compiler/rustc_lint_defs/src/lib.rs

   1 #[macro_use]
   2 extern crate rustc_macros;
   3
   4 pub use self::Level::*;
   5 use rustc_ast::node_id::{NodeId, NodeMap};
   6 use rustc_data_structures::stable_hasher::{HashStable, StableHasher, ToStableHashKey};
   7 use rustc_span::edition::Edition;
   8 use rustc_span::{sym, symbol::Ident, MultiSpan, Span, Symbol};
   9
  10 pub mod builtin;
  11
  12 #[macro_export]
  13 macro_rules! pluralize {
  14     ($x:expr) => {
  15         if $x != 1 { "s" } else { "" }
  16     };
  17 }
  18
  19 /// Indicates the confidence in the correctness of a suggestion.
  20 ///
  21 /// All suggestions are marked with an `Applicability`. Tools use the applicability of a suggestion
  22 /// to determine whether it should be automatically applied or if the user should be consulted
  23 /// before applying the suggestion.
  24 #[derive(Copy, Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
  25 pub enum Applicability {
  26     /// The suggestion is definitely what the user intended. This suggestion should be
  27     /// automatically applied.
  28     MachineApplicable,
  29
  30     /// The suggestion may be what the user intended, but it is uncertain. The suggestion should
  31     /// result in valid Rust code if it is applied.
  32     MaybeIncorrect,
  33
  34     /// The suggestion contains placeholders like `(...)` or `{ /* fields */ }`. The suggestion
  35     /// cannot be applied automatically because it will not result in valid Rust code. The user
  36     /// will need to fill in the placeholders.
  37     HasPlaceholders,
  38
  39     /// The applicability of the suggestion is unknown.
  40     Unspecified,
  41 }
  42
  43 /// Setting for how to handle a lint.
  44 #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
  45 pub enum Level {
  46     Allow,
  47     Warn,
  48     Deny,
  49     Forbid,
  50 }
  51
  52 rustc_data_structures::impl_stable_hash_via_hash!(Level);
  53
  54 impl Level {
  55     /// Converts a level to a lower-case string.
  56     pub fn as_str(self) -> &'static str {
  57         match self {
  58             Level::Allow => "allow",
  59             Level::Warn => "warn",
  60             Level::Deny => "deny",
  61             Level::Forbid => "forbid",
  62         }
  63     }
  64
  65     /// Converts a lower-case string to a level.
  66     pub fn from_str(x: &str) -> Option<Level> {
  67         match x {
  68             "allow" => Some(Level::Allow),
  69             "warn" => Some(Level::Warn),
  70             "deny" => Some(Level::Deny),
  71             "forbid" => Some(Level::Forbid),
  72             _ => None,
  73         }
  74     }
  75
  76     /// Converts a symbol to a level.
  77     pub fn from_symbol(x: Symbol) -> Option<Level> {
  78         match x {
  79             sym::allow => Some(Level::Allow),
  80             sym::warn => Some(Level::Warn),
  81             sym::deny => Some(Level::Deny),
  82             sym::forbid => Some(Level::Forbid),
  83             _ => None,
  84         }
  85     }
  86 }
  87
  88 /// Specification of a single lint.
  89 #[derive(Copy, Clone, Debug)]
  90 pub struct Lint {
  91     /// A string identifier for the lint.
  92     ///
  93     /// This identifies the lint in attributes and in command-line arguments.
  94     /// In those contexts it is always lowercase, but this field is compared
  95     /// in a way which is case-insensitive for ASCII characters. This allows
  96     /// `declare_lint!()` invocations to follow the convention of upper-case
  97     /// statics without repeating the name.
  98     ///
  99     /// The name is written with underscores, e.g., "unused_imports".
 100     /// On the command line, underscores become dashes.
 101     ///
 102     /// See <https://rustc-dev-guide.rust-lang.org/diagnostics.html#lint-naming>
 103     /// for naming guidelines.
 104     pub name: &'static str,
 105
 106     /// Default level for the lint.
 107     ///
 108     /// See <https://rustc-dev-guide.rust-lang.org/diagnostics.html#diagnostic-levels>
 109     /// for guidelines on choosing a default level.
 110     pub default_level: Level,
 111
 112     /// Description of the lint or the issue it detects.
 113     ///
 114     /// e.g., "imports that are never used"
 115     pub desc: &'static str,
 116
 117     /// Starting at the given edition, default to the given lint level. If this is `None`, then use
 118     /// `default_level`.
 119     pub edition_lint_opts: Option<(Edition, Level)>,
 120
 121     /// `true` if this lint is reported even inside expansions of external macros.
