clippy_lints/src/utils/internal_lints.rs

   1 use crate::consts::{constant_simple, Constant};
   2 use crate::utils::{
   3     is_expn_of, match_def_path, match_qpath, match_type, method_calls, path_to_res, paths, qpath_res, run_lints,
   4     snippet, span_lint, span_lint_and_help, span_lint_and_sugg, SpanlessEq,
   5 };
   6 use if_chain::if_chain;
   7 use rustc_ast::ast::{Crate as AstCrate, ItemKind, LitKind, NodeId};
   8 use rustc_ast::visit::FnKind;
   9 use rustc_data_structures::fx::{FxHashMap, FxHashSet};
  10 use rustc_errors::Applicability;
  11 use rustc_hir as hir;
  12 use rustc_hir::def::{DefKind, Res};
  13 use rustc_hir::def_id::DefId;
  14 use rustc_hir::hir_id::CRATE_HIR_ID;
  15 use rustc_hir::intravisit::{NestedVisitorMap, Visitor};
  16 use rustc_hir::{Crate, Expr, ExprKind, HirId, Item, MutTy, Mutability, Node, Path, StmtKind, Ty, TyKind};
  17 use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass};
  18 use rustc_middle::hir::map::Map;
  19 use rustc_middle::mir::interpret::ConstValue;
  20 use rustc_middle::ty;
  21 use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
  22 use rustc_span::source_map::{Span, Spanned};
  23 use rustc_span::symbol::{Symbol, SymbolStr};
  24 use rustc_typeck::hir_ty_to_ty;
  25
  26 use std::borrow::{Borrow, Cow};
  27
  28 declare_clippy_lint! {
  29     /// **What it does:** Checks for various things we like to keep tidy in clippy.
  30     ///
  31     /// **Why is this bad?** We like to pretend we're an example of tidy code.
  32     ///
  33     /// **Known problems:** None.
  34     ///
  35     /// **Example:** Wrong ordering of the util::paths constants.
  36     pub CLIPPY_LINTS_INTERNAL,
  37     internal,
  38     "various things that will negatively affect your clippy experience"
  39 }
  40
  41 declare_clippy_lint! {
  42     /// **What it does:** Ensures every lint is associated to a `LintPass`.
  43     ///
  44     /// **Why is this bad?** The compiler only knows lints via a `LintPass`. Without
  45     /// putting a lint to a `LintPass::get_lints()`'s return, the compiler will not
  46     /// know the name of the lint.
  47     ///
  48     /// **Known problems:** Only checks for lints associated using the
  49     /// `declare_lint_pass!`, `impl_lint_pass!`, and `lint_array!` macros.
  50     ///
  51     /// **Example:**
  52     /// ```rust,ignore
  53     /// declare_lint! { pub LINT_1, ... }
  54     /// declare_lint! { pub LINT_2, ... }
  55     /// declare_lint! { pub FORGOTTEN_LINT, ... }
  56     /// // ...
  57     /// declare_lint_pass!(Pass => [LINT_1, LINT_2]);
  58     /// // missing FORGOTTEN_LINT
  59     /// ```
  60     pub LINT_WITHOUT_LINT_PASS,
  61     internal,
  62     "declaring a lint without associating it in a LintPass"
  63 }
  64
  65 declare_clippy_lint! {
  66     /// **What it does:** Checks for calls to `cx.span_lint*` and suggests to use the `utils::*`
  67     /// variant of the function.
  68     ///
  69     /// **Why is this bad?** The `utils::*` variants also add a link to the Clippy documentation to the
  70     /// warning/error messages.
  71     ///
  72     /// **Known problems:** None.
  73     ///
  74     /// **Example:**
  75     /// Bad:
  76     /// ```rust,ignore
  77     /// cx.span_lint(LINT_NAME, "message");
  78     /// ```
  79     ///
  80     /// Good:
  81     /// ```rust,ignore
  82     /// utils::span_lint(cx, LINT_NAME, "message");
  83     /// ```
  84     pub COMPILER_LINT_FUNCTIONS,
  85     internal,
  86     "usage of the lint functions of the compiler instead of the utils::* variant"
  87 }
  88
  89 declare_clippy_lint! {
  90     /// **What it does:** Checks for calls to `cx.outer().expn_data()` and suggests to use
  91     /// the `cx.outer_expn_data()`
  92     ///
  93     /// **Why is this bad?** `cx.outer_expn_data()` is faster and more concise.
  94     ///
  95     /// **Known problems:** None.
