rustc_lint: Prevent triplication of various lints

[Enselic]

Prevent triplication of various lints. The triplication happens because we run the same lint three times (or less in some cases):

• In BuiltinCombinedPreExpansionLintPass
• In BuiltinCombinedEarlyLintPass
• In shallow_lint_levels_on()

Only run the lints one time by checking the lint_added_lints bool.

Set your GitHub diff setting to ignore whitespaces changes when reviewing this PR, since I had to enclose a block inside an if.

Closes #73301

(I found this while exploring the code related to this comment.)

[rustbot]

r? @davidtwco

(rustbot has picked a reviewer for you, use r? to override)

[Enselic]

davidtwco seems to be on vacation, so I'll go ahead and re-roll reviewer.

r? compiler

[cjgillot]

Why does it still appear twice?

[Enselic]

It is emitted twice via with_lint_attrs(), first from visit_stmt() and then from visit_expr() (from inside visit_stmt()). For reference, the code looks like this:

    fn visit_expr(&mut self, e: &'a ast::Expr) {
        self.with_lint_attrs(e.id, &e.attrs, |cx| {
            lint_callback!(cx, check_expr, e);
            ast_visit::walk_expr(cx, e);
        })
    }

   // ...

    fn visit_stmt(&mut self, s: &'a ast::Stmt) {
        // Add the statement's lint attributes to our
        // current state when checking the statement itself.
        // This allows us to handle attributes like
        // `#[allow(unused_doc_comments)]`, which apply to
        // sibling attributes on the same target
        //
        // Note that statements get their attributes from
        // the AST struct that they wrap (e.g. an item)
        self.with_lint_attrs(s.id, s.attrs(), |cx| {
            lint_callback!(cx, check_stmt, s);
            cx.check_id(s.id);
        });
        // The visitor for the AST struct wrapped
        // by the statement (e.g. `Item`) will call
        // `with_lint_attrs`, so do this walk
        // outside of the above `with_lint_attrs` call
        ast_visit::walk_stmt(self, s);
    }

I can look into fixing that, but I would prefer to do it in a separate PR after this PR lands since it is a separate problem.

[Enselic]

For reference, here is the top of the backtrace of err.emit() of the second emit:

