src/tools/clippy/clippy_lints/src/utils/internal_lints.rs

   1 use crate::consts::{constant_simple, Constant};
   2 use clippy_utils::diagnostics::{span_lint, span_lint_and_help, span_lint_and_sugg};
   3 use clippy_utils::source::snippet;
   4 use clippy_utils::ty::match_type;
   5 use clippy_utils::{is_expn_of, match_def_path, match_qpath, method_calls, path_to_res, paths, run_lints, SpanlessEq};
   6 use if_chain::if_chain;
   7 use rustc_ast::ast::{Crate as AstCrate, ItemKind, LitKind, ModKind, 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::{
  17     BinOpKind, Crate, Expr, ExprKind, HirId, Item, MutTy, Mutability, Node, Path, StmtKind, Ty, TyKind, UnOp,
  18 };
  19 use rustc_lint::{EarlyContext, EarlyLintPass, LateContext, LateLintPass};
  20 use rustc_middle::hir::map::Map;
  21 use rustc_middle::mir::interpret::ConstValue;
  22 use rustc_middle::ty;
  23 use rustc_session::{declare_lint_pass, declare_tool_lint, impl_lint_pass};
  24 use rustc_span::source_map::{Span, Spanned};
  25 use rustc_span::symbol::{Symbol, SymbolStr};
  26 use rustc_typeck::hir_ty_to_ty;
  27
  28 use std::borrow::{Borrow, Cow};
  29
  30 declare_clippy_lint! {
  31     /// **What it does:** Checks for various things we like to keep tidy in clippy.
  32     ///
  33     /// **Why is this bad?** We like to pretend we're an example of tidy code.
  34     ///
  35     /// **Known problems:** None.
  36     ///
  37     /// **Example:** Wrong ordering of the util::paths constants.
  38     pub CLIPPY_LINTS_INTERNAL,
  39     internal,
  40     "various things that will negatively affect your clippy experience"
  41 }
  42
  43 declare_clippy_lint! {
  44     /// **What it does:** Ensures every lint is associated to a `LintPass`.
  45     ///
  46     /// **Why is this bad?** The compiler only knows lints via a `LintPass`. Without
  47     /// putting a lint to a `LintPass::get_lints()`'s return, the compiler will not
  48     /// know the name of the lint.
  49     ///
  50     /// **Known problems:** Only checks for lints associated using the
  51     /// `declare_lint_pass!`, `impl_lint_pass!`, and `lint_array!` macros.
  52     ///
  53     /// **Example:**
  54     /// ```rust,ignore
  55     /// declare_lint! { pub LINT_1, ... }
  56     /// declare_lint! { pub LINT_2, ... }
  57     /// declare_lint! { pub FORGOTTEN_LINT, ... }
  58     /// // ...
  59     /// declare_lint_pass!(Pass => [LINT_1, LINT_2]);
  60     /// // missing FORGOTTEN_LINT
  61     /// ```
  62     pub LINT_WITHOUT_LINT_PASS,
  63     internal,
  64     "declaring a lint without associating it in a LintPass"
  65 }
  66
  67 declare_clippy_lint! {
  68     /// **What it does:** Checks for calls to `cx.span_lint*` and suggests to use the `utils::*`
  69     /// variant of the function.
  70     ///
  71     /// **Why is this bad?** The `utils::*` variants also add a link to the Clippy documentation to the
  72     /// warning/error messages.
  73     ///
  74     /// **Known problems:** None.
  75     ///
  76     /// **Example:**
  77     /// Bad:
  78     /// ```rust,ignore
  79     /// cx.span_lint(LINT_NAME, "message");
  80     /// ```
  81     ///
  82     /// Good:
  83     /// ```rust,ignore
  84     /// utils::span_lint(cx, LINT_NAME, "message");
  85     /// ```
  86     pub COMPILER_LINT_FUNCTIONS,
  87     internal,
  88     "usage of the lint functions of the compiler instead of the utils::* variant"
  89 }
  90
  91 declare_clippy_lint! {
  92     /// **What it does:** Checks for calls to `cx.outer().expn_data()` and suggests to use
  93     /// the `cx.outer_expn_data()`
  94     ///
  95     /// **Why is this bad?** `cx.outer_expn_data()` is faster and more concise.
