1 // Copyright 2012-2014 The Rust Project Developers. See the COPYRIGHT
2 // file at the top-level directory of this distribution and at
3 // http://rust-lang.org/COPYRIGHT.
5 // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
6 // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
7 // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
8 // option. This file may not be copied, modified, or distributed
9 // except according to those terms.
11 //! Lints, aka compiler warnings.
13 //! A 'lint' check is a kind of miscellaneous constraint that a user _might_
14 //! want to enforce, but might reasonably want to permit as well, on a
15 //! module-by-module basis. They contrast with static constraints enforced by
16 //! other phases of the compiler, which are generally required to hold in order
17 //! to compile the program at all.
19 //! Most lints can be written as `LintPass` instances. These run just before
20 //! translation to LLVM bytecode. The `LintPass`es built into rustc are defined
21 //! within `builtin.rs`, which has further comments on how to add such a lint.
22 //! rustc can also load user-defined lint plugins via the plugin mechanism.
24 //! Some of rustc's lints are defined elsewhere in the compiler and work by
25 //! calling `add_lint()` on the overall `Session` object. This works when
26 //! it happens before the main lint pass, which emits the lints stored by
27 //! `add_lint()`. To emit lints after the main lint pass (from trans, for
28 //! example) requires more effort. See `emit_lint` and `GatherNodeLevels`
31 pub use self::Level::*;
32 pub use self::LintSource::*;
35 use std::ascii::AsciiExt;
36 use syntax::codemap::Span;
37 use rustc_front::visit::FnKind;
38 use syntax::visit as ast_visit;
42 pub use lint::context::{LateContext, EarlyContext, LintContext, LintStore,
43 raw_emit_lint, check_crate, check_ast_crate, gather_attrs,
46 /// Specification of a single lint.
47 #[derive(Copy, Clone, Debug)]
49 /// A string identifier for the lint.
51 /// This identifies the lint in attributes and in command-line arguments.
52 /// In those contexts it is always lowercase, but this field is compared
53 /// in a way which is case-insensitive for ASCII characters. This allows
54 /// `declare_lint!()` invocations to follow the convention of upper-case
55 /// statics without repeating the name.
57 /// The name is written with underscores, e.g. "unused_imports".
58 /// On the command line, underscores become dashes.
59 pub name: &'static str,
61 /// Default level for the lint.
62 pub default_level: Level,
64 /// Description of the lint or the issue it detects.
66 /// e.g. "imports that are never used"
67 pub desc: &'static str,
71 /// Get the lint's name, with ASCII letters converted to lowercase.
72 pub fn name_lower(&self) -> String {
73 self.name.to_ascii_lowercase()
77 /// Build a `Lint` initializer.
79 macro_rules! lint_initializer {
80 ($name:ident, $level:ident, $desc:expr) => (
82 name: stringify!($name),
83 default_level: ::rustc::lint::$level,
89 /// Declare a static item of type `&'static Lint`.
91 macro_rules! declare_lint {
92 // FIXME(#14660): deduplicate
93 (pub $name:ident, $level:ident, $desc:expr) => (
94 pub static $name: &'static ::rustc::lint::Lint
95 = &lint_initializer!($name, $level, $desc);
97 ($name:ident, $level:ident, $desc:expr) => (
98 static $name: &'static ::rustc::lint::Lint
99 = &lint_initializer!($name, $level, $desc);
103 /// Declare a static `LintArray` and return it as an expression.
105 macro_rules! lint_array { ($( $lint:expr ),*) => (
107 static ARRAY: LintArray = &[ $( &$lint ),* ];
112 pub type LintArray = &'static [&'static &'static Lint];
115 /// Get descriptions of the lints this `LintPass` object can emit.
117 /// NB: there is no enforcement that the object only emits lints it registered.
118 /// And some `rustc` internal `LintPass`es register lints to be emitted by other
119 /// parts of the compiler. If you want enforced access restrictions for your
120 /// `Lint`, make it a private `static` item in its own module.
121 fn get_lints(&self) -> LintArray;
125 /// Trait for types providing lint checks.
127 /// Each `check` method checks a single syntax node, and should not
128 /// invoke methods recursively (unlike `Visitor`). By default they
131 // FIXME: eliminate the duplication with `Visitor`. But this also
132 // contains a few lint-specific methods with no equivalent in `Visitor`.