backtrace

rustc_middle::lint::struct_lint_level::struct_lint_level_impl::<rustc_error_messages::DiagnosticMessage> (\home\martin\src\rust\compiler\rustc_middle\src\lint.rs:406)
rustc_middle::lint::struct_lint_level::<rustc_error_messages::DiagnosticMessage, <rustc_lint::levels::LintLevelsBuilder<rustc_lint::levels::TopDown>>::check_gated_lint::{closure#0}> (\home\martin\src\rust\compiler\rustc_middle\src\lint.rs:408)
<rustc_lint::levels::LintLevelsBuilder<rustc_lint::levels::TopDown>>::check_gated_lint (\home\martin\src\rust\compiler\rustc_lint\src\levels.rs:1064)
<rustc_lint::levels::LintLevelsBuilder<rustc_lint::levels::TopDown>>::add (\home\martin\src\rust\compiler\rustc_lint\src\levels.rs:897)
<rustc_lint::levels::LintLevelsBuilder<rustc_lint::levels::TopDown>>::push (\home\martin\src\rust\compiler\rustc_lint\src\levels.rs:517)
<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>>::with_lint_attrs::<<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass> as rustc_ast::visit::Visitor>::visit_expr::{closure#0}> (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:66)
<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass> as rustc_ast::visit::Visitor>::visit_expr (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:119)
<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass> as rustc_ast::visit::Visitor>::visit_stmt (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:148)
rustc_ast::visit::walk_block::<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>> (\home\martin\src\rust\compiler\rustc_ast\src\visit.rs:724)
<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass> as rustc_ast::visit::Visitor>::visit_fn (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:154)
rustc_ast::visit::walk_item::<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>> (\home\martin\src\rust\compiler\rustc_ast\src\visit.rs:326)
<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass> as rustc_ast::visit::Visitor>::visit_item::{closure#0} (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:89)
<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>>::with_lint_attrs::<<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass> as rustc_ast::visit::Visitor>::visit_item::{closure#0}>::{closure#0} (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:71)
stacker::maybe_grow::<(), <rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>>::with_lint_attrs<<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass> as rustc_ast::visit::Visitor>::visit_item::{closure#0}>::{closure#0}> (\home\martin\.cargo\registry\src\index.crates.io-6f17d22bba15001f\stacker-0.1.15\src\lib.rs:55)
rustc_data_structures::stack::ensure_sufficient_stack::<(), <rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>>::with_lint_attrs<<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass> as rustc_ast::visit::Visitor>::visit_item::{closure#0}>::{closure#0}> (\home\martin\src\rust\compiler\rustc_data_structures\src\stack.rs:17)
<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>>::with_lint_attrs::<<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass> as rustc_ast::visit::Visitor>::visit_item::{closure#0}> (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:71)
<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass> as rustc_ast::visit::Visitor>::visit_item (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:87)
rustc_ast::visit::walk_crate::<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>> (\home\martin\src\rust\compiler\rustc_ast\src\visit.rs:272)
<(&rustc_ast::ast::Crate, &[rustc_ast::ast::Attribute]) as rustc_lint::early::EarlyCheckNode>::check::<rustc_lint::BuiltinCombinedEarlyLintPass> (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:356)
rustc_lint::early::check_ast_node_inner::<rustc_lint::BuiltinCombinedEarlyLintPass, (&rustc_ast::ast::Crate, &[rustc_ast::ast::Attribute])>::{closure#0} (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:422)
<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>>::with_lint_attrs::<rustc_lint::early::check_ast_node_inner<rustc_lint::BuiltinCombinedEarlyLintPass, (&rustc_ast::ast::Crate, &[rustc_ast::ast::Attribute])>::{closure#0}>::{closure#0} (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:71)
stacker::maybe_grow::<(), <rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>>::with_lint_attrs<rustc_lint::early::check_ast_node_inner<rustc_lint::BuiltinCombinedEarlyLintPass, (&rustc_ast::ast::Crate, &[rustc_ast::ast::Attribute])>::{closure#0}>::{closure#0}> (\home\martin\.cargo\registry\src\index.crates.io-6f17d22bba15001f\stacker-0.1.15\src\lib.rs:55)
rustc_data_structures::stack::ensure_sufficient_stack::<(), <rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>>::with_lint_attrs<rustc_lint::early::check_ast_node_inner<rustc_lint::BuiltinCombinedEarlyLintPass, (&rustc_ast::ast::Crate, &[rustc_ast::ast::Attribute])>::{closure#0}>::{closure#0}> (\home\martin\src\rust\compiler\rustc_data_structures\src\stack.rs:17)