  96     ///
  97     /// **Known problems:** None.
  98     ///
  99     /// **Example:**
 100     /// Bad:
 101     /// ```rust,ignore
 102     /// expr.span.ctxt().outer().expn_data()
 103     /// ```
 104     ///
 105     /// Good:
 106     /// ```rust,ignore
 107     /// expr.span.ctxt().outer_expn_data()
 108     /// ```
 109     pub OUTER_EXPN_EXPN_DATA,
 110     internal,
 111     "using `cx.outer_expn().expn_data()` instead of `cx.outer_expn_data()`"
 112 }
 113
 114 declare_clippy_lint! {
 115     /// **What it does:** Not an actual lint. This lint is only meant for testing our customized internal compiler
 116     /// error message by calling `panic`.
 117     ///
 118     /// **Why is this bad?** ICE in large quantities can damage your teeth
 119     ///
 120     /// **Known problems:** None
 121     ///
 122     /// **Example:**
 123     /// Bad:
 124     /// ```rust,ignore
 125     /// 🍦🍦🍦🍦🍦
 126     /// ```
 127     pub PRODUCE_ICE,
 128     internal,
 129     "this message should not appear anywhere as we ICE before and don't emit the lint"
 130 }
 131
 132 declare_clippy_lint! {
 133     /// **What it does:** Checks for cases of an auto-generated lint without an updated description,
 134     /// i.e. `default lint description`.
 135     ///
 136     /// **Why is this bad?** Indicates that the lint is not finished.
 137     ///
 138     /// **Known problems:** None
 139     ///
 140     /// **Example:**
 141     /// Bad:
 142     /// ```rust,ignore
 143     /// declare_lint! { pub COOL_LINT, nursery, "default lint description" }
 144     /// ```
 145     ///
 146     /// Good:
 147     /// ```rust,ignore
 148     /// declare_lint! { pub COOL_LINT, nursery, "a great new lint" }
 149     /// ```
 150     pub DEFAULT_LINT,
 151     internal,
 152     "found 'default lint description' in a lint declaration"
 153 }
 154
 155 declare_clippy_lint! {
 156     /// **What it does:** Lints `span_lint_and_then` function calls, where the
 157     /// closure argument has only one statement and that statement is a method
 158     /// call to `span_suggestion`, `span_help`, `span_note` (using the same
 159     /// span), `help` or `note`.
 160     ///
 161     /// These usages of `span_lint_and_then` should be replaced with one of the
 162     /// wrapper functions `span_lint_and_sugg`, span_lint_and_help`, or
 163     /// `span_lint_and_note`.
 164     ///
 165     /// **Why is this bad?** Using the wrapper `span_lint_and_*` functions, is more
 166     /// convenient, readable and less error prone.
 167     ///
 168     /// **Known problems:** None
 169     ///
 170     /// *Example:**
 171     /// Bad:
 172     /// ```rust,ignore
 173     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 174     ///     diag.span_suggestion(
 175     ///         expr.span,
 176     ///         help_msg,
 177     ///         sugg.to_string(),
 178     ///         Applicability::MachineApplicable,
 179     ///     );
 180     /// });
 181     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 182     ///     diag.span_help(expr.span, help_msg);
 183     /// });
 184     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 185     ///     diag.help(help_msg);
 186     /// });
 187     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 188     ///     diag.span_note(expr.span, note_msg);
 189     /// });
 190     /// span_lint_and_then(cx, TEST_LINT, expr.span, lint_msg, |diag| {
 191     ///     diag.note(note_msg);
 192     /// });
 193     /// ```
 194     ///
 195     /// Good:
 196     /// ```rust,ignore
 197     /// span_lint_and_sugg(
 198     ///     cx,
 199     ///     TEST_LINT,
 200     ///     expr.span,
 201     ///     lint_msg,
 202     ///     help_msg,
 203     ///     sugg.to_string(),
 204     ///     Applicability::MachineApplicable,
 205     /// );
 206     /// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), help_msg);
 207     /// span_lint_and_help(cx, TEST_LINT, expr.span, lint_msg, None, help_msg);
 208     /// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, Some(expr.span), note_msg);
 209     /// span_lint_and_note(cx, TEST_LINT, expr.span, lint_msg, None, note_msg);
 210     /// ```
 211     pub COLLAPSIBLE_SPAN_LINT_CALLS,
 212     internal,
 213     "found collapsible `span_lint_and_then` calls"
 214 }
 215
 216 declare_clippy_lint! {
 217     /// **What it does:** Checks for calls to `utils::match_type()` on a type diagnostic item
 218     /// and suggests to use `utils::is_type_diagnostic_item()` instead.
