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rust/compiler/rustc_passes/src/check_attr.rs
David Wood 7bab769b58 lint: add bad opt access internal lint 
Some command-line options accessible through `sess.opts` are best
accessed through wrapper functions on `Session`, `TyCtxt` or otherwise,
rather than through field access on the option struct in the `Session`.

Adds a new lint which triggers on those options that should be accessed
through a wrapper function so that this is prohibited. Options are
annotated with a new attribute `rustc_lint_opt_deny_field_access` which
can specify the error message (i.e. "use this other function instead")
to be emitted.

A simpler alternative would be to simply rename the options in the
option type so that it is clear they should not be used, however this
doesn't prevent uses, just discourages them. Another alternative would
be to make the option fields private, and adding accessor functions on
the option types, however the wrapper functions sometimes rely on
additional state from `Session` or `TyCtxt` which wouldn't be available
in an function on the option type, so the accessor would simply make the
field available and its use would be discouraged too.

Signed-off-by: David Wood <david.wood@huawei.com>
2022-07-27 11:24:27 +01:00

2198 lines
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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;
use rustc_ast::{ast, AttrStyle, Attribute, Lit, LitKind, MetaItemKind, NestedMetaItem};
use rustc_data_structures::fx::FxHashMap;
use rustc_errors::{fluent, struct_span_err, Applicability, MultiSpan};
use rustc_expand::base::resolve_path;
use rustc_feature::{AttributeDuplicates, AttributeType, BuiltinAttribute, BUILTIN_ATTRIBUTE_MAP};
use rustc_hir as hir;
use rustc_hir::def_id::{LocalDefId, CRATE_DEF_ID};
use rustc_hir::intravisit::{self, Visitor};
use rustc_hir::{self, FnSig, ForeignItem, HirId, Item, ItemKind, TraitItem, CRATE_HIR_ID};
use rustc_hir::{MethodKind, Target};
use rustc_middle::hir::nested_filter;
use rustc_middle::ty::query::Providers;
use rustc_middle::ty::TyCtxt;
use rustc_session::lint::builtin::{
CONFLICTING_REPR_HINTS, INVALID_DOC_ATTRIBUTES, UNUSED_ATTRIBUTES,
};
use rustc_session::parse::feature_err;
use rustc_span::symbol::{kw, sym, Symbol};
use rustc_span::{Span, DUMMY_SP};
use rustc_target::spec::abi::Abi;
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_hir_id = tcx.hir().get_parent_item(impl_item.hir_id());
let containing_item = tcx.hir().expect_item(parent_hir_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::TyAlias(..) => Target::AssocTy,
}
}
#[derive(Clone, Copy)]
enum ItemLike<'tcx> {
Item(&'tcx Item<'tcx>),
ForeignItem(&'tcx ForeignItem<'tcx>),
}
struct CheckAttrVisitor<'tcx> {
tcx: TyCtxt<'tcx>,
}
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 is_valid = true;
let mut specified_inline = None;
let mut seen = FxHashMap::default();
let attrs = self.tcx.hir().attrs(hir_id);
for attr in attrs {
let attr_is_valid = match attr.name_or_empty() {
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::rustc_must_implement_one_of => {
self.check_rustc_must_implement_one_of(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(&attr, span, target, item)
}
sym::rustc_lint_query_instability => {
self.check_rustc_lint_query_instability(&attr, span, target)
}
sym::rustc_lint_diagnostics => {
self.check_rustc_lint_diagnostics(&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::cmse_nonsecure_entry => self.check_cmse_nonsecure_entry(attr, span, target),
sym::const_trait => self.check_const_trait(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, span, 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::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),
_ => true,
};
is_valid &= attr_is_valid;
// 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 | sym::proc_macro_derive => {
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])
}
_ => {}
}
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)
}
if !is_valid {
return;
}
// FIXME(@lcnr): this doesn't belong here.
