| //! Implementation of lint checking. |
| //! |
| //! The lint checking is mostly consolidated into one pass which runs |
| //! after all other analyses. Throughout compilation, lint warnings |
| //! can be added via the `add_lint` method on the Session structure. This |
| //! requires a span and an ID of the node that the lint is being added to. The |
| //! lint isn't actually emitted at that time because it is unknown what the |
| //! actual lint level at that location is. |
| //! |
| //! To actually emit lint warnings/errors, a separate pass is used. |
| //! A context keeps track of the current state of all lint levels. |
| //! Upon entering a node of the ast which can modify the lint settings, the |
| //! previous lint state is pushed onto a stack and the ast is then recursed |
| //! upon. As the ast is traversed, this keeps track of the current lint level |
| //! for all lint attributes. |
| |
| use crate::{passes::LateLintPassObject, LateContext, LateLintPass, LintStore}; |
| use rustc::hir::map::Map; |
| use rustc::ty::{self, TyCtxt}; |
| use rustc_ast::ast; |
| use rustc_ast::walk_list; |
| use rustc_data_structures::sync::{join, par_iter, ParallelIterator}; |
| use rustc_hir as hir; |
| use rustc_hir::def_id::{DefId, LOCAL_CRATE}; |
| use rustc_hir::intravisit as hir_visit; |
| use rustc_hir::intravisit::Visitor; |
| use rustc_session::lint::LintPass; |
| use rustc_span::Span; |
| |
| use log::debug; |
| use std::any::Any; |
| use std::slice; |
| |
| /// Extract the `LintStore` from the query context. |
| /// This function exists because we've erased `LintStore` as `dyn Any` in the context. |
| crate fn unerased_lint_store<'tcx>(tcx: TyCtxt<'tcx>) -> &'tcx LintStore { |
| let store: &dyn Any = &*tcx.lint_store; |
| store.downcast_ref().unwrap() |
| } |
| |
| macro_rules! lint_callback { ($cx:expr, $f:ident, $($args:expr),*) => ({ |
| $cx.pass.$f(&$cx.context, $($args),*); |
| }) } |
| |
| struct LateContextAndPass<'a, 'tcx, T: LateLintPass<'a, 'tcx>> { |
| context: LateContext<'a, 'tcx>, |
| pass: T, |
| } |
| |
| impl<'a, 'tcx, T: LateLintPass<'a, 'tcx>> LateContextAndPass<'a, 'tcx, T> { |
| /// Merge the lints specified by any lint attributes into the |
| /// current lint context, call the provided function, then reset the |
| /// lints in effect to their previous state. |
| fn with_lint_attrs<F>(&mut self, id: hir::HirId, attrs: &'tcx [ast::Attribute], f: F) |
| where |
| F: FnOnce(&mut Self), |
| { |
| let prev = self.context.last_node_with_lint_attrs; |
| self.context.last_node_with_lint_attrs = id; |
| self.enter_attrs(attrs); |
| f(self); |
| self.exit_attrs(attrs); |
| self.context.last_node_with_lint_attrs = prev; |
| } |
| |
| fn with_param_env<F>(&mut self, id: hir::HirId, f: F) |
| where |
| F: FnOnce(&mut Self), |
| { |
| let old_param_env = self.context.param_env; |
| self.context.param_env = |
| self.context.tcx.param_env(self.context.tcx.hir().local_def_id(id)); |
| f(self); |
| self.context.param_env = old_param_env; |
| } |
| |
| fn process_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) { |
| lint_callback!(self, check_mod, m, s, n); |
| hir_visit::walk_mod(self, m, n); |
| lint_callback!(self, check_mod_post, m, s, n); |
| } |
| |
| fn enter_attrs(&mut self, attrs: &'tcx [ast::Attribute]) { |
| debug!("late context: enter_attrs({:?})", attrs); |
| lint_callback!(self, enter_lint_attrs, attrs); |
| } |
| |
| fn exit_attrs(&mut self, attrs: &'tcx [ast::Attribute]) { |