 219     ///
 220     /// **Why is this bad?** `utils::is_type_diagnostic_item()` does not require hardcoded paths.
 221     ///
 222     /// **Known problems:** None.
 223     ///
 224     /// **Example:**
 225     /// Bad:
 226     /// ```rust,ignore
 227     /// utils::match_type(cx, ty, &paths::VEC)
 228     /// ```
 229     ///
 230     /// Good:
 231     /// ```rust,ignore
 232     /// utils::is_type_diagnostic_item(cx, ty, sym::vec_type)
 233     /// ```
 234     pub MATCH_TYPE_ON_DIAGNOSTIC_ITEM,
 235     internal,
 236     "using `utils::match_type()` instead of `utils::is_type_diagnostic_item()`"
 237 }
 238
 239 declare_clippy_lint! {
 240     /// **What it does:**
 241     /// Checks the paths module for invalid paths.
 242     ///
 243     /// **Why is this bad?**
 244     /// It indicates a bug in the code.
 245     ///
 246     /// **Known problems:** None.
 247     ///
 248     /// **Example:** None.
 249     pub INVALID_PATHS,
 250     internal,
 251     "invalid path"
 252 }
 253
 254 declare_clippy_lint! {
 255     /// **What it does:**
 256     /// Checks for interning symbols that have already been pre-interned and defined as constants.
 257     ///
 258     /// **Why is this bad?**
 259     /// It's faster and easier to use the symbol constant.
 260     ///
 261     /// **Known problems:** None.
 262     ///
 263     /// **Example:**
 264     /// Bad:
 265     /// ```rust,ignore
 266     /// let _ = sym!(f32);
 267     /// ```
 268     ///
 269     /// Good:
 270     /// ```rust,ignore
 271     /// let _ = sym::f32;
 272     /// ```
 273     pub INTERNING_DEFINED_SYMBOL,
 274     internal,
 275     "interning a symbol that is pre-interned and defined as a constant"
 276 }
 277
 278 declare_clippy_lint! {
 279     /// **What it does:** Checks for unnecessary conversion from Symbol to a string.
 280     ///
 281     /// **Why is this bad?** It's faster use symbols directly intead of strings.
 282     ///
 283     /// **Known problems:** None.
