link_ordinal => self.check_link_ordinal(&attr, span, target),
_ => true,
};
// lint-only checks
match attr.name_or_empty() {
sym::cold => self.check_cold(hir_id, attr, span, target),
sym::link => self.check_link(hir_id, attr, span, target),
sym::link_name => self.check_link_name(hir_id, attr, span, target),
sym::link_section => self.check_link_section(hir_id, attr, span, target),
sym::no_mangle => self.check_no_mangle(hir_id, attr, span, target),
sym::deprecated => self.check_deprecated(hir_id, attr, span, target),
sym::macro_use | sym::macro_escape => self.check_macro_use(hir_id, attr, target),
sym::path => self.check_generic_attr(hir_id, attr, target, Target::Mod),
sym::plugin_registrar => self.check_plugin_registrar(hir_id, attr, target),
sym::macro_export => self.check_macro_export(hir_id, attr, target),
sym::ignore | sym::should_panic => {
self.check_generic_attr(hir_id, attr, target, Target::Fn)
}
sym::automatically_derived => {
self.check_generic_attr(hir_id, attr, target, Target::Impl)
}
sym::no_implicit_prelude => {
self.check_generic_attr(hir_id, attr, target, Target::Mod)
}
sym::rustc_object_lifetime_default => self.check_object_lifetime_default(hir_id),
sym::proc_macro => {
self.check_proc_macro(hir_id, target, ProcMacroKind::FunctionLike)
}
sym::proc_macro_attribute => {
self.check_proc_macro(hir_id, target, ProcMacroKind::Attribute);
}
sym::proc_macro_derive => {
self.check_generic_attr(hir_id, attr, target, Target::Fn);
self.check_proc_macro(hir_id, target, ProcMacroKind::Derive)
}
_ => {}
}
let builtin = attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name));
if hir_id != CRATE_HIR_ID {
if let Some(BuiltinAttribute { type_: AttributeType::CrateLevel, .. }) =
attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name))
{
match attr.style {
ast::AttrStyle::Outer => self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::OuterCrateLevelAttr,
),
ast::AttrStyle::Inner => self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::InnerCrateLevelAttr,
),
}
}
}
if let Some(BuiltinAttribute { duplicates, .. }) = builtin {
check_duplicates(self.tcx, attr, hir_id, *duplicates, &mut seen);
}
self.check_unused_attribute(hir_id, attr)
}
self.check_repr(attrs, span, target, item, hir_id);
self.check_used(attrs, target);
}
fn inline_attr_str_error_with_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::IgnoredAttrWithMacro { sym },
);
}
fn inline_attr_str_error_without_macro_def(&self, hir_id: HirId, attr: &Attribute, sym: &str) {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::IgnoredAttr { sym },
);
}
/// Checks if `#[do_not_recommend]` is applied on a trait impl.
fn check_do_not_recommend(&self, attr_span: Span, target: Target) -> bool {
if let Target::Impl = target {
true
} else {
self.tcx.sess.emit_err(errors::IncorrectDoNotRecommendLocation { span: attr_span });
false
}
}
/// Checks if an `#[inline]` is applied to a function or a closure. Returns `true` if valid.
fn check_inline(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::Fn
| Target::Closure
| Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::IgnoredInlineAttrFnProto,
);
true
}
// FIXME(#65833): We permit associated consts to have an `#[inline]` attribute with
// just a lint, because we previously erroneously allowed it and some crates used it
// accidentally, to be compatible with crates depending on them, we can't throw an
// error here.
Target::AssocConst => {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::IgnoredInlineAttrConstants,
);
true
}
// FIXME(#80564): Same for fields, arms, and macro defs
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "inline");
true
}
_ => {
self.tcx.sess.emit_err(errors::InlineNotFnOrClosure {
attr_span: attr.span,
defn_span: span,
});
false
}
}
}
/// Checks if a `#[no_coverage]` is applied directly to a function
fn check_no_coverage(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
match target {
// no_coverage on function is fine
Target::Fn
| Target::Closure
| Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
// function prototypes can't be covered
Target::Method(MethodKind::Trait { body: false }) | Target::ForeignFn => {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::IgnoredNoCoverageFnProto,
);
true
}
Target::Mod | Target::ForeignMod | Target::Impl | Target::Trait => {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::IgnoredNoCoveragePropagate,
);
true
}
Target::Expression | Target::Statement | Target::Arm => {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::IgnoredNoCoverageFnDefn,
);
true
}
_ => {
self.tcx.sess.emit_err(errors::IgnoredNoCoverageNotCoverable {
attr_span: attr.span,
defn_span: span,
});
false
}
}
}
fn check_generic_attr(
&self,
hir_id: HirId,
attr: &Attribute,
target: Target,
allowed_target: Target,
) {
if target != allowed_target {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::OnlyHasEffectOn {
attr_name: attr.name_or_empty(),
target_name: allowed_target.name().replace(' ', "_"),
},
);
}
}
/// Checks if `#[naked]` is applied to a function definition.
fn check_naked(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::Fn
| Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[allow_internal_unstable]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "naked");
true
}
_ => {
self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
attr_span: attr.span,
defn_span: span,
on_crate: hir_id == CRATE_HIR_ID,
});
false
}
}
}
/// Checks if `#[cmse_nonsecure_entry]` is applied to a function definition.
fn check_cmse_nonsecure_entry(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
match target {
Target::Fn
| Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
_ => {
self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
attr_span: attr.span,
defn_span: span,
on_crate: hir_id == CRATE_HIR_ID,
});
false
}
}
}
/// Debugging aid for `object_lifetime_default` query.
fn check_object_lifetime_default(&self, hir_id: HirId) {
let tcx = self.tcx;
if let Some(owner_id) = hir_id.as_owner()
&& let Some(generics) = tcx.hir().get_generics(owner_id.def_id)
{
for p in generics.params {
let hir::GenericParamKind::Type { .. } = p.kind else { continue };
let default = tcx.object_lifetime_default(p.def_id);
let repr = match default {
ObjectLifetimeDefault::Empty => "BaseDefault".to_owned(),
ObjectLifetimeDefault::Static => "'static".to_owned(),
ObjectLifetimeDefault::Param(def_id) => tcx.item_name(def_id).to_string(),
ObjectLifetimeDefault::Ambiguous => "Ambiguous".to_owned(),
};
tcx.sess.emit_err(errors::ObjectLifetimeErr { span: p.span, repr });
}
}
}
/// Checks if `#[collapse_debuginfo]` is applied to a macro.
fn check_collapse_debuginfo(&self, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::MacroDef => true,
_ => {
self.tcx
.sess
.emit_err(errors::CollapseDebuginfo { attr_span: attr.span, defn_span: span });
false
}
}
}
/// Checks if a `#[track_caller]` is applied to a non-naked function. Returns `true` if valid.