| debug!("late context: exit_attrs({:?})", attrs); |
| lint_callback!(self, exit_lint_attrs, attrs); |
| } |
| } |
| |
| impl<'a, 'tcx, T: LateLintPass<'a, 'tcx>> hir_visit::Visitor<'tcx> |
| for LateContextAndPass<'a, 'tcx, T> |
| { |
| type Map = Map<'tcx>; |
| |
| /// Because lints are scoped lexically, we want to walk nested |
| /// items in the context of the outer item, so enable |
| /// deep-walking. |
| fn nested_visit_map<'this>(&'this mut self) -> hir_visit::NestedVisitorMap<'this, Self::Map> { |
| hir_visit::NestedVisitorMap::All(&self.context.tcx.hir()) |
| } |
| |
| fn visit_nested_body(&mut self, body: hir::BodyId) { |
| let old_tables = self.context.tables; |
| self.context.tables = self.context.tcx.body_tables(body); |
| let body = self.context.tcx.hir().body(body); |
| self.visit_body(body); |
| self.context.tables = old_tables; |
| } |
| |
| fn visit_param(&mut self, param: &'tcx hir::Param<'tcx>) { |
| self.with_lint_attrs(param.hir_id, ¶m.attrs, |cx| { |
| lint_callback!(cx, check_param, param); |
| hir_visit::walk_param(cx, param); |
| }); |
| } |
| |
| fn visit_body(&mut self, body: &'tcx hir::Body<'tcx>) { |
| lint_callback!(self, check_body, body); |
| hir_visit::walk_body(self, body); |
| lint_callback!(self, check_body_post, body); |
| } |
| |
| fn visit_item(&mut self, it: &'tcx hir::Item<'tcx>) { |
| let generics = self.context.generics.take(); |
| self.context.generics = it.kind.generics(); |
| self.with_lint_attrs(it.hir_id, &it.attrs, |cx| { |
| cx.with_param_env(it.hir_id, |cx| { |
| lint_callback!(cx, check_item, it); |
| hir_visit::walk_item(cx, it); |
| lint_callback!(cx, check_item_post, it); |
| }); |
| }); |
| self.context.generics = generics; |
| } |
| |
| fn visit_foreign_item(&mut self, it: &'tcx hir::ForeignItem<'tcx>) { |
| self.with_lint_attrs(it.hir_id, &it.attrs, |cx| { |
| cx.with_param_env(it.hir_id, |cx| { |
| lint_callback!(cx, check_foreign_item, it); |
| hir_visit::walk_foreign_item(cx, it); |
| lint_callback!(cx, check_foreign_item_post, it); |
| }); |
| }) |
| } |
| |
| fn visit_pat(&mut self, p: &'tcx hir::Pat<'tcx>) { |
| lint_callback!(self, check_pat, p); |
| hir_visit::walk_pat(self, p); |
| } |
| |
| fn visit_expr(&mut self, e: &'tcx hir::Expr<'tcx>) { |
| self.with_lint_attrs(e.hir_id, &e.attrs, |cx| { |
| lint_callback!(cx, check_expr, e); |
| hir_visit::walk_expr(cx, e); |
| lint_callback!(cx, check_expr_post, e); |
| }) |
| } |
| |
| fn visit_stmt(&mut self, s: &'tcx hir::Stmt<'tcx>) { |
| // statement attributes are actually just attributes on one of |
| // - item |
| // - local |
| // - expression |
| // so we keep track of lint levels there |
| lint_callback!(self, check_stmt, s); |
| hir_visit::walk_stmt(self, s); |
| } |
| |
| fn visit_fn( |
| &mut self, |
| fk: hir_visit::FnKind<'tcx>, |
| decl: &'tcx hir::FnDecl<'tcx>, |
| body_id: hir::BodyId, |
| span: Span, |
| id: hir::HirId, |
| ) { |
| // Wrap in tables here, not just in visit_nested_body, |
| // in order for `check_fn` to be able to use them. |
| let old_tables = self.context.tables; |
| self.context.tables = self.context.tcx.body_tables(body_id); |
| let body = self.context.tcx.hir().body(body_id); |
| lint_callback!(self, check_fn, fk, decl, body, span, id); |
| hir_visit::walk_fn(self, fk, decl, body_id, span, id); |
| lint_callback!(self, check_fn_post, fk, decl, body, span, id); |
| self.context.tables = old_tables; |
| } |
| |
| fn visit_variant_data( |
| &mut self, |
| s: &'tcx hir::VariantData<'tcx>, |
