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_serialize::json::Json;
   8 use rustc_span::edition::Edition;
   9 use rustc_span::{sym, symbol::Ident, MultiSpan, Span, Symbol};
  10 use rustc_target::spec::abi::Abi;
  11
  12 pub mod builtin;
  13
  14 #[macro_export]
  15 macro_rules! pluralize {
  16     ($x:expr) => {
  17         if $x != 1 { "s" } else { "" }
  18     };
  19 }
  20
  21 /// Indicates the confidence in the correctness of a suggestion.
  22 ///
  23 /// All suggestions are marked with an `Applicability`. Tools use the applicability of a suggestion
  24 /// to determine whether it should be automatically applied or if the user should be consulted
  25 /// before applying the suggestion.
  26 #[derive(Copy, Clone, Debug, PartialEq, Hash, Encodable, Decodable)]
  27 pub enum Applicability {
  28     /// The suggestion is definitely what the user intended. This suggestion should be
  29     /// automatically applied.
  30     MachineApplicable,
  31
  32     /// The suggestion may be what the user intended, but it is uncertain. The suggestion should
  33     /// result in valid Rust code if it is applied.
  34     MaybeIncorrect,
  35
  36     /// The suggestion contains placeholders like `(...)` or `{ /* fields */ }`. The suggestion
  37     /// cannot be applied automatically because it will not result in valid Rust code. The user
  38     /// will need to fill in the placeholders.
  39     HasPlaceholders,
  40
  41     /// The applicability of the suggestion is unknown.
  42     Unspecified,
  43 }
  44
  45 /// Setting for how to handle a lint.
  46 #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
  47 pub enum Level {
  48     Allow,
  49     Warn,
  50     Deny,
  51     Forbid,
  52 }
  53
  54 rustc_data_structures::impl_stable_hash_via_hash!(Level);
  55
  56 impl Level {
  57     /// Converts a level to a lower-case string.
  58     pub fn as_str(self) -> &'static str {
  59         match self {
  60             Level::Allow => "allow",
  61             Level::Warn => "warn",
  62             Level::Deny => "deny",
  63             Level::Forbid => "forbid",
  64         }
  65     }
  66
  67     /// Converts a lower-case string to a level.
  68     pub fn from_str(x: &str) -> Option<Level> {
  69         match x {
  70             "allow" => Some(Level::Allow),
  71             "warn" => Some(Level::Warn),
  72             "deny" => Some(Level::Deny),
  73             "forbid" => Some(Level::Forbid),
  74             _ => None,
  75         }
  76     }
  77
  78     /// Converts a symbol to a level.
  79     pub fn from_symbol(x: Symbol) -> Option<Level> {
  80         match x {
  81             sym::allow => Some(Level::Allow),
  82             sym::warn => Some(Level::Warn),
  83             sym::deny => Some(Level::Deny),
  84             sym::forbid => Some(Level::Forbid),
  85             _ => None,
  86         }
  87     }
  88 }
  89
  90 /// Specification of a single lint.
  91 #[derive(Copy, Clone, Debug)]
  92 pub struct Lint {
  93     /// A string identifier for the lint.
  94     ///
  95     /// This identifies the lint in attributes and in command-line arguments.
  96     /// In those contexts it is always lowercase, but this field is compared
  97     /// in a way which is case-insensitive for ASCII characters. This allows
  98     /// `declare_lint!()` invocations to follow the convention of upper-case
  99     /// statics without repeating the name.
 100     ///
 101     /// The name is written with underscores, e.g., "unused_imports".
 102     /// On the command line, underscores become dashes.
 103     ///
 104     /// See <https://rustc-dev-guide.rust-lang.org/diagnostics.html#lint-naming>
 105     /// for naming guidelines.
 106     pub name: &'static str,
 107
 108     /// Default level for the lint.
 109     ///
 110     /// See <https://rustc-dev-guide.rust-lang.org/diagnostics.html#diagnostic-levels>
 111     /// for guidelines on choosing a default level.
 112     pub default_level: Level,
 113
 114     /// Description of the lint or the issue it detects.
 115     ///
 116     /// e.g., "imports that are never used"
 117     pub desc: &'static str,
 118
 119     /// Starting at the given edition, default to the given lint level. If this is `None`, then use
 120     /// `default_level`.
 121     pub edition_lint_opts: Option<(Edition, Level)>,
 122
 123     /// `true` if this lint is reported even inside expansions of external macros.
 124     pub report_in_external_macro: bool,
 125
 126     pub future_incompatible: Option<FutureIncompatibleInfo>,
 127
 128     pub is_plugin: bool,
 129
 130     /// `Some` if this lint is feature gated, otherwise `None`.
 131     pub feature_gate: Option<Symbol>,
 132
 133     pub crate_level_only: bool,
 134 }
 135
 136 /// Extra information for a future incompatibility lint.