  96     ///
  97     /// **Example:**
  98     /// Bad:
  99     /// ```rust,ignore
 100     /// expr.span.ctxt().outer().expn_data()
 101     /// ```
 102     ///
 103     /// Good:
 104     /// ```rust,ignore
 105     /// expr.span.ctxt().outer_expn_data()
 106     /// ```
 107     pub OUTER_EXPN_EXPN_DATA,
 108     internal,
 109     "using `cx.outer_expn().expn_data()` instead of `cx.outer_expn_data()`"
 110 }
 111
 112 declare_clippy_lint! {
 113     /// **What it does:** Not an actual lint. This lint is only meant for testing our customized internal compiler
 114     /// error message by calling `panic`.
 115     ///
 116     /// **Why is this bad?** ICE in large quantities can damage your teeth
 117     ///
 118     /// **Known problems:** None
 119     ///
 120     /// **Example:**
 121     /// Bad:
 122     /// ```rust,ignore
 123     /// 🍦🍦🍦🍦🍦
 124     /// ```
 125     pub PRODUCE_ICE,
 126     internal,
 127     "this message should not appear anywhere as we ICE before and don't emit the lint"
 128 }
 129
 130 declare_clippy_lint! {
 131     /// **What it does:** Checks for cases of an auto-generated lint without an updated description,
 132     /// i.e. `default lint description`.
 133     ///
 134     /// **Why is this bad?** Indicates that the lint is not finished.
 135     ///
 136     /// **Known problems:** None
 137     ///
 138     /// **Example:**
 139     /// Bad:
 140     /// ```rust,ignore
 141     /// declare_lint! { pub COOL_LINT, nursery, "default lint description" }
 142     /// ```
 143     ///
 144     /// Good:
 145     /// ```rust,ignore
 146     /// declare_lint! { pub COOL_LINT, nursery, "a great new lint" }
 147     /// ```
 148     pub DEFAULT_LINT,
 149     internal,
 150     "found 'default lint description' in a lint declaration"
 151 }
 152
 153 declare_clippy_lint! {
 154     /// **What it does:** Lints `span_lint_and_then` function calls, where the
 155     /// closure argument has only one statement and that statement is a method
 156     /// call to `span_suggestion`, `span_help`, `span_note` (using the same
 157     /// span), `help` or `note`.
 158     ///
 159     /// These usages of `span_lint_and_then` should be replaced with one of the
 160     /// wrapper functions `span_lint_and_sugg`, span_lint_and_help`, or
 161     /// `span_lint_and_note`.
 162     ///
 163     /// **Why is this bad?** Using the wrapper `span_lint_and_*` functions, is more
 164     /// convenient, readable and less error prone.
 165     ///
 166     /// **Known problems:** None
 167     ///
 168     /// *Example:**
 169     /// Bad:
 170     /// ```rust,ignore
 171     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 172     ///     diag.span_suggestion(
 173     ///         expr.span,
 174     ///         help_msg,
 175     ///         sugg.to_string(),
 176     ///         Applicability::MachineApplicable,
 177     ///     );
 178     /// });
 179     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 180     ///     diag.span_help(expr.span, help_msg);
 181     /// });
 182     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 183     ///     diag.help(help_msg);
 184     /// });
 185     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 186     ///     diag.span_note(expr.span, note_msg);
 187     /// });
 188     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 189     ///     diag.note(note_msg);
 190     /// });
 191     /// ```
 192     ///
 193     /// Good:
 194     /// ```rust,ignore
 195     /// span_lint_and_sugg(
 196     ///     cx,
 197     ///     TEST_LINT,
 198     ///     expr.span,
 199     ///     lint_msg,
 200     ///     help_msg,
 201     ///     sugg.to_string(),
 202     ///     Applicability::MachineApplicable,
 203     /// );
 204     /// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), help_msg);
 205     /// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, None, help_msg);
 206     /// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), note_msg);
 207     /// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, None, note_msg);
 208     /// ```
 209     pub COLLAPSIBLE_SPAN_LINT_CALLS,
 210     internal,
 211     "found collapsible `span_lint_and_then` calls"
 212 }
 213
 214 declare_clippy_lint! {
 215     /// **What it does:** Checks for calls to `utils::match_type()` on a type diagnostic item
 216     /// and suggests to use `utils::is_type_diagnostic_item()` instead.
 217     ///
 218     /// **Why is this bad?** `utils::is_type_diagnostic_item()` does not require hardcoded paths.
 219     ///
 220     /// **Known problems:** None.
