445 lines
15 KiB
Rust
445 lines
15 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::context::{EarlyContext, LintContext, LintStore};
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use crate::passes::{EarlyLintPass, EarlyLintPassObject};
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use rustc_ast::ptr::P;
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use rustc_ast::visit::{self as ast_visit, Visitor};
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use rustc_ast::{self as ast, walk_list, HasAttrs};
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use rustc_data_structures::stack::ensure_sufficient_stack;
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use rustc_feature::Features;
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use rustc_middle::ty::RegisteredTools;
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use rustc_session::lint::{BufferedEarlyLint, LintBuffer, LintPass};
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use rustc_session::Session;
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use rustc_span::symbol::Ident;
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use rustc_span::Span;
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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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/// Implements the AST traversal for early lint passes. `T` provides the
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/// `check_*` methods.
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pub struct EarlyContextAndPass<'a, T: EarlyLintPass> {
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context: EarlyContext<'a>,
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pass: T,
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}
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impl<'a, T: EarlyLintPass> EarlyContextAndPass<'a, T> {
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// This always-inlined function is for the hot call site.
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#[inline(always)]
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#[allow(rustc::diagnostic_outside_of_impl)]
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fn inlined_check_id(&mut self, id: ast::NodeId) {
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for early_lint in self.context.buffered.take(id) {
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let BufferedEarlyLint { span, msg, node_id: _, lint_id, diagnostic } = early_lint;
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self.context.span_lint_with_diagnostics(
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lint_id.lint,
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Some(span),
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msg,
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|_| {},
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diagnostic,
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);
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}
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}
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// This non-inlined function is for the cold call sites.
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fn check_id(&mut self, id: ast::NodeId) {
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self.inlined_check_id(id)
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}
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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: ast::NodeId, attrs: &'a [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 is_crate_node = id == ast::CRATE_NODE_ID;
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debug!(?id);
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let push = self.context.builder.push(attrs, is_crate_node, None);
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self.inlined_check_id(id);
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debug!("early context: enter_attrs({:?})", attrs);
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lint_callback!(self, enter_lint_attrs, attrs);
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ensure_sufficient_stack(|| f(self));
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debug!("early context: exit_attrs({:?})", attrs);
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lint_callback!(self, exit_lint_attrs, attrs);
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self.context.builder.pop(push);
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}
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}
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impl<'a, T: EarlyLintPass> ast_visit::Visitor<'a> for EarlyContextAndPass<'a, T> {
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fn visit_param(&mut self, param: &'a ast::Param) {
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self.with_lint_attrs(param.id, ¶m.attrs, |cx| {
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lint_callback!(cx, check_param, param);
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ast_visit::walk_param(cx, param);
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});
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}
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fn visit_item(&mut self, it: &'a ast::Item) {
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self.with_lint_attrs(it.id, &it.attrs, |cx| {
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lint_callback!(cx, check_item, it);
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ast_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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fn visit_foreign_item(&mut self, it: &'a ast::ForeignItem) {
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self.with_lint_attrs(it.id, &it.attrs, |cx| {
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ast_visit::walk_foreign_item(cx, it);
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})
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}
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fn visit_pat(&mut self, p: &'a ast::Pat) {
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lint_callback!(self, check_pat, p);
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self.check_id(p.id);
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ast_visit::walk_pat(self, p);
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lint_callback!(self, check_pat_post, p);
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}
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fn visit_pat_field(&mut self, field: &'a ast::PatField) {
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self.with_lint_attrs(field.id, &field.attrs, |cx| {
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ast_visit::walk_pat_field(cx, field);
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});
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}
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fn visit_anon_const(&mut self, c: &'a ast::AnonConst) {
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self.check_id(c.id);
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ast_visit::walk_anon_const(self, c);
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}
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fn visit_expr(&mut self, e: &'a ast::Expr) {
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self.with_lint_attrs(e.id, &e.attrs, |cx| {
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lint_callback!(cx, check_expr, e);
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ast_visit::walk_expr(cx, e);
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})
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}
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fn visit_expr_field(&mut self, f: &'a ast::ExprField) {
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self.with_lint_attrs(f.id, &f.attrs, |cx| {
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ast_visit::walk_expr_field(cx, f);
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})
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}
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fn visit_stmt(&mut self, s: &'a ast::Stmt) {
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// Add the statement's lint attributes to our
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// current state when checking the statement itself.