<rustc_lint::early::EarlyContextAndPass<rustc_lint::BuiltinCombinedEarlyLintPass>>::with_lint_attrs::<rustc_lint::early::check_ast_node_inner<rustc_lint::BuiltinCombinedEarlyLintPass, (&rustc_ast::ast::Crate, &[rustc_ast::ast::Attribute])>::{closure#0}> (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:71)
rustc_lint::early::check_ast_node_inner::<rustc_lint::BuiltinCombinedEarlyLintPass, (&rustc_ast::ast::Crate, &[rustc_ast::ast::Attribute])> (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:422)
rustc_lint::early::check_ast_node::<rustc_lint::BuiltinCombinedEarlyLintPass, (&rustc_ast::ast::Crate, &[rustc_ast::ast::Attribute])> (\home\martin\src\rust\compiler\rustc_lint\src\early.rs:405)
rustc_interface::passes::early_lint_checks (\home\martin\src\rust\compiler\rustc_interface\src\passes.rs:325)
rustc_query_impl::query_impl::early_lint_checks::dynamic_query::{closure#2}::{closure#0} (\home\martin\src\rust\compiler\rustc_query_impl\src\plumbing.rs:589)
rustc_query_impl::plumbing::__rust_begin_short_backtrace::<rustc_query_impl::query_impl::early_lint_checks::dynamic_query::{closure#2}::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>> (\home\martin\src\rust\compiler\rustc_query_impl\src\plumbing.rs:513)
rustc_query_impl::query_impl::early_lint_checks::dynamic_query::{closure#2} (\home\martin\src\rust\compiler\rustc_query_impl\src\plumbing.rs:585)
<rustc_query_impl::query_impl::early_lint_checks::dynamic_query::{closure#2} as core::ops::function::FnOnce<(rustc_middle::ty::context::TyCtxt, ())>>::call_once (\home\martin\src\rust\library\core\src\ops\function.rs:250)
<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false> as rustc_query_system::query::config::QueryConfig<rustc_query_impl::plumbing::QueryCtxt>>::compute (\home\martin\src\rust\compiler\rustc_query_impl\src\lib.rs:119)
rustc_query_system::query::plumbing::execute_job_non_incr::<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>::{closure#0} (\home\martin\src\rust\compiler\rustc_query_system\src\query\plumbing.rs:464)
rustc_middle::ty::context::tls::enter_context::<rustc_query_system::query::plumbing::execute_job_non_incr<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>::{closure#0} (\home\martin\src\rust\compiler\rustc_middle\src\ty\context\tls.rs:82)
<std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::try_with::<rustc_middle::ty::context::tls::enter_context<rustc_query_system::query::plumbing::execute_job_non_incr<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>> (\home\martin\src\rust\library\std\src\thread\local.rs:270)
<std::thread::local::LocalKey<core::cell::Cell<*const ()>>>::with::<rustc_middle::ty::context::tls::enter_context<rustc_query_system::query::plumbing::execute_job_non_incr<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>> (\home\martin\src\rust\library\std\src\thread\local.rs:246)
rustc_middle::ty::context::tls::enter_context::<rustc_query_system::query::plumbing::execute_job_non_incr<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>> (\home\martin\src\rust\compiler\rustc_middle\src\ty\context\tls.rs:79)
<rustc_query_impl::plumbing::QueryCtxt as rustc_query_system::query::QueryContext>::start_query::<rustc_middle::query::erase::Erased<[u8; 0]>, rustc_query_system::query::plumbing::execute_job_non_incr<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>::{closure#0}>::{closure#0} (\home\martin\src\rust\compiler\rustc_query_impl\src\plumbing.rs:151)
rustc_middle::ty::context::tls::with_related_context::<<rustc_query_impl::plumbing::QueryCtxt as rustc_query_system::query::QueryContext>::start_query<rustc_middle::query::erase::Erased<[u8; 0]>, rustc_query_system::query::plumbing::execute_job_non_incr<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>::{closure#0}>::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>::{closure#0} (\home\martin\src\rust\compiler\rustc_middle\src\ty\context\tls.rs:133)
rustc_middle::ty::context::tls::with_context::<rustc_middle::ty::context::tls::with_related_context<<rustc_query_impl::plumbing::QueryCtxt as rustc_query_system::query::QueryContext>::start_query<rustc_middle::query::erase::Erased<[u8; 0]>, rustc_query_system::query::plumbing::execute_job_non_incr<rustc_query_impl::DynamicConfig<rustc_query_system::query::caches::SingleCache<rustc_middle::query::erase::Erased<[u8; 0]>>, false, false, false>, rustc_query_impl::plumbing::QueryCtxt>::{closure#0}>::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>::{closure#0}, rustc_middle::query::erase::Erased<[u8; 0]>>::{closure#0} (\home\martin\src\rust\compiler\rustc_middle\src\ty\context\tls.rs:111)

The first err.emit() backtrace looks exactly the same, except it does not have the visit_expr() stack frame.

[cjgillot]

Here too?

[Enselic]

(See above)

[cjgillot]

@bors r+ rollup

[bors]

📌 Commit 7ca4e9f has been approved by cjgillot

It is now in the queue for this repository.