fn check_track_caller(
&self,
hir_id: HirId,
attr_span: Span,
attrs: &[Attribute],
span: Span,
target: Target,
) -> bool {
match target {
_ if attrs.iter().any(|attr| attr.has_name(sym::naked)) => {
self.tcx.sess.emit_err(errors::NakedTrackedCaller { attr_span });
false
}
Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => true,
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[track_caller]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
for attr in attrs {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "track_caller");
}
true
}
_ => {
self.tcx.sess.emit_err(errors::TrackedCallerWrongLocation {
attr_span,
defn_span: span,
on_crate: hir_id == CRATE_HIR_ID,
});
false
}
}
}
/// Checks if the `#[non_exhaustive]` attribute on an `item` is valid. Returns `true` if valid.
fn check_non_exhaustive(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
match target {
Target::Struct | Target::Enum | Target::Variant => true,
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[non_exhaustive]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "non_exhaustive");
true
}
_ => {
self.tcx.sess.emit_err(errors::NonExhaustiveWrongLocation {
attr_span: attr.span,
defn_span: span,
});
false
}
}
}
/// Checks if the `#[marker]` attribute on an `item` is valid. Returns `true` if valid.
fn check_marker(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::Trait => true,
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[marker]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "marker");
true
}
_ => {
self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait {
attr_span: attr.span,
defn_span: span,
});
false
}
}
}
/// Checks if the `#[target_feature]` attribute on `item` is valid. Returns `true` if valid.
fn check_target_feature(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
match target {
Target::Fn
| Target::Method(MethodKind::Trait { body: true } | MethodKind::Inherent) => true,
// FIXME: #[target_feature] was previously erroneously allowed on statements and some
// crates used this, so only emit a warning.
Target::Statement => {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::TargetFeatureOnStatement,
);
true
}
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[target_feature]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "target_feature");
true
}
_ => {
self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
attr_span: attr.span,
defn_span: span,
on_crate: hir_id == CRATE_HIR_ID,
});
false
}
}
}
/// Checks if the `#[thread_local]` attribute on `item` is valid. Returns `true` if valid.
fn check_thread_local(&self, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::ForeignStatic | Target::Static => true,
_ => {
self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToStatic {
attr_span: attr.span,
defn_span: span,
});
false
}
}
}
fn doc_attr_str_error(&self, meta: &NestedMetaItem, attr_name: &str) {
self.tcx.sess.emit_err(errors::DocExpectStr { attr_span: meta.span(), attr_name });
}
fn check_doc_alias_value(
&self,
meta: &NestedMetaItem,
doc_alias: Symbol,
hir_id: HirId,
target: Target,
is_list: bool,
aliases: &mut FxHashMap<String, Span>,
) -> bool {
let tcx = self.tcx;
let span = meta.name_value_literal_span().unwrap_or_else(|| meta.span());
let attr_str =
&format!("`#[doc(alias{})]`", if is_list { "(\"...\")" } else { " = \"...\"" });
if doc_alias == kw::Empty {
tcx.sess.emit_err(errors::DocAliasEmpty { span, attr_str });
return false;
}
let doc_alias_str = doc_alias.as_str();
if let Some(c) = doc_alias_str
.chars()
.find(|&c| c == '"' || c == '\'' || (c.is_whitespace() && c != ' '))
{
tcx.sess.emit_err(errors::DocAliasBadChar { span, attr_str, char_: c });
return false;
}
if doc_alias_str.starts_with(' ') || doc_alias_str.ends_with(' ') {
tcx.sess.emit_err(errors::DocAliasStartEnd { span, attr_str });
return false;
}
let span = meta.span();
if let Some(location) = match target {
Target::AssocTy => {
let parent_def_id = self.tcx.hir().get_parent_item(hir_id).def_id;
let containing_item = self.tcx.hir().expect_item(parent_def_id);
if Target::from_item(containing_item) == Target::Impl {
Some("type alias in implementation block")
} else {
None
}
}
Target::AssocConst => {
let parent_def_id = self.tcx.hir().get_parent_item(hir_id).def_id;
let containing_item = self.tcx.hir().expect_item(parent_def_id);
// We can't link to trait impl's consts.
let err = "associated constant in trait implementation block";
match containing_item.kind {
ItemKind::Impl(hir::Impl { of_trait: Some(_), .. }) => Some(err),
_ => None,
}
}
// we check the validity of params elsewhere
Target::Param => return false,
Target::Expression
| Target::Statement
| Target::Arm
| Target::ForeignMod
| Target::Closure
| Target::Impl => Some(target.name()),
Target::ExternCrate
| Target::Use
| Target::Static
| Target::Const
| Target::Fn
| Target::Mod
| Target::GlobalAsm
| Target::TyAlias
| Target::OpaqueTy
| Target::ImplTraitPlaceholder
| Target::Enum
| Target::Variant
| Target::Struct
| Target::Field
| Target::Union
| Target::Trait
| Target::TraitAlias
| Target::Method(..)
| Target::ForeignFn
| Target::ForeignStatic
| Target::ForeignTy
| Target::GenericParam(..)
| Target::MacroDef
| Target::PatField
| Target::ExprField => None,
} {
tcx.sess.emit_err(errors::DocAliasBadLocation { span, attr_str, location });
return false;
}
let item_name = self.tcx.hir().name(hir_id);
if item_name == doc_alias {
tcx.sess.emit_err(errors::DocAliasNotAnAlias { span, attr_str });
return false;
}
if let Err(entry) = aliases.try_insert(doc_alias_str.to_owned(), span) {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
span,
errors::DocAliasDuplicated { first_defn: *entry.entry.get() },
);
}
true
}
fn check_doc_alias(
&self,
meta: &NestedMetaItem,
hir_id: HirId,
target: Target,
aliases: &mut FxHashMap<String, Span>,
) -> bool {
if let Some(values) = meta.meta_item_list() {
let mut errors = 0;
for v in values {
match v.lit() {
Some(l) => match l.kind {
LitKind::Str(s, _) => {
if !self.check_doc_alias_value(v, s, hir_id, target, true, aliases) {
errors += 1;
}
}
_ => {
self.tcx
.sess
.emit_err(errors::DocAliasNotStringLiteral { span: v.span() });
errors += 1;
}
},
None => {
self.tcx.sess.emit_err(errors::DocAliasNotStringLiteral { span: v.span() });
errors += 1;
}
}
}
errors == 0
} else if let Some(doc_alias) = meta.value_str() {
self.check_doc_alias_value(meta, doc_alias, hir_id, target, false, aliases)
} else {
self.tcx.sess.emit_err(errors::DocAliasMalformed { span: meta.span() });
false
}
}
fn check_doc_keyword(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
let doc_keyword = meta.value_str().unwrap_or(kw::Empty);
if doc_keyword == kw::Empty {
self.doc_attr_str_error(meta, "keyword");
return false;
}
match self.tcx.hir().find(hir_id).and_then(|node| match node {
hir::Node::Item(item) => Some(&item.kind),
_ => None,
}) {
Some(ItemKind::Mod(ref module)) => {
if !module.item_ids.is_empty() {
self.tcx.sess.emit_err(errors::DocKeywordEmptyMod { span: meta.span() });
return false;
}
}
_ => {
self.tcx.sess.emit_err(errors::DocKeywordNotMod { span: meta.span() });
return false;
}
}
if !rustc_lexer::is_ident(doc_keyword.as_str()) {
self.tcx.sess.emit_err(errors::DocKeywordInvalidIdent {
span: meta.name_value_literal_span().unwrap_or_else(|| meta.span()),
doc_keyword,
});
return false;
}
true
}
fn check_doc_fake_variadic(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
match self.tcx.hir().find(hir_id).and_then(|node| match node {
hir::Node::Item(item) => Some(&item.kind),
_ => None,
}) {
Some(ItemKind::Impl(ref i)) => {
let is_valid = matches!(&i.self_ty.kind, hir::TyKind::Tup([_]))
|| if let hir::TyKind::BareFn(bare_fn_ty) = &i.self_ty.kind {
bare_fn_ty.decl.inputs.len() == 1
} else {
false
};
if !is_valid {
self.tcx.sess.emit_err(errors::DocFakeVariadicNotValid { span: meta.span() });
return false;
}
}
_ => {
self.tcx.sess.emit_err(errors::DocKeywordOnlyImpl { span: meta.span() });
return false;
}
}
true
}
/// Checks `#[doc(inline)]`/`#[doc(no_inline)]` attributes. Returns `true` if valid.