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// This allows us to handle attributes like
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// `#[allow(unused_doc_comments)]`, which apply to
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// sibling attributes on the same target
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//
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// Note that statements get their attributes from
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// the AST struct that they wrap (e.g. an item)
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self.with_lint_attrs(s.id, s.attrs(), |cx| {
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lint_callback!(cx, check_stmt, s);
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cx.check_id(s.id);
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});
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// The visitor for the AST struct wrapped
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// by the statement (e.g. `Item`) will call
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// `with_lint_attrs`, so do this walk
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// outside of the above `with_lint_attrs` call
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ast_visit::walk_stmt(self, s);
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}
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fn visit_fn(&mut self, fk: ast_visit::FnKind<'a>, span: Span, id: ast::NodeId) {
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lint_callback!(self, check_fn, fk, span, id);
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self.check_id(id);
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ast_visit::walk_fn(self, fk);
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// Explicitly check for lints associated with 'closure_id', since
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// it does not have a corresponding AST node
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if let ast_visit::FnKind::Fn(_, _, sig, _, _, _) = fk {
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if let Some(coroutine_kind) = sig.header.coroutine_kind {
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self.check_id(coroutine_kind.closure_id());
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}
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}
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}
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fn visit_variant_data(&mut self, s: &'a ast::VariantData) {
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if let Some(ctor_node_id) = s.ctor_node_id() {
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self.check_id(ctor_node_id);
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}
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ast_visit::walk_struct_def(self, s);
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}
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fn visit_field_def(&mut self, s: &'a ast::FieldDef) {
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self.with_lint_attrs(s.id, &s.attrs, |cx| {
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ast_visit::walk_field_def(cx, s);
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})
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}
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fn visit_variant(&mut self, v: &'a ast::Variant) {
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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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ast_visit::walk_variant(cx, v);
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})
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}
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fn visit_ty(&mut self, t: &'a ast::Ty) {
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lint_callback!(self, check_ty, t);
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self.check_id(t.id);
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ast_visit::walk_ty(self, t);
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}
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fn visit_ident(&mut self, ident: Ident) {
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lint_callback!(self, check_ident, ident);
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}
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fn visit_local(&mut self, l: &'a ast::Local) {
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self.with_lint_attrs(l.id, &l.attrs, |cx| {
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lint_callback!(cx, check_local, l);
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ast_visit::walk_local(cx, l);
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})
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}
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fn visit_block(&mut self, b: &'a ast::Block) {
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lint_callback!(self, check_block, b);
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self.check_id(b.id);
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ast_visit::walk_block(self, b);
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}
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fn visit_arm(&mut self, a: &'a ast::Arm) {
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self.with_lint_attrs(a.id, &a.attrs, |cx| {
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lint_callback!(cx, check_arm, a);
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ast_visit::walk_arm(cx, a);
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})
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}
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fn visit_expr_post(&mut self, e: &'a ast::Expr) {
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// Explicitly check for lints associated with 'closure_id', since
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// it does not have a corresponding AST node
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match e.kind {
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ast::ExprKind::Closure(box ast::Closure {
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coroutine_kind: Some(coroutine_kind),
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..
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}) => {
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self.check_id(coroutine_kind.closure_id());
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}
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_ => {}
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}
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lint_callback!(self, check_expr_post, e);
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}
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fn visit_generic_arg(&mut self, arg: &'a ast::GenericArg) {
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lint_callback!(self, check_generic_arg, arg);
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ast_visit::walk_generic_arg(self, arg);
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}
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fn visit_generic_param(&mut self, param: &'a ast::GenericParam) {
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self.with_lint_attrs(param.id, ¶m.attrs, |cx| {
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lint_callback!(cx, check_generic_param, param);
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ast_visit::walk_generic_param(cx, param);
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});
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}
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fn visit_generics(&mut self, g: &'a ast::Generics) {
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lint_callback!(self, check_generics, g);
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ast_visit::walk_generics(self, g);
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}
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fn visit_where_predicate(&mut self, p: &'a ast::WherePredicate) {
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lint_callback!(self, enter_where_predicate, p);
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ast_visit::walk_where_predicate(self, p);
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lint_callback!(self, exit_where_predicate, p);
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}
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fn visit_poly_trait_ref(&mut self, t: &'a ast::PolyTraitRef) {
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lint_callback!(self, check_poly_trait_ref, t);
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ast_visit::walk_poly_trait_ref(self, t);
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}
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fn visit_assoc_item(&mut self, item: &'a ast::AssocItem, ctxt: ast_visit::AssocCtxt) {
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self.with_lint_attrs(item.id, &item.attrs, |cx| match ctxt {
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ast_visit::AssocCtxt::Trait => {
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lint_callback!(cx, check_trait_item, item);
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ast_visit::walk_assoc_item(cx, item, ctxt);
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}
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ast_visit::AssocCtxt::Impl => {
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lint_callback!(cx, check_impl_item, item);
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ast_visit::walk_assoc_item(cx, item, ctxt);
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}
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});
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}
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fn visit_lifetime(&mut self, lt: &'a ast::Lifetime, _: ast_visit::LifetimeCtxt) {
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self.check_id(lt.id);
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}
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fn visit_path(&mut self, p: &'a ast::Path, id: ast::NodeId) {
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self.check_id(id);
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ast_visit::walk_path(self, p);
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}
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fn visit_path_segment(&mut self, s: &'a ast::PathSegment) {
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self.check_id(s.id);
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ast_visit::walk_path_segment(self, s);
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}
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fn visit_attribute(&mut self, attr: &'a ast::Attribute) {
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lint_callback!(self, check_attribute, attr);
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}
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fn visit_mac_def(&mut self, mac: &'a ast::MacroDef, id: ast::NodeId) {
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lint_callback!(self, check_mac_def, mac);
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self.check_id(id);
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}
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fn visit_mac_call(&mut self, mac: &'a ast::MacCall) {
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lint_callback!(self, check_mac, mac);
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ast_visit::walk_mac(self, mac);
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}
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}
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// Combines multiple lint passes into a single pass, at runtime. Each
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// `check_foo` method in `$methods` within this pass simply calls `check_foo`
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// once per `$pass`. Compare with `declare_combined_early_lint_pass`, which is
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// similar, but combines lint passes at compile time.
