593 lines
22 KiB
Rust
593 lines
22 KiB
Rust
//! Lints, aka compiler warnings.
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//!
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//! A 'lint' check is a kind of miscellaneous constraint that a user _might_
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//! want to enforce, but might reasonably want to permit as well, on a
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//! module-by-module basis. They contrast with static constraints enforced by
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//! other phases of the compiler, which are generally required to hold in order
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//! to compile the program at all.
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//!
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//! Most lints can be written as `LintPass` instances. These run after
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//! all other analyses. The `LintPass`es built into rustc are defined
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//! within `builtin.rs`, which has further comments on how to add such a lint.
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//! rustc can also load user-defined lint plugins via the plugin mechanism.
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//!
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//! Some of rustc's lints are defined elsewhere in the compiler and work by
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//! calling `add_lint()` on the overall `Session` object. This works when
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//! it happens before the main lint pass, which emits the lints stored by
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//! `add_lint()`. To emit lints after the main lint pass (from codegen, for
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//! example) requires more effort. See `emit_lint` and `GatherNodeLevels`
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//! in `context.rs`.
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pub use self::Level::*;
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pub use self::LintSource::*;
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use crate::lint::builtin::BuiltinLintDiagnostics;
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use crate::ty::TyCtxt;
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use rustc_data_structures::sync;
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use rustc_errors::{DiagnosticBuilder, DiagnosticId};
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use rustc_hir as hir;
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use rustc_session::node_id::NodeMap;
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use rustc_session::{DiagnosticMessageId, Session};
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use rustc_span::hygiene::MacroKind;
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use rustc_span::source_map::{DesugaringKind, ExpnKind, MultiSpan};
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use rustc_span::symbol::Symbol;
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use rustc_span::Span;
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use syntax::ast;
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pub use crate::lint::context::{
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BufferedEarlyLint, CheckLintNameResult, EarlyContext, LateContext, LintContext, LintStore,
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};
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pub use rustc_session::lint::{FutureIncompatibleInfo, Level, Lint, LintId};
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/// Declares a static `LintArray` and return it as an expression.
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#[macro_export]
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macro_rules! lint_array {
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($( $lint:expr ),* ,) => { lint_array!( $($lint),* ) };
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($( $lint:expr ),*) => {{
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vec![$($lint),*]
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}}
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}
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pub type LintArray = Vec<&'static Lint>;
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pub trait LintPass {
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fn name(&self) -> &'static str;
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}
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/// Implements `LintPass for $name` with the given list of `Lint` statics.
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#[macro_export]
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macro_rules! impl_lint_pass {
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($name:ident => [$($lint:expr),* $(,)?]) => {
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impl LintPass for $name {
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fn name(&self) -> &'static str { stringify!($name) }
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}
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impl $name {
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pub fn get_lints() -> LintArray { $crate::lint_array!($($lint),*) }
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}
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};
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}
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/// Declares a type named `$name` which implements `LintPass`.
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/// To the right of `=>` a comma separated list of `Lint` statics is given.