///
/// A doc inlining attribute is invalid if it is applied to a non-`use` item, or
/// if there are conflicting attributes for one item.
///
/// `specified_inline` is used to keep track of whether we have
/// already seen an inlining attribute for this item.
/// If so, `specified_inline` holds the value and the span of
/// the first `inline`/`no_inline` attribute.
fn check_doc_inline(
&self,
attr: &Attribute,
meta: &NestedMetaItem,
hir_id: HirId,
target: Target,
specified_inline: &mut Option<(bool, Span)>,
) -> bool {
match target {
Target::Use | Target::ExternCrate => {
let do_inline = meta.name_or_empty() == sym::inline;
if let Some((prev_inline, prev_span)) = *specified_inline {
if do_inline != prev_inline {
let mut spans = MultiSpan::from_spans(vec![prev_span, meta.span()]);
spans.push_span_label(prev_span, fluent::passes_doc_inline_conflict_first);
spans.push_span_label(
meta.span(),
fluent::passes_doc_inline_conflict_second,
);
self.tcx.sess.emit_err(errors::DocKeywordConflict { spans });
return false;
}
true
} else {
*specified_inline = Some((do_inline, meta.span()));
true
}
}
_ => {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
meta.span(),
errors::DocInlineOnlyUse {
attr_span: meta.span(),
item_span: (attr.style == AttrStyle::Outer)
.then(|| self.tcx.hir().span(hir_id)),
},
);
false
}
}
}
/// Checks that an attribute is *not* used at the crate level. Returns `true` if valid.
fn check_attr_not_crate_level(
&self,
meta: &NestedMetaItem,
hir_id: HirId,
attr_name: &str,
) -> bool {
if CRATE_HIR_ID == hir_id {
self.tcx.sess.emit_err(errors::DocAttrNotCrateLevel { span: meta.span(), attr_name });
return false;
}
true
}
/// Checks that an attribute is used at the crate level. Returns `true` if valid.
fn check_attr_crate_level(
&self,
attr: &Attribute,
meta: &NestedMetaItem,
hir_id: HirId,
) -> bool {
if hir_id != CRATE_HIR_ID {
// insert a bang between `#` and `[...`
let bang_span = attr.span.lo() + BytePos(1);
let sugg = (attr.style == AttrStyle::Outer
&& self.tcx.hir().get_parent_item(hir_id) == CRATE_OWNER_ID)
.then_some(errors::AttrCrateLevelOnlySugg {
attr: attr.span.with_lo(bang_span).with_hi(bang_span),
});
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
meta.span(),
errors::AttrCrateLevelOnly { sugg },
);
return false;
}
true
}
/// Checks that `doc(test(...))` attribute contains only valid attributes. Returns `true` if
/// valid.
fn check_test_attr(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
let mut is_valid = true;
if let Some(metas) = meta.meta_item_list() {
for i_meta in metas {
match (i_meta.name_or_empty(), i_meta.meta_item()) {
(sym::attr | sym::no_crate_inject, _) => {}
(_, Some(m)) => {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
i_meta.span(),
errors::DocTestUnknown {
path: rustc_ast_pretty::pprust::path_to_string(&m.path),
},
);
is_valid = false;
}
(_, None) => {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
i_meta.span(),
errors::DocTestLiteral,
);
is_valid = false;
}
}
}
} else {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
meta.span(),
errors::DocTestTakesList,
);
is_valid = false;
}
is_valid
}
/// Check that the `#![doc(cfg_hide(...))]` attribute only contains a list of attributes.
/// Returns `true` if valid.
fn check_doc_cfg_hide(&self, meta: &NestedMetaItem, hir_id: HirId) -> bool {
if meta.meta_item_list().is_some() {
true
} else {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
meta.span(),
errors::DocCfgHideTakesList,
);
false
}
}
/// Runs various checks on `#[doc]` attributes. Returns `true` if valid.
///
/// `specified_inline` should be initialized to `None` and kept for the scope
/// of one item. Read the documentation of [`check_doc_inline`] for more information.
///
/// [`check_doc_inline`]: Self::check_doc_inline
fn check_doc_attrs(
&self,
attr: &Attribute,
hir_id: HirId,
target: Target,
specified_inline: &mut Option<(bool, Span)>,
aliases: &mut FxHashMap<String, Span>,
) -> bool {
let mut is_valid = true;
if let Some(mi) = attr.meta() && let Some(list) = mi.meta_item_list() {
for meta in list {
if let Some(i_meta) = meta.meta_item() {
match i_meta.name_or_empty() {
sym::alias
if !self.check_attr_not_crate_level(meta, hir_id, "alias")
|| !self.check_doc_alias(meta, hir_id, target, aliases) =>
{
is_valid = false
}
sym::keyword
if !self.check_attr_not_crate_level(meta, hir_id, "keyword")
|| !self.check_doc_keyword(meta, hir_id) =>
{
is_valid = false
}
sym::fake_variadic
if !self.check_attr_not_crate_level(meta, hir_id, "fake_variadic")
|| !self.check_doc_fake_variadic(meta, hir_id) =>
{
is_valid = false
}
sym::html_favicon_url
| sym::html_logo_url
| sym::html_playground_url
| sym::issue_tracker_base_url
| sym::html_root_url
| sym::html_no_source
| sym::test
if !self.check_attr_crate_level(attr, meta, hir_id) =>
{
is_valid = false;
}
sym::cfg_hide
if !self.check_attr_crate_level(attr, meta, hir_id)
|| !self.check_doc_cfg_hide(meta, hir_id) =>
{
is_valid = false;
}
sym::inline | sym::no_inline
if !self.check_doc_inline(
attr,
meta,
hir_id,
target,
specified_inline,
) =>
{
is_valid = false;
}
// no_default_passes: deprecated
// passes: deprecated
// plugins: removed, but rustdoc warns about it itself
sym::alias
| sym::cfg
| sym::cfg_hide
| sym::hidden
| sym::html_favicon_url
| sym::html_logo_url
| sym::html_no_source
| sym::html_playground_url
| sym::html_root_url
| sym::inline
| sym::issue_tracker_base_url
| sym::keyword
| sym::masked
| sym::no_default_passes
| sym::no_inline
| sym::notable_trait
| sym::passes
| sym::plugins
| sym::fake_variadic => {}
sym::test => {
if !self.check_test_attr(meta, hir_id) {
is_valid = false;
}
}
_ => {
let path = rustc_ast_pretty::pprust::path_to_string(&i_meta.path);
if i_meta.has_name(sym::spotlight) {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
i_meta.span,
errors::DocTestUnknownSpotlight {
path,
span: i_meta.span
}
);
} else if i_meta.has_name(sym::include) &&
let Some(value) = i_meta.value_str() {
let applicability = if list.len() == 1 {
Applicability::MachineApplicable
} else {
Applicability::MaybeIncorrect
};
// If there are multiple attributes, the suggestion would suggest
// deleting all of them, which is incorrect.
