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, or maintains the exact meaning of the code.
  29     /// This suggestion should be automatically applied.
  30     ///
  31     /// In case of multiple `MachineApplicable` suggestions (whether as part of
  32     /// the same `multipart_suggestion` or not), all of them should be
  33     /// automatically applied.
  34     MachineApplicable,
  35
  36     /// The suggestion may be what the user intended, but it is uncertain. The suggestion should
  37     /// result in valid Rust code if it is applied.
  38     MaybeIncorrect,
  39
  40     /// The suggestion contains placeholders like `(...)` or `{ /* fields */ }`. The suggestion
  41     /// cannot be applied automatically because it will not result in valid Rust code. The user
  42     /// will need to fill in the placeholders.
  43     HasPlaceholders,
  44
  45     /// The applicability of the suggestion is unknown.
  46     Unspecified,
  47 }
  48
  49 /// Setting for how to handle a lint.
  50 #[derive(Clone, Copy, PartialEq, PartialOrd, Eq, Ord, Debug, Hash)]
  51 pub enum Level {
  52     Allow,
  53     Warn,
  54     ForceWarn,
  55     Deny,
  56     Forbid,
  57 }
  58
  59 rustc_data_structures::impl_stable_hash_via_hash!(Level);
  60
  61 impl Level {
  62     /// Converts a level to a lower-case string.
  63     pub fn as_str(self) -> &'static str {
  64         match self {
  65             Level::Allow => "allow",
  66             Level::Warn => "warn",
  67             Level::ForceWarn => "force-warn",
  68             Level::Deny => "deny",
  69             Level::Forbid => "forbid",
  70         }
  71     }
  72
  73     /// Converts a lower-case string to a level.
  74     pub fn from_str(x: &str) -> Option<Level> {
  75         match x {
  76             "allow" => Some(Level::Allow),
  77             "warn" => Some(Level::Warn),
  78             "deny" => Some(Level::Deny),
  79             "forbid" => Some(Level::Forbid),
  80             _ => None,
  81         }
  82     }
  83
  84     /// Converts a symbol to a level.
  85     pub fn from_symbol(x: Symbol) -> Option<Level> {
  86         match x {
  87             sym::allow => Some(Level::Allow),
  88             sym::warn => Some(Level::Warn),
  89             sym::deny => Some(Level::Deny),
  90             sym::forbid => Some(Level::Forbid),
  91             _ => None,
  92         }
  93     }
  94 }
  95
  96 /// Specification of a single lint.
  97 #[derive(Copy, Clone, Debug)]
  98 pub struct Lint {
  99     /// A string identifier for the lint.
 100     ///
 101     /// This identifies the lint in attributes and in command-line arguments.
 102     /// In those contexts it is always lowercase, but this field is compared
 103     /// in a way which is case-insensitive for ASCII characters. This allows
 104     /// `declare_lint!()` invocations to follow the convention of upper-case
 105     /// statics without repeating the name.
 106     ///
 107     /// The name is written with underscores, e.g., "unused_imports".
 108     /// On the command line, underscores become dashes.
 109     ///
 110     /// See <https://rustc-dev-guide.rust-lang.org/diagnostics.html#lint-naming>
 111     /// for naming guidelines.
 112     pub name: &'static str,
 113
 114     /// Default level for the lint.
 115     ///
 116     /// See <https://rustc-dev-guide.rust-lang.org/diagnostics.html#diagnostic-levels>
 117     /// for guidelines on choosing a default level.
 118     pub default_level: Level,
 119
 120     /// Description of the lint or the issue it detects.
 121     ///
 122     /// e.g., "imports that are never used"
 123     pub desc: &'static str,
 124
 125     /// Starting at the given edition, default to the given lint level. If this is `None`, then use
 126     /// `default_level`.
 127     pub edition_lint_opts: Option<(Edition, Level)>,
 128
 129     /// `true` if this lint is reported even inside expansions of external macros.
 130     pub report_in_external_macro: bool,
 131
 132     pub future_incompatible: Option<FutureIncompatibleInfo>,
 133
 134     pub is_plugin: bool,
 135
 136     /// `Some` if this lint is feature gated, otherwise `None`.