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#[macro_export]
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macro_rules! declare_lint_pass {
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($(#[$m:meta])* $name:ident => [$($lint:expr),* $(,)?]) => {
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$(#[$m])* #[derive(Copy, Clone)] pub struct $name;
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$crate::impl_lint_pass!($name => [$($lint),*]);
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};
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}
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#[macro_export]
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macro_rules! late_lint_methods {
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($macro:path, $args:tt, [$hir:tt]) => (
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$macro!($args, [$hir], [
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fn check_param(a: &$hir hir::Param<$hir>);
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fn check_body(a: &$hir hir::Body<$hir>);
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fn check_body_post(a: &$hir hir::Body<$hir>);
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fn check_name(a: Span, b: ast::Name);
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fn check_crate(a: &$hir hir::Crate<$hir>);
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fn check_crate_post(a: &$hir hir::Crate<$hir>);
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fn check_mod(a: &$hir hir::Mod<$hir>, b: Span, c: hir::HirId);
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fn check_mod_post(a: &$hir hir::Mod<$hir>, b: Span, c: hir::HirId);
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fn check_foreign_item(a: &$hir hir::ForeignItem<$hir>);
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fn check_foreign_item_post(a: &$hir hir::ForeignItem<$hir>);
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fn check_item(a: &$hir hir::Item<$hir>);
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fn check_item_post(a: &$hir hir::Item<$hir>);
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fn check_local(a: &$hir hir::Local<$hir>);
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fn check_block(a: &$hir hir::Block<$hir>);
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fn check_block_post(a: &$hir hir::Block<$hir>);
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fn check_stmt(a: &$hir hir::Stmt<$hir>);
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fn check_arm(a: &$hir hir::Arm<$hir>);
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fn check_pat(a: &$hir hir::Pat<$hir>);
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fn check_expr(a: &$hir hir::Expr<$hir>);
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fn check_expr_post(a: &$hir hir::Expr<$hir>);
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fn check_ty(a: &$hir hir::Ty<$hir>);
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fn check_generic_param(a: &$hir hir::GenericParam<$hir>);
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fn check_generics(a: &$hir hir::Generics<$hir>);
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fn check_where_predicate(a: &$hir hir::WherePredicate<$hir>);
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fn check_poly_trait_ref(a: &$hir hir::PolyTraitRef<$hir>, b: hir::TraitBoundModifier);
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fn check_fn(
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a: rustc_hir::intravisit::FnKind<$hir>,
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b: &$hir hir::FnDecl<$hir>,
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c: &$hir hir::Body<$hir>,
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d: Span,
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e: hir::HirId);
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fn check_fn_post(
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a: rustc_hir::intravisit::FnKind<$hir>,
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b: &$hir hir::FnDecl<$hir>,
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c: &$hir hir::Body<$hir>,
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d: Span,
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e: hir::HirId
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);
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fn check_trait_item(a: &$hir hir::TraitItem<$hir>);
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fn check_trait_item_post(a: &$hir hir::TraitItem<$hir>);
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fn check_impl_item(a: &$hir hir::ImplItem<$hir>);
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fn check_impl_item_post(a: &$hir hir::ImplItem<$hir>);
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fn check_struct_def(a: &$hir hir::VariantData<$hir>);
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fn check_struct_def_post(a: &$hir hir::VariantData<$hir>);
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fn check_struct_field(a: &$hir hir::StructField<$hir>);
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fn check_variant(a: &$hir hir::Variant<$hir>);
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fn check_variant_post(a: &$hir hir::Variant<$hir>);
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fn check_lifetime(a: &$hir hir::Lifetime);
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fn check_path(a: &$hir hir::Path<$hir>, b: hir::HirId);
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fn check_attribute(a: &$hir ast::Attribute);
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/// Called when entering a syntax node that can have lint attributes such
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/// as `#[allow(...)]`. Called with *all* the attributes of that node.
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fn enter_lint_attrs(a: &$hir [ast::Attribute]);
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/// Counterpart to `enter_lint_attrs`.
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fn exit_lint_attrs(a: &$hir [ast::Attribute]);
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]);
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)
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}
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/// Trait for types providing lint checks.
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///
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/// Each `check` method checks a single syntax node, and should not
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/// invoke methods recursively (unlike `Visitor`). By default they
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/// do nothing.
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//
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// FIXME: eliminate the duplication with `Visitor`. But this also
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// contains a few lint-specific methods with no equivalent in `Visitor`.