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
i_meta.span,
errors::DocTestUnknownInclude {
path,
value: value.to_string(),
inner: match attr.style { AttrStyle::Inner=> "!" , AttrStyle::Outer => "" },
sugg: (attr.meta().unwrap().span, applicability),
}
);
} else {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
i_meta.span,
errors::DocTestUnknownAny { path }
);
}
is_valid = false;
}
}
} else {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
meta.span(),
errors::DocInvalid,
);
is_valid = false;
}
}
}
is_valid
}
/// Warns against some misuses of `#[pass_by_value]`
fn check_pass_by_value(&self, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::Struct | Target::Enum | Target::TyAlias => true,
_ => {
self.tcx.sess.emit_err(errors::PassByValue { attr_span: attr.span, span });
false
}
}
}
fn check_allow_incoherent_impl(&self, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::Method(MethodKind::Inherent) => true,
_ => {
self.tcx.sess.emit_err(errors::AllowIncoherentImpl { attr_span: attr.span, span });
false
}
}
}
fn check_has_incoherent_inherent_impls(
&self,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
match target {
Target::Trait | Target::Struct | Target::Enum | Target::Union | Target::ForeignTy => {
true
}
_ => {
self.tcx
.sess
.emit_err(errors::HasIncoherentInherentImpl { attr_span: attr.span, span });
false
}
}
}
fn check_ffi_pure(&self, attr_span: Span, attrs: &[Attribute], target: Target) -> bool {
if target != Target::ForeignFn {
self.tcx.sess.emit_err(errors::FfiPureInvalidTarget { attr_span });
return false;
}
if attrs.iter().any(|a| a.has_name(sym::ffi_const)) {
// `#[ffi_const]` functions cannot be `#[ffi_pure]`
self.tcx.sess.emit_err(errors::BothFfiConstAndPure { attr_span });
false
} else {
true
}
}
fn check_ffi_const(&self, attr_span: Span, target: Target) -> bool {
if target == Target::ForeignFn {
true
} else {
self.tcx.sess.emit_err(errors::FfiConstInvalidTarget { attr_span });
false
}
}
fn check_ffi_returns_twice(&self, attr_span: Span, target: Target) -> bool {
if target == Target::ForeignFn {
true
} else {
self.tcx.sess.emit_err(errors::FfiReturnsTwiceInvalidTarget { attr_span });
false
}
}
/// Warns against some misuses of `#[must_use]`
fn check_must_use(&self, hir_id: HirId, attr: &Attribute, target: Target) -> bool {
if !matches!(
target,
Target::Fn
| Target::Enum
| Target::Struct
| Target::Union
| Target::Method(_)
| Target::ForeignFn
// `impl Trait` in return position can trip
// `unused_must_use` if `Trait` is marked as
// `#[must_use]`
| Target::Trait
) {
let article = match target {
Target::ExternCrate
| Target::OpaqueTy
| Target::Enum
| Target::Impl
| Target::Expression
| Target::Arm
| Target::AssocConst
| Target::AssocTy => "an",
_ => "a",
};
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::MustUseNoEffect { article, target },
);
}
// For now, its always valid
true
}
/// Checks if `#[must_not_suspend]` is applied to a function. Returns `true` if valid.
fn check_must_not_suspend(&self, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::Struct | Target::Enum | Target::Union | Target::Trait => true,
_ => {
self.tcx.sess.emit_err(errors::MustNotSuspend { attr_span: attr.span, span });
false
}
}
}
/// Checks if `#[cold]` is applied to a non-function. Returns `true` if valid.
fn check_cold(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
match target {
Target::Fn | Target::Method(..) | Target::ForeignFn | Target::Closure => {}
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[cold]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "cold");
}
_ => {
// FIXME: #[cold] was previously allowed on non-functions and some crates used
// this, so only emit a warning.
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::Cold { span, on_crate: hir_id == CRATE_HIR_ID },
);
}
}
}
/// Checks if `#[link]` is applied to an item other than a foreign module.
fn check_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
if target == Target::ForeignMod
&& let hir::Node::Item(item) = self.tcx.hir().get(hir_id)
&& let Item { kind: ItemKind::ForeignMod { abi, .. }, .. } = item
&& !matches!(abi, Abi::Rust | Abi::RustIntrinsic | Abi::PlatformIntrinsic)
{
return;
}
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::Link { span: (target != Target::ForeignMod).then_some(span) },
);
}
/// Checks if `#[link_name]` is applied to an item other than a foreign function or static.
fn check_link_name(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
match target {
Target::ForeignFn | Target::ForeignStatic => {}
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[link_name]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_name");
}
_ => {
// FIXME: #[cold] was previously allowed on non-functions/statics and some crates
// used this, so only emit a warning.
let attr_span = matches!(target, Target::ForeignMod).then_some(attr.span);
if let Some(s) = attr.value_str() {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::LinkName { span, attr_span, value: s.as_str() },
);
} else {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::LinkName { span, attr_span, value: "..." },
);
};
}
}
}
/// Checks if `#[no_link]` is applied to an `extern crate`. Returns `true` if valid.
fn check_no_link(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::ExternCrate => true,
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[no_link]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_link");
true
}
_ => {
self.tcx.sess.emit_err(errors::NoLink { attr_span: attr.span, span });
false
}
}
}
fn is_impl_item(&self, hir_id: HirId) -> bool {
matches!(self.tcx.hir().get(hir_id), hir::Node::ImplItem(..))