 137     pub feature_gate: Option<Symbol>,
 138
 139     pub crate_level_only: bool,
 140 }
 141
 142 /// Extra information for a future incompatibility lint.
 143 #[derive(Copy, Clone, Debug)]
 144 pub struct FutureIncompatibleInfo {
 145     /// e.g., a URL for an issue/PR/RFC or error code
 146     pub reference: &'static str,
 147     /// The reason for the lint used by diagnostics to provide
 148     /// the right help message
 149     pub reason: FutureIncompatibilityReason,
 150     /// Whether to explain the reason to the user.
 151     ///
 152     /// Set to false for lints that already include a more detailed
 153     /// explanation.
 154     pub explain_reason: bool,
 155 }
 156
 157 /// The reason for future incompatibility
 158 #[derive(Copy, Clone, Debug)]
 159 pub enum FutureIncompatibilityReason {
 160     /// This will be an error in a future release
 161     /// for all editions
 162     FutureReleaseError,
 163     /// This will be an error in a future release, and
 164     /// Cargo should create a report even for dependencies
 165     FutureReleaseErrorReportNow,
 166     /// Previously accepted code that will become an
 167     /// error in the provided edition
 168     EditionError(Edition),
 169     /// Code that changes meaning in some way in
 170     /// the provided edition
 171     EditionSemanticsChange(Edition),
 172 }
 173
 174 impl FutureIncompatibilityReason {
 175     pub fn edition(self) -> Option<Edition> {
 176         match self {
 177             Self::EditionError(e) => Some(e),
 178             Self::EditionSemanticsChange(e) => Some(e),
 179             _ => None,
 180         }
 181     }
 182 }
 183
 184 impl FutureIncompatibleInfo {
 185     pub const fn default_fields_for_macro() -> Self {
 186         FutureIncompatibleInfo {
 187             reference: "",
 188             reason: FutureIncompatibilityReason::FutureReleaseError,
 189             explain_reason: true,
 190         }
 191     }
 192 }
 193
 194 impl Lint {
 195     pub const fn default_fields_for_macro() -> Self {
 196         Lint {
 197             name: "",
 198             default_level: Level::Forbid,
 199             desc: "",
 200             edition_lint_opts: None,
 201             is_plugin: false,
 202             report_in_external_macro: false,
 203             future_incompatible: None,
 204             feature_gate: None,
 205             crate_level_only: false,
 206         }
 207     }
 208
 209     /// Gets the lint's name, with ASCII letters converted to lowercase.
 210     pub fn name_lower(&self) -> String {
 211         self.name.to_ascii_lowercase()
 212     }
 213
 214     pub fn default_level(&self, edition: Edition) -> Level {
 215         self.edition_lint_opts
 216             .filter(|(e, _)| *e <= edition)
 217             .map(|(_, l)| l)
 218             .unwrap_or(self.default_level)
 219     }
 220 }
 221
 222 /// Identifies a lint known to the compiler.
 223 #[derive(Clone, Copy, Debug)]
 224 pub struct LintId {
 225     // Identity is based on pointer equality of this field.
 226     pub lint: &'static Lint,
 227 }
 228
 229 impl PartialEq for LintId {
 230     fn eq(&self, other: &LintId) -> bool {
 231         std::ptr::eq(self.lint, other.lint)
 232     }
 233 }
 234
 235 impl Eq for LintId {}
 236
 237 impl std::hash::Hash for LintId {
 238     fn hash<H: std::hash::Hasher>(&self, state: &mut H) {
 239         let ptr = self.lint as *const Lint;
 240         ptr.hash(state);
 241     }
 242 }
 243
 244 impl LintId {
 245     /// Gets the `LintId` for a `Lint`.
 246     pub fn of(lint: &'static Lint) -> LintId {
 247         LintId { lint }
 248     }
 249
 250     pub fn lint_name_raw(&self) -> &'static str {
 251         self.lint.name
 252     }
 253
 254     /// Gets the name of the lint.