 137 #[derive(Copy, Clone, Debug)]
 138 pub struct FutureIncompatibleInfo {
 139     /// e.g., a URL for an issue/PR/RFC or error code
 140     pub reference: &'static str,
 141     /// If this is an edition fixing lint, the edition in which
 142     /// this lint becomes obsolete
 143     pub edition: Option<Edition>,
 144     /// Information about a future breakage, which will
 145     /// be emitted in JSON messages to be displayed by Cargo
 146     /// for upstream deps
 147     pub future_breakage: Option<FutureBreakage>,
 148 }
 149
 150 #[derive(Copy, Clone, Debug)]
 151 pub struct FutureBreakage {
 152     pub date: Option<&'static str>,
 153 }
 154
 155 impl FutureIncompatibleInfo {
 156     pub const fn default_fields_for_macro() -> Self {
 157         FutureIncompatibleInfo { reference: "", edition: None, future_breakage: None }
 158     }
 159 }
 160
 161 impl Lint {
 162     pub const fn default_fields_for_macro() -> Self {
 163         Lint {
 164             name: "",
 165             default_level: Level::Forbid,
 166             desc: "",
 167             edition_lint_opts: None,
 168             is_plugin: false,
 169             report_in_external_macro: false,
 170             future_incompatible: None,
 171             feature_gate: None,
 172             crate_level_only: false,
 173         }
 174     }
 175
 176     /// Gets the lint's name, with ASCII letters converted to lowercase.
 177     pub fn name_lower(&self) -> String {
 178         self.name.to_ascii_lowercase()
 179     }
 180
 181     pub fn default_level(&self, edition: Edition) -> Level {
 182         self.edition_lint_opts
 183             .filter(|(e, _)| *e <= edition)
 184             .map(|(_, l)| l)
 185             .unwrap_or(self.default_level)
 186     }
 187 }
 188
 189 /// Identifies a lint known to the compiler.
 190 #[derive(Clone, Copy, Debug)]
 191 pub struct LintId {
 192     // Identity is based on pointer equality of this field.
 193     pub lint: &'static Lint,
 194 }
 195
 196 impl PartialEq for LintId {
 197     fn eq(&self, other: &LintId) -> bool {
 198         std::ptr::eq(self.lint, other.lint)
 199     }
 200 }
 201
 202 impl Eq for LintId {}
 203
 204 impl std::hash::Hash for LintId {
 205     fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 206         let ptr = self.lint as *const Lint;
 207         ptr.hash(state);
 208     }
 209 }
 210
 211 impl LintId {
 212     /// Gets the `LintId` for a `Lint`.
 213     pub fn of(lint: &'static Lint) -> LintId {
 214         LintId { lint }
 215     }
 216
 217     pub fn lint_name_raw(&self) -> &'static str {
 218         self.lint.name
 219     }
 220
 221     /// Gets the name of the lint.
 222     pub fn to_string(&self) -> String {
 223         self.lint.name_lower()
 224     }
 225 }
 226
 227 impl<HCX> HashStable<HCX> for LintId {
 228     #[inline]
 229     fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
 230         self.lint_name_raw().hash_stable(hcx, hasher);
 231     }
 232 }
 233
 234 impl<HCX> ToStableHashKey<HCX> for LintId {
 235     type KeyType = &'static str;
 236
 237     #[inline]
 238     fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
 239         self.lint_name_raw()
 240     }
 241 }
 242
 243 // Duplicated from rustc_session::config::ExternDepSpec to avoid cyclic dependency
 244 #[derive(PartialEq)]
 245 pub enum ExternDepSpec {
 246     Json(Json),
 247     Raw(String),
 248 }
 249
 250 // This could be a closure, but then implementing derive trait
 251 // becomes hacky (and it gets allocated).
 252 #[derive(PartialEq)]
 253 pub enum BuiltinLintDiagnostics {
 254     Normal,
 255     BareTraitObject(Span, /* is_global */ bool),
 256     AbsPathWithModule(Span),
 257     ProcMacroDeriveResolutionFallback(Span),
 258     MacroExpandedMacroExportsAccessedByAbsolutePaths(Span),
 259     ElidedLifetimesInPaths(usize, Span, bool, Span, String),
 260     UnknownCrateTypes(Span, String, String),
 261     UnusedImports(String, Vec<(Span, String)>),
 262     RedundantImport(Vec<(Span, bool)>, Ident),
 263     DeprecatedMacro(Option<Symbol>, Span),
 264     MissingAbi(Span, Abi),
 265     UnusedDocComment(Span),
 266     PatternsInFnsWithoutBody(Span, Ident),
 267     LegacyDeriveHelpers(Span),
 268     ExternDepSpec(String, ExternDepSpec),
 269     ProcMacroBackCompat(String),
 270 }
 271
 272 /// Lints that are buffered up early on in the `Session` before the
 273 /// `LintLevels` is calculated.