}
/// Checks if `#[export_name]` is applied to a function or static. Returns `true` if valid.
fn check_export_name(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
match target {
Target::Static | Target::Fn => true,
Target::Method(..) if self.is_impl_item(hir_id) => true,
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[export_name]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "export_name");
true
}
_ => {
self.tcx.sess.emit_err(errors::ExportName { attr_span: attr.span, span });
false
}
}
}
fn check_rustc_layout_scalar_valid_range(
&self,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
if target != Target::Struct {
self.tcx.sess.emit_err(errors::RustcLayoutScalarValidRangeNotStruct {
attr_span: attr.span,
span,
});
return false;
}
let Some(list) = attr.meta_item_list() else {
return false;
};
if matches!(&list[..], &[NestedMetaItem::Lit(MetaItemLit { kind: LitKind::Int(..), .. })]) {
true
} else {
self.tcx.sess.emit_err(errors::RustcLayoutScalarValidRangeArg { attr_span: attr.span });
false
}
}
/// Checks if `#[rustc_legacy_const_generics]` is applied to a function and has a valid argument.
fn check_rustc_legacy_const_generics(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
item: Option<ItemLike<'_>>,
) -> bool {
let is_function = matches!(target, Target::Fn);
if !is_function {
self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
attr_span: attr.span,
defn_span: span,
on_crate: hir_id == CRATE_HIR_ID,
});
return false;
}
let Some(list) = attr.meta_item_list() else {
// The attribute form is validated on AST.
return false;
};
let Some(ItemLike::Item(Item {
kind: ItemKind::Fn(FnSig { decl, .. }, generics, _),
..
})) = item else {
bug!("should be a function item");
};
for param in generics.params {
match param.kind {
hir::GenericParamKind::Const { .. } => {}
_ => {
self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsOnly {
attr_span: attr.span,
param_span: param.span,
});
return false;
}
}
}
if list.len() != generics.params.len() {
self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndex {
attr_span: attr.span,
generics_span: generics.span,
});
return false;
}
let arg_count = decl.inputs.len() as u128 + generics.params.len() as u128;
let mut invalid_args = vec![];
for meta in list {
if let Some(LitKind::Int(val, _)) = meta.lit().map(|lit| &lit.kind) {
if *val >= arg_count {
let span = meta.span();
self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndexExceed {
span,
arg_count: arg_count as usize,
});
return false;
}
} else {
invalid_args.push(meta.span());
}
}
if !invalid_args.is_empty() {
self.tcx.sess.emit_err(errors::RustcLegacyConstGenericsIndexNegative { invalid_args });
false
} else {
true
}
}
/// Helper function for checking that the provided attribute is only applied to a function or
/// method.
fn check_applied_to_fn_or_method(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
let is_function = matches!(target, Target::Fn | Target::Method(..));
if !is_function {
self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToFn {
attr_span: attr.span,
defn_span: span,
on_crate: hir_id == CRATE_HIR_ID,
});
false
} else {
true
}
}
/// Checks that the `#[rustc_lint_query_instability]` attribute is only applied to a function
/// or method.
fn check_rustc_lint_query_instability(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
self.check_applied_to_fn_or_method(hir_id, attr, span, target)
}
/// Checks that the `#[rustc_lint_diagnostics]` attribute is only applied to a function or
/// method.
fn check_rustc_lint_diagnostics(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
self.check_applied_to_fn_or_method(hir_id, attr, span, target)
}
/// Checks that the `#[rustc_lint_opt_ty]` attribute is only applied to a struct.
fn check_rustc_lint_opt_ty(&self, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::Struct => true,
_ => {
self.tcx.sess.emit_err(errors::RustcLintOptTy { attr_span: attr.span, span });
false
}
}
}
/// Checks that the `#[rustc_lint_opt_deny_field_access]` attribute is only applied to a field.
fn check_rustc_lint_opt_deny_field_access(
&self,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
match target {
Target::Field => true,
_ => {
self.tcx
.sess
.emit_err(errors::RustcLintOptDenyFieldAccess { attr_span: attr.span, span });
false
}
}
}
/// Checks that the dep-graph debugging attributes are only present when the query-dep-graph
/// option is passed to the compiler.
fn check_rustc_dirty_clean(&self, attr: &Attribute) -> bool {
if self.tcx.sess.opts.unstable_opts.query_dep_graph {
true
} else {
self.tcx.sess.emit_err(errors::RustcDirtyClean { span: attr.span });
false
}
}
/// Checks if the attribute is applied to a trait.
fn check_must_be_applied_to_trait(&self, attr: &Attribute, span: Span, target: Target) -> bool {
match target {
Target::Trait => true,
_ => {
self.tcx.sess.emit_err(errors::AttrShouldBeAppliedToTrait {
attr_span: attr.span,
defn_span: span,
});
false
}
}
}
/// Checks if `#[link_section]` is applied to a function or static.
fn check_link_section(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
match target {
Target::Static | Target::Fn | Target::Method(..) => {}
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[link_section]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "link_section");
}
_ => {
// FIXME: #[link_section] was previously allowed on non-functions/statics and some
// crates used this, so only emit a warning.
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::LinkSection { span },
);
}
}
}
/// Checks if `#[no_mangle]` is applied to a function or static.
fn check_no_mangle(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) {
match target {
Target::Static | Target::Fn => {}
Target::Method(..) if self.is_impl_item(hir_id) => {}
// FIXME(#80564): We permit struct fields, match arms and macro defs to have an
// `#[no_mangle]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "no_mangle");
}
// FIXME: #[no_mangle] was previously allowed on non-functions/statics, this should be an error
// The error should specify that the item that is wrong is specifically a *foreign* fn/static
// otherwise the error seems odd
Target::ForeignFn | Target::ForeignStatic => {
let foreign_item_kind = match target {
Target::ForeignFn => "function",
Target::ForeignStatic => "static",
_ => unreachable!(),
};
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::NoMangleForeign { span, attr_span: attr.span, foreign_item_kind },
);
}
_ => {
// FIXME: #[no_mangle] was previously allowed on non-functions/statics and some
// crates used this, so only emit a warning.
