src/librustc_session/lint.rs

   1 pub use self::Level::*;
   2 use rustc_ast::node_id::{NodeId, NodeMap};
   3 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
   4 use rustc_span::edition::Edition;
   5 use rustc_span::{sym, symbol::Ident, MultiSpan, Span, Symbol};
   6
   7 pub mod builtin;
   8
   9 /// Setting for how to handle a lint.
  10 #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
  11 pub enum Level {
  12     Allow,
  13     Warn,
  14     Deny,
  15     Forbid,
  16 }
  17
  18 rustc_data_structures::impl_stable_hash_via_hash!(Level);
  19
  20 impl Level {
  21     /// Converts a level to a lower-case string.
  22     pub fn as_str(self) -> &'static str {
  23         match self {
  24             Level::Allow => "allow",
  25             Level::Warn => "warn",
  26             Level::Deny => "deny",
  27             Level::Forbid => "forbid",
  28         }
  29     }
  30
  31     /// Converts a lower-case string to a level.
  32     pub fn from_str(x: &str) -> Option<Level> {
  33         match x {
  34             "allow" => Some(Level::Allow),
  35             "warn" => Some(Level::Warn),
  36             "deny" => Some(Level::Deny),
  37             "forbid" => Some(Level::Forbid),
  38             _ => None,
  39         }
  40     }
  41
  42     /// Converts a symbol to a level.
  43     pub fn from_symbol(x: Symbol) -> Option<Level> {
  44         match x {
  45             sym::allow => Some(Level::Allow),
  46             sym::warn => Some(Level::Warn),
  47             sym::deny => Some(Level::Deny),
  48             sym::forbid => Some(Level::Forbid),
  49             _ => None,
  50         }
  51     }
  52 }
  53
  54 /// Specification of a single lint.
  55 #[derive(Copy, Clone, Debug)]
  56 pub struct Lint {
  57     /// A string identifier for the lint.
  58     ///
  59     /// This identifies the lint in attributes and in command-line arguments.
  60     /// In those contexts it is always lowercase, but this field is compared
  61     /// in a way which is case-insensitive for ASCII characters. This allows
  62     /// `declare_lint!()` invocations to follow the convention of upper-case
  63     /// statics without repeating the name.
  64     ///
  65     /// The name is written with underscores, e.g., "unused_imports".
  66     /// On the command line, underscores become dashes.
  67     pub name: &'static str,
  68
  69     /// Default level for the lint.
  70     pub default_level: Level,
  71
  72     /// Description of the lint or the issue it detects.
  73     ///
  74     /// e.g., "imports that are never used"
  75     pub desc: &'static str,
  76
  77     /// Starting at the given edition, default to the given lint level. If this is `None`, then use
  78     /// `default_level`.
  79     pub edition_lint_opts: Option<(Edition, Level)>,
  80
  81     /// `true` if this lint is reported even inside expansions of external macros.
  82     pub report_in_external_macro: bool,
  83
  84     pub future_incompatible: Option<FutureIncompatibleInfo>,
  85
  86     pub is_plugin: bool,
  87 }
  88
  89 /// Extra information for a future incompatibility lint.
  90 #[derive(Copy, Clone, Debug)]
  91 pub struct FutureIncompatibleInfo {
  92     /// e.g., a URL for an issue/PR/RFC or error code
  93     pub reference: &'static str,
  94     /// If this is an edition fixing lint, the edition in which
  95     /// this lint becomes obsolete
  96     pub edition: Option<Edition>,
  97 }
  98
  99 impl Lint {
 100     pub const fn default_fields_for_macro() -> Self {
 101         Lint {
 102             name: "",
 103             default_level: Level::Forbid,
 104             desc: "",
 105             edition_lint_opts: None,
 106             is_plugin: false,
 107             report_in_external_macro: false,
 108             future_incompatible: None,
 109         }
 110     }
 111
 112     /// Gets the lint's name, with ASCII letters converted to lowercase.
 113     pub fn name_lower(&self) -> String {
 114         self.name.to_ascii_lowercase()
 115     }
 116
 117     pub fn default_level(&self, edition: Edition) -> Level {
 118         self.edition_lint_opts
 119             .filter(|(e, _)| *e <= edition)
 120             .map(|(_, l)| l)
 121             .unwrap_or(self.default_level)
 122     }
 123 }
 124
 125 /// Identifies a lint known to the compiler.
 126 #[derive(Clone, Copy, Debug)]
 127 pub struct LintId {
 128     // Identity is based on pointer equality of this field.