if matches!(target, Target::Closure | Target::Fn | Target::Method(_) | Target::ForeignFn) {
self.tcx.ensure().codegen_fn_attrs(self.tcx.hir().local_def_id(hir_id));
}
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 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 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_targets: &[Target],
) {
if !allowed_targets.iter().any(|t| t == &target) {
let name = attr.name_or_empty();
let mut i = allowed_targets.iter();
// Pluralize
let b = i.next().map_or_else(String::new, |t| t.to_string() + "s");
let supported_names = i.enumerate().fold(b, |mut b, (i, allowed_target)| {
if allowed_targets.len() > 2 && i == allowed_targets.len() - 2 {
b.push_str(", and ");
} else if allowed_targets.len() == 2 && i == allowed_targets.len() - 2 {
b.push_str(" and ");
} else {
b.push_str(", ");
}
// Pluralize
b.push_str(&(allowed_target.to_string() + "s"));
b
});
self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
lint.build(&format!("`#[{name}]` only has an effect on {}", supported_names))
.emit();
});
}
}
/// 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 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,
});
false
}
}
}
/// Checks if `#[cmse_nonsecure_entry]` is applied to a function definition.
fn check_cmse_nonsecure_entry(&self, 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,
});
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 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 });
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 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 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 `#[rustc_must_implement_one_of]` attribute on a `target` is valid. Returns `true` if valid.
fn check_rustc_must_implement_one_of(
&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 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 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,
});
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::Impl => Some("implementation block"),
Target::ForeignMod => Some("extern block"),
Target::AssocTy => {
let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
let containing_item = self.tcx.hir().expect_item(parent_hir_id);
if Target::from_item(containing_item) == Target::Impl {
Some("type alias in implementation block")
} else {
None
}
}
Target::AssocConst => {
let parent_hir_id = self.tcx.hir().get_parent_item(hir_id);
let containing_item = self.tcx.hir().expect_item(parent_hir_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,
_ => 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.literal() {
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 {
if target == Target::Use || target == 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
}
} else {
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 {
self.tcx.struct_span_lint_hir(INVALID_DOC_ATTRIBUTES, hir_id, meta.span(), |lint| {
let mut err = lint.build(fluent::passes::attr_crate_level);
if attr.style == AttrStyle::Outer
&& self.tcx.hir().get_parent_item(hir_id) == CRATE_DEF_ID
{
if let Ok(mut src) = self.tcx.sess.source_map().span_to_snippet(attr.span) {
src.insert(1, '!');
err.span_suggestion_verbose(
attr.span,
fluent::passes::suggestion,
src,
Applicability::MaybeIncorrect,
);
} else {
err.span_help(attr.span, fluent::passes::help);
}
}
err.note(fluent::passes::note).emit();
});
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() {
sym::attr | sym::no_crate_inject => {}
_ => {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
i_meta.span(),
errors::DocTestUnknown {
path: rustc_ast_pretty::pprust::path_to_string(
&i_meta.meta_item().unwrap().path,
),
},
);
is_valid = false;
}
}
}
} else {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
meta.span(),
errors::DocTestTakesList,
);
is_valid = false;
}
is_valid
}
/// 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::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;
}
}
sym::primitive => {
if !self.tcx.features().rustdoc_internals {
self.tcx.emit_spanned_lint(
INVALID_DOC_ATTRIBUTES,
hir_id,
i_meta.span,
errors::DocPrimitive,
);
}
}
_ => {
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: (attr.style == AttrStyle::Inner)
.then_some("!")
.unwrap_or(""),
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
}
}
}
/// Warns against some misuses of `#[must_use]`
fn check_must_use(&self, hir_id: HirId, attr: &Attribute, span: Span, target: Target) -> bool {
let node = self.tcx.hir().get(hir_id);
if let Some(kind) = node.fn_kind() && let rustc_hir::IsAsync::Async = kind.asyncness() {
self.tcx.emit_spanned_lint(
UNUSED_ATTRIBUTES,
hir_id,
attr.span,
errors::MustUseAsync { span }
);
}
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 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 },
);
}
}
}
/// 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 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 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 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::Literal(Lit { 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,
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,
});
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.literal().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, 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,
});
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,
attr: &Attribute,
span: Span,
target: Target,
) -> bool {
self.check_applied_to_fn_or_method(attr, span, target)
}
/// Checks that the `#[rustc_lint_diagnostics]` attribute is only applied to a function or
/// method.