 284     ///
 285     /// **Example:**
 286     /// Bad:
 287     /// ```rust,ignore
 288     /// symbol.as_str() == "clippy";
 289     /// ```
 290     ///
 291     /// Good:
 292     /// ```rust,ignore
 293     /// symbol == sym::clippy;
 294     /// ```
 295     pub UNNECESSARY_SYMBOL_STR,
 296     internal,
 297     "unnecessary conversion between Symbol and string"
 298 }
 299
 300 declare_lint_pass!(ClippyLintsInternal => [CLIPPY_LINTS_INTERNAL]);
 301
 302 impl EarlyLintPass for ClippyLintsInternal {
 303     fn check_crate(&mut self, cx: &EarlyContext<'_>, krate: &AstCrate) {
 304         if let Some(utils) = krate.items.iter().find(|item| item.ident.name.as_str() == "utils") {
 305             if let ItemKind::Mod(_, ModKind::Loaded(ref items, ..)) = utils.kind {
 306                 if let Some(paths) = items.iter().find(|item| item.ident.name.as_str() == "paths") {
 307                     if let ItemKind::Mod(_, ModKind::Loaded(ref items, ..)) = paths.kind {
 308                         let mut last_name: Option<SymbolStr> = None;
 309                         for item in items {
 310                             let name = item.ident.as_str();
 311                             if let Some(ref last_name) = last_name {
 312                                 if **last_name > *name {
 313                                     span_lint(
 314                                         cx,
 315                                         CLIPPY_LINTS_INTERNAL,
 316                                         item.span,
 317                                         "this constant should be before the previous constant due to lexical \
 318                                          ordering",
 319                                     );
 320                                 }
 321                             }
 322                             last_name = Some(name);
 323                         }
 324                     }
 325                 }
 326             }
 327         }
 328     }
 329 }
 330
 331 #[derive(Clone, Debug, Default)]
 332 pub struct LintWithoutLintPass {
 333     declared_lints: FxHashMap<Symbol, Span>,
 334     registered_lints: FxHashSet<Symbol>,
 335 }
 336
 337 impl_lint_pass!(LintWithoutLintPass => [DEFAULT_LINT, LINT_WITHOUT_LINT_PASS]);
 338
 339 impl<'tcx> LateLintPass<'tcx> for LintWithoutLintPass {
 340     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
 341         if !run_lints(cx, &[DEFAULT_LINT], item.hir_id()) {
 342             return;
 343         }
 344
 345         if let hir::ItemKind::Static(ref ty, Mutability::Not, body_id) = item.kind {
 346             if is_lint_ref_type(cx, ty) {
 347                 let expr = &cx.tcx.hir().body(body_id).value;
 348                 if_chain! {
 349                     if let ExprKind::AddrOf(_, _, ref inner_exp) = expr.kind;
 350                     if let ExprKind::Struct(_, ref fields, _) = inner_exp.kind;
 351                     let field = fields
 352                         .iter()
 353                         .find(|f| f.ident.as_str() == "desc")
 354                         .expect("lints must have a description field");
 355                     if let ExprKind::Lit(Spanned {
 356                         node: LitKind::Str(ref sym, _),
 357                         ..
 358                     }) = field.expr.kind;
 359                     if sym.as_str() == "default lint description";
 360
 361                     then {
 362                         span_lint(
 363                             cx,
 364                             DEFAULT_LINT,
 365                             item.span,
 366                             &format!("the lint `{}` has the default lint description", item.ident.name),
 367                         );
 368                     }
 369                 }
 370                 self.declared_lints.insert(item.ident.name, item.span);
 371             }
 372         } else if is_expn_of(item.span, "impl_lint_pass").is_some()
 373             || is_expn_of(item.span, "declare_lint_pass").is_some()
 374         {
 375             if let hir::ItemKind::Impl(hir::Impl {
 376                 of_trait: None,
 377                 items: ref impl_item_refs,
 378                 ..
 379             }) = item.kind
 380             {
 381                 let mut collector = LintCollector {
 382                     output: &mut self.registered_lints,
 383                     cx,
 384                 };
 385                 let body_id = cx.tcx.hir().body_owned_by(
 386                     impl_item_refs
 387                         .iter()
 388                         .find(|iiref| iiref.ident.as_str() == "get_lints")
 389                         .expect("LintPass needs to implement get_lints")
 390                         .id
 391                         .hir_id(),
 392                 );
 393                 collector.visit_expr(&cx.tcx.hir().body(body_id).value);
 394             }
 395         }
 396     }
 397
 398     fn check_crate_post(&mut self, cx: &LateContext<'tcx>, _: &'tcx Crate<'_>) {
 399         if !run_lints(cx, &[LINT_WITHOUT_LINT_PASS], CRATE_HIR_ID) {
 400             return;
 401         }
 402
 403         for (lint_name, &lint_span) in &self.declared_lints {
 404             // When using the `declare_tool_lint!` macro, the original `lint_span`'s
 405             // file points to "<rustc macros>".
 406             // `compiletest-rs` thinks that's an error in a different file and
 407             // just ignores it. This causes the test in compile-fail/lint_pass
 408             // not able to capture the error.