 122     pub report_in_external_macro: bool,
 123
 124     pub future_incompatible: Option<FutureIncompatibleInfo>,
 125
 126     pub is_plugin: bool,
 127
 128     /// `Some` if this lint is feature gated, otherwise `None`.
 129     pub feature_gate: Option<Symbol>,
 130
 131     pub crate_level_only: bool,
 132 }
 133
 134 /// Extra information for a future incompatibility lint.
 135 #[derive(Copy, Clone, Debug)]
 136 pub struct FutureIncompatibleInfo {
 137     /// e.g., a URL for an issue/PR/RFC or error code
 138     pub reference: &'static str,
 139     /// If this is an edition fixing lint, the edition in which
 140     /// this lint becomes obsolete
 141     pub edition: Option<Edition>,
 142     /// Information about a future breakage, which will
 143     /// be emitted in JSON messages to be displayed by Cargo
 144     /// for upstream deps
 145     pub future_breakage: Option<FutureBreakage>,
 146 }
 147
 148 #[derive(Copy, Clone, Debug)]
 149 pub struct FutureBreakage {
 150     pub date: Option<&'static str>,
 151 }
 152
 153 impl FutureIncompatibleInfo {
 154     pub const fn default_fields_for_macro() -> Self {
 155         FutureIncompatibleInfo { reference: "", edition: None, future_breakage: None }
 156     }
 157 }
 158
 159 impl Lint {
 160     pub const fn default_fields_for_macro() -> Self {
 161         Lint {
 162             name: "",
 163             default_level: Level::Forbid,
 164             desc: "",
 165             edition_lint_opts: None,
 166             is_plugin: false,
 167             report_in_external_macro: false,
 168             future_incompatible: None,
 169             feature_gate: None,
 170             crate_level_only: false,
 171         }
 172     }
 173
 174     /// Gets the lint's name, with ASCII letters converted to lowercase.
 175     pub fn name_lower(&self) -> String {
 176         self.name.to_ascii_lowercase()
 177     }
 178
 179     pub fn default_level(&self, edition: Edition) -> Level {
 180         self.edition_lint_opts
 181             .filter(|(e, _)| *e <= edition)
 182             .map(|(_, l)| l)
 183             .unwrap_or(self.default_level)
 184     }
 185 }
 186
 187 /// Identifies a lint known to the compiler.
 188 #[derive(Clone, Copy, Debug)]
 189 pub struct LintId {
 190     // Identity is based on pointer equality of this field.
 191     pub lint: &'static Lint,
 192 }
 193
 194 impl PartialEq for LintId {
 195     fn eq(&self, other: &LintId) -> bool {
 196         std::ptr::eq(self.lint, other.lint)
 197     }
 198 }
 199
 200 impl Eq for LintId {}
 201
 202 impl std::hash::Hash for LintId {
 203     fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 204         let ptr = self.lint as *const Lint;
 205         ptr.hash(state);
 206     }
 207 }
 208
 209 impl LintId {
 210     /// Gets the `LintId` for a `Lint`.
 211     pub fn of(lint: &'static Lint) -> LintId {
 212         LintId { lint }
 213     }
 214
 215     pub fn lint_name_raw(&self) -> &'static str {
 216         self.lint.name
 217     }
 218
 219     /// Gets the name of the lint.
 220     pub fn to_string(&self) -> String {
 221         self.lint.name_lower()
 222     }
 223 }
 224
 225 impl<HCX> HashStable<HCX> for LintId {
 226     #[inline]
 227     fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
 228         self.lint_name_raw().hash_stable(hcx, hasher);
 229     }
 230 }
 231
 232 impl<HCX> ToStableHashKey<HCX> for LintId {
 233     type KeyType = &'static str;
 234
 235     #[inline]
 236     fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
 237         self.lint_name_raw()
 238     }
 239 }
 240
 241 // This could be a closure, but then implementing derive trait
 242 // becomes hacky (and it gets allocated).
 243 #[derive(PartialEq)]
 244 pub enum BuiltinLintDiagnostics {
 245     Normal,
 246     BareTraitObject(Span, /* is_global */ bool),
 247     AbsPathWithModule(Span),
 248     ProcMacroDeriveResolutionFallback(Span),
 249     MacroExpandedMacroExportsAccessedByAbsolutePaths(Span),
 250     ElidedLifetimesInPaths(usize, Span, bool, Span, String),
 251     UnknownCrateTypes(Span, String, String),
 252     UnusedImports(String, Vec<(Span, String)>),
 253     RedundantImport(Vec<(Span, bool)>, Ident),
 254     DeprecatedMacro(Option<Symbol>, Span),
 255     UnusedDocComment(Span),
 256 }
 257
 258 /// Lints that are buffered up early on in the `Session` before the
 259 /// `LintLevels` is calculated.