fn check_rustc_lint_diagnostics(&self, attr: &Attribute, span: Span, target: Target) -> bool {
self.check_applied_to_fn_or_method(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 `#[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 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 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;
}
let (article, allowed_targets) = match hint.name_or_empty() {
sym::C => {
is_c = true;
match target {
Target::Struct | Target::Union | Target::Enum => continue,
_ => ("a", "struct, enum, or union"),
}
}
sym::align => {
if let (Target::Fn, 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 => continue,
_ => ("a", "struct, enum, function, or union"),
}
}
sym::packed => {
if target != Target::Struct && target != Target::Union {
("a", "struct or union")
} else {
continue;
}
}
sym::simd => {
is_simd = true;
if target != Target::Struct {
("a", "struct")
} else {
continue;
}
}
sym::transparent => {
is_transparent = true;
match target {
Target::Struct | Target::Union | Target::Enum => continue,
_ => ("a", "struct, enum, or union"),
}
}
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 {
("an", "enum")
} else {
continue;
}
}
_ => {
struct_span_err!(
self.tcx.sess,
hint.span(),
E0552,
"unrecognized representation hint"
)
.emit();
continue;
}
};
struct_span_err!(
self.tcx.sess,
hint.span(),
E0517,
"{}",
&format!("attribute should be applied to {article} {allowed_targets}")
)
.span_label(span, &format!("not {article} {allowed_targets}"))
.emit();
}
// 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();
struct_span_err!(
self.tcx.sess,
hint_spans,
E0692,
"transparent {} cannot have other repr hints",
target
)
.emit();
}
// 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.map_or(false, |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_typeck::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 self.tcx.sess.is_proc_macro_attr(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 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 {
match target {
Target::Mod => {}
_ => {
self.tcx.sess.emit_err(errors::DebugVisualizerPlacement { span: attr.span });
return false;
}
}
let Some(hints) = attr.meta_item_list() else {
self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
return false;
};
let hint = match hints.len() {
1 => &hints[0],
_ => {
self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
return false;
}
};
let Some(meta_item) = hint.meta_item() else {
self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: attr.span });
return false;
};
let visualizer_path = match (meta_item.name_or_empty(), meta_item.value_str()) {
(sym::natvis_file, Some(value)) => value,
(sym::gdb_script_file, Some(value)) => value,
(_, _) => {
self.tcx.sess.emit_err(errors::DebugVisualizerInvalid { span: meta_item.span });
return false;
}
};
let file =
match resolve_path(&self.tcx.sess.parse_sess, visualizer_path.as_str(), attr.span) {
Ok(file) => file,
Err(mut err) => {
err.emit();
return false;
}
};
match std::fs::File::open(&file) {
Ok(_) => true,
Err(err) => {
self.tcx
.sess
.struct_span_err(
meta_item.span,
&format!("couldn't read {}: {}", file.display(), err),
)
.emit();
false
}
}
}
/// 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(self.tcx.hir().local_def_id(hir_id).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 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
}
}
}
/// `#[const_trait]` only applies to traits.
fn check_const_trait(&self, attr: &Attribute, _span: Span, target: Target) -> bool {
match target {
Target::Trait => true,
_ => {
self.tcx.sess.emit_err(errors::ConstTrait { attr_span: attr.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_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);
}
}
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().map_or(false, |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 },
);
}
}
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.def_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(f_item)),
);
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_variant(
&mut self,
variant: &'tcx hir::Variant<'tcx>,
generics: &'tcx hir::Generics<'tcx>,
item_id: HirId,
) {
self.check_attributes(variant.id, variant.span, Target::Variant, None);
intravisit::walk_variant(self, variant, generics, item_id)
}
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 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::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) {
let mut err = tcx.sess.struct_span_err(
attr.span,
&format!(
"`{}` attribute cannot be used at crate level",
attr_to_check.to_ident_string()
),
);
// Only emit an error with a suggestion if we can create a
// string out of the attribute span
if let Ok(src) = tcx.sess.source_map().span_to_snippet(attr.span) {
let replacement = src.replace("#!", "#");
err.span_suggestion_verbose(
attr.span,
"perhaps you meant to use an outer attribute",
replacement,
rustc_errors::Applicability::MachineApplicable,
);
}
err.emit();
}
}
}
}
}
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 };
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());
}
}
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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