 409             // Therefore, we need to climb the macro expansion tree and find the
 410             // actual span that invoked `declare_tool_lint!`:
 411             let lint_span = lint_span.ctxt().outer_expn_data().call_site;
 412
 413             if !self.registered_lints.contains(lint_name) {
 414                 span_lint(
 415                     cx,
 416                     LINT_WITHOUT_LINT_PASS,
 417                     lint_span,
 418                     &format!("the lint `{}` is not added to any `LintPass`", lint_name),
 419                 );
 420             }
 421         }
 422     }
 423 }
 424
 425 fn is_lint_ref_type<'tcx>(cx: &LateContext<'tcx>, ty: &Ty<'_>) -> bool {
 426     if let TyKind::Rptr(
 427         _,
 428         MutTy {
 429             ty: ref inner,
 430             mutbl: Mutability::Not,
 431         },
 432     ) = ty.kind
 433     {
 434         if let TyKind::Path(ref path) = inner.kind {
 435             if let Res::Def(DefKind::Struct, def_id) = cx.qpath_res(path, inner.hir_id) {
 436                 return match_def_path(cx, def_id, &paths::LINT);
 437             }
 438         }
 439     }
 440
 441     false
 442 }
 443
 444 struct LintCollector<'a, 'tcx> {
 445     output: &'a mut FxHashSet<Symbol>,
 446     cx: &'a LateContext<'tcx>,
 447 }
 448
 449 impl<'a, 'tcx> Visitor<'tcx> for LintCollector<'a, 'tcx> {
 450     type Map = Map<'tcx>;
 451
 452     fn visit_path(&mut self, path: &'tcx Path<'_>, _: HirId) {
 453         if path.segments.len() == 1 {
 454             self.output.insert(path.segments[0].ident.name);
 455         }
 456     }
 457
 458     fn nested_visit_map(&mut self) -> NestedVisitorMap<Self::Map> {
 459         NestedVisitorMap::All(self.cx.tcx.hir())
 460     }
 461 }
 462
 463 #[derive(Clone, Default)]
 464 pub struct CompilerLintFunctions {
 465     map: FxHashMap<&'static str, &'static str>,
 466 }
 467
 468 impl CompilerLintFunctions {
 469     #[must_use]
 470     pub fn new() -> Self {
 471         let mut map = FxHashMap::default();
 472         map.insert("span_lint", "utils::span_lint");
 473         map.insert("struct_span_lint", "utils::span_lint");
 474         map.insert("lint", "utils::span_lint");
 475         map.insert("span_lint_note", "utils::span_lint_and_note");
 476         map.insert("span_lint_help", "utils::span_lint_and_help");
 477         Self { map }
 478     }
 479 }
 480
 481 impl_lint_pass!(CompilerLintFunctions => [COMPILER_LINT_FUNCTIONS]);
 482
 483 impl<'tcx> LateLintPass<'tcx> for CompilerLintFunctions {
 484     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 485         if !run_lints(cx, &[COMPILER_LINT_FUNCTIONS], expr.hir_id) {
 486             return;
 487         }
 488
 489         if_chain! {
 490             if let ExprKind::MethodCall(ref path, _, ref args, _) = expr.kind;
 491             let fn_name = path.ident;
 492             if let Some(sugg) = self.map.get(&*fn_name.as_str());
 493             let ty = cx.typeck_results().expr_ty(&args[0]).peel_refs();
 494             if match_type(cx, ty, &paths::EARLY_CONTEXT)
 495                 || match_type(cx, ty, &paths::LATE_CONTEXT);
 496             then {
 497                 span_lint_and_help(
 498                     cx,
 499                     COMPILER_LINT_FUNCTIONS,
 500                     path.ident.span,
 501                     "usage of a compiler lint function",
 502                     None,
 503                     &format!("please use the Clippy variant of this function: `{}`", sugg),
 504                 );
 505             }
 506         }
 507     }
 508 }
 509
 510 declare_lint_pass!(OuterExpnDataPass => [OUTER_EXPN_EXPN_DATA]);
 511
 512 impl<'tcx> LateLintPass<'tcx> for OuterExpnDataPass {