 221     ///
 222     /// **Example:**
 223     /// Bad:
 224     /// ```rust,ignore
 225     /// utils::match_type(cx, ty, &paths::VEC)
 226     /// ```
 227     ///
 228     /// Good:
 229     /// ```rust,ignore
 230     /// utils::is_type_diagnostic_item(cx, ty, sym::vec_type)
 231     /// ```
 232     pub MATCH_TYPE_ON_DIAGNOSTIC_ITEM,
 233     internal,
 234     "using `utils::match_type()` instead of `utils::is_type_diagnostic_item()`"
 235 }
 236
 237 declare_clippy_lint! {
 238     /// **What it does:**
 239     /// Checks the paths module for invalid paths.
 240     ///
 241     /// **Why is this bad?**
 242     /// It indicates a bug in the code.
 243     ///
 244     /// **Known problems:** None.
 245     ///
 246     /// **Example:** None.
 247     pub INVALID_PATHS,
 248     internal,
 249     "invalid path"
 250 }
 251
 252 declare_clippy_lint! {
 253     /// **What it does:**
 254     /// Checks for interning symbols that have already been pre-interned and defined as constants.
 255     ///
 256     /// **Why is this bad?**
 257     /// It's faster and easier to use the symbol constant.
 258     ///
 259     /// **Known problems:** None.
 260     ///
 261     /// **Example:**
 262     /// Bad:
 263     /// ```rust,ignore
 264     /// let _ = sym!(f32);
 265     /// ```
 266     ///
 267     /// Good:
 268     /// ```rust,ignore
 269     /// let _ = sym::f32;
 270     /// ```
 271     pub INTERNING_DEFINED_SYMBOL,
 272     internal,
 273     "interning a symbol that is pre-interned and defined as a constant"
 274 }
 275
 276 declare_lint_pass!(ClippyLintsInternal => [CLIPPY_LINTS_INTERNAL]);
 277
 278 impl EarlyLintPass for ClippyLintsInternal {
 279     fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &AstCrate) {
 280         if let Some(utils) = krate
 281             .module
 282             .items
 283             .iter()
 284             .find(|item| item.ident.name.as_str() == "utils")
 285         {
 286             if let ItemKind::Mod(ref utils_mod) = utils.kind {
 287                 if let Some(paths) = utils_mod.items.iter().find(|item| item.ident.name.as_str() == "paths") {
 288                     if let ItemKind::Mod(ref paths_mod) = paths.kind {
 289                         let mut last_name: Option<SymbolStr> = None;
 290                         for item in &*paths_mod.items {
 291                             let name = item.ident.as_str();
 292                             if let Some(ref last_name) = last_name {
 293                                 if **last_name > *name {
 294                                     span_lint(
 295                                         cx,
 296                                         CLIPPY_LINTS_INTERNAL,
 297                                         item.span,
 298                                         "this constant should be before the previous constant due to lexical \
 299                                          ordering",
 300                                     );
 301                                 }
 302                             }
 303                             last_name = Some(name);
 304                         }
 305                     }
 306                 }
 307             }
 308         }
 309     }
 310 }
 311
 312 #[derive(Clone, Debug, Default)]
 313 pub struct LintWithoutLintPass {
 314     declared_lints: FxHashMap<Symbol, Span>,
 315     registered_lints: FxHashSet<Symbol>,
 316 }
 317
 318 impl_lint_pass!(LintWithoutLintPass => [DEFAULT_LINT, LINT_WITHOUT_LINT_PASS]);
 319
 320 impl<'tcx> LateLintPass<'tcx> for LintWithoutLintPass {
 321     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
 322         if !run_lints(cx, &[DEFAULT_LINT], item.hir_id) {
 323             return;
 324         }
 325
 326         if let hir::ItemKind::Static(ref ty, Mutability::Not, body_id) = item.kind {
 327             if is_lint_ref_type(cx, ty) {
 328                 let expr = &cx.tcx.hir().body(body_id).value;
 329                 if_chain! {
 330                     if let ExprKind::AddrOf(_, _, ref inner_exp) = expr.kind;
 331                     if let ExprKind::Struct(_, ref fields, _) = inner_exp.kind;
 332                     let field = fields
 333                         .iter()
 334                         .find(|f| f.ident.as_str() == "desc")
 335                         .expect("lints must have a description field");
 336                     if let ExprKind::Lit(Spanned {
 337                         node: LitKind::Str(ref sym, _),
 338                         ..
 339                     }) = field.expr.kind;
 340                     if sym.as_str() == "default lint description";
 341
 342                     then {
 343                         span_lint(
 344                             cx,
 345                             DEFAULT_LINT,
 346                             item.span,
 347                             &format!("the lint `{}` has the default lint description", item.ident.name),
 348                         );
 349                     }
 350                 }
 351                 self.declared_lints.insert(item.ident.name, item.span);
 352             }
 353         } else if is_expn_of(item.span, "impl_lint_pass").is_some()
 354             || is_expn_of(item.span, "declare_lint_pass").is_some()
 355         {
 356             if let hir::ItemKind::Impl {
 357                 of_trait: None,
 358                 items: ref impl_item_refs,
 359                 ..