 129     pub lint: &'static Lint,
 130 }
 131
 132 impl PartialEq for LintId {
 133     fn eq(&self, other: &LintId) -> bool {
 134         std::ptr::eq(self.lint, other.lint)
 135     }
 136 }
 137
 138 impl Eq for LintId {}
 139
 140 impl std::hash::Hash for LintId {
 141     fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 142         let ptr = self.lint as *const Lint;
 143         ptr.hash(state);
 144     }
 145 }
 146
 147 impl LintId {
 148     /// Gets the `LintId` for a `Lint`.
 149     pub fn of(lint: &'static Lint) -> LintId {
 150         LintId { lint }
 151     }
 152
 153     pub fn lint_name_raw(&self) -> &'static str {
 154         self.lint.name
 155     }
 156
 157     /// Gets the name of the lint.
 158     pub fn to_string(&self) -> String {
 159         self.lint.name_lower()
 160     }
 161 }
 162
 163 impl<HCX> HashStable<HCX> for LintId {
 164     #[inline]
 165     fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
 166         self.lint_name_raw().hash_stable(hcx, hasher);
 167     }
 168 }
 169
 170 impl<HCX> ToStableHashKey<HCX> for LintId {
 171     type KeyType = &'static str;
 172
 173     #[inline]
 174     fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
 175         self.lint_name_raw()
 176     }
 177 }
 178
 179 // This could be a closure, but then implementing derive trait
 180 // becomes hacky (and it gets allocated).
 181 #[derive(PartialEq)]
 182 pub enum BuiltinLintDiagnostics {
 183     Normal,
 184     BareTraitObject(Span, /* is_global */ bool),
 185     AbsPathWithModule(Span),
 186     ProcMacroDeriveResolutionFallback(Span),
 187     MacroExpandedMacroExportsAccessedByAbsolutePaths(Span),
 188     ElidedLifetimesInPaths(usize, Span, bool, Span, String),
 189     UnknownCrateTypes(Span, String, String),
 190     UnusedImports(String, Vec<(Span, String)>),
 191     RedundantImport(Vec<(Span, bool)>, Ident),
 192     DeprecatedMacro(Option<Symbol>, Span),
 193     UnusedDocComment(Span),
 194 }
 195
 196 /// Lints that are buffered up early on in the `Session` before the
 197 /// `LintLevels` is calculated. These are later passed to `librustc`.
 198 #[derive(PartialEq)]
 199 pub struct BufferedEarlyLint {
 200     /// The span of code that we are linting on.
 201     pub span: MultiSpan,
 202
 203     /// The lint message.
 204     pub msg: String,
 205
 206     /// The `NodeId` of the AST node that generated the lint.
 207     pub node_id: NodeId,
 208
 209     /// A lint Id that can be passed to `rustc::lint::Lint::from_parser_lint_id`.
 210     pub lint_id: LintId,
 211
 212     /// Customization of the `DiagnosticBuilder<'_>` for the lint.
 213     pub diagnostic: BuiltinLintDiagnostics,
 214 }
 215
 216 #[derive(Default)]
 217 pub struct LintBuffer {
 218     pub map: NodeMap<Vec<BufferedEarlyLint>>,
 219 }
 220
 221 impl LintBuffer {
 222     pub fn add_early_lint(&mut self, early_lint: BufferedEarlyLint) {
 223         let arr = self.map.entry(early_lint.node_id).or_default();
 224         if !arr.contains(&early_lint) {
 225             arr.push(early_lint);
 226         }
 227     }
 228
 229     pub fn add_lint(
 230         &mut self,
 231         lint: &'static Lint,
 232         node_id: NodeId,
 233         span: MultiSpan,
 234         msg: &str,
 235         diagnostic: BuiltinLintDiagnostics,
 236     ) {
 237         let lint_id = LintId::of(lint);
 238         let msg = msg.to_string();
 239         self.add_early_lint(BufferedEarlyLint { lint_id, node_id, span, msg, diagnostic });
 240     }
 241
 242     pub fn take(&mut self, id: NodeId) -> Vec<BufferedEarlyLint> {
 243         self.map.remove(&id).unwrap_or_default()
 244     }
 245
 246     pub fn buffer_lint(
 247         &mut self,
 248         lint: &'static Lint,
 249         id: NodeId,
 250         sp: impl Into<MultiSpan>,
 251         msg: &str,
 252     ) {
 253         self.add_lint(lint, id, sp.into(), msg, BuiltinLintDiagnostics::Normal)
 254     }
 255
 256     pub fn buffer_lint_with_diagnostic(
 257         &mut self,
 258         lint: &'static Lint,
 259         id: NodeId,
 260         sp: impl Into<MultiSpan>,
 261         msg: &str,
 262         diagnostic: BuiltinLintDiagnostics,
 263     ) {
 264         self.add_lint(lint, id, sp.into(), msg, diagnostic)
 265     }
 266 }
 267
 268 /// Declares a static item of type `&'static Lint`.