 513     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 514         if !run_lints(cx, &[OUTER_EXPN_EXPN_DATA], expr.hir_id) {
 515             return;
 516         }
 517
 518         let (method_names, arg_lists, spans) = method_calls(expr, 2);
 519         let method_names: Vec<SymbolStr> = method_names.iter().map(|s| s.as_str()).collect();
 520         let method_names: Vec<&str> = method_names.iter().map(|s| &**s).collect();
 521         if_chain! {
 522             if let ["expn_data", "outer_expn"] = method_names.as_slice();
 523             let args = arg_lists[1];
 524             if args.len() == 1;
 525             let self_arg = &args[0];
 526             let self_ty = cx.typeck_results().expr_ty(self_arg).peel_refs();
 527             if match_type(cx, self_ty, &paths::SYNTAX_CONTEXT);
 528             then {
 529                 span_lint_and_sugg(
 530                     cx,
 531                     OUTER_EXPN_EXPN_DATA,
 532                     spans[1].with_hi(expr.span.hi()),
 533                     "usage of `outer_expn().expn_data()`",
 534                     "try",
 535                     "outer_expn_data()".to_string(),
 536                     Applicability::MachineApplicable,
 537                 );
 538             }
 539         }
 540     }
 541 }
 542
 543 declare_lint_pass!(ProduceIce => [PRODUCE_ICE]);
 544
 545 impl EarlyLintPass for ProduceIce {
 546     fn check_fn(&mut self, _: &EarlyContext<'_>, fn_kind: FnKind<'_>, _: Span, _: NodeId) {
 547         if is_trigger_fn(fn_kind) {
 548             panic!("Would you like some help with that?");
 549         }
 550     }
 551 }
 552
 553 fn is_trigger_fn(fn_kind: FnKind<'_>) -> bool {
 554     match fn_kind {
 555         FnKind::Fn(_, ident, ..) => ident.name.as_str() == "it_looks_like_you_are_trying_to_kill_clippy",
 556         FnKind::Closure(..) => false,
 557     }
 558 }
 559
 560 declare_lint_pass!(CollapsibleCalls => [COLLAPSIBLE_SPAN_LINT_CALLS]);
 561
 562 impl<'tcx> LateLintPass<'tcx> for CollapsibleCalls {
 563     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 564         if !run_lints(cx, &[COLLAPSIBLE_SPAN_LINT_CALLS], expr.hir_id) {
 565             return;
 566         }
 567
 568         if_chain! {
 569             if let ExprKind::Call(ref func, ref and_then_args) = expr.kind;
 570             if let ExprKind::Path(ref path) = func.kind;
 571             if match_qpath(path, &["span_lint_and_then"]);
 572             if and_then_args.len() == 5;
 573             if let ExprKind::Closure(_, _, body_id, _, _) = &and_then_args[4].kind;
 574             let body = cx.tcx.hir().body(*body_id);
 575             if let ExprKind::Block(block, _) = &body.value.kind;
 576             let stmts = &block.stmts;
 577             if stmts.len() == 1 && block.expr.is_none();
 578             if let StmtKind::Semi(only_expr) = &stmts[0].kind;
 579             if let ExprKind::MethodCall(ref ps, _, ref span_call_args, _) = &only_expr.kind;
 580             let and_then_snippets = get_and_then_snippets(cx, and_then_args);
 581             let mut sle = SpanlessEq::new(cx).deny_side_effects();
 582             then {
 583                 match &*ps.ident.as_str() {
 584                     "span_suggestion" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 585                         suggest_suggestion(cx, expr, &and_then_snippets, &span_suggestion_snippets(cx, span_call_args));
 586                     },
 587                     "span_help" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 588                         let help_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 589                         suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), true);
 590                     },
 591                     "span_note" if sle.eq_expr(&and_then_args[2], &span_call_args[1]) => {