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::NoMangle { span },
);
}
}
}
/// Checks if the `#[repr]` attributes on `item` are valid.
fn check_repr(
&self,
attrs: &[Attribute],
span: Span,
target: Target,
item: Option<ItemLike<'_>>,
hir_id: HirId,
) {
// Extract the names of all repr hints, e.g., [foo, bar, align] for:
// ```
// #[repr(foo)]
// #[repr(bar, align(8))]
// ```
let hints: Vec<_> = attrs
.iter()
.filter(|attr| attr.has_name(sym::repr))
.filter_map(|attr| attr.meta_item_list())
.flatten()
.collect();
let mut int_reprs = 0;
let mut is_c = false;
let mut is_simd = false;
let mut is_transparent = false;
for hint in &hints {
if !hint.is_meta_item() {
self.tcx.sess.emit_err(errors::ReprIdent { span: hint.span() });
continue;
}
match hint.name_or_empty() {
sym::C => {
is_c = true;
match target {
Target::Struct | Target::Union | Target::Enum => continue,
_ => {
self.tcx.sess.emit_err(errors::AttrApplication::StructEnumUnion {
hint_span: hint.span(),
span,
});
}
}
}
sym::align => {
if let (Target::Fn | Target::Method(MethodKind::Inherent), false) =
(target, self.tcx.features().fn_align)
{
feature_err(
&self.tcx.sess.parse_sess,
sym::fn_align,
hint.span(),
"`repr(align)` attributes on functions are unstable",
)
.emit();
}
match target {
Target::Struct
| Target::Union
| Target::Enum
| Target::Fn
| Target::Method(_) => continue,
_ => {
self.tcx.sess.emit_err(
errors::AttrApplication::StructEnumFunctionMethodUnion {
hint_span: hint.span(),
span,
},
);
}
}
}
sym::packed => {
if target != Target::Struct && target != Target::Union {
self.tcx.sess.emit_err(errors::AttrApplication::StructUnion {
hint_span: hint.span(),
span,
});
} else {
continue;
}
}
sym::simd => {
is_simd = true;
if target != Target::Struct {
self.tcx.sess.emit_err(errors::AttrApplication::Struct {
hint_span: hint.span(),
span,
});
} else {
continue;
}
}
sym::transparent => {
is_transparent = true;
match target {
Target::Struct | Target::Union | Target::Enum => continue,
_ => {
self.tcx.sess.emit_err(errors::AttrApplication::StructEnumUnion {
hint_span: hint.span(),
span,
});
}
}
}
sym::i8
| sym::u8
| sym::i16
| sym::u16
| sym::i32
| sym::u32
| sym::i64
| sym::u64
| sym::i128
| sym::u128
| sym::isize
| sym::usize => {
int_reprs += 1;
if target != Target::Enum {
self.tcx.sess.emit_err(errors::AttrApplication::Enum {
hint_span: hint.span(),
span,
});
} else {
continue;
}
}
_ => {
self.tcx.sess.emit_err(errors::UnrecognizedReprHint { span: hint.span() });
continue;
}
};
}
// Just point at all repr hints if there are any incompatibilities.
// This is not ideal, but tracking precisely which ones are at fault is a huge hassle.
let hint_spans = hints.iter().map(|hint| hint.span());
// Error on repr(transparent, <anything else>).
if is_transparent && hints.len() > 1 {
let hint_spans: Vec<_> = hint_spans.clone().collect();
self.tcx.sess.emit_err(errors::TransparentIncompatible {
hint_spans,
target: target.to_string(),
});
}
// Warn on repr(u8, u16), repr(C, simd), and c-like-enum-repr(C, u8)
if (int_reprs > 1)
|| (is_simd && is_c)
|| (int_reprs == 1
&& is_c
&& item.is_some_and(|item| {
if let ItemLike::Item(item) = item {
return is_c_like_enum(item);
}
return false;
}))
{
self.tcx.emit_spanned_lint(
CONFLICTING_REPR_HINTS,
hir_id,
hint_spans.collect::<Vec<Span>>(),
errors::ReprConflicting,
);
}
}
fn check_used(&self, attrs: &[Attribute], target: Target) {
let mut used_linker_span = None;
let mut used_compiler_span = None;
for attr in attrs.iter().filter(|attr| attr.has_name(sym::used)) {
if target != Target::Static {
self.tcx.sess.emit_err(errors::UsedStatic { span: attr.span });
}
let inner = attr.meta_item_list();
match inner.as_deref() {
Some([item]) if item.has_name(sym::linker) => {
if used_linker_span.is_none() {
used_linker_span = Some(attr.span);
}
}
Some([item]) if item.has_name(sym::compiler) => {
if used_compiler_span.is_none() {
used_compiler_span = Some(attr.span);
}
}
Some(_) => {
// This error case is handled in rustc_hir_analysis::collect.
}
None => {
// Default case (compiler) when arg isn't defined.
if used_compiler_span.is_none() {
used_compiler_span = Some(attr.span);
}
}
}
}
if let (Some(linker_span), Some(compiler_span)) = (used_linker_span, used_compiler_span) {
self.tcx
.sess
.emit_err(errors::UsedCompilerLinker { spans: vec![linker_span, compiler_span] });
}
}
/// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
/// (Allows proc_macro functions)
fn check_allow_internal_unstable(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
attrs: &[Attribute],
) -> bool {
debug!("Checking target: {:?}", target);
match target {
Target::Fn => {
for attr in attrs {
if attr.is_proc_macro_attr() {
debug!("Is proc macro attr");
return true;
}
}
debug!("Is not proc macro attr");
false
}
Target::MacroDef => true,
// FIXME(#80564): We permit struct fields and match arms to have an
// `#[allow_internal_unstable]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm => {
self.inline_attr_str_error_without_macro_def(
hir_id,
attr,
"allow_internal_unstable",
);
true
}
_ => {
self.tcx
.sess
.emit_err(errors::AllowInternalUnstable { attr_span: attr.span, span });
false
}
}
}
/// Checks if the items on the `#[debugger_visualizer]` attribute are valid.
fn check_debugger_visualizer(&self, attr: &Attribute, target: Target) -> bool {
// Here we only check that the #[debugger_visualizer] attribute is attached
// to nothing other than a module. All other checks are done in the
// `debugger_visualizer` query where they need to be done for decoding
// anyway.
match target {
Target::Mod => {}
_ => {
self.tcx.sess.emit_err(errors::DebugVisualizerPlacement { span: attr.span });
return false;
}
}
true
}
/// Outputs an error for `#[allow_internal_unstable]` which can only be applied to macros.
/// (Allows proc_macro functions)
fn check_rustc_allow_const_fn_unstable(
&self,
hir_id: HirId,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
match target {
Target::Fn | Target::Method(_)
if self.tcx.is_const_fn_raw(hir_id.expect_owner().to_def_id()) =>
{
true
}
// FIXME(#80564): We permit struct fields and match arms to have an
// `#[allow_internal_unstable]` attribute with just a lint, because we previously
// erroneously allowed it and some crates used it accidentally, to be compatible
// with crates depending on them, we can't throw an error here.