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macro_rules! expand_lint_pass_methods {
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($context:ty, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
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$(#[inline(always)] fn $name(&mut self, _: $context, $(_: $arg),*) {})*
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)
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}
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macro_rules! declare_late_lint_pass {
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([], [$hir:tt], [$($methods:tt)*]) => (
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pub trait LateLintPass<'a, $hir>: LintPass {
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expand_lint_pass_methods!(&LateContext<'a, $hir>, [$($methods)*]);
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}
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)
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}
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late_lint_methods!(declare_late_lint_pass, [], ['tcx]);
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#[macro_export]
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macro_rules! expand_combined_late_lint_pass_method {
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([$($passes:ident),*], $self: ident, $name: ident, $params:tt) => ({
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$($self.$passes.$name $params;)*
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})
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}
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#[macro_export]
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macro_rules! expand_combined_late_lint_pass_methods {
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($passes:tt, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
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$(fn $name(&mut self, context: &LateContext<'a, 'tcx>, $($param: $arg),*) {
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expand_combined_late_lint_pass_method!($passes, self, $name, (context, $($param),*));
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})*
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)
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}
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#[macro_export]
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macro_rules! declare_combined_late_lint_pass {
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([$v:vis $name:ident, [$($passes:ident: $constructor:expr,)*]], [$hir:tt], $methods:tt) => (
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#[allow(non_snake_case)]
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$v struct $name {
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$($passes: $passes,)*
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}
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impl $name {
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$v fn new() -> Self {
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Self {
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$($passes: $constructor,)*
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}
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}
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$v fn get_lints() -> LintArray {
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let mut lints = Vec::new();
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$(lints.extend_from_slice(&$passes::get_lints());)*
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lints
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}
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}
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impl<'a, 'tcx> LateLintPass<'a, 'tcx> for $name {
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expand_combined_late_lint_pass_methods!([$($passes),*], $methods);
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}
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impl LintPass for $name {
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fn name(&self) -> &'static str {
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panic!()
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}
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}
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)
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}
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#[macro_export]
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macro_rules! early_lint_methods {
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($macro:path, $args:tt) => (
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$macro!($args, [
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fn check_param(a: &ast::Param);
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fn check_ident(a: ast::Ident);
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fn check_crate(a: &ast::Crate);
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fn check_crate_post(a: &ast::Crate);
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fn check_mod(a: &ast::Mod, b: Span, c: ast::NodeId);
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fn check_mod_post(a: &ast::Mod, b: Span, c: ast::NodeId);
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fn check_foreign_item(a: &ast::ForeignItem);
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fn check_foreign_item_post(a: &ast::ForeignItem);
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fn check_item(a: &ast::Item);
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fn check_item_post(a: &ast::Item);
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fn check_local(a: &ast::Local);
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fn check_block(a: &ast::Block);
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fn check_block_post(a: &ast::Block);
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fn check_stmt(a: &ast::Stmt);
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fn check_arm(a: &ast::Arm);
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fn check_pat(a: &ast::Pat);
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fn check_pat_post(a: &ast::Pat);
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fn check_expr(a: &ast::Expr);
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fn check_expr_post(a: &ast::Expr);
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fn check_ty(a: &ast::Ty);
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fn check_generic_param(a: &ast::GenericParam);
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fn check_generics(a: &ast::Generics);
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fn check_where_predicate(a: &ast::WherePredicate);
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fn check_poly_trait_ref(a: &ast::PolyTraitRef,
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b: &ast::TraitBoundModifier);
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fn check_fn(a: syntax::visit::FnKind<'_>, b: &ast::FnDecl, c: Span, d_: ast::NodeId);
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fn check_fn_post(
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a: syntax::visit::FnKind<'_>,
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b: &ast::FnDecl,
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c: Span,
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d: ast::NodeId
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);
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fn check_trait_item(a: &ast::AssocItem);
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fn check_trait_item_post(a: &ast::AssocItem);
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fn check_impl_item(a: &ast::AssocItem);
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fn check_impl_item_post(a: &ast::AssocItem);
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fn check_struct_def(a: &ast::VariantData);
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fn check_struct_def_post(a: &ast::VariantData);
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fn check_struct_field(a: &ast::StructField);
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fn check_variant(a: &ast::Variant);
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fn check_variant_post(a: &ast::Variant);
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fn check_lifetime(a: &ast::Lifetime);
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fn check_path(a: &ast::Path, b: ast::NodeId);
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fn check_attribute(a: &ast::Attribute);
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fn check_mac_def(a: &ast::MacroDef, b: ast::NodeId);
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fn check_mac(a: &ast::Mac);
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/// Called when entering a syntax node that can have lint attributes such
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/// as `#[allow(...)]`. Called with *all* the attributes of that node.
