ac384ac2db
When the 'early' and 'late' visitors visit an attribute target, they
activate any lint attributes (e.g. `#[allow]`) that apply to it.
This can affect warnings emitted on sibiling attributes. For example,
the following code does not produce an `unused_attributes` for
`#[inline]`, since the sibiling `#[allow(unused_attributes)]` suppressed
the warning.
```rust
trait Foo {
#[allow(unused_attributes)] #[inline] fn first();
#[inline] #[allow(unused_attributes)] fn second();
}
```
However, we do not do this for statements - instead, the lint attributes
only become active when we visit the struct nested inside `StmtKind`
(e.g. `Item`).
Currently, this is difficult to observe due to another issue - the
`HasAttrs` impl for `StmtKind` ignores attributes for `StmtKind::Item`.
As a result, the `unused_doc_comments` lint will never see attributes on
item statements.
This commit makes two interrelated fixes to the handling of inert
(non-proc-macro) attributes on statements:
* The `HasAttr` impl for `StmtKind` now returns attributes for
`StmtKind::Item`, treating it just like every other `StmtKind`
variant. The only place relying on the old behavior was macro
which has been updated to explicitly ignore attributes on item
statements. This allows the `unused_doc_comments` lint to fire for
item statements.
* The `early` and `late` lint visitors now activate lint attributes when
invoking the callback for `Stmt`. This ensures that a lint
attribute (e.g. `#[allow(unused_doc_comments)]`) can be applied to
sibiling attributes on an item statement.
For now, the `unused_doc_comments` lint is explicitly disabled on item
statements, which preserves the current behavior. The exact locatiosn
where this lint should fire are being discussed in PR #78306
501 lines
17 KiB
Rust
501 lines
17 KiB
Rust
//! Implementation of lint checking.
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//!
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//! The lint checking is mostly consolidated into one pass which runs
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//! after all other analyses. Throughout compilation, lint warnings
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//! can be added via the `add_lint` method on the Session structure. This
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//! requires a span and an ID of the node that the lint is being added to. The
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//! lint isn't actually emitted at that time because it is unknown what the
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//! actual lint level at that location is.
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//!
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//! To actually emit lint warnings/errors, a separate pass is used.
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//! A context keeps track of the current state of all lint levels.
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//! Upon entering a node of the ast which can modify the lint settings, the
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//! previous lint state is pushed onto a stack and the ast is then recursed
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//! upon. As the ast is traversed, this keeps track of the current lint level
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//! for all lint attributes.
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use crate::{passes::LateLintPassObject, LateContext, LateLintPass, LintStore};
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use rustc_ast as ast;
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use rustc_ast::walk_list;
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use rustc_data_structures::sync::{join, par_iter, ParallelIterator};
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use rustc_hir as hir;
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use rustc_hir::def_id::{LocalDefId, LOCAL_CRATE};
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use rustc_hir::intravisit as hir_visit;
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use rustc_hir::intravisit::Visitor;
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use rustc_middle::hir::map::Map;
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use rustc_middle::ty::{self, TyCtxt};
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use rustc_session::lint::LintPass;
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use rustc_span::symbol::Symbol;
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use rustc_span::Span;
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use std::any::Any;
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use std::cell::Cell;
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use std::slice;
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use tracing::debug;
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/// Extract the `LintStore` from the query context.
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/// This function exists because we've erased `LintStore` as `dyn Any` in the context.
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crate fn unerased_lint_store(tcx: TyCtxt<'_>) -> &LintStore {
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let store: &dyn Any = &*tcx.lint_store;
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store.downcast_ref().unwrap()
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}
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macro_rules! lint_callback { ($cx:expr, $f:ident, $($args:expr),*) => ({
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$cx.pass.$f(&$cx.context, $($args),*);
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}) }
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struct LateContextAndPass<'tcx, T: LateLintPass<'tcx>> {
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context: LateContext<'tcx>,
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pass: T,
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}
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impl<'tcx, T: LateLintPass<'tcx>> LateContextAndPass<'tcx, T> {
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/// Merge the lints specified by any lint attributes into the
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/// current lint context, call the provided function, then reset the
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/// lints in effect to their previous state.