 260 #[derive(PartialEq)]
 261 pub struct BufferedEarlyLint {
 262     /// The span of code that we are linting on.
 263     pub span: MultiSpan,
 264
 265     /// The lint message.
 266     pub msg: String,
 267
 268     /// The `NodeId` of the AST node that generated the lint.
 269     pub node_id: NodeId,
 270
 271     /// A lint Id that can be passed to
 272     /// `rustc_lint::early::EarlyContextAndPass::check_id`.
 273     pub lint_id: LintId,
 274
 275     /// Customization of the `DiagnosticBuilder<'_>` for the lint.
 276     pub diagnostic: BuiltinLintDiagnostics,
 277 }
 278
 279 #[derive(Default)]
 280 pub struct LintBuffer {
 281     pub map: NodeMap<Vec<BufferedEarlyLint>>,
 282 }
 283
 284 impl LintBuffer {
 285     pub fn add_early_lint(&mut self, early_lint: BufferedEarlyLint) {
 286         let arr = self.map.entry(early_lint.node_id).or_default();
 287         if !arr.contains(&early_lint) {
 288             arr.push(early_lint);
 289         }
 290     }
 291
 292     pub fn add_lint(
 293         &mut self,
 294         lint: &'static Lint,
 295         node_id: NodeId,
 296         span: MultiSpan,
 297         msg: &str,
 298         diagnostic: BuiltinLintDiagnostics,
 299     ) {
 300         let lint_id = LintId::of(lint);
 301         let msg = msg.to_string();
 302         self.add_early_lint(BufferedEarlyLint { lint_id, node_id, span, msg, diagnostic });
 303     }
 304
 305     pub fn take(&mut self, id: NodeId) -> Vec<BufferedEarlyLint> {
 306         self.map.remove(&id).unwrap_or_default()
 307     }
 308
 309     pub fn buffer_lint(
 310         &mut self,
 311         lint: &'static Lint,
 312         id: NodeId,
 313         sp: impl Into<MultiSpan>,
 314         msg: &str,
 315     ) {
 316         self.add_lint(lint, id, sp.into(), msg, BuiltinLintDiagnostics::Normal)
 317     }
 318
 319     pub fn buffer_lint_with_diagnostic(
 320         &mut self,
 321         lint: &'static Lint,
 322         id: NodeId,
 323         sp: impl Into<MultiSpan>,
 324         msg: &str,
 325         diagnostic: BuiltinLintDiagnostics,
 326     ) {
 327         self.add_lint(lint, id, sp.into(), msg, diagnostic)
 328     }
 329 }
 330
 331 /// Declares a static item of type `&'static Lint`.
 332 ///
 333 /// See <https://rustc-dev-guide.rust-lang.org/diagnostics.html> for
 334 /// documentation and guidelines on writing lints.
 335 ///
 336 /// The macro call should start with a doc comment explaining the lint
 337 /// which will be embedded in the rustc user documentation book. It should
 338 /// be written in markdown and have a format that looks like this:
 339 ///
 340 /// ```rust,ignore (doc-example)
 341 /// /// The `my_lint_name` lint detects [short explanation here].
 342 /// ///
 343 /// /// ### Example
 344 /// ///
 345 /// /// ```rust
 346 /// /// [insert a concise example that triggers the lint]
 347 /// /// ```
 348 /// ///
 349 /// /// {{produces}}
 350 /// ///
 351 /// /// ### Explanation
 352 /// ///
 353 /// /// This should be a detailed explanation of *why* the lint exists,
 354 /// /// and also include suggestions on how the user should fix the problem.
 355 /// /// Try to keep the text simple enough that a beginner can understand,
 356 /// /// and include links to other documentation for terminology that a
 357 /// /// beginner may not be familiar with. If this is "allow" by default,
 358 /// /// it should explain why (are there false positives or other issues?). If
 359 /// /// this is a future-incompatible lint, it should say so, with text that
 360 /// /// looks roughly like this:
 361 /// ///
 362 /// /// This is a [future-incompatible] lint to transition this to a hard
 363 /// /// error in the future. See [issue #xxxxx] for more details.