 269 #[macro_export]
 270 macro_rules! declare_lint {
 271     ($vis: vis $NAME: ident, $Level: ident, $desc: expr) => (
 272         $crate::declare_lint!(
 273             $vis $NAME, $Level, $desc,
 274         );
 275     );
 276     ($vis: vis $NAME: ident, $Level: ident, $desc: expr,
 277      $(@future_incompatible = $fi:expr;)? $($v:ident),*) => (
 278         $vis static $NAME: &$crate::lint::Lint = &$crate::lint::Lint {
 279             name: stringify!($NAME),
 280             default_level: $crate::lint::$Level,
 281             desc: $desc,
 282             edition_lint_opts: None,
 283             is_plugin: false,
 284             $($v: true,)*
 285             $(future_incompatible: Some($fi),)*
 286             ..$crate::lint::Lint::default_fields_for_macro()
 287         };
 288     );
 289     ($vis: vis $NAME: ident, $Level: ident, $desc: expr,
 290      $lint_edition: expr => $edition_level: ident
 291     ) => (
 292         $vis static $NAME: &$crate::lint::Lint = &$crate::lint::Lint {
 293             name: stringify!($NAME),
 294             default_level: $crate::lint::$Level,
 295             desc: $desc,
 296             edition_lint_opts: Some(($lint_edition, $crate::lint::Level::$edition_level)),
 297             report_in_external_macro: false,
 298             is_plugin: false,
 299         };
 300     );
 301 }
 302
 303 #[macro_export]
 304 macro_rules! declare_tool_lint {
 305     (
 306         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level: ident, $desc: expr
 307     ) => (
 308         $crate::declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, false}
 309     );
 310     (
 311         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
 312         report_in_external_macro: $rep:expr
 313     ) => (
 314          $crate::declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, $rep}
 315     );
 316     (
 317         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
 318         $external:expr
 319     ) => (
 320         $(#[$attr])*
 321         $vis static $NAME: &$crate::lint::Lint = &$crate::lint::Lint {
 322             name: &concat!(stringify!($tool), "::", stringify!($NAME)),
 323             default_level: $crate::lint::$Level,
 324             desc: $desc,
 325             edition_lint_opts: None,
 326             report_in_external_macro: $external,
 327             future_incompatible: None,
 328             is_plugin: true,
 329         };
 330     );
 331 }
 332
 333 /// Declares a static `LintArray` and return it as an expression.
 334 #[macro_export]
 335 macro_rules! lint_array {
 336     ($( $lint:expr ),* ,) => { lint_array!( $($lint),* ) };
 337     ($( $lint:expr ),*) => {{
 338         vec![$($lint),*]
 339     }}
 340 }
 341
 342 pub type LintArray = Vec<&'static Lint>;
 343
 344 pub trait LintPass {
 345     fn name(&self) -> &'static str;
 346 }
 347
 348 /// Implements `LintPass for $name` with the given list of `Lint` statics.
 349 #[macro_export]
 350 macro_rules! impl_lint_pass {
 351     ($name:ident => [$($lint:expr),* $(,)?]) => {
 352         impl $crate::lint::LintPass for $name {
 353             fn name(&self) -> &'static str { stringify!($name) }
 354         }
 355         impl $name {
 356             pub fn get_lints() -> $crate::lint::LintArray { $crate::lint_array!($($lint),*) }
 357         }
 358     };
 359 }
 360
 361 /// Declares a type named `$name` which implements `LintPass`.
 362 /// To the right of `=>` a comma separated list of `Lint` statics is given.
 363 #[macro_export]
 364 macro_rules! declare_lint_pass {
 365     ($(#[$m:meta])* $name:ident => [$($lint:expr),* $(,)?]) => {
 366         $(#[$m])* #[derive(Copy, Clone)] pub struct $name;
 367         $crate::impl_lint_pass!($name => [$($lint),*]);
 368     };
 369 }