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fn enter_lint_attrs(a: &[ast::Attribute]);
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/// Counterpart to `enter_lint_attrs`.
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fn exit_lint_attrs(a: &[ast::Attribute]);
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]);
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)
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}
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macro_rules! expand_early_lint_pass_methods {
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($context:ty, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
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$(#[inline(always)] fn $name(&mut self, _: $context, $(_: $arg),*) {})*
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)
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}
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macro_rules! declare_early_lint_pass {
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([], [$($methods:tt)*]) => (
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pub trait EarlyLintPass: LintPass {
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expand_early_lint_pass_methods!(&EarlyContext<'_>, [$($methods)*]);
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}
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)
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}
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early_lint_methods!(declare_early_lint_pass, []);
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#[macro_export]
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macro_rules! expand_combined_early_lint_pass_method {
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([$($passes:ident),*], $self: ident, $name: ident, $params:tt) => ({
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$($self.$passes.$name $params;)*
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})
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}
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#[macro_export]
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macro_rules! expand_combined_early_lint_pass_methods {
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($passes:tt, [$($(#[$attr:meta])* fn $name:ident($($param:ident: $arg:ty),*);)*]) => (
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$(fn $name(&mut self, context: &EarlyContext<'_>, $($param: $arg),*) {
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expand_combined_early_lint_pass_method!($passes, self, $name, (context, $($param),*));
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})*
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)
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}
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#[macro_export]
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macro_rules! declare_combined_early_lint_pass {
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([$v:vis $name:ident, [$($passes:ident: $constructor:expr,)*]], $methods:tt) => (
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#[allow(non_snake_case)]
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$v struct $name {
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$($passes: $passes,)*
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}
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impl $name {
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$v fn new() -> Self {
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Self {
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$($passes: $constructor,)*
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}
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}
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$v fn get_lints() -> LintArray {
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let mut lints = Vec::new();
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$(lints.extend_from_slice(&$passes::get_lints());)*
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lints
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}
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}
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impl EarlyLintPass for $name {
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expand_combined_early_lint_pass_methods!([$($passes),*], $methods);
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}
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impl LintPass for $name {
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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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)
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}
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/// A lint pass boxed up as a trait object.
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pub type EarlyLintPassObject = Box<dyn EarlyLintPass + sync::Send + sync::Sync + 'static>;
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pub type LateLintPassObject =
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Box<dyn for<'a, 'tcx> LateLintPass<'a, 'tcx> + sync::Send + sync::Sync + 'static>;
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/// How a lint level was set.
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#[derive(Clone, Copy, PartialEq, Eq, HashStable)]
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pub enum LintSource {
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/// Lint is at the default level as declared
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/// in rustc or a plugin.
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Default,
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/// Lint level was set by an attribute.
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Node(ast::Name, Span, Option<Symbol> /* RFC 2383 reason */),
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/// Lint level was set by a command-line flag.