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fn with_lint_attrs<F>(&mut self, id: hir::HirId, attrs: &'tcx [ast::Attribute], f: F)
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where
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F: FnOnce(&mut Self),
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{
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let prev = self.context.last_node_with_lint_attrs;
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self.context.last_node_with_lint_attrs = id;
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self.enter_attrs(attrs);
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f(self);
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self.exit_attrs(attrs);
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self.context.last_node_with_lint_attrs = prev;
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}
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fn with_param_env<F>(&mut self, id: hir::HirId, f: F)
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where
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F: FnOnce(&mut Self),
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{
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let old_param_env = self.context.param_env;
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self.context.param_env =
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self.context.tcx.param_env(self.context.tcx.hir().local_def_id(id));
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f(self);
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self.context.param_env = old_param_env;
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}
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fn process_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
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lint_callback!(self, check_mod, m, s, n);
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hir_visit::walk_mod(self, m, n);
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lint_callback!(self, check_mod_post, m, s, n);
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}
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fn enter_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
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debug!("late context: enter_attrs({:?})", attrs);
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lint_callback!(self, enter_lint_attrs, attrs);
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}
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fn exit_attrs(&mut self, attrs: &'tcx [ast::Attribute]) {
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debug!("late context: exit_attrs({:?})", attrs);
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lint_callback!(self, exit_lint_attrs, attrs);
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}
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}
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impl<'tcx, T: LateLintPass<'tcx>> hir_visit::Visitor<'tcx> for LateContextAndPass<'tcx, T> {
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type Map = Map<'tcx>;
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/// Because lints are scoped lexically, we want to walk nested
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/// items in the context of the outer item, so enable
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/// deep-walking.
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fn nested_visit_map(&mut self) -> hir_visit::NestedVisitorMap<Self::Map> {
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hir_visit::NestedVisitorMap::All(self.context.tcx.hir())
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}
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fn visit_nested_body(&mut self, body_id: hir::BodyId) {
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let old_enclosing_body = self.context.enclosing_body.replace(body_id);
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let old_cached_typeck_results = self.context.cached_typeck_results.get();
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// HACK(eddyb) avoid trashing `cached_typeck_results` when we're
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// nested in `visit_fn`, which may have already resulted in them
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// being queried.
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if old_enclosing_body != Some(body_id) {
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self.context.cached_typeck_results.set(None);
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}
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let body = self.context.tcx.hir().body(body_id);
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self.visit_body(body);
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self.context.enclosing_body = old_enclosing_body;
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// See HACK comment above.
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if old_enclosing_body != Some(body_id) {
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self.context.cached_typeck_results.set(old_cached_typeck_results);
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}
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}
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fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) {
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self.with_lint_attrs(param.hir_id, ¶m.attrs, |cx| {
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lint_callback!(cx, check_param, param);
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hir_visit::walk_param(cx, param);
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});
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}
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fn visit_body(&mut self, body: &'tcx hir::Body<'tcx>) {
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lint_callback!(self, check_body, body);
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hir_visit::walk_body(self, body);
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lint_callback!(self, check_body_post, body);
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}
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fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) {
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let generics = self.context.generics.take();
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self.context.generics = it.kind.generics();
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self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
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cx.with_param_env(it.hir_id, |cx| {
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lint_callback!(cx, check_item, it);
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hir_visit::walk_item(cx, it);
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lint_callback!(cx, check_item_post, it);
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});
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});
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self.context.generics = generics;
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}
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fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) {
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self.with_lint_attrs(it.hir_id, &it.attrs, |cx| {
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cx.with_param_env(it.hir_id, |cx| {
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lint_callback!(cx, check_foreign_item, it);
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hir_visit::walk_foreign_item(cx, it);
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lint_callback!(cx, check_foreign_item_post, it);
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});
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})
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}
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fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) {
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lint_callback!(self, check_pat, p);
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hir_visit::walk_pat(self, p);
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}
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fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) {
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self.with_lint_attrs(e.hir_id, &e.attrs, |cx| {
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lint_callback!(cx, check_expr, e);
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hir_visit::walk_expr(cx, e);
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lint_callback!(cx, check_expr_post, e);
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})
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}
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fn visit_stmt(&mut self, s: &'tcx hir::Stmt<'tcx>) {
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let get_item = |id: hir::ItemId| self.context.tcx.hir().item(id.id);
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let attrs = &s.kind.attrs(get_item);
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// See `EarlyContextAndPass::visit_stmt` for an explanation
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// of why we call `walk_stmt` outside of `with_lint_attrs`
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self.with_lint_attrs(s.hir_id, attrs, |cx| {
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lint_callback!(cx, check_stmt, s);
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});
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hir_visit::walk_stmt(self, s);
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}
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fn visit_fn(
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&mut self,
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fk: hir_visit::FnKind<'tcx>,
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decl: &'tcx hir::FnDecl<'tcx>,
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body_id: hir::BodyId,
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span: Span,
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id: hir::HirId,
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) {
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// Wrap in typeck results here, not just in visit_nested_body,
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// in order for `check_fn` to be able to use them.
