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`
33 pub use self::Level::*;
34 pub use self::LintSource::*;
37 use std::ascii::AsciiExt;
38 use syntax::codemap::Span;
39 use syntax::visit::FnKind;
42 pub use lint::context::{Context, LintStore, raw_emit_lint, check_crate, gather_attrs};
44 /// Specification of a single lint.
47 /// A string identifier for the lint.
49 /// This identifies the lint in attributes and in command-line arguments.
50 /// In those contexts it is always lowercase, but this field is compared
51 /// in a way which is case-insensitive for ASCII characters. This allows
52 /// `declare_lint!()` invocations to follow the convention of upper-case
53 /// statics without repeating the name.
55 /// The name is written with underscores, e.g. "unused_imports".
56 /// On the command line, underscores become dashes.
57 pub name: &'static str,
59 /// Default level for the lint.
60 pub default_level: Level,
62 /// Description of the lint or the issue it detects.
64 /// e.g. "imports that are never used"
65 pub desc: &'static str,
69 /// Get the lint's name, with ASCII letters converted to lowercase.
70 pub fn name_lower(&self) -> String {
71 self.name.to_ascii_lowercase()
75 /// Build a `Lint` initializer.
77 macro_rules! lint_initializer {
78 ($name:ident, $level:ident, $desc:expr) => (
80 name: stringify!($name),
81 default_level: ::rustc::lint::$level,
87 /// Declare a static item of type `&'static Lint`.
89 macro_rules! declare_lint {
90 // FIXME(#14660): deduplicate
91 (pub $name:ident, $level:ident, $desc:expr) => (
92 pub static $name: &'static ::rustc::lint::Lint
93 = &lint_initializer!($name, $level, $desc);
95 ($name:ident, $level:ident, $desc:expr) => (
96 static $name: &'static ::rustc::lint::Lint
97 = &lint_initializer!($name, $level, $desc);
101 /// Declare a static `LintArray` and return it as an expression.
103 macro_rules! lint_array { ($( $lint:expr ),*) => (
105 #[allow(non_upper_case_globals)]
106 static array: LintArray = &[ $( &$lint ),* ];
111 pub type LintArray = &'static [&'static &'static Lint];
113 /// Trait for types providing lint checks.
115 /// Each `check` method checks a single syntax node, and should not
116 /// invoke methods recursively (unlike `Visitor`). By default they
119 // FIXME: eliminate the duplication with `Visitor`. But this also
120 // contains a few lint-specific methods with no equivalent in `Visitor`.
122 /// Get descriptions of the lints this `LintPass` object can emit.
124 /// NB: there is no enforcement that the object only emits lints it registered.
125 /// And some `rustc` internal `LintPass`es register lints to be emitted by other
126 /// parts of the compiler. If you want enforced access restrictions for your
127 /// `Lint`, make it a private `static` item in its own module.