 360             } = item.kind
 361             {
 362                 let mut collector = LintCollector {
 363                     output: &mut self.registered_lints,
 364                     cx,
 365                 };
 366                 let body_id = cx.tcx.hir().body_owned_by(
 367                     impl_item_refs
 368                         .iter()
 369                         .find(|iiref| iiref.ident.as_str() == "get_lints")
 370                         .expect("LintPass needs to implement get_lints")
 371                         .id
 372                         .hir_id,
 373                 );
 374                 collector.visit_expr(&cx.tcx.hir().body(body_id).value);
 375             }
 376         }
 377     }
 378
 379     fn check_crate_post(&mut self, cx: &LateContext<'tcx>, _: &'tcx Crate<'_>) {
 380         if !run_lints(cx, &[LINT_WITHOUT_LINT_PASS], CRATE_HIR_ID) {
 381             return;
 382         }
 383
 384         for (lint_name, &lint_span) in &self.declared_lints {
 385             // When using the `declare_tool_lint!` macro, the original `lint_span`'s
 386             // file points to "<rustc macros>".
 387             // `compiletest-rs` thinks that's an error in a different file and
 388             // just ignores it. This causes the test in compile-fail/lint_pass
 389             // not able to capture the error.
 390             // Therefore, we need to climb the macro expansion tree and find the
 391             // actual span that invoked `declare_tool_lint!`:
 392             let lint_span = lint_span.ctxt().outer_expn_data().call_site;
 393
 394             if !self.registered_lints.contains(lint_name) {
 395                 span_lint(
 396                     cx,
 397                     LINT_WITHOUT_LINT_PASS,
 398                     lint_span,
 399                     &format!("the lint `{}` is not added to any `LintPass`", lint_name),
 400                 );
 401             }
 402         }
 403     }
 404 }
 405
 406 fn is_lint_ref_type<'tcx>(cx: &LateContext<'tcx>, ty: &Ty<'_>) -> bool {
 407     if let TyKind::Rptr(
 408         _,
 409         MutTy {
 410             ty: ref inner,
 411             mutbl: Mutability::Not,
 412         },
 413     ) = ty.kind
 414     {
 415         if let TyKind::Path(ref path) = inner.kind {
 416             if let Res::Def(DefKind::Struct, def_id) = cx.qpath_res(path, inner.hir_id) {
 417                 return match_def_path(cx, def_id, &paths::LINT);
 418             }
 419         }
 420     }
 421
 422     false
 423 }
 424
 425 struct LintCollector<'a, 'tcx> {
 426     output: &'a mut FxHashSet<Symbol>,
 427     cx: &'a LateContext<'tcx>,
 428 }
 429
 430 impl<'a, 'tcx> Visitor<'tcx> for LintCollector<'a, 'tcx> {
 431     type Map = Map<'tcx>;
 432
 433     fn visit_path(&mut self, path: &'tcx Path<'_>, _: HirId) {
 434         if path.segments.len() == 1 {
 435             self.output.insert(path.segments[0].ident.name);
 436         }
 437     }
 438
 439     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
 440         NestedVisitorMap::All(self.cx.tcx.hir())
 441     }
 442 }
 443
 444 #[derive(Clone, Default)]
 445 pub struct CompilerLintFunctions {
 446     map: FxHashMap<&'static str, &'static str>,
 447 }
 448
 449 impl CompilerLintFunctions {
 450     #[must_use]
 451     pub fn new() -> Self {
 452         let mut map = FxHashMap::default();
 453         map.insert("span_lint", "utils::span_lint");
 454         map.insert("struct_span_lint", "utils::span_lint");
 455         map.insert("lint", "utils::span_lint");
 456         map.insert("span_lint_note", "utils::span_lint_and_note");
 457         map.insert("span_lint_help", "utils::span_lint_and_help");
 458         Self { map }
 459     }
 460 }
 461
 462 impl_lint_pass!(CompilerLintFunctions => [COMPILER_LINT_FUNCTIONS]);
 463
 464 impl<'tcx> LateLintPass<'tcx> for CompilerLintFunctions {
 465     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 466         if !run_lints(cx, &[COMPILER_LINT_FUNCTIONS], expr.hir_id) {
 467             return;
 468         }
 469
 470         if_chain! {
 471             if let ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind;
 472             let fn_name = path.ident;
 473             if let Some(sugg) = self.map.get(&*fn_name.as_str());
 474             let ty = cx.typeck_results().expr_ty(&args[0]).peel_refs();
 475             if match_type(cx, ty, &paths::EARLY_CONTEXT)
 476                 || match_type(cx, ty, &paths::LATE_CONTEXT);
 477             then {
 478                 span_lint_and_help(
