Remove Session.used_attrs and move logic to CheckAttrVisitor
Instead of updating global state to mark attributes as used, we now explicitly emit a warning when an attribute is used in an unsupported position. As a side effect, we are to emit more detailed warning messages (instead of just a generic "unused" message). `Session.check_name` is removed, since its only purpose was to mark the attribute as used. All of the callers are modified to use `Attribute.has_name` Additionally, `AttributeType::AssumedUsed` is removed - an 'assumed used' attribute is implemented by simply not performing any checks in `CheckAttrVisitor` for a particular attribute. We no longer emit unused attribute warnings for the `#[rustc_dummy]` attribute - it's an internal attribute used for tests, so it doesn't mark sense to treat it as 'unused'. With this commit, a large source of global untracked state is removed.
This commit is contained in:
Aaron Hill
parent
b6e334d873
commit
af46699f81
62 changed files with 535 additions and 739 deletions
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@ -8,8 +8,10 @@ use rustc_middle::hir::map::Map;
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use rustc_middle::ty::query::Providers;
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use rustc_middle::ty::TyCtxt;
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use rustc_ast::{AttrStyle, Attribute, Lit, LitKind, NestedMetaItem};
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use rustc_ast::{ast, AttrStyle, Attribute, Lit, LitKind, NestedMetaItem};
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use rustc_data_structures::stable_set::FxHashSet;
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use rustc_errors::{pluralize, struct_span_err, Applicability};
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use rustc_feature::{AttributeType, BUILTIN_ATTRIBUTE_MAP};
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use rustc_hir as hir;
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use rustc_hir::def_id::LocalDefId;
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use rustc_hir::intravisit::{self, NestedVisitorMap, Visitor};
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@ -66,9 +68,10 @@ impl CheckAttrVisitor<'tcx> {
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) {
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let mut is_valid = true;
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let mut specified_inline = None;
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let mut seen = FxHashSet::default();
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let attrs = self.tcx.hir().attrs(hir_id);
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for attr in attrs {
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is_valid &= match attr.name_or_empty() {
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let attr_is_valid = match attr.name_or_empty() {
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sym::inline => self.check_inline(hir_id, attr, span, target),
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sym::non_exhaustive => self.check_non_exhaustive(hir_id, attr, span, target),
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sym::marker => self.check_marker(hir_id, attr, span, target),
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@ -101,14 +104,66 @@ impl CheckAttrVisitor<'tcx> {
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sym::default_method_body_is_const => {
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self.check_default_method_body_is_const(attr, span, target)
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}
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sym::rustc_const_unstable
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| sym::rustc_const_stable
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| sym::unstable
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| sym::stable
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| sym::rustc_promotable => self.check_stability_promotable(&attr, span, target),
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_ => true,
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};
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is_valid &= attr_is_valid;
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// lint-only checks
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match attr.name_or_empty() {
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sym::cold => self.check_cold(hir_id, attr, span, target),
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sym::link_name => self.check_link_name(hir_id, attr, span, target),
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sym::link_section => self.check_link_section(hir_id, attr, span, target),
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sym::no_mangle => self.check_no_mangle(hir_id, attr, span, target),
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sym::deprecated | sym::rustc_deprecated => {
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self.check_deprecated(hir_id, attr, span, target)
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}
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sym::macro_use | sym::macro_escape => self.check_macro_use(hir_id, attr, target),
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sym::path => self.check_generic_attr(hir_id, attr, target, &[Target::Mod]),
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sym::cfg_attr => self.check_cfg_attr(hir_id, attr),
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sym::plugin_registrar => self.check_plugin_registrar(hir_id, attr, target),
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sym::macro_export => self.check_macro_export(hir_id, attr, target),
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sym::ignore | sym::should_panic | sym::proc_macro_derive => {
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self.check_generic_attr(hir_id, attr, target, &[Target::Fn])
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}
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_ => {}
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}
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if hir_id != CRATE_HIR_ID {
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if let Some((_, AttributeType::CrateLevel, ..)) =
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attr.ident().and_then(|ident| BUILTIN_ATTRIBUTE_MAP.get(&ident.name))
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{
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self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
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let msg = match attr.style {
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ast::AttrStyle::Outer => {
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"crate-level attribute should be an inner attribute: add an exclamation \
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mark: `#![foo]`"
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}
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ast::AttrStyle::Inner => "crate-level attribute should be in the root module",
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};
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lint.build(msg).emit()
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});
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}
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}
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// Duplicate attributes
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match attr.name_or_empty() {
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name @ sym::macro_use => {
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let args = attr.meta_item_list().unwrap_or_else(Vec::new);
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let args: Vec<_> = args.iter().map(|arg| arg.name_or_empty()).collect();
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if !seen.insert((name, args)) {
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self.tcx.struct_span_lint_hir(
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UNUSED_ATTRIBUTES,
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hir_id,
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attr.span,
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|lint| lint.build("unused attribute").emit(),
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);
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}
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}
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_ => {}
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}
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}
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@ -211,6 +266,38 @@ impl CheckAttrVisitor<'tcx> {
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}
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}
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fn check_generic_attr(
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&self,
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hir_id: HirId,
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attr: &Attribute,
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target: Target,