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let old_enclosing_body = self.context.enclosing_body.replace(body_id);
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let old_cached_typeck_results = self.context.cached_typeck_results.take();
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let body = self.context.tcx.hir().body(body_id);
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lint_callback!(self, check_fn, fk, decl, body, span, id);
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hir_visit::walk_fn(self, fk, decl, body_id, span, id);
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lint_callback!(self, check_fn_post, fk, decl, body, span, id);
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self.context.enclosing_body = old_enclosing_body;
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self.context.cached_typeck_results.set(old_cached_typeck_results);
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}
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fn visit_variant_data(
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&mut self,
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s: &'tcx hir::VariantData<'tcx>,
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_: Symbol,
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_: &'tcx hir::Generics<'tcx>,
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_: hir::HirId,
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_: Span,
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) {
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lint_callback!(self, check_struct_def, s);
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hir_visit::walk_struct_def(self, s);
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lint_callback!(self, check_struct_def_post, s);
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}
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fn visit_struct_field(&mut self, s: &'tcx hir::StructField<'tcx>) {
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self.with_lint_attrs(s.hir_id, &s.attrs, |cx| {
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lint_callback!(cx, check_struct_field, s);
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hir_visit::walk_struct_field(cx, s);
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})
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}
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fn visit_variant(
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&mut self,
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v: &'tcx hir::Variant<'tcx>,
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g: &'tcx hir::Generics<'tcx>,
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item_id: hir::HirId,
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) {
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self.with_lint_attrs(v.id, &v.attrs, |cx| {
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lint_callback!(cx, check_variant, v);
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hir_visit::walk_variant(cx, v, g, item_id);
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lint_callback!(cx, check_variant_post, v);
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})
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}
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fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) {
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lint_callback!(self, check_ty, t);
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hir_visit::walk_ty(self, t);
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}
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fn visit_name(&mut self, sp: Span, name: Symbol) {
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lint_callback!(self, check_name, sp, name);
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}
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fn visit_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) {
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if !self.context.only_module {
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self.process_mod(m, s, n);
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}
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}
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fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) {
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self.with_lint_attrs(l.hir_id, &l.attrs, |cx| {
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lint_callback!(cx, check_local, l);
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hir_visit::walk_local(cx, l);
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})
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}
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fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) {
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lint_callback!(self, check_block, b);
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hir_visit::walk_block(self, b);
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lint_callback!(self, check_block_post, b);
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}
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fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) {
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lint_callback!(self, check_arm, a);
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hir_visit::walk_arm(self, a);
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}
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fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) {
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lint_callback!(self, check_generic_param, p);
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hir_visit::walk_generic_param(self, p);
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}
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fn visit_generics(&mut self, g: &'tcx hir::Generics<'tcx>) {
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lint_callback!(self, check_generics, g);