 479                     cx,
 480                     COMPILER_LINT_FUNCTIONS,
 481                     path.ident.span,
 482                     "usage of a compiler lint function",
 483                     None,
 484                     &format!("please use the Clippy variant of this function: `{}`", sugg),
 485                 );
 486             }
 487         }
 488     }
 489 }
 490
 491 declare_lint_pass!(OuterExpnDataPass => [OUTER_EXPN_EXPN_DATA]);
 492
 493 impl<'tcx> LateLintPass<'tcx> for OuterExpnDataPass {
 494     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 495         if !run_lints(cx, &[OUTER_EXPN_EXPN_DATA], expr.hir_id) {
 496             return;
 497         }
 498
 499         let (method_names, arg_lists, spans) = method_calls(expr, 2);
 500         let method_names: Vec<SymbolStr> = method_names.iter().map(|s| s.as_str()).collect();
 501         let method_names: Vec<&str> = method_names.iter().map(|s| &**s).collect();
 502         if_chain! {
 503             if let ["expn_data", "outer_expn"] = method_names.as_slice();
 504             let args = arg_lists[1];
 505             if args.len() == 1;
 506             let self_arg = &args[0];
 507             let self_ty = cx.typeck_results().expr_ty(self_arg).peel_refs();
 508             if match_type(cx, self_ty, &paths::SYNTAX_CONTEXT);
 509             then {
 510                 span_lint_and_sugg(
 511                     cx,
 512                     OUTER_EXPN_EXPN_DATA,
 513                     spans[1].with_hi(expr.span.hi()),
 514                     "usage of `outer_expn().expn_data()`",
 515                     "try",
 516                     "outer_expn_data()".to_string(),
 517                     Applicability::MachineApplicable,
 518                 );
 519             }
 520         }
 521     }
 522 }
 523
 524 declare_lint_pass!(ProduceIce => [PRODUCE_ICE]);
 525
 526 impl EarlyLintPass for ProduceIce {
 527     fn check_fn(&mut self, _: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
 528         if is_trigger_fn(fn_kind) {
 529             panic!("Would you like some help with that?");
 530         }
 531     }
 532 }
 533
 534 fn is_trigger_fn(fn_kind: FnKind<'_>) -> bool {
 535     match fn_kind {
 536         FnKind::Fn(_, ident, ..) => ident.name.as_str() == "it_looks_like_you_are_trying_to_kill_clippy",
 537         FnKind::Closure(..) => false,
 538     }
 539 }
 540
 541 declare_lint_pass!(CollapsibleCalls => [COLLAPSIBLE_SPAN_LINT_CALLS]);
 542
 543 impl<'tcx> LateLintPass<'tcx> for CollapsibleCalls {
 544     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 545         if !run_lints(cx, &[COLLAPSIBLE_SPAN_LINT_CALLS], expr.hir_id) {
 546             return;
 547         }
 548
 549         if_chain! {
 550             if let ExprKind::Call(ref func, ref and_then_args) = expr.kind;
 551             if let ExprKind::Path(ref path) = func.kind;
 552             if match_qpath(path, &["span_lint_and_then"]);
 553             if and_then_args.len() == 5;
 554             if let ExprKind::Closure(_, _, body_id, _, _) = &and_then_args[4].kind;
 555             let body = cx.tcx.hir().body(*body_id);
 556             if let ExprKind::Block(block, _) = &body.value.kind;
 557             let stmts = &block.stmts;
 558             if stmts.len() == 1 && block.expr.is_none();
 559             if let StmtKind::Semi(only_expr) = &stmts[0].kind;
 560             if let ExprKind::MethodCall(ref ps, _, ref span_call_args, _) = &only_expr.kind;
 561             let and_then_snippets = get_and_then_snippets(cx, and_then_args);
 562             let mut sle = SpanlessEq::new(cx).deny_side_effects();
 563             then {
 564                 match &*ps.ident.as_str() {
 565                     "span_suggestion" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 566                         suggest_suggestion(cx, expr, &and_then_snippets, &span_suggestion_snippets(cx, span_call_args));
 567                     },
 568                     "span_help" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 569                         let help_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 570                         suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), true);
 571                     },
 572                     "span_note" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 573                         let note_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 574                         suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), true);
 575                     },