 255     pub fn to_string(&self) -> String {
 256         self.lint.name_lower()
 257     }
 258 }
 259
 260 impl<HCX> HashStable<HCX> for LintId {
 261     #[inline]
 262     fn hash_stable(&self, hcx: &mut HCX, hasher: &mut StableHasher) {
 263         self.lint_name_raw().hash_stable(hcx, hasher);
 264     }
 265 }
 266
 267 impl<HCX> ToStableHashKey<HCX> for LintId {
 268     type KeyType = &'static str;
 269
 270     #[inline]
 271     fn to_stable_hash_key(&self, _: &HCX) -> &'static str {
 272         self.lint_name_raw()
 273     }
 274 }
 275
 276 // Duplicated from rustc_session::config::ExternDepSpec to avoid cyclic dependency
 277 #[derive(PartialEq, Debug)]
 278 pub enum ExternDepSpec {
 279     Json(Json),
 280     Raw(String),
 281 }
 282
 283 // This could be a closure, but then implementing derive trait
 284 // becomes hacky (and it gets allocated).
 285 #[derive(PartialEq, Debug)]
 286 pub enum BuiltinLintDiagnostics {
 287     Normal,
 288     BareTraitObject(Span, /* is_global */ bool),
 289     AbsPathWithModule(Span),
 290     ProcMacroDeriveResolutionFallback(Span),
 291     MacroExpandedMacroExportsAccessedByAbsolutePaths(Span),
 292     ElidedLifetimesInPaths(usize, Span, bool, Span, String),
 293     UnknownCrateTypes(Span, String, String),
 294     UnusedImports(String, Vec<(Span, String)>),
 295     RedundantImport(Vec<(Span, bool)>, Ident),
 296     DeprecatedMacro(Option<Symbol>, Span),
 297     MissingAbi(Span, Abi),
 298     UnusedDocComment(Span),
 299     PatternsInFnsWithoutBody(Span, Ident),
 300     LegacyDeriveHelpers(Span),
 301     ExternDepSpec(String, ExternDepSpec),
 302     ProcMacroBackCompat(String),
 303     OrPatternsBackCompat(Span, String),
 304     ReservedPrefix(Span),
 305 }
 306
 307 /// Lints that are buffered up early on in the `Session` before the
 308 /// `LintLevels` is calculated.
 309 #[derive(PartialEq)]
 310 pub struct BufferedEarlyLint {
 311     /// The span of code that we are linting on.
 312     pub span: MultiSpan,
 313
 314     /// The lint message.
 315     pub msg: String,
 316
 317     /// The `NodeId` of the AST node that generated the lint.
 318     pub node_id: NodeId,
 319
 320     /// A lint Id that can be passed to
 321     /// `rustc_lint::early::EarlyContextAndPass::check_id`.
 322     pub lint_id: LintId,
 323
 324     /// Customization of the `DiagnosticBuilder<'_>` for the lint.
 325     pub diagnostic: BuiltinLintDiagnostics,
 326 }
 327
 328 #[derive(Default)]
 329 pub struct LintBuffer {
 330     pub map: NodeMap<Vec<BufferedEarlyLint>>,
 331 }
 332
 333 impl LintBuffer {
 334     pub fn add_early_lint(&mut self, early_lint: BufferedEarlyLint) {
 335         let arr = self.map.entry(early_lint.node_id).or_default();
 336         if !arr.contains(&early_lint) {
 337             arr.push(early_lint);
 338         }
 339     }
 340
 341     pub fn add_lint(
 342         &mut self,
 343         lint: &'static Lint,
 344         node_id: NodeId,
 345         span: MultiSpan,
 346         msg: &str,
 347         diagnostic: BuiltinLintDiagnostics,
 348     ) {
 349         let lint_id = LintId::of(lint);
 350         let msg = msg.to_string();
 351         self.add_early_lint(BufferedEarlyLint { lint_id, node_id, span, msg, diagnostic });
 352     }
 353
 354     pub fn take(&mut self, id: NodeId) -> Vec<BufferedEarlyLint> {
 355         self.map.remove(&id).unwrap_or_default()
 356     }
 357
 358     pub fn buffer_lint(
 359         &mut self,
 360         lint: &'static Lint,
 361         id: NodeId,
 362         sp: impl Into<MultiSpan>,
 363         msg: &str,
 364     ) {
 365         self.add_lint(lint, id, sp.into(), msg, BuiltinLintDiagnostics::Normal)
 366     }
 367
 368     pub fn buffer_lint_with_diagnostic(
 369         &mut self,
 370         lint: &'static Lint,
 371         id: NodeId,
 372         sp: impl Into<MultiSpan>,
 373         msg: &str,
 374         diagnostic: BuiltinLintDiagnostics,
 375     ) {
 376         self.add_lint(lint, id, sp.into(), msg, diagnostic)
 377     }
 378 }
 379
 380 /// Declares a static item of type `&'static Lint`.