 274 #[derive(PartialEq)]
 275 pub struct BufferedEarlyLint {
 276     /// The span of code that we are linting on.
 277     pub span: MultiSpan,
 278
 279     /// The lint message.
 280     pub msg: String,
 281
 282     /// The `NodeId` of the AST node that generated the lint.
 283     pub node_id: NodeId,
 284
 285     /// A lint Id that can be passed to
 286     /// `rustc_lint::early::EarlyContextAndPass::check_id`.
 287     pub lint_id: LintId,
 288
 289     /// Customization of the `DiagnosticBuilder<'_>` for the lint.
 290     pub diagnostic: BuiltinLintDiagnostics,
 291 }
 292
 293 #[derive(Default)]
 294 pub struct LintBuffer {
 295     pub map: NodeMap<Vec<BufferedEarlyLint>>,
 296 }
 297
 298 impl LintBuffer {
 299     pub fn add_early_lint(&mut self, early_lint: BufferedEarlyLint) {
 300         let arr = self.map.entry(early_lint.node_id).or_default();
 301         if !arr.contains(&early_lint) {
 302             arr.push(early_lint);
 303         }
 304     }
 305
 306     pub fn add_lint(
 307         &mut self,
 308         lint: &'static Lint,
 309         node_id: NodeId,
 310         span: MultiSpan,
 311         msg: &str,
 312         diagnostic: BuiltinLintDiagnostics,
 313     ) {
 314         let lint_id = LintId::of(lint);
 315         let msg = msg.to_string();
 316         self.add_early_lint(BufferedEarlyLint { lint_id, node_id, span, msg, diagnostic });
 317     }
 318
 319     pub fn take(&mut self, id: NodeId) -> Vec<BufferedEarlyLint> {
 320         self.map.remove(&id).unwrap_or_default()
 321     }
 322
 323     pub fn buffer_lint(
 324         &mut self,
 325         lint: &'static Lint,
 326         id: NodeId,
 327         sp: impl Into<MultiSpan>,
 328         msg: &str,
 329     ) {
 330         self.add_lint(lint, id, sp.into(), msg, BuiltinLintDiagnostics::Normal)
 331     }
 332
 333     pub fn buffer_lint_with_diagnostic(
 334         &mut self,
 335         lint: &'static Lint,
 336         id: NodeId,
 337         sp: impl Into<MultiSpan>,
 338         msg: &str,
 339         diagnostic: BuiltinLintDiagnostics,
 340     ) {
 341         self.add_lint(lint, id, sp.into(), msg, diagnostic)
 342     }
 343 }
 344
 345 /// Declares a static item of type `&'static Lint`.
 346 ///
 347 /// See <https://rustc-dev-guide.rust-lang.org/diagnostics.html> for
 348 /// documentation and guidelines on writing lints.
 349 ///
 350 /// The macro call should start with a doc comment explaining the lint
 351 /// which will be embedded in the rustc user documentation book. It should
 352 /// be written in markdown and have a format that looks like this:
 353 ///
 354 /// ```rust,ignore (doc-example)
 355 /// /// The `my_lint_name` lint detects [short explanation here].
 356 /// ///
 357 /// /// ### Example
 358 /// ///
 359 /// /// ```rust
 360 /// /// [insert a concise example that triggers the lint]
 361 /// /// ```
 362 /// ///
 363 /// /// {{produces}}
 364 /// ///
 365 /// /// ### Explanation
 366 /// ///
 367 /// /// This should be a detailed explanation of *why* the lint exists,
 368 /// /// and also include suggestions on how the user should fix the problem.
 369 /// /// Try to keep the text simple enough that a beginner can understand,
 370 /// /// and include links to other documentation for terminology that a
 371 /// /// beginner may not be familiar with. If this is "allow" by default,
 372 /// /// it should explain why (are there false positives or other issues?). If
 373 /// /// this is a future-incompatible lint, it should say so, with text that
 374 /// /// looks roughly like this:
 375 /// ///
 376 /// /// This is a [future-incompatible] lint to transition this to a hard
 377 /// /// error in the future. See [issue #xxxxx] for more details.
 378 /// ///
 379 /// /// [issue #xxxxx]: https://github.com/rust-lang/rust/issues/xxxxx
 380 /// ```
 381 ///
 382 /// The `{{produces}}` tag will be automatically replaced with the output from
 383 /// the example by the build system. If the lint example is too complex to run
 384 /// as a simple example (for example, it needs an extern crate), mark the code
 385 /// block with `ignore` and manually replace the `{{produces}}` line with the
 386 /// expected output in a `text` code block.