 592                         let note_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 593                         suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), true);
 594                     },
 595                     "help" => {
 596                         let help_snippet = snippet(cx, span_call_args[1].span, r#""...""#);
 597                         suggest_help(cx, expr, &and_then_snippets, help_snippet.borrow(), false);
 598                     }
 599                     "note" => {
 600                         let note_snippet = snippet(cx, span_call_args[1].span, r#""...""#);
 601                         suggest_note(cx, expr, &and_then_snippets, note_snippet.borrow(), false);
 602                     }
 603                     _  => (),
 604                 }
 605             }
 606         }
 607     }
 608 }
 609
 610 struct AndThenSnippets<'a> {
 611     cx: Cow<'a, str>,
 612     lint: Cow<'a, str>,
 613     span: Cow<'a, str>,
 614     msg: Cow<'a, str>,
 615 }
 616
 617 fn get_and_then_snippets<'a, 'hir>(cx: &LateContext<'_>, and_then_snippets: &'hir [Expr<'hir>]) -> AndThenSnippets<'a> {
 618     let cx_snippet = snippet(cx, and_then_snippets[0].span, "cx");
 619     let lint_snippet = snippet(cx, and_then_snippets[1].span, "..");
 620     let span_snippet = snippet(cx, and_then_snippets[2].span, "span");
 621     let msg_snippet = snippet(cx, and_then_snippets[3].span, r#""...""#);
 622
 623     AndThenSnippets {
 624         cx: cx_snippet,
 625         lint: lint_snippet,
 626         span: span_snippet,
 627         msg: msg_snippet,
 628     }
 629 }
 630
 631 struct SpanSuggestionSnippets<'a> {
 632     help: Cow<'a, str>,
 633     sugg: Cow<'a, str>,
 634     applicability: Cow<'a, str>,
 635 }
 636
 637 fn span_suggestion_snippets<'a, 'hir>(
 638     cx: &LateContext<'_>,
 639     span_call_args: &'hir [Expr<'hir>],
 640 ) -> SpanSuggestionSnippets<'a> {
 641     let help_snippet = snippet(cx, span_call_args[2].span, r#""...""#);
 642     let sugg_snippet = snippet(cx, span_call_args[3].span, "..");
 643     let applicability_snippet = snippet(cx, span_call_args[4].span, "Applicability::MachineApplicable");
 644
 645     SpanSuggestionSnippets {
 646         help: help_snippet,
 647         sugg: sugg_snippet,
 648         applicability: applicability_snippet,
 649     }
 650 }
 651
 652 fn suggest_suggestion(
 653     cx: &LateContext<'_>,
 654     expr: &Expr<'_>,
 655     and_then_snippets: &AndThenSnippets<'_>,
 656     span_suggestion_snippets: &SpanSuggestionSnippets<'_>,
 657 ) {
 658     span_lint_and_sugg(
 659         cx,
 660         COLLAPSIBLE_SPAN_LINT_CALLS,
 661         expr.span,
 662         "this call is collapsible",
 663         "collapse into",
 664         format!(
 665             "span_lint_and_sugg({}, {}, {}, {}, {}, {}, {})",
 666             and_then_snippets.cx,
 667             and_then_snippets.lint,
 668             and_then_snippets.span,
 669             and_then_snippets.msg,
 670             span_suggestion_snippets.help,
 671             span_suggestion_snippets.sugg,
 672             span_suggestion_snippets.applicability
 673         ),
 674         Applicability::MachineApplicable,
 675     );
 676 }
 677
 678 fn suggest_help(
 679     cx: &LateContext<'_>,
 680     expr: &Expr<'_>,
 681     and_then_snippets: &AndThenSnippets<'_>,
 682     help: &str,
 683     with_span: bool,
 684 ) {
 685     let option_span = if with_span {
 686         format!("Some({})", and_then_snippets.span)
 687     } else {
 688         "None".to_string()
 689     };
 690
 691     span_lint_and_sugg(
 692         cx,
 693         COLLAPSIBLE_SPAN_LINT_CALLS,
 694         expr.span,
 695         "this call is collapsible",
 696         "collapse into",
 697         format!(
 698             "span_lint_and_help({}, {}, {}, {}, {}, {})",