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hir_visit::walk_generics(self, g);
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}
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fn visit_where_predicate(&mut self, p: &'tcx hir::WherePredicate<'tcx>) {
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lint_callback!(self, check_where_predicate, p);
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hir_visit::walk_where_predicate(self, p);
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}
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fn visit_poly_trait_ref(
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&mut self,
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t: &'tcx hir::PolyTraitRef<'tcx>,
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m: hir::TraitBoundModifier,
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) {
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lint_callback!(self, check_poly_trait_ref, t, m);
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hir_visit::walk_poly_trait_ref(self, t, m);
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}
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fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) {
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let generics = self.context.generics.take();
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self.context.generics = Some(&trait_item.generics);
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self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |cx| {
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cx.with_param_env(trait_item.hir_id, |cx| {
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lint_callback!(cx, check_trait_item, trait_item);
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hir_visit::walk_trait_item(cx, trait_item);
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lint_callback!(cx, check_trait_item_post, trait_item);
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});
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});
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self.context.generics = generics;
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}
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fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) {
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let generics = self.context.generics.take();
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self.context.generics = Some(&impl_item.generics);
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self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |cx| {
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cx.with_param_env(impl_item.hir_id, |cx| {
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lint_callback!(cx, check_impl_item, impl_item);
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hir_visit::walk_impl_item(cx, impl_item);
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lint_callback!(cx, check_impl_item_post, impl_item);
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});
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});
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self.context.generics = generics;
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}
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fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) {
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lint_callback!(self, check_lifetime, lt);
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hir_visit::walk_lifetime(self, lt);
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}
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fn visit_path(&mut self, p: &'tcx hir::Path<'tcx>, id: hir::HirId) {
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lint_callback!(self, check_path, p, id);
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hir_visit::walk_path(self, p);
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}
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fn visit_attribute(&mut self, attr: &'tcx ast::Attribute) {
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lint_callback!(self, check_attribute, attr);
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}
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}
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struct LateLintPassObjects<'a> {
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lints: &'a mut [LateLintPassObject],
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}
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#[allow(rustc::lint_pass_impl_without_macro)]
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impl LintPass for LateLintPassObjects<'_> {
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fn name(&self) -> &'static str {
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panic!()
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}
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}
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macro_rules! expand_late_lint_pass_impl_methods {
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([$hir:tt], [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
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$(fn $name(&mut self, context: &LateContext<$hir>, $($param: $arg),*) {
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for obj in self.lints.iter_mut() {
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obj.$name(context, $($param),*);
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}
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})*
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)
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}
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macro_rules! late_lint_pass_impl {
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([], [$hir:tt], $methods:tt) => {
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impl<$hir> LateLintPass<$hir> for LateLintPassObjects<'_> {
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expand_late_lint_pass_impl_methods!([$hir], $methods);