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allowed_targets: &[Target],
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) {
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if !allowed_targets.iter().any(|t| t == &target) {
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let name = attr.name_or_empty();
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let mut i = allowed_targets.iter();
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// Pluralize
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let b = i.next().map_or_else(String::new, |t| t.to_string() + "s");
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let supported_names = i.enumerate().fold(b, |mut b, (i, allowed_target)| {
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if allowed_targets.len() > 2 && i == allowed_targets.len() - 2 {
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b.push_str(", and ");
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} else if allowed_targets.len() == 2 && i == allowed_targets.len() - 2 {
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b.push_str(" and ");
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} else {
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b.push_str(", ");
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}
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// Pluralize
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b.push_str(&(allowed_target.to_string() + "s"));
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b
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});
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//let supported_names = allowed_targets.iter().fold(String::new(), |msg, t| msg + ", " + &t.to_string());
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self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
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lint.build(&format!("`#[{name}]` only has an effect on {}", supported_names))
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.emit();
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});
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}
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}
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/// Checks if `#[naked]` is applied to a function definition.
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fn check_naked(&self, hir_id: HirId, attr: &Attribute, span: &Span, target: Target) -> bool {
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match target {
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@ -1555,6 +1642,72 @@ impl CheckAttrVisitor<'tcx> {
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}
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}
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}
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fn check_stability_promotable(&self, attr: &Attribute, _span: &Span, target: Target) -> bool {
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match target {
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Target::Expression => {
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self.tcx
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.sess
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.struct_span_err(attr.span, "attribute cannot be applied to an expression")
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.emit();
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false
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}
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_ => true,
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}
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}
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fn check_deprecated(&self, hir_id: HirId, attr: &Attribute, _span: &Span, target: Target) {
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match target {
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Target::Closure | Target::Expression | Target::Statement | Target::Arm => {
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self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
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lint.build("attribute is ignored here").emit();
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});
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}
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_ => {}
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}
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}
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fn check_macro_use(&self, hir_id: HirId, attr: &Attribute, target: Target) {
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let name = attr.name_or_empty();
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match target {
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Target::ExternCrate | Target::Mod => {}
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_ => {
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self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
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lint.build(&format!(
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"`#[{name}]` only has an effect on `extern crate` and modules"
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))
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.emit();
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});
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}
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}
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}
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fn check_macro_export(&self, hir_id: HirId, attr: &Attribute, target: Target) {
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if target != Target::MacroDef {
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self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
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lint.build(&format!("`#[macro_export]` only has an effect on macro definitions"))
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.emit();
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});
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}
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}
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fn check_cfg_attr(&self, hir_id: HirId, attr: &Attribute) {
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if let Some((_, attrs)) = rustc_parse::parse_cfg_attr(&attr, &self.tcx.sess.parse_sess) {
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if attrs.is_empty() {
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self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
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lint.build("`#[cfg_attr]` does not expand to any attributes").emit();
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});
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}
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}
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}
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fn check_plugin_registrar(&self, hir_id: HirId, attr: &Attribute, target: Target) {
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if target != Target::Fn {
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self.tcx.struct_span_lint_hir(UNUSED_ATTRIBUTES, hir_id, attr.span, |lint| {
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lint.build("`#[plugin_registrar]` only has an effect on functions").emit();
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});
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}
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}
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}
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impl Visitor<'tcx> for CheckAttrVisitor<'tcx> {
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@ -1675,7 +1828,7 @@ fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
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for attr in attrs {
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for attr_to_check in ATTRS_TO_CHECK {
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if tcx.sess.check_name(attr, *attr_to_check) {
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if attr.has_name(*attr_to_check) {
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tcx.sess
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.struct_span_err(
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attr.span,
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@ -1692,7 +1845,7 @@ fn check_invalid_crate_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
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fn check_invalid_macro_level_attr(tcx: TyCtxt<'_>, attrs: &[Attribute]) {
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for attr in attrs {
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if tcx.sess.check_name(attr, sym::inline) {
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if attr.has_name(sym::inline) {
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struct_span_err!(
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tcx.sess,
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attr.span,
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