 576                     "help" => {
 577                         let help_snippet = snippet(cx, span_call_args[1].span, r#""...""#);
 578                         suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), false);
 579                     }
 580                     "note" => {
 581                         let note_snippet = snippet(cx, span_call_args[1].span, r#""...""#);
 582                         suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), false);
 583                     }
 584                     _  => (),
 585                 }
 586             }
 587         }
 588     }
 589 }
 590
 591 struct AndThenSnippets<'a> {
 592     cx: Cow<'a, str>,
 593     lint: Cow<'a, str>,
 594     span: Cow<'a, str>,
 595     msg: Cow<'a, str>,
 596 }
 597
 598 fn get_and_then_snippets<'a, 'hir>(cx: &LateContext<'_>, and_then_snippets: &'hir [Expr<'hir>]) -> AndThenSnippets<'a> {
 599     let cx_snippet = snippet(cx, and_then_snippets[0].span, "cx");
 600     let lint_snippet = snippet(cx, and_then_snippets[1].span, "..");
 601     let span_snippet = snippet(cx, and_then_snippets[2].span, "span");
 602     let msg_snippet = snippet(cx, and_then_snippets[3].span, r#""...""#);
 603
 604     AndThenSnippets {
 605         cx: cx_snippet,
 606         lint: lint_snippet,
 607         span: span_snippet,
 608         msg: msg_snippet,
 609     }
 610 }
 611
 612 struct SpanSuggestionSnippets<'a> {
 613     help: Cow<'a, str>,
 614     sugg: Cow<'a, str>,
 615     applicability: Cow<'a, str>,
 616 }
 617
 618 fn span_suggestion_snippets<'a, 'hir>(
 619     cx: &LateContext<'_>,
 620     span_call_args: &'hir [Expr<'hir>],
 621 ) -> SpanSuggestionSnippets<'a> {
 622     let help_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 623     let sugg_snippet = snippet(cx, span_call_args[3].span, "..");
 624     let applicability_snippet = snippet(cx, span_call_args[4].span, "Applicability::MachineApplicable");
 625
 626     SpanSuggestionSnippets {
 627         help: help_snippet,
 628         sugg: sugg_snippet,
 629         applicability: applicability_snippet,
 630     }
 631 }
 632
 633 fn suggest_suggestion(
 634     cx: &LateContext<'_>,
 635     expr: &Expr<'_>,
 636     and_then_snippets: &AndThenSnippets<'_>,
 637     span_suggestion_snippets: &SpanSuggestionSnippets<'_>,
 638 ) {
 639     span_lint_and_sugg(
 640         cx,
 641         COLLAPSIBLE_SPAN_LINT_CALLS,
 642         expr.span,
 643         "this call is collapsible",
 644         "collapse into",
 645         format!(
 646             "span_lint_and_sugg({}, {}, {}, {}, {}, {}, {})",
 647             and_then_snippets.cx,
 648             and_then_snippets.lint,
 649             and_then_snippets.span,
 650             and_then_snippets.msg,
 651             span_suggestion_snippets.help,
 652             span_suggestion_snippets.sugg,
 653             span_suggestion_snippets.applicability
 654         ),
 655         Applicability::MachineApplicable,
 656     );
 657 }
 658
 659 fn suggest_help(
 660     cx: &LateContext<'_>,
 661     expr: &Expr<'_>,
 662     and_then_snippets: &AndThenSnippets<'_>,
 663     help: &str,
 664     with_span: bool,
 665 ) {
 666     let option_span = if with_span {
 667         format!("Some({})", and_then_snippets.span)
 668     } else {
 669         "None".to_string()
 670     };
 671
 672     span_lint_and_sugg(
 673         cx,
 674         COLLAPSIBLE_SPAN_LINT_CALLS,
 675         expr.span,
 676         "this call is collapsible",
 677         "collapse into",
 678         format!(
 679             "span_lint_and_help({}, {}, {}, {}, {}, {})",
 680             and_then_snippets.cx,
 681             and_then_snippets.lint,
 682             and_then_snippets.span,
 683             and_then_snippets.msg,
 684             &option_span,
 685             help
 686         ),
 687         Applicability::MachineApplicable,
 688     );
 689 }
 690
 691 fn suggest_note(
 692     cx: &LateContext<'_>,
 693     expr: &Expr<'_>,
 694     and_then_snippets: &AndThenSnippets<'_>,
 695     note: &str,
 696     with_span: bool,
 697 ) {
 698     let note_span = if with_span {
 699         format!("Some({})", and_then_snippets.span)
 700     } else {
 701         "None".to_string()
 702     };
 703
 704     span_lint_and_sugg(
 705         cx,
 706         COLLAPSIBLE_SPAN_LINT_CALLS,
 707         expr.span,
 708         "this call is collspible",
 709         "collapse into",
 710         format!(
 711             "span_lint_and_note({}, {}, {}, {}, {}, {})",
 712             and_then_snippets.cx,
 713             and_then_snippets.lint,