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}
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};
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}
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crate::late_lint_methods!(late_lint_pass_impl, [], ['tcx]);
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fn late_lint_mod_pass<'tcx, T: LateLintPass<'tcx>>(
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tcx: TyCtxt<'tcx>,
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module_def_id: LocalDefId,
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pass: T,
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) {
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let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
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let context = LateContext {
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tcx,
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enclosing_body: None,
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cached_typeck_results: Cell::new(None),
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param_env: ty::ParamEnv::empty(),
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access_levels,
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lint_store: unerased_lint_store(tcx),
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last_node_with_lint_attrs: tcx.hir().local_def_id_to_hir_id(module_def_id),
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generics: None,
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only_module: true,
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};
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let mut cx = LateContextAndPass { context, pass };
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let (module, span, hir_id) = tcx.hir().get_module(module_def_id);
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cx.process_mod(module, span, hir_id);
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|
|
// Visit the crate attributes
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|
if hir_id == hir::CRATE_HIR_ID {
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walk_list!(cx, visit_attribute, tcx.hir().attrs(hir::CRATE_HIR_ID));
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|
}
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|
}
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|
pub fn late_lint_mod<'tcx, T: LateLintPass<'tcx>>(
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tcx: TyCtxt<'tcx>,
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|
module_def_id: LocalDefId,
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|
builtin_lints: T,
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|
) {
|
|
if tcx.sess.opts.debugging_opts.no_interleave_lints {
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|
// These passes runs in late_lint_crate with -Z no_interleave_lints
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|
return;
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}
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|
late_lint_mod_pass(tcx, module_def_id, builtin_lints);
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|
|
let mut passes: Vec<_> =
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unerased_lint_store(tcx).late_module_passes.iter().map(|pass| (pass)()).collect();
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|
|
if !passes.is_empty() {
|
|
late_lint_mod_pass(tcx, module_def_id, LateLintPassObjects { lints: &mut passes[..] });
|
|
}
|
|
}
|
|
|
|
fn late_lint_pass_crate<'tcx, T: LateLintPass<'tcx>>(tcx: TyCtxt<'tcx>, pass: T) {
|
|
let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE);
|
|
|
|
let krate = tcx.hir().krate();
|
|
|
|
let context = LateContext {
|
|
tcx,
|
|
enclosing_body: None,
|
|
cached_typeck_results: Cell::new(None),
|
|
param_env: ty::ParamEnv::empty(),
|
|
access_levels,
|
|
lint_store: unerased_lint_store(tcx),
|
|
last_node_with_lint_attrs: hir::CRATE_HIR_ID,
|
|
generics: None,
|
|
only_module: false,
|
|
};
|
|
|
|
let mut cx = LateContextAndPass { context, pass };
|
|
|
|
// Visit the whole crate.
|
|
cx.with_lint_attrs(hir::CRATE_HIR_ID, &krate.item.attrs, |cx| {
|
|
// since the root module isn't visited as an item (because it isn't an
|
|
// item), warn for it here.
|
|
lint_callback!(cx, check_crate, krate);
|
|
|
|
hir_visit::walk_crate(cx, krate);
|
|
|
|
lint_callback!(cx, check_crate_post, krate);
|
|
})
|
|
}
|
|
|
|
fn late_lint_crate<'tcx, T: LateLintPass<'tcx>>(tcx: TyCtxt<'tcx>, builtin_lints: T) {
|
|
let mut passes = unerased_lint_store(tcx).late_passes.iter().map(|p| (p)()).collect::<Vec<_>>();
|
|
|
|
if !tcx.sess.opts.debugging_opts.no_interleave_lints {
|
|
if !passes.is_empty() {
|
|
late_lint_pass_crate(tcx, LateLintPassObjects { lints: &mut passes[..] });
|
|
}
|
|
|
|
late_lint_pass_crate(tcx, builtin_lints);
|
|
} else {
|
|
for pass in &mut passes {
|
|
tcx.sess.prof.extra_verbose_generic_activity("run_late_lint", pass.name()).run(|| {
|
|
late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
|
|
});
|
|
}
|
|
|
|
let mut passes: Vec<_> =
|
|
unerased_lint_store(tcx).late_module_passes.iter().map(|pass| (pass)()).collect();
|
|
|
|
for pass in &mut passes {
|
|
tcx.sess.prof.extra_verbose_generic_activity("run_late_module_lint", pass.name()).run(
|
|
|| {
|
|
late_lint_pass_crate(tcx, LateLintPassObjects { lints: slice::from_mut(pass) });
|
|
},
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
/// Performs lint checking on a crate.
|
|
pub fn check_crate<'tcx, T: LateLintPass<'tcx>>(
|
|
tcx: TyCtxt<'tcx>,
|
|
builtin_lints: impl FnOnce() -> T + Send,
|
|
) {
|
|
join(
|
|
|| {
|
|
tcx.sess.time("crate_lints", || {
|
|
// Run whole crate non-incremental lints
|
|
late_lint_crate(tcx, builtin_lints());
|
|
});
|
|
},
|
|
|| {
|
|
tcx.sess.time("module_lints", || {
|
|
// Run per-module lints
|
|
par_iter(&tcx.hir().krate().modules).for_each(|(&module, _)| {
|
|
tcx.ensure().lint_mod(tcx.hir().local_def_id(module));
|
|
});
|
|
});
|
|
},
|
|
);
|
|
}
|