| _: ast::Name, |
| _: &'tcx hir::Generics<'tcx>, |
| _: hir::HirId, |
| _: Span, |
| ) { |
| lint_callback!(self, check_struct_def, s); |
| hir_visit::walk_struct_def(self, s); |
| lint_callback!(self, check_struct_def_post, s); |
| } |
| |
| fn visit_struct_field(&mut self, s: &'tcx hir::StructField<'tcx>) { |
| self.with_lint_attrs(s.hir_id, &s.attrs, |cx| { |
| lint_callback!(cx, check_struct_field, s); |
| hir_visit::walk_struct_field(cx, s); |
| }) |
| } |
| |
| fn visit_variant( |
| &mut self, |
| v: &'tcx hir::Variant<'tcx>, |
| g: &'tcx hir::Generics<'tcx>, |
| item_id: hir::HirId, |
| ) { |
| self.with_lint_attrs(v.id, &v.attrs, |cx| { |
| lint_callback!(cx, check_variant, v); |
| hir_visit::walk_variant(cx, v, g, item_id); |
| lint_callback!(cx, check_variant_post, v); |
| }) |
| } |
| |
| fn visit_ty(&mut self, t: &'tcx hir::Ty<'tcx>) { |
| lint_callback!(self, check_ty, t); |
| hir_visit::walk_ty(self, t); |
| } |
| |
| fn visit_name(&mut self, sp: Span, name: ast::Name) { |
| lint_callback!(self, check_name, sp, name); |
| } |
| |
| fn visit_mod(&mut self, m: &'tcx hir::Mod<'tcx>, s: Span, n: hir::HirId) { |
| if !self.context.only_module { |
| self.process_mod(m, s, n); |
| } |
| } |
| |
| fn visit_local(&mut self, l: &'tcx hir::Local<'tcx>) { |
| self.with_lint_attrs(l.hir_id, &l.attrs, |cx| { |
| lint_callback!(cx, check_local, l); |
| hir_visit::walk_local(cx, l); |
| }) |
| } |
| |
| fn visit_block(&mut self, b: &'tcx hir::Block<'tcx>) { |
| lint_callback!(self, check_block, b); |
| hir_visit::walk_block(self, b); |
| lint_callback!(self, check_block_post, b); |
| } |
| |
| fn visit_arm(&mut self, a: &'tcx hir::Arm<'tcx>) { |
| lint_callback!(self, check_arm, a); |
| hir_visit::walk_arm(self, a); |
| } |
| |
| fn visit_generic_param(&mut self, p: &'tcx hir::GenericParam<'tcx>) { |
| lint_callback!(self, check_generic_param, p); |
| hir_visit::walk_generic_param(self, p); |
| } |
| |
| fn visit_generics(&mut self, g: &'tcx hir::Generics<'tcx>) { |
| lint_callback!(self, check_generics, g); |
| hir_visit::walk_generics(self, g); |
| } |
| |
| fn visit_where_predicate(&mut self, p: &'tcx hir::WherePredicate<'tcx>) { |
| lint_callback!(self, check_where_predicate, p); |
| hir_visit::walk_where_predicate(self, p); |
| } |
| |
| fn visit_poly_trait_ref( |
| &mut self, |
| t: &'tcx hir::PolyTraitRef<'tcx>, |
| m: hir::TraitBoundModifier, |
| ) { |
| lint_callback!(self, check_poly_trait_ref, t, m); |
| hir_visit::walk_poly_trait_ref(self, t, m); |
| } |
| |
| fn visit_trait_item(&mut self, trait_item: &'tcx hir::TraitItem<'tcx>) { |
| let generics = self.context.generics.take(); |
| self.context.generics = Some(&trait_item.generics); |
| self.with_lint_attrs(trait_item.hir_id, &trait_item.attrs, |cx| { |
| cx.with_param_env(trait_item.hir_id, |cx| { |
| lint_callback!(cx, check_trait_item, trait_item); |
| hir_visit::walk_trait_item(cx, trait_item); |
| lint_callback!(cx, check_trait_item_post, trait_item); |
| }); |
| }); |
| self.context.generics = generics; |
| } |
| |
| fn visit_impl_item(&mut self, impl_item: &'tcx hir::ImplItem<'tcx>) { |
| let generics = self.context.generics.take(); |
| self.context.generics = Some(&impl_item.generics); |
| self.with_lint_attrs(impl_item.hir_id, &impl_item.attrs, |cx| { |
| cx.with_param_env(impl_item.hir_id, |cx| { |
| lint_callback!(cx, check_impl_item, impl_item); |
| hir_visit::walk_impl_item(cx, impl_item); |
| lint_callback!(cx, check_impl_item_post, impl_item); |