133 pub trait LateLintPass: LintPass {
134 fn check_ident(&mut self, _: &LateContext, _: Span, _: ast::Ident) { }
135 fn check_crate(&mut self, _: &LateContext, _: &hir::Crate) { }
136 fn check_mod(&mut self, _: &LateContext, _: &hir::Mod, _: Span, _: ast::NodeId) { }
137 fn check_foreign_item(&mut self, _: &LateContext, _: &hir::ForeignItem) { }
138 fn check_item(&mut self, _: &LateContext, _: &hir::Item) { }
139 fn check_local(&mut self, _: &LateContext, _: &hir::Local) { }
140 fn check_block(&mut self, _: &LateContext, _: &hir::Block) { }
141 fn check_stmt(&mut self, _: &LateContext, _: &hir::Stmt) { }
142 fn check_arm(&mut self, _: &LateContext, _: &hir::Arm) { }
143 fn check_pat(&mut self, _: &LateContext, _: &hir::Pat) { }
144 fn check_decl(&mut self, _: &LateContext, _: &hir::Decl) { }
145 fn check_expr(&mut self, _: &LateContext, _: &hir::Expr) { }
146 fn check_expr_post(&mut self, _: &LateContext, _: &hir::Expr) { }
147 fn check_ty(&mut self, _: &LateContext, _: &hir::Ty) { }
148 fn check_generics(&mut self, _: &LateContext, _: &hir::Generics) { }
149 fn check_fn(&mut self, _: &LateContext,
150 _: FnKind, _: &hir::FnDecl, _: &hir::Block, _: Span, _: ast::NodeId) { }
151 fn check_trait_item(&mut self, _: &LateContext, _: &hir::TraitItem) { }
152 fn check_impl_item(&mut self, _: &LateContext, _: &hir::ImplItem) { }
153 fn check_struct_def(&mut self, _: &LateContext,
154 _: &hir::StructDef, _: ast::Ident, _: &hir::Generics, _: ast::NodeId) { }
155 fn check_struct_def_post(&mut self, _: &LateContext,
156 _: &hir::StructDef, _: ast::Ident, _: &hir::Generics, _: ast::NodeId) { }
157 fn check_struct_field(&mut self, _: &LateContext, _: &hir::StructField) { }
158 fn check_variant(&mut self, _: &LateContext, _: &hir::Variant, _: &hir::Generics) { }
159 fn check_variant_post(&mut self, _: &LateContext, _: &hir::Variant, _: &hir::Generics) { }
160 fn check_opt_lifetime_ref(&mut self, _: &LateContext, _: Span, _: &Option<hir::Lifetime>) { }
161 fn check_lifetime_ref(&mut self, _: &LateContext, _: &hir::Lifetime) { }
162 fn check_lifetime_def(&mut self, _: &LateContext, _: &hir::LifetimeDef) { }
163 fn check_explicit_self(&mut self, _: &LateContext, _: &hir::ExplicitSelf) { }
164 // Note that you shouldn't implement both check_mac and check_ast_mac,
165 // because then your lint will be called twice. Prefer check_ast_mac.
166 fn check_mac(&mut self, _: &LateContext, _: &ast::Mac) { }
167 fn check_path(&mut self, _: &LateContext, _: &hir::Path, _: ast::NodeId) { }
168 fn check_attribute(&mut self, _: &LateContext, _: &ast::Attribute) { }
170 /// Called when entering a syntax node that can have lint attributes such
171 /// as `#[allow(...)]`. Called with *all* the attributes of that node.
172 fn enter_lint_attrs(&mut self, _: &LateContext, _: &[ast::Attribute]) { }
174 /// Counterpart to `enter_lint_attrs`.