 714             and_then_snippets.span,
 715             and_then_snippets.msg,
 716             note_span,
 717             note
 718         ),
 719         Applicability::MachineApplicable,
 720     );
 721 }
 722
 723 declare_lint_pass!(MatchTypeOnDiagItem => [MATCH_TYPE_ON_DIAGNOSTIC_ITEM]);
 724
 725 impl<'tcx> LateLintPass<'tcx> for MatchTypeOnDiagItem {
 726     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 727         if !run_lints(cx, &[MATCH_TYPE_ON_DIAGNOSTIC_ITEM], expr.hir_id) {
 728             return;
 729         }
 730
 731         if_chain! {
 732             // Check if this is a call to utils::match_type()
 733             if let ExprKind::Call(fn_path, [context, ty, ty_path]) = expr.kind;
 734             if let ExprKind::Path(fn_qpath) = &fn_path.kind;
 735             if match_qpath(&fn_qpath, &["utils", "match_type"]);
 736             // Extract the path to the matched type
 737             if let Some(segments) = path_to_matched_type(cx, ty_path);
 738             let segments: Vec<&str> = segments.iter().map(|sym| &**sym).collect();
 739             if let Some(ty_did) = path_to_res(cx, &segments[..]).and_then(|res| res.opt_def_id());
 740             // Check if the matched type is a diagnostic item
 741             let diag_items = cx.tcx.diagnostic_items(ty_did.krate);
 742             if let Some(item_name) = diag_items.iter().find_map(|(k, v)| if *v == ty_did { Some(k) } else { None });
 743             then {
 744                 let cx_snippet = snippet(cx, context.span, "_");
 745                 let ty_snippet = snippet(cx, ty.span, "_");
 746
 747                 span_lint_and_sugg(
 748                     cx,
 749                     MATCH_TYPE_ON_DIAGNOSTIC_ITEM,
 750                     expr.span,
 751                     "usage of `utils::match_type()` on a type diagnostic item",
 752                     "try",
 753                     format!("utils::is_type_diagnostic_item({}, {}, sym::{})", cx_snippet, ty_snippet, item_name),
 754                     Applicability::MaybeIncorrect,
 755                 );
 756             }
 757         }
 758     }
 759 }
 760
 761 fn path_to_matched_type(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<Vec<SymbolStr>> {
 762     use rustc_hir::ItemKind;
 763
 764     match &expr.kind {
 765         ExprKind::AddrOf(.., expr) => return path_to_matched_type(cx, expr),
 766         ExprKind::Path(qpath) => match qpath_res(cx, qpath, expr.hir_id) {
 767             Res::Local(hir_id) => {
 768                 let parent_id = cx.tcx.hir().get_parent_node(hir_id);
 769                 if let Some(Node::Local(local)) = cx.tcx.hir().find(parent_id) {
 770                     if let Some(init) = local.init {
 771                         return path_to_matched_type(cx, init);
 772                     }
 773                 }
 774             },
 775             Res::Def(DefKind::Const | DefKind::Static, def_id) => {
 776                 if let Some(Node::Item(item)) = cx.tcx.hir().get_if_local(def_id) {
 777                     if let ItemKind::Const(.., body_id) | ItemKind::Static(.., body_id) = item.kind {
 778                         let body = cx.tcx.hir().body(body_id);
 779                         return path_to_matched_type(cx, &body.value);
 780                     }
 781                 }
 782             },
 783             _ => {},
 784         },
 785         ExprKind::Array(exprs) => {
 786             let segments: Vec<SymbolStr> = exprs
 787                 .iter()
 788                 .filter_map(|expr| {
 789                     if let ExprKind::Lit(lit) = &expr.kind {
 790                         if let LitKind::Str(sym, _) = lit.node {
 791                             return Some(sym.as_str());
 792                         }
 793                     }
 794
 795                     None
 796                 })
 797                 .collect();
 798
 799             if segments.len() == exprs.len() {
 800                 return Some(segments);
 801             }
 802         },
 803         _ => {},
 804     }
 805
 806     None
 807 }
 808
 809 // This is not a complete resolver for paths. It works on all the paths currently used in the paths
 810 // module.  That's all it does and all it needs to do.
 811 pub fn check_path(cx: &LateContext<'_>, path: &[&str]) -> bool {
 812     if path_to_res(cx, path).is_some() {
 813         return true;
 814     }
 815
 816     // Some implementations can't be found by `path_to_res`, particularly inherent
 817     // implementations of native types. Check lang items.