 387 ///
 388 /// If this is a rustdoc-only lint, then only include a brief introduction
 389 /// with a link with the text `[rustdoc book]` so that the validator knows
 390 /// that this is for rustdoc only (see BROKEN_INTRA_DOC_LINKS as an example).
 391 ///
 392 /// Commands to view and test the documentation:
 393 ///
 394 /// * `./x.py doc --stage=1 src/doc/rustc --open`: Builds the rustc book and opens it.
 395 /// * `./x.py test src/tools/lint-docs`: Validates that the lint docs have the
 396 ///   correct style, and that the code example actually emits the expected
 397 ///   lint.
 398 ///
 399 /// If you have already built the compiler, and you want to make changes to
 400 /// just the doc comments, then use the `--keep-stage=0` flag with the above
 401 /// commands to avoid rebuilding the compiler.
 402 #[macro_export]
 403 macro_rules! declare_lint {
 404     ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr) => (
 405         $crate::declare_lint!(
 406             $(#[$attr])* $vis $NAME, $Level, $desc,
 407         );
 408     );
 409     ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr,
 410      $(@feature_gate = $gate:expr;)?
 411      $(@future_incompatible = FutureIncompatibleInfo { $($field:ident : $val:expr),* $(,)*  }; )?
 412      $($v:ident),*) => (
 413         $(#[$attr])*
 414         $vis static $NAME: &$crate::Lint = &$crate::Lint {
 415             name: stringify!($NAME),
 416             default_level: $crate::$Level,
 417             desc: $desc,
 418             edition_lint_opts: None,
 419             is_plugin: false,
 420             $($v: true,)*
 421             $(feature_gate: Some($gate),)*
 422             $(future_incompatible: Some($crate::FutureIncompatibleInfo {
 423                 $($field: $val,)*
 424                 ..$crate::FutureIncompatibleInfo::default_fields_for_macro()
 425             }),)*
 426             ..$crate::Lint::default_fields_for_macro()
 427         };
 428     );
 429     ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr,
 430      $lint_edition: expr => $edition_level: ident
 431     ) => (
 432         $(#[$attr])*
 433         $vis static $NAME: &$crate::Lint = &$crate::Lint {
 434             name: stringify!($NAME),
 435             default_level: $crate::$Level,
 436             desc: $desc,
 437             edition_lint_opts: Some(($lint_edition, $crate::Level::$edition_level)),
 438             report_in_external_macro: false,
 439             is_plugin: false,
 440         };
 441     );
 442 }
 443
 444 #[macro_export]
 445 macro_rules! declare_tool_lint {
 446     (
 447         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level: ident, $desc: expr
 448     ) => (
 449         $crate::declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, false}
 450     );
 451     (
 452         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
 453         report_in_external_macro: $rep:expr
 454     ) => (
 455          $crate::declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, $rep}
 456     );
 457     (
 458         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
 459         $external:expr
 460     ) => (
 461         $(#[$attr])*
 462         $vis static $NAME: &$crate::Lint = &$crate::Lint {
 463             name: &concat!(stringify!($tool), "::", stringify!($NAME)),
 464             default_level: $crate::$Level,
 465             desc: $desc,
 466             edition_lint_opts: None,
 467             report_in_external_macro: $external,
 468             future_incompatible: None,
 469             is_plugin: true,
 470             feature_gate: None,
 471             crate_level_only: false,
 472         };
 473     );
 474 }
 475
 476 /// Declares a static `LintArray` and return it as an expression.
 477 #[macro_export]
 478 macro_rules! lint_array {
 479     ($( $lint:expr ),* ,) => { lint_array!( $($lint),* ) };
 480     ($( $lint:expr ),*) => {{
 481         vec![$($lint),*]
 482     }}
 483 }
 484
 485 pub type LintArray = Vec<&'static Lint>;
 486
 487 pub trait LintPass {
 488     fn name(&self) -> &'static str;
 489 }
 490
 491 /// Implements `LintPass for $ty` with the given list of `Lint` statics.
 492 #[macro_export]
 493 macro_rules! impl_lint_pass {
 494     ($ty:ty => [$($lint:expr),* $(,)?]) => {
 495         impl $crate::LintPass for $ty {
 496             fn name(&self) -> &'static str { stringify!($ty) }
 497         }
 498         impl $ty {
 499             pub fn get_lints() -> $crate::LintArray { $crate::lint_array!($($lint),*) }
 500         }
 501     };
 502 }
 503
 504 /// Declares a type named `$name` which implements `LintPass`.
 505 /// To the right of `=>` a comma separated list of `Lint` statics is given.
 506 #[macro_export]
 507 macro_rules! declare_lint_pass {
 508     ($(#[$m:meta])* $name:ident => [$($lint:expr),* $(,)?]) => {
 509         $(#[$m])* #[derive(Copy, Clone)] pub struct $name;
 510         $crate::impl_lint_pass!($name => [$($lint),*]);
 511     };
 512 }