175 fn exit_lint_attrs(&mut self, _: &LateContext, _: &[ast::Attribute]) { }
178 pub trait EarlyLintPass: LintPass {
179 fn check_ident(&mut self, _: &EarlyContext, _: Span, _: ast::Ident) { }
180 fn check_crate(&mut self, _: &EarlyContext, _: &ast::Crate) { }
181 fn check_mod(&mut self, _: &EarlyContext, _: &ast::Mod, _: Span, _: ast::NodeId) { }
182 fn check_foreign_item(&mut self, _: &EarlyContext, _: &ast::ForeignItem) { }
183 fn check_item(&mut self, _: &EarlyContext, _: &ast::Item) { }
184 fn check_local(&mut self, _: &EarlyContext, _: &ast::Local) { }
185 fn check_block(&mut self, _: &EarlyContext, _: &ast::Block) { }
186 fn check_stmt(&mut self, _: &EarlyContext, _: &ast::Stmt) { }
187 fn check_arm(&mut self, _: &EarlyContext, _: &ast::Arm) { }
188 fn check_pat(&mut self, _: &EarlyContext, _: &ast::Pat) { }
189 fn check_decl(&mut self, _: &EarlyContext, _: &ast::Decl) { }
190 fn check_expr(&mut self, _: &EarlyContext, _: &ast::Expr) { }
191 fn check_expr_post(&mut self, _: &EarlyContext, _: &ast::Expr) { }
192 fn check_ty(&mut self, _: &EarlyContext, _: &ast::Ty) { }
193 fn check_generics(&mut self, _: &EarlyContext, _: &ast::Generics) { }
194 fn check_fn(&mut self, _: &EarlyContext,
195 _: ast_visit::FnKind, _: &ast::FnDecl, _: &ast::Block, _: Span, _: ast::NodeId) { }
196 fn check_trait_item(&mut self, _: &EarlyContext, _: &ast::TraitItem) { }
197 fn check_impl_item(&mut self, _: &EarlyContext, _: &ast::ImplItem) { }
198 fn check_struct_def(&mut self, _: &EarlyContext,
199 _: &ast::StructDef, _: ast::Ident, _: &ast::Generics, _: ast::NodeId) { }
200 fn check_struct_def_post(&mut self, _: &EarlyContext,
201 _: &ast::StructDef, _: ast::Ident, _: &ast::Generics, _: ast::NodeId) { }
202 fn check_struct_field(&mut self, _: &EarlyContext, _: &ast::StructField) { }
203 fn check_variant(&mut self, _: &EarlyContext, _: &ast::Variant, _: &ast::Generics) { }
204 fn check_variant_post(&mut self, _: &EarlyContext, _: &ast::Variant, _: &ast::Generics) { }
205 fn check_opt_lifetime_ref(&mut self,
208 _: &Option<ast::Lifetime>) { }
209 fn check_lifetime_ref(&mut self, _: &EarlyContext, _: &ast::Lifetime) { }
210 fn check_lifetime_def(&mut self, _: &EarlyContext, _: &ast::LifetimeDef) { }
211 fn check_explicit_self(&mut self, _: &EarlyContext, _: &ast::ExplicitSelf) { }
212 fn check_mac(&mut self, _: &EarlyContext, _: &ast::Mac) { }
213 fn check_path(&mut self, _: &EarlyContext, _: &ast::Path, _: ast::NodeId) { }
214 fn check_attribute(&mut self, _: &EarlyContext, _: &ast::Attribute) { }
216 /// Called when entering a syntax node that can have lint attributes such
217 /// as `#[allow(...)]`. Called with *all* the attributes of that node.
218 fn enter_lint_attrs(&mut self, _: &EarlyContext, _: &[ast::Attribute]) { }
220 /// Counterpart to `enter_lint_attrs`.
221 fn exit_lint_attrs(&mut self, _: &EarlyContext, _: &[ast::Attribute]) { }
224 /// A lint pass boxed up as a trait object.
225 pub type EarlyLintPassObject = Box<EarlyLintPass + 'static>;
226 pub type LateLintPassObject = Box<LateLintPass + 'static>;
228 /// Identifies a lint known to the compiler.
229 #[derive(Clone, Copy)]
231 // Identity is based on pointer equality of this field.
235 impl PartialEq for LintId {
236 fn eq(&self, other: &LintId) -> bool {
237 (self.lint as *const Lint) == (other.lint as *const Lint)
241 impl Eq for LintId { }
243 impl hash::Hash for LintId {
244 fn hash<H: hash::Hasher>(&self, state: &mut H) {
245 let ptr = self.lint as *const Lint;
251 /// Get the `LintId` for a `Lint`.
252 pub fn of(lint: &'static Lint) -> LintId {
258 /// Get the name of the lint.
259 pub fn as_str(&self) -> String {
260 self.lint.name_lower()
264 /// Setting for how to handle a lint.
265 #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug)]
267 Allow, Warn, Deny, Forbid
271 /// Convert a level to a lower-case string.
272 pub fn as_str(self) -> &'static str {
281 /// Convert a lower-case string to a level.
282 pub fn from_str(x: &str) -> Option<Level> {
284 "allow" => Some(Allow),
285 "warn" => Some(Warn),
286 "deny" => Some(Deny),
287 "forbid" => Some(Forbid),
293 /// How a lint level was set.
294 #[derive(Clone, Copy, PartialEq, Eq)]
295 pub enum LintSource {
296 /// Lint is at the default level as declared
297 /// in rustc or a plugin.
300 /// Lint level was set by an attribute.
303 /// Lint level was set by a command-line flag.
307 pub type LevelSource = (Level, LintSource);