Target::Field | Target::Arm | Target::MacroDef => {
self.inline_attr_str_error_with_macro_def(hir_id, attr, "allow_internal_unstable");
true
}
_ => {
self.tcx
.sess
.emit_err(errors::RustcAllowConstFnUnstable { attr_span: attr.span, span });
false
}
}
}
fn check_rustc_std_internal_symbol(
&self,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
match target {
Target::Fn | Target::Static => true,
_ => {
self.tcx
.sess
.emit_err(errors::RustcStdInternalSymbol { attr_span: attr.span, span });
false
}
}
}
fn check_stability_promotable(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
match target {
Target::Expression => {
self.tcx.sess.emit_err(errors::StabilityPromotable { attr_span: attr.span });
false
}
_ => true,
}
}
fn check_link_ordinal(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
match target {
Target::ForeignFn | Target::ForeignStatic => true,
_ => {
self.tcx.sess.emit_err(errors::LinkOrdinal { attr_span: attr.span });
false
}
}
}
fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: Span, target: Target) {
match target {
Target::Closure | Target::Expression | Target::Statement | Target::Arm => {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::Deprecated,
);
}
_ => {}
}
}
fn check_macro_use(&self, hir_id: HirId, attr: &Attribute, target: Target) {
let name = attr.name_or_empty();
match target {
Target::ExternCrate | Target::Mod => {}
_ => {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::MacroUse { name },
);
}
}
}
fn check_macro_export(&self, hir_id: HirId, attr: &Attribute, target: Target) {
if target != Target::MacroDef {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::MacroExport::Normal,
);
} else if let Some(meta_item_list) = attr.meta_item_list() &&
!meta_item_list.is_empty() {
if meta_item_list.len() > 1 {
self.tcx.emit_spanned_lint(
INVALID_MACRO_EXPORT_ARGUMENTS,
hir_id,
attr.span,
errors::MacroExport::TooManyItems,
);
} else {
if meta_item_list[0].name_or_empty() != sym::local_inner_macros {
self.tcx.emit_spanned_lint(
INVALID_MACRO_EXPORT_ARGUMENTS,
hir_id,
meta_item_list[0].span(),
errors::MacroExport::UnknownItem {
name: meta_item_list[0].name_or_empty(),
},
);
}
}
}
}
fn check_plugin_registrar(&self, hir_id: HirId, attr: &Attribute, target: Target) {
if target != Target::Fn {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::PluginRegistrar,
);
}
}
fn check_unused_attribute(&self, hir_id: HirId, attr: &Attribute) {
// Warn on useless empty attributes.
let note = if matches!(
attr.name_or_empty(),
sym::macro_use
| sym::allow
| sym::expect
| sym::warn
| sym::deny
| sym::forbid
| sym::feature
| sym::repr
| sym::target_feature
) && attr.meta_item_list().is_some_and(|list| list.is_empty())
{
errors::UnusedNote::EmptyList { name: attr.name_or_empty() }
} else if matches!(
attr.name_or_empty(),
sym::allow | sym::warn | sym::deny | sym::forbid | sym::expect
) && let Some(meta) = attr.meta_item_list()
&& meta.len() == 1
&& let Some(item) = meta[0].meta_item()
&& let MetaItemKind::NameValue(_) = &item.kind
&& item.path == sym::reason
{
errors::UnusedNote::NoLints { name: attr.name_or_empty() }
} else if attr.name_or_empty() == sym::default_method_body_is_const {
errors::UnusedNote::DefaultMethodBodyConst
} else {
return;
};
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::Unused { attr_span: attr.span, note },
);
}
/// A best effort attempt to create an error for a mismatching proc macro signature.
///
/// If this best effort goes wrong, it will just emit a worse error later (see #102923)
fn check_proc_macro(&self, hir_id: HirId, target: Target, kind: ProcMacroKind) {
if target != Target::Fn {
return;
}
let tcx = self.tcx;
let Some(token_stream_def_id) = tcx.get_diagnostic_item(sym::TokenStream) else { return; };
let Some(token_stream) = tcx.type_of(token_stream_def_id).no_bound_vars() else { return; };
let def_id = hir_id.expect_owner().def_id;
let param_env = ty::ParamEnv::empty();
let infcx = tcx.infer_ctxt().build();
let ocx = ObligationCtxt::new(&infcx);
let span = tcx.def_span(def_id);
let fresh_substs = infcx.fresh_substs_for_item(span, def_id.to_def_id());
let sig = tcx.liberate_late_bound_regions(
def_id.to_def_id(),
tcx.fn_sig(def_id).subst(tcx, fresh_substs),
);
let mut cause = ObligationCause::misc(span, def_id);
let sig = ocx.normalize(&cause, param_env, sig);
// proc macro is not WF.
let errors = ocx.select_where_possible();
if !errors.is_empty() {
return;
}
let expected_sig = tcx.mk_fn_sig(
std::iter::repeat(token_stream).take(match kind {
ProcMacroKind::Attribute => 2,
ProcMacroKind::Derive | ProcMacroKind::FunctionLike => 1,
}),
token_stream,
false,
Unsafety::Normal,
Abi::Rust,
);
if let Err(terr) = ocx.eq(&cause, param_env, expected_sig, sig) {
let mut diag = tcx.sess.create_err(errors::ProcMacroBadSig { span, kind });
let hir_sig = tcx.hir().fn_sig_by_hir_id(hir_id);
if let Some(hir_sig) = hir_sig {
match terr {
TypeError::ArgumentMutability(idx) | TypeError::ArgumentSorts(_, idx) => {
if let Some(ty) = hir_sig.decl.inputs.get(idx) {
diag.set_span(ty.span);
cause.span = ty.span;
} else if idx == hir_sig.decl.inputs.len() {
let span = hir_sig.decl.output.span();
diag.set_span(span);
cause.span = span;
}
}
TypeError::ArgCount => {
if let Some(ty) = hir_sig.decl.inputs.get(expected_sig.inputs().len()) {
diag.set_span(ty.span);
cause.span = ty.span;
}
}
TypeError::UnsafetyMismatch(_) => {
// FIXME: Would be nice if we had a span here..
}
TypeError::AbiMismatch(_) => {
// FIXME: Would be nice if we had a span here..
}
TypeError::VariadicMismatch(_) => {
// FIXME: Would be nice if we had a span here..
}
_ => {}
}
}
infcx.err_ctxt().note_type_err(
&mut diag,
&cause,
None,
Some(ValuePairs::Sigs(ExpectedFound { expected: expected_sig, found: sig })),
terr,
false,
false,
);
diag.emit();
self.abort.set(true);
}
let errors = ocx.select_all_or_error();
if !errors.is_empty() {
infcx.err_ctxt().report_fulfillment_errors(&errors);
self.abort.set(true);
}
}
}
impl<'tcx> Visitor<'tcx> for CheckAttrVisitor<'tcx> {
type NestedFilter = nested_filter::OnlyBodies;
fn nested_visit_map(&mut self) -> Self::Map {
self.tcx.hir()
}
fn visit_item(&mut self, item: &'tcx Item<'tcx>) {
// Historically we've run more checks on non-exported than exported macros,
// so this lets us continue to run them while maintaining backwards compatibility.