 381 ///
 382 /// See <https://rustc-dev-guide.rust-lang.org/diagnostics.html> for
 383 /// documentation and guidelines on writing lints.
 384 ///
 385 /// The macro call should start with a doc comment explaining the lint
 386 /// which will be embedded in the rustc user documentation book. It should
 387 /// be written in markdown and have a format that looks like this:
 388 ///
 389 /// ```rust,ignore (doc-example)
 390 /// /// The `my_lint_name` lint detects [short explanation here].
 391 /// ///
 392 /// /// ### Example
 393 /// ///
 394 /// /// ```rust
 395 /// /// [insert a concise example that triggers the lint]
 396 /// /// ```
 397 /// ///
 398 /// /// {{produces}}
 399 /// ///
 400 /// /// ### Explanation
 401 /// ///
 402 /// /// This should be a detailed explanation of *why* the lint exists,
 403 /// /// and also include suggestions on how the user should fix the problem.
 404 /// /// Try to keep the text simple enough that a beginner can understand,
 405 /// /// and include links to other documentation for terminology that a
 406 /// /// beginner may not be familiar with. If this is "allow" by default,
 407 /// /// it should explain why (are there false positives or other issues?). If
 408 /// /// this is a future-incompatible lint, it should say so, with text that
 409 /// /// looks roughly like this:
 410 /// ///
 411 /// /// This is a [future-incompatible] lint to transition this to a hard
 412 /// /// error in the future. See [issue #xxxxx] for more details.
 413 /// ///
 414 /// /// [issue #xxxxx]: https://github.com/rust-lang/rust/issues/xxxxx
 415 /// ```
 416 ///
 417 /// The `{{produces}}` tag will be automatically replaced with the output from
 418 /// the example by the build system. If the lint example is too complex to run
 419 /// as a simple example (for example, it needs an extern crate), mark the code
 420 /// block with `ignore` and manually replace the `{{produces}}` line with the
 421 /// expected output in a `text` code block.
 422 ///
 423 /// If this is a rustdoc-only lint, then only include a brief introduction
 424 /// with a link with the text `[rustdoc book]` so that the validator knows
 425 /// that this is for rustdoc only (see BROKEN_INTRA_DOC_LINKS as an example).
 426 ///
 427 /// Commands to view and test the documentation:
 428 ///
 429 /// * `./x.py doc --stage=1 src/doc/rustc --open`: Builds the rustc book and opens it.
 430 /// * `./x.py test src/tools/lint-docs`: Validates that the lint docs have the
 431 ///   correct style, and that the code example actually emits the expected
 432 ///   lint.
 433 ///
 434 /// If you have already built the compiler, and you want to make changes to
 435 /// just the doc comments, then use the `--keep-stage=0` flag with the above
 436 /// commands to avoid rebuilding the compiler.
 437 #[macro_export]
 438 macro_rules! declare_lint {
 439     ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr) => (
 440         $crate::declare_lint!(
 441             $(#[$attr])* $vis $NAME, $Level, $desc,
 442         );
 443     );
 444     ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr,
 445      $(@feature_gate = $gate:expr;)?
 446      $(@future_incompatible = FutureIncompatibleInfo { $($field:ident : $val:expr),* $(,)*  }; )?