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CommandLine(Symbol),
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}
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pub type LevelSource = (Level, LintSource);
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pub mod builtin;
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mod context;
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pub mod internal;
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mod levels;
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pub use self::levels::{LintLevelMap, LintLevelSets, LintLevelsBuilder};
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#[derive(Default)]
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pub struct LintBuffer {
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pub map: NodeMap<Vec<BufferedEarlyLint>>,
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}
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impl LintBuffer {
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pub fn add_lint(
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&mut self,
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lint: &'static Lint,
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id: ast::NodeId,
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sp: MultiSpan,
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msg: &str,
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diagnostic: BuiltinLintDiagnostics,
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) {
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let early_lint = BufferedEarlyLint {
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lint_id: LintId::of(lint),
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ast_id: id,
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span: sp,
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msg: msg.to_string(),
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diagnostic,
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};
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let arr = self.map.entry(id).or_default();
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if !arr.contains(&early_lint) {
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arr.push(early_lint);
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}
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}
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pub fn take(&mut self, id: ast::NodeId) -> Vec<BufferedEarlyLint> {
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self.map.remove(&id).unwrap_or_default()
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}
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pub fn buffer_lint<S: Into<MultiSpan>>(
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&mut self,
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lint: &'static Lint,
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id: ast::NodeId,
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sp: S,
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msg: &str,
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) {
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self.add_lint(lint, id, sp.into(), msg, BuiltinLintDiagnostics::Normal)
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}
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pub fn buffer_lint_with_diagnostic<S: Into<MultiSpan>>(
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&mut self,
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lint: &'static Lint,
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id: ast::NodeId,
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sp: S,
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msg: &str,
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diagnostic: BuiltinLintDiagnostics,
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) {
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self.add_lint(lint, id, sp.into(), msg, diagnostic)
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}
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}
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pub fn struct_lint_level<'a>(
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sess: &'a Session,
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lint: &'static Lint,
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level: Level,
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src: LintSource,
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span: Option<MultiSpan>,
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msg: &str,
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) -> DiagnosticBuilder<'a> {
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let mut err = match (level, span) {
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(Level::Allow, _) => return sess.diagnostic().struct_dummy(),
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(Level::Warn, Some(span)) => sess.struct_span_warn(span, msg),
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(Level::Warn, None) => sess.struct_warn(msg),
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(Level::Deny, Some(span)) | (Level::Forbid, Some(span)) => sess.struct_span_err(span, msg),
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(Level::Deny, None) | (Level::Forbid, None) => sess.struct_err(msg),