| }); |
| }); |
| self.context.generics = generics; |
| } |
| |
| fn visit_lifetime(&mut self, lt: &'tcx hir::Lifetime) { |
| lint_callback!(self, check_lifetime, lt); |
| hir_visit::walk_lifetime(self, lt); |
| } |
| |
| fn visit_path(&mut self, p: &'tcx hir::Path<'tcx>, id: hir::HirId) { |
| lint_callback!(self, check_path, p, id); |
| hir_visit::walk_path(self, p); |
| } |
| |
| fn visit_attribute(&mut self, attr: &'tcx ast::Attribute) { |
| lint_callback!(self, check_attribute, attr); |
| } |
| } |
| |
| struct LateLintPassObjects<'a> { |
| lints: &'a mut [LateLintPassObject], |
| } |
| |
| #[allow(rustc::lint_pass_impl_without_macro)] |
| impl LintPass for LateLintPassObjects<'_> { |
| fn name(&self) -> &'static str { |
| panic!() |
| } |
| } |
| |
| macro_rules! expand_late_lint_pass_impl_methods { |
| ([$a:tt, $hir:tt], [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => ( |
| $(fn $name(&mut self, context: &LateContext<$a, $hir>, $($param: $arg),*) { |
| for obj in self.lints.iter_mut() { |
| obj.$name(context, $($param),*); |
| } |
| })* |
| ) |
| } |
| |
| macro_rules! late_lint_pass_impl { |
| ([], [$hir:tt], $methods:tt) => ( |
| impl<'a, $hir> LateLintPass<'a, $hir> for LateLintPassObjects<'_> { |
| expand_late_lint_pass_impl_methods!(['a, $hir], $methods); |
| } |
| ) |
| } |
| |
| crate::late_lint_methods!(late_lint_pass_impl, [], ['tcx]); |
| |
| fn late_lint_mod_pass<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>( |
| tcx: TyCtxt<'tcx>, |
| module_def_id: DefId, |
| pass: T, |
| ) { |
| let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE); |
| |
| let context = LateContext { |
| tcx, |
| tables: &ty::TypeckTables::empty(None), |
| param_env: ty::ParamEnv::empty(), |
| access_levels, |
| lint_store: unerased_lint_store(tcx), |
| last_node_with_lint_attrs: tcx.hir().as_local_hir_id(module_def_id).unwrap(), |
| generics: None, |
| only_module: true, |
| }; |
| |
| let mut cx = LateContextAndPass { context, pass }; |
| |
| let (module, span, hir_id) = tcx.hir().get_module(module_def_id); |
| cx.process_mod(module, span, hir_id); |
| |
| // Visit the crate attributes |
| if hir_id == hir::CRATE_HIR_ID { |
| walk_list!(cx, visit_attribute, tcx.hir().attrs(hir::CRATE_HIR_ID)); |
| } |
| } |
| |
| pub fn late_lint_mod<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>( |
| tcx: TyCtxt<'tcx>, |
| module_def_id: DefId, |
| builtin_lints: T, |
| ) { |
| if tcx.sess.opts.debugging_opts.no_interleave_lints { |
| // These passes runs in late_lint_crate with -Z no_interleave_lints |
| return; |
| } |
| |
| late_lint_mod_pass(tcx, module_def_id, builtin_lints); |
| |
| let mut passes: Vec<_> = |
| unerased_lint_store(tcx).late_module_passes.iter().map(|pass| (pass)()).collect(); |
| |
| if !passes.is_empty() { |
| late_lint_mod_pass(tcx, module_def_id, LateLintPassObjects { lints: &mut passes[..] }); |
| } |
| } |
| |
| fn late_lint_pass_crate<'tcx, T: for<'a> LateLintPass<'a, 'tcx>>(tcx: TyCtxt<'tcx>, pass: T) { |
| let access_levels = &tcx.privacy_access_levels(LOCAL_CRATE); |
| |
| let krate = tcx.hir().krate(); |
| |
| let context = LateContext { |
| tcx, |
| tables: &ty::TypeckTables::empty(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.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: for<'a> LateLintPass<'a, '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: for<'a> LateLintPass<'a, '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)); |
| }); |
| }); |
| }, |
| ); |
| } |