128 fn get_lints(&self) -> LintArray;
130 fn check_crate(&mut self, _: &Context, _: &ast::Crate) { }
131 fn check_ident(&mut self, _: &Context, _: Span, _: ast::Ident) { }
132 fn check_mod(&mut self, _: &Context, _: &ast::Mod, _: Span, _: ast::NodeId) { }
133 fn check_view_item(&mut self, _: &Context, _: &ast::ViewItem) { }
134 fn check_foreign_item(&mut self, _: &Context, _: &ast::ForeignItem) { }
135 fn check_item(&mut self, _: &Context, _: &ast::Item) { }
136 fn check_local(&mut self, _: &Context, _: &ast::Local) { }
137 fn check_block(&mut self, _: &Context, _: &ast::Block) { }
138 fn check_stmt(&mut self, _: &Context, _: &ast::Stmt) { }
139 fn check_arm(&mut self, _: &Context, _: &ast::Arm) { }
140 fn check_pat(&mut self, _: &Context, _: &ast::Pat) { }
141 fn check_decl(&mut self, _: &Context, _: &ast::Decl) { }
142 fn check_expr(&mut self, _: &Context, _: &ast::Expr) { }
143 fn check_expr_post(&mut self, _: &Context, _: &ast::Expr) { }
144 fn check_ty(&mut self, _: &Context, _: &ast::Ty) { }
145 fn check_generics(&mut self, _: &Context, _: &ast::Generics) { }
146 fn check_fn(&mut self, _: &Context,
147 _: FnKind, _: &ast::FnDecl, _: &ast::Block, _: Span, _: ast::NodeId) { }
148 fn check_ty_method(&mut self, _: &Context, _: &ast::TypeMethod) { }
149 fn check_trait_method(&mut self, _: &Context, _: &ast::TraitItem) { }
150 fn check_struct_def(&mut self, _: &Context,
151 _: &ast::StructDef, _: ast::Ident, _: &ast::Generics, _: ast::NodeId) { }
152 fn check_struct_def_post(&mut self, _: &Context,
153 _: &ast::StructDef, _: ast::Ident, _: &ast::Generics, _: ast::NodeId) { }
154 fn check_struct_field(&mut self, _: &Context, _: &ast::StructField) { }
155 fn check_variant(&mut self, _: &Context, _: &ast::Variant, _: &ast::Generics) { }
156 fn check_variant_post(&mut self, _: &Context, _: &ast::Variant, _: &ast::Generics) { }
157 fn check_opt_lifetime_ref(&mut self, _: &Context, _: Span, _: &Option<ast::Lifetime>) { }
158 fn check_lifetime_ref(&mut self, _: &Context, _: &ast::Lifetime) { }
159 fn check_lifetime_def(&mut self, _: &Context, _: &ast::LifetimeDef) { }
160 fn check_explicit_self(&mut self, _: &Context, _: &ast::ExplicitSelf) { }
161 fn check_mac(&mut self, _: &Context, _: &ast::Mac) { }
162 fn check_path(&mut self, _: &Context, _: &ast::Path, _: ast::NodeId) { }
163 fn check_attribute(&mut self, _: &Context, _: &ast::Attribute) { }
165 /// Called when entering a syntax node that can have lint attributes such
166 /// as `#[allow(...)]`. Called with *all* the attributes of that node.
167 fn enter_lint_attrs(&mut self, _: &Context, _: &[ast::Attribute]) { }
169 /// Counterpart to `enter_lint_attrs`.
170 fn exit_lint_attrs(&mut self, _: &Context, _: &[ast::Attribute]) { }
173 /// A lint pass boxed up as a trait object.
174 pub type LintPassObject = Box<LintPass + 'static>;
176 /// Identifies a lint known to the compiler.
177 #[derive(Clone, Copy)]
179 // Identity is based on pointer equality of this field.
183 impl PartialEq for LintId {
184 fn eq(&self, other: &LintId) -> bool {
185 (self.lint as *const Lint) == (other.lint as *const Lint)
189 impl Eq for LintId { }
191 impl<S: hash::Writer> hash::Hash<S> for LintId {
192 fn hash(&self, state: &mut S) {
193 let ptr = self.lint as *const Lint;
199 /// Get the `LintId` for a `Lint`.
200 pub fn of(lint: &'static Lint) -> LintId {
206 /// Get the name of the lint.
207 pub fn as_str(&self) -> String {
208 self.lint.name_lower()
212 /// Setting for how to handle a lint.
213 #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord)]
215 Allow, Warn, Deny, Forbid
219 /// Convert a level to a lower-case string.
220 pub fn as_str(self) -> &'static str {
229 /// Convert a lower-case string to a level.
230 pub fn from_str(x: &str) -> Option<Level> {
232 "allow" => Some(Allow),
233 "warn" => Some(Warn),
234 "deny" => Some(Deny),
235 "forbid" => Some(Forbid),
241 /// How a lint level was set.
242 #[derive(Clone, Copy, PartialEq, Eq)]
243 pub enum LintSource {
244 /// Lint is at the default level as declared
245 /// in rustc or a plugin.
248 /// Lint level was set by an attribute.
251 /// Lint level was set by a command-line flag.
255 pub type LevelSource = (Level, LintSource);