// In the long run, the checks should be harmonized.
if let ItemKind::Macro(ref macro_def, _) = item.kind {
let def_id = item.owner_id.to_def_id();
if macro_def.macro_rules && !self.tcx.has_attr(def_id, sym::macro_export) {
check_non_exported_macro_for_invalid_attrs(self.tcx, item);
}
}
let target = Target::from_item(item);
self.check_attributes(item.hir_id(), item.span, target, Some(ItemLike::Item(item)));
intravisit::walk_item(self, item)
}
fn visit_generic_param(&mut self, generic_param: &'tcx hir::GenericParam<'tcx>) {
let target = Target::from_generic_param(generic_param);
self.check_attributes(generic_param.hir_id, generic_param.span, target, None);
intravisit::walk_generic_param(self, generic_param)
}
fn visit_trait_item(&mut self, trait_item: &'tcx TraitItem<'tcx>) {
let target = Target::from_trait_item(trait_item);
self.check_attributes(trait_item.hir_id(), trait_item.span, target, None);
intravisit::walk_trait_item(self, trait_item)
}
fn visit_field_def(&mut self, struct_field: &'tcx hir::FieldDef<'tcx>) {
self.check_attributes(struct_field.hir_id, struct_field.span, Target::Field, None);
intravisit::walk_field_def(self, struct_field);
}
fn visit_arm(&mut self, arm: &'tcx hir::Arm<'tcx>) {
self.check_attributes(arm.hir_id, arm.span, Target::Arm, None);
intravisit::walk_arm(self, arm);
}
fn visit_foreign_item(&mut self, f_item: &'tcx ForeignItem<'tcx>) {
let target = Target::from_foreign_item(f_item);
self.check_attributes(f_item.hir_id(), f_item.span, target, Some(ItemLike::ForeignItem));
intravisit::walk_foreign_item(self, f_item)
}
fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
let target = target_from_impl_item(self.tcx, impl_item);
self.check_attributes(impl_item.hir_id(), impl_item.span, target, None);
intravisit::walk_impl_item(self, impl_item)
}
fn visit_stmt(&mut self, stmt: &'tcx hir::Stmt<'tcx>) {
// When checking statements ignore expressions, they will be checked later.
if let hir::StmtKind::Local(ref l) = stmt.kind {
self.check_attributes(l.hir_id, stmt.span, Target::Statement, None);
}
intravisit::walk_stmt(self, stmt)
}
fn visit_expr(&mut self, expr: &'tcx hir::Expr<'tcx>) {
let target = match expr.kind {
hir::ExprKind::Closure { .. } => Target::Closure,
_ => Target::Expression,
};
self.check_attributes(expr.hir_id, expr.span, target, None);
intravisit::walk_expr(self, expr)
}
fn visit_expr_field(&mut self, field: &'tcx hir::ExprField<'tcx>) {
self.check_attributes(field.hir_id, field.span, Target::ExprField, None);
intravisit::walk_expr_field(self, field)
}
fn visit_variant(&mut self, variant: &'tcx hir::Variant<'tcx>) {
self.check_attributes(variant.hir_id, variant.span, Target::Variant, None);
intravisit::walk_variant(self, variant)
}
fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
self.check_attributes(param.hir_id, param.span, Target::Param, None);
intravisit::walk_param(self, param);
}
fn visit_pat_field(&mut self, field: &'tcx hir::PatField<'tcx>) {
self.check_attributes(field.hir_id, field.span, Target::PatField, None);
intravisit::walk_pat_field(self, field);
}
}
fn is_c_like_enum(item: &Item<'_>) -> bool {
if let ItemKind::Enum(ref def, _) = item.kind {
for variant in def.variants {
match variant.data {
hir::VariantData::Unit(..) => { /* continue */ }
_ => return false,
}
}
true
} else {
false
}
}
// FIXME: Fix "Cannot determine resolution" error and remove built-in macros
// from this check.
fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
// Check for builtin attributes at the crate level
// which were unsuccessfully resolved due to cannot determine
// resolution for the attribute macro error.
const ATTRS_TO_CHECK: &[Symbol] = &[
sym::macro_export,
sym::repr,
sym::path,
sym::automatically_derived,
sym::start,
sym::rustc_main,
sym::unix_sigpipe,
sym::derive,
sym::test,
sym::test_case,
sym::global_allocator,
sym::bench,
];
for attr in attrs {
// This function should only be called with crate attributes
// which are inner attributes always but lets check to make sure
if attr.style == AttrStyle::Inner {
for attr_to_check in ATTRS_TO_CHECK {
if attr.has_name(*attr_to_check) {
tcx.sess.emit_err(errors::InvalidAttrAtCrateLevel {
span: attr.span,
snippet: tcx.sess.source_map().span_to_snippet(attr.span).ok(),
name: *attr_to_check,
});
}
}
}
}
}
fn check_non_exported_macro_for_invalid_attrs(tcx: TyCtxt<'_>, item: &Item<'_>) {
let attrs = tcx.hir().attrs(item.hir_id());
for attr in attrs {
if attr.has_name(sym::inline) {
tcx.sess.emit_err(errors::NonExportedMacroInvalidAttrs { attr_span: attr.span });
}
}
}
fn check_mod_attrs(tcx: TyCtxt<'_>, module_def_id: LocalDefId) {
let check_attr_visitor = &mut CheckAttrVisitor { tcx, abort: Cell::new(false) };
tcx.hir().visit_item_likes_in_module(module_def_id, check_attr_visitor);
if module_def_id.is_top_level_module() {
check_attr_visitor.check_attributes(CRATE_HIR_ID, DUMMY_SP, Target::Mod, None);
check_invalid_crate_level_attr(tcx, tcx.hir().krate_attrs());
}
if check_attr_visitor.abort.get() {
tcx.sess.abort_if_errors()
}
}
pub(crate) fn provide(providers: &mut Providers) {
*providers = Providers { check_mod_attrs, ..*providers };
}
fn check_duplicates(
tcx: TyCtxt<'_>,
attr: &Attribute,
hir_id: HirId,
duplicates: AttributeDuplicates,
seen: &mut FxHashMap<Symbol, Span>,
) {
use AttributeDuplicates::*;
if matches!(duplicates, WarnFollowingWordOnly) && !attr.is_word() {
return;
}
match duplicates {
DuplicatesOk => {}
WarnFollowing | FutureWarnFollowing | WarnFollowingWordOnly | FutureWarnPreceding => {
match seen.entry(attr.name_or_empty()) {
Entry::Occupied(mut entry) => {
let (this, other) = if matches!(duplicates, FutureWarnPreceding) {
let to_remove = entry.insert(attr.span);
(to_remove, attr.span)
} else {
(attr.span, *entry.get())
};
tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
this,
errors::UnusedDuplicate {
this,
other,
warning: matches!(
duplicates,
FutureWarnFollowing | FutureWarnPreceding
)
.then_some(()),
},
);
}
Entry::Vacant(entry) => {
entry.insert(attr.span);
}
}
}
ErrorFollowing | ErrorPreceding => match seen.entry(attr.name_or_empty()) {
Entry::Occupied(mut entry) => {
let (this, other) = if matches!(duplicates, ErrorPreceding) {
let to_remove = entry.insert(attr.span);
(to_remove, attr.span)
} else {
(attr.span, *entry.get())
};
tcx.sess.emit_err(errors::UnusedMultiple {
this,
other,
name: attr.name_or_empty(),
});
}
Entry::Vacant(entry) => {
entry.insert(attr.span);
}
},
}
}
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