 447      $($v:ident),*) => (
 448         $(#[$attr])*
 449         $vis static $NAME: &$crate::Lint = &$crate::Lint {
 450             name: stringify!($NAME),
 451             default_level: $crate::$Level,
 452             desc: $desc,
 453             edition_lint_opts: None,
 454             is_plugin: false,
 455             $($v: true,)*
 456             $(feature_gate: Some($gate),)*
 457             $(future_incompatible: Some($crate::FutureIncompatibleInfo {
 458                 $($field: $val,)*
 459                 ..$crate::FutureIncompatibleInfo::default_fields_for_macro()
 460             }),)*
 461             ..$crate::Lint::default_fields_for_macro()
 462         };
 463     );
 464     ($(#[$attr:meta])* $vis: vis $NAME: ident, $Level: ident, $desc: expr,
 465      $lint_edition: expr => $edition_level: ident
 466     ) => (
 467         $(#[$attr])*
 468         $vis static $NAME: &$crate::Lint = &$crate::Lint {
 469             name: stringify!($NAME),
 470             default_level: $crate::$Level,
 471             desc: $desc,
 472             edition_lint_opts: Some(($lint_edition, $crate::Level::$edition_level)),
 473             report_in_external_macro: false,
 474             is_plugin: false,
 475         };
 476     );
 477 }
 478
 479 #[macro_export]
 480 macro_rules! declare_tool_lint {
 481     (
 482         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level: ident, $desc: expr
 483     ) => (
 484         $crate::declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, false}
 485     );
 486     (
 487         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
 488         report_in_external_macro: $rep:expr
 489     ) => (
 490          $crate::declare_tool_lint!{$(#[$attr])* $vis $tool::$NAME, $Level, $desc, $rep}
 491     );
 492     (
 493         $(#[$attr:meta])* $vis:vis $tool:ident ::$NAME:ident, $Level:ident, $desc:expr,
 494         $external:expr
 495     ) => (
 496         $(#[$attr])*
 497         $vis static $NAME: &$crate::Lint = &$crate::Lint {
 498             name: &concat!(stringify!($tool), "::", stringify!($NAME)),
 499             default_level: $crate::$Level,
 500             desc: $desc,
 501             edition_lint_opts: None,
 502             report_in_external_macro: $external,
 503             future_incompatible: None,
 504             is_plugin: true,
 505             feature_gate: None,
 506             crate_level_only: false,
 507         };
 508     );
 509 }
 510
 511 /// Declares a static `LintArray` and return it as an expression.
 512 #[macro_export]
 513 macro_rules! lint_array {
 514     ($( $lint:expr ),* ,) => { lint_array!( $($lint),* ) };
 515     ($( $lint:expr ),*) => {{
 516         vec![$($lint),*]
 517     }}
 518 }
 519
 520 pub type LintArray = Vec<&'static Lint>;
 521
 522 pub trait LintPass {
 523     fn name(&self) -> &'static str;
 524 }
 525
 526 /// Implements `LintPass for $ty` with the given list of `Lint` statics.
 527 #[macro_export]
 528 macro_rules! impl_lint_pass {
 529     ($ty:ty => [$($lint:expr),* $(,)?]) => {
 530         impl $crate::LintPass for $ty {
 531             fn name(&self) -> &'static str { stringify!($ty) }
 532         }
 533         impl $ty {
 534             pub fn get_lints() -> $crate::LintArray { $crate::lint_array!($($lint),*) }
 535         }
 536     };
 537 }
 538
 539 /// Declares a type named `$name` which implements `LintPass`.
 540 /// To the right of `=>` a comma separated list of `Lint` statics is given.
 541 #[macro_export]
 542 macro_rules! declare_lint_pass {
 543     ($(#[$m:meta])* $name:ident => [$($lint:expr),* $(,)?]) => {
 544         $(#[$m])* #[derive(Copy, Clone)] pub struct $name;
 545         $crate::impl_lint_pass!($name => [$($lint),*]);
 546     };
 547 }