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};
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// Check for future incompatibility lints and issue a stronger warning.
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let lint_id = LintId::of(lint);
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let future_incompatible = lint.future_incompatible;
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|
|
// If this code originates in a foreign macro, aka something that this crate
|
|
// did not itself author, then it's likely that there's nothing this crate
|
|
// can do about it. We probably want to skip the lint entirely.
|
|
if err.span.primary_spans().iter().any(|s| in_external_macro(sess, *s)) {
|
|
// Any suggestions made here are likely to be incorrect, so anything we
|
|
// emit shouldn't be automatically fixed by rustfix.
|
|
err.allow_suggestions(false);
|
|
|
|
// If this is a future incompatible lint it'll become a hard error, so
|
|
// we have to emit *something*. Also allow lints to whitelist themselves
|
|
// on a case-by-case basis for emission in a foreign macro.
|
|
if future_incompatible.is_none() && !lint.report_in_external_macro {
|
|
err.cancel();
|
|
// Don't continue further, since we don't want to have
|
|
// `diag_span_note_once` called for a diagnostic that isn't emitted.
|
|
return err;
|
|
}
|
|
}
|
|
|
|
let name = lint.name_lower();
|
|
match src {
|
|
LintSource::Default => {
|
|
sess.diag_note_once(
|
|
&mut err,
|
|
DiagnosticMessageId::from(lint),
|
|
&format!("`#[{}({})]` on by default", level.as_str(), name),
|
|
);
|
|
}
|
|
LintSource::CommandLine(lint_flag_val) => {
|
|
let flag = match level {
|
|
Level::Warn => "-W",
|
|
Level::Deny => "-D",
|
|
Level::Forbid => "-F",
|
|
Level::Allow => panic!(),
|
|
};
|
|
let hyphen_case_lint_name = name.replace("_", "-");
|
|
if lint_flag_val.as_str() == name {
|
|
sess.diag_note_once(
|
|
&mut err,
|
|
DiagnosticMessageId::from(lint),
|
|
&format!(
|
|
"requested on the command line with `{} {}`",
|
|
flag, hyphen_case_lint_name
|
|
),
|
|
);
|
|
} else {
|
|
let hyphen_case_flag_val = lint_flag_val.as_str().replace("_", "-");
|
|
sess.diag_note_once(
|
|
&mut err,
|
|
DiagnosticMessageId::from(lint),
|
|
&format!(
|
|
"`{} {}` implied by `{} {}`",
|
|
flag, hyphen_case_lint_name, flag, hyphen_case_flag_val
|
|
),
|
|
);
|
|
}
|
|
}
|
|
LintSource::Node(lint_attr_name, src, reason) => {
|
|
if let Some(rationale) = reason {
|
|
err.note(&rationale.as_str());
|
|
}
|
|
sess.diag_span_note_once(
|
|
&mut err,
|
|
DiagnosticMessageId::from(lint),
|
|
src,
|
|
"lint level defined here",
|
|
);
|
|
if lint_attr_name.as_str() != name {
|
|
let level_str = level.as_str();
|
|
sess.diag_note_once(
|
|
&mut err,
|
|
DiagnosticMessageId::from(lint),
|
|
&format!(
|
|
"`#[{}({})]` implied by `#[{}({})]`",
|
|
level_str, name, level_str, lint_attr_name
|
|
),
|
|
);
|
|
}
|
|
}
|
|
}
|
|
|
|
err.code(DiagnosticId::Lint(name));
|
|
|
|
if let Some(future_incompatible) = future_incompatible {
|
|
const STANDARD_MESSAGE: &str = "this was previously accepted by the compiler but is being phased out; \
|
|
it will become a hard error";
|
|
|
|
let explanation = if lint_id == LintId::of(builtin::UNSTABLE_NAME_COLLISIONS) {
|
|
"once this method is added to the standard library, \
|
|
the ambiguity may cause an error or change in behavior!"
|
|
.to_owned()
|
|
} else if lint_id == LintId::of(builtin::MUTABLE_BORROW_RESERVATION_CONFLICT) {
|
|
"this borrowing pattern was not meant to be accepted, \
|
|
and may become a hard error in the future"
|
|
.to_owned()
|
|
} else if let Some(edition) = future_incompatible.edition {
|
|
format!("{} in the {} edition!", STANDARD_MESSAGE, edition)
|
|
} else {
|
|
format!("{} in a future release!", STANDARD_MESSAGE)
|
|
};
|
|
let citation = format!("for more information, see {}", future_incompatible.reference);
|
|
err.warn(&explanation);
|
|
err.note(&citation);
|
|
}
|
|
|
|
return err;
|
|
}
|
|
|
|
pub fn maybe_lint_level_root(tcx: TyCtxt<'_>, id: hir::HirId) -> bool {
|
|
let attrs = tcx.hir().attrs(id);
|
|
attrs.iter().any(|attr| Level::from_symbol(attr.name_or_empty()).is_some())
|
|
}
|
|
|
|
/// Returns whether `span` originates in a foreign crate's external macro.
|
|
///
|
|
/// This is used to test whether a lint should not even begin to figure out whether it should
|
|
/// be reported on the current node.
|
|
pub fn in_external_macro(sess: &Session, span: Span) -> bool {
|
|
let expn_data = span.ctxt().outer_expn_data();
|
|
match expn_data.kind {
|
|
ExpnKind::Root | ExpnKind::Desugaring(DesugaringKind::ForLoop) => false,
|
|
ExpnKind::AstPass(_) | ExpnKind::Desugaring(_) => true, // well, it's "external"
|
|
ExpnKind::Macro(MacroKind::Bang, _) => {
|
|
if expn_data.def_site.is_dummy() {
|
|
// Dummy span for the `def_site` means it's an external macro.
|
|
return true;
|
|
}
|
|
match sess.source_map().span_to_snippet(expn_data.def_site) {
|
|
Ok(code) => !code.starts_with("macro_rules"),
|
|
// No snippet means external macro or compiler-builtin expansion.
|
|
Err(_) => true,
|
|
}
|
|
}
|
|
ExpnKind::Macro(..) => true, // definitely a plugin
|
|
}
|
|
}
|
|
|
|
/// Returns `true` if `span` originates in a derive-macro's expansion.
|
|
pub fn in_derive_expansion(span: Span) -> bool {
|
|
if let ExpnKind::Macro(MacroKind::Derive, _) = span.ctxt().outer_expn_data().kind {
|
|
return true;
|
|
}
|
|
false
|
|
}
|