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struct RuntimeCombinedEarlyLintPass<'a> {
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passes: &'a mut [EarlyLintPassObject],
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}
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#[allow(rustc::lint_pass_impl_without_macro)]
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impl LintPass for RuntimeCombinedEarlyLintPass<'_> {
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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! impl_early_lint_pass {
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([], [$($(#[$attr:meta])* fn $f:ident($($param:ident: $arg:ty),*);)*]) => (
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impl EarlyLintPass for RuntimeCombinedEarlyLintPass<'_> {
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$(fn $f(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
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for pass in self.passes.iter_mut() {
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pass.$f(context, $($param),*);
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}
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})*
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}
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)
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}
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crate::early_lint_methods!(impl_early_lint_pass, []);
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/// Early lints work on different nodes - either on the crate root, or on freshly loaded modules.
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/// This trait generalizes over those nodes.
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pub trait EarlyCheckNode<'a>: Copy {
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fn id(self) -> ast::NodeId;
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fn attrs<'b>(self) -> &'b [ast::Attribute]
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where
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'a: 'b;
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fn check<'b, T: EarlyLintPass>(self, cx: &mut EarlyContextAndPass<'b, T>)
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where
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'a: 'b;
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}
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impl<'a> EarlyCheckNode<'a> for (&'a ast::Crate, &'a [ast::Attribute]) {
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fn id(self) -> ast::NodeId {
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ast::CRATE_NODE_ID
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}
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fn attrs<'b>(self) -> &'b [ast::Attribute]
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where
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'a: 'b,
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{
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self.1
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}
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fn check<'b, T: EarlyLintPass>(self, cx: &mut EarlyContextAndPass<'b, T>)
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where
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'a: 'b,
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{
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lint_callback!(cx, check_crate, self.0);
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ast_visit::walk_crate(cx, self.0);
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lint_callback!(cx, check_crate_post, self.0);
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}
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}
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impl<'a> EarlyCheckNode<'a> for (ast::NodeId, &'a [ast::Attribute], &'a [P<ast::Item>]) {
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fn id(self) -> ast::NodeId {
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self.0
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}
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fn attrs<'b>(self) -> &'b [ast::Attribute]
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where
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'a: 'b,
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{
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self.1
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}
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fn check<'b, T: EarlyLintPass>(self, cx: &mut EarlyContextAndPass<'b, T>)
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where
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'a: 'b,
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{
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walk_list!(cx, visit_attribute, self.1);
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walk_list!(cx, visit_item, self.2);
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}
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}
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pub fn check_ast_node<'a>(
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sess: &Session,
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features: &Features,
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pre_expansion: bool,
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lint_store: &LintStore,
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registered_tools: &RegisteredTools,
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lint_buffer: Option<LintBuffer>,
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builtin_lints: impl EarlyLintPass + 'static,
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check_node: impl EarlyCheckNode<'a>,
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) {
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let context = EarlyContext::new(
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sess,
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features,
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!pre_expansion,
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lint_store,
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registered_tools,
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lint_buffer.unwrap_or_default(),
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);
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// Note: `passes` is often empty. In that case, it's faster to run
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// `builtin_lints` directly rather than bundling it up into the
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// `RuntimeCombinedEarlyLintPass`.
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let passes =
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if pre_expansion { &lint_store.pre_expansion_passes } else { &lint_store.early_passes };
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if passes.is_empty() {
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check_ast_node_inner(sess, check_node, context, builtin_lints);
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} else {
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let mut passes: Vec<_> = passes.iter().map(|mk_pass| (mk_pass)()).collect();
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passes.push(Box::new(builtin_lints));
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let pass = RuntimeCombinedEarlyLintPass { passes: &mut passes[..] };
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check_ast_node_inner(sess, check_node, context, pass);
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}
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}
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pub fn check_ast_node_inner<'a, T: EarlyLintPass>(
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sess: &Session,
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check_node: impl EarlyCheckNode<'a>,
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context: EarlyContext<'_>,
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pass: T,
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) {
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let mut cx = EarlyContextAndPass { context, pass };
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cx.with_lint_attrs(check_node.id(), check_node.attrs(), |cx| check_node.check(cx));
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// All of the buffered lints should have been emitted at this point.
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// If not, that means that we somehow buffered a lint for a node id
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// that was not lint-checked (perhaps it doesn't exist?). This is a bug.
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for (id, lints) in cx.context.buffered.map {
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for early_lint in lints {
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sess.dcx().span_delayed_bug(
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early_lint.span,
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format!(
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"failed to process buffered lint here (dummy = {})",
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id == ast::DUMMY_NODE_ID
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),
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);
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}
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}
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}
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