 364 /// ///
 365 /// /// [issue #xxxxx]: https://github.com/rust-lang/rust/issues/xxxxx
 366 /// ```
 367 ///
 368 /// The `{{produces}}` tag will be automatically replaced with the output from
 369 /// the example by the build system. You can build and view the rustc book
 370 /// with `x.py doc --stage=1 src/doc/rustc --open`. If the lint example is too
 371 /// complex to run as a simple example (for example, it needs an extern
 372 /// crate), mark it with `ignore` and manually paste the expected output below
 373 /// the example.
 374 #[macro_export]
 375 macro_rules! declare_lint {
 376     ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr) => (
 377         $crate::declare_lint!(
 378             $(#[$attr])* $vis $NAME, $Level, $desc,
 379         );
 380     );
 381     ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr,
 382      $(@feature_gate = $gate:expr;)?
 383      $(@future_incompatible = FutureIncompatibleInfo { $($field:ident : $val:expr),* $(,)*  }; )?
 384      $($v:ident),*) => (
 385         $(#[$attr])*
 386         $vis static $NAME: &$crate::Lint = &$crate::Lint {
 387             name: stringify!($NAME),
 388             default_level: $crate::$Level,
 389             desc: $desc,
 390             edition_lint_opts: None,
 391             is_plugin: false,
 392             $($v: true,)*
 393             $(feature_gate: Some($gate),)*
 394             $(future_incompatible: Some($crate::FutureIncompatibleInfo {
 395                 $($field: $val,)*
 396                 ..$crate::FutureIncompatibleInfo::default_fields_for_macro()
 397             }),)*
 398             ..$crate::Lint::default_fields_for_macro()
 399         };
 400     );
 401     ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr,
 402      $lint_edition: expr => $edition_level: ident
 403     ) => (
 404         $(#[$attr])*
 405         $vis static $NAME: &$crate::Lint = &$crate::Lint {
 406             name: stringify!($NAME),
 407             default_level: $crate::$Level,
 408             desc: $desc,
 409             edition_lint_opts: Some(($lint_edition, $crate::Level::$edition_level)),
 410             report_in_external_macro: false,
 411             is_plugin: false,
 412         };
 413     );
 414 }
 415
 416 #[macro_export]
 417 macro_rules! declare_tool_lint {
 418     (
 419         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level: ident, $desc: expr
 420     ) => (
 421         $crate::declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, false}
 422     );
 423     (
 424         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
 425         report_in_external_macro: $rep:expr
 426     ) => (
 427          $crate::declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, $rep}
 428     );
 429     (
 430         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
 431         $external:expr
 432     ) => (
 433         $(#[$attr])*
 434         $vis static $NAME: &$crate::Lint = &$crate::Lint {
 435             name: &concat!(stringify!($tool), "::", stringify!($NAME)),
 436             default_level: $crate::$Level,
 437             desc: $desc,
 438             edition_lint_opts: None,
 439             report_in_external_macro: $external,
 440             future_incompatible: None,
 441             is_plugin: true,
 442             feature_gate: None,
 443             crate_level_only: false,
 444         };
 445     );
 446 }
 447
 448 /// Declares a static `LintArray` and return it as an expression.
 449 #[macro_export]
 450 macro_rules! lint_array {
 451     ($( $lint:expr ),* ,) => { lint_array!( $($lint),* ) };
 452     ($( $lint:expr ),*) => {{
 453         vec![$($lint),*]
 454     }}
 455 }
 456
 457 pub type LintArray = Vec<&'static Lint>;
 458
 459 pub trait LintPass {
 460     fn name(&self) -> &'static str;
 461 }
 462
 463 /// Implements `LintPass for $ty` with the given list of `Lint` statics.
 464 #[macro_export]
 465 macro_rules! impl_lint_pass {
 466     ($ty:ty => [$($lint:expr),* $(,)?]) => {
 467         impl $crate::LintPass for $ty {
 468             fn name(&self) -> &'static str { stringify!($ty) }
 469         }
 470         impl $ty {
 471             pub fn get_lints() -> $crate::LintArray { $crate::lint_array!($($lint),*) }
 472         }
 473     };
 474 }
 475
 476 /// Declares a type named `$name` which implements `LintPass`.
 477 /// To the right of `=>` a comma separated list of `Lint` statics is given.
 478 #[macro_export]
 479 macro_rules! declare_lint_pass {
 480     ($(#[$m:meta])* $name:ident => [$($lint:expr),* $(,)?]) => {
 481         $(#[$m])* #[derive(Copy, Clone)] pub struct $name;
 482         $crate::impl_lint_pass!($name => [$($lint),*]);
 483     };
 484 }