 818     let path_syms: Vec<_> = path.iter().map(|p| Symbol::intern(p)).collect();
 819     let lang_items = cx.tcx.lang_items();
 820     for lang_item in lang_items.items() {
 821         if let Some(def_id) = lang_item {
 822             let lang_item_path = cx.get_def_path(*def_id);
 823             if path_syms.starts_with(&lang_item_path) {
 824                 if let [item] = &path_syms[lang_item_path.len()..] {
 825                     for child in cx.tcx.item_children(*def_id) {
 826                         if child.ident.name == *item {
 827                             return true;
 828                         }
 829                     }
 830                 }
 831             }
 832         }
 833     }
 834
 835     false
 836 }
 837
 838 declare_lint_pass!(InvalidPaths => [INVALID_PATHS]);
 839
 840 impl<'tcx> LateLintPass<'tcx> for InvalidPaths {
 841     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
 842         let local_def_id = &cx.tcx.parent_module(item.hir_id);
 843         let mod_name = &cx.tcx.item_name(local_def_id.to_def_id());
 844         if_chain! {
 845             if mod_name.as_str() == "paths";
 846             if let hir::ItemKind::Const(ty, body_id) = item.kind;
 847             let ty = hir_ty_to_ty(cx.tcx, ty);
 848             if let ty::Array(el_ty, _) = &ty.kind();
 849             if let ty::Ref(_, el_ty, _) = &el_ty.kind();
 850             if el_ty.is_str();
 851             let body = cx.tcx.hir().body(body_id);
 852             let typeck_results = cx.tcx.typeck_body(body_id);
 853             if let Some(Constant::Vec(path)) = constant_simple(cx, typeck_results, &body.value);
 854             let path: Vec<&str> = path.iter().map(|x| {
 855                     if let Constant::Str(s) = x {
 856                         s.as_str()
 857                     } else {
 858                         // We checked the type of the constant above
 859                         unreachable!()
 860                     }
 861                 }).collect();
 862             if !check_path(cx, &path[..]);
 863             then {
 864                 span_lint(cx, CLIPPY_LINTS_INTERNAL, item.span, "invalid path");
 865             }
 866         }
 867     }
 868 }
 869
 870 #[derive(Default)]
 871 pub struct InterningDefinedSymbol {
 872     // Maps the symbol value to the constant DefId.
 873     symbol_map: FxHashMap<u32, DefId>,
 874 }
 875
 876 impl_lint_pass!(InterningDefinedSymbol => [INTERNING_DEFINED_SYMBOL]);
 877
 878 impl<'tcx> LateLintPass<'tcx> for InterningDefinedSymbol {
 879     fn check_crate(&mut self, cx: &LateContext<'_>, _: &Crate<'_>) {
 880         if !self.symbol_map.is_empty() {
 881             return;
 882         }
 883
 884         if let Some(Res::Def(_, def_id)) = path_to_res(cx, &paths::SYM_MODULE) {
 885             for item in cx.tcx.item_children(def_id).iter() {
 886                 if_chain! {
 887                     if let Res::Def(DefKind::Const, item_def_id) = item.res;
 888                     let ty = cx.tcx.type_of(item_def_id);
 889                     if match_type(cx, ty, &paths::SYMBOL);
 890                     if let Ok(ConstValue::Scalar(value)) = cx.tcx.const_eval_poly(item_def_id);
 891                     if let Ok(value) = value.to_u32();
 892                     then {
 893                         self.symbol_map.insert(value, item_def_id);
 894                     }
 895                 }
 896             }
 897         }
 898     }
 899
 900     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 901         if_chain! {
 902             if let ExprKind::Call(func, [arg]) = &expr.kind;
 903             if let ty::FnDef(def_id, _) = cx.typeck_results().expr_ty(func).kind();
 904             if match_def_path(cx, *def_id, &paths::SYMBOL_INTERN);
 905             if let Some(Constant::Str(arg)) = constant_simple(cx, cx.typeck_results(), arg);
 906             let value = Symbol::intern(&arg).as_u32();
 907             if let Some(&def_id) = self.symbol_map.get(&value);
 908             then {
 909                 span_lint_and_sugg(
 910                     cx,
 911                     INTERNING_DEFINED_SYMBOL,
 912                     is_expn_of(expr.span, "sym").unwrap_or(expr.span),
 913                     "interning a defined symbol",
 914                     "try",
 915                     cx.tcx.def_path_str(def_id),
 916                     Applicability::MachineApplicable,
 917                 );
 918             }
 919         }
 920     }
 921 }