 699             and_then_snippets.cx,
 700             and_then_snippets.lint,
 701             and_then_snippets.span,
 702             and_then_snippets.msg,
 703             &option_span,
 704             help
 705         ),
 706         Applicability::MachineApplicable,
 707     );
 708 }
 709
 710 fn suggest_note(
 711     cx: &LateContext<'_>,
 712     expr: &Expr<'_>,
 713     and_then_snippets: &AndThenSnippets<'_>,
 714     note: &str,
 715     with_span: bool,
 716 ) {
 717     let note_span = if with_span {
 718         format!("Some({})", and_then_snippets.span)
 719     } else {
 720         "None".to_string()
 721     };
 722
 723     span_lint_and_sugg(
 724         cx,
 725         COLLAPSIBLE_SPAN_LINT_CALLS,
 726         expr.span,
 727         "this call is collspible",
 728         "collapse into",
 729         format!(
 730             "span_lint_and_note({}, {}, {}, {}, {}, {})",
 731             and_then_snippets.cx,
 732             and_then_snippets.lint,
 733             and_then_snippets.span,
 734             and_then_snippets.msg,
 735             note_span,
 736             note
 737         ),
 738         Applicability::MachineApplicable,
 739     );
 740 }
 741
 742 declare_lint_pass!(MatchTypeOnDiagItem => [MATCH_TYPE_ON_DIAGNOSTIC_ITEM]);
 743
 744 impl<'tcx> LateLintPass<'tcx> for MatchTypeOnDiagItem {
 745     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx hir::Expr<'_>) {
 746         if !run_lints(cx, &[MATCH_TYPE_ON_DIAGNOSTIC_ITEM], expr.hir_id) {
 747             return;
 748         }
 749
 750         if_chain! {
 751             // Check if this is a call to utils::match_type()
 752             if let ExprKind::Call(fn_path, [context, ty, ty_path]) = expr.kind;
 753             if let ExprKind::Path(fn_qpath) = &fn_path.kind;
 754             if match_qpath(&fn_qpath, &["utils", "match_type"]);
 755             // Extract the path to the matched type
 756             if let Some(segments) = path_to_matched_type(cx, ty_path);
 757             let segments: Vec<&str> = segments.iter().map(|sym| &**sym).collect();
 758             if let Some(ty_did) = path_to_res(cx, &segments[..]).opt_def_id();
 759             // Check if the matched type is a diagnostic item
 760             let diag_items = cx.tcx.diagnostic_items(ty_did.krate);
 761             if let Some(item_name) = diag_items.iter().find_map(|(k, v)| if *v == ty_did { Some(k) } else { None });
 762             then {
 763                 let cx_snippet = snippet(cx, context.span, "_");
 764                 let ty_snippet = snippet(cx, ty.span, "_");
 765
 766                 span_lint_and_sugg(
 767                     cx,
 768                     MATCH_TYPE_ON_DIAGNOSTIC_ITEM,
 769                     expr.span,
 770                     "usage of `utils::match_type()` on a type diagnostic item",
 771                     "try",
 772                     format!("utils::is_type_diagnostic_item({}, {}, sym::{})", cx_snippet, ty_snippet, item_name),
 773                     Applicability::MaybeIncorrect,
 774                 );
 775             }
 776         }
 777     }
 778 }
 779
 780 fn path_to_matched_type(cx: &LateContext<'_>, expr: &hir::Expr<'_>) -> Option<Vec<SymbolStr>> {
 781     use rustc_hir::ItemKind;
 782
 783     match &expr.kind {
 784         ExprKind::AddrOf(.., expr) => return path_to_matched_type(cx, expr),
 785         ExprKind::Path(qpath) => match cx.qpath_res(qpath, expr.hir_id) {
 786             Res::Local(hir_id) => {
 787                 let parent_id = cx.tcx.hir().get_parent_node(hir_id);
 788                 if let Some(Node::Local(local)) = cx.tcx.hir().find(parent_id) {
 789                     if let Some(init) = local.init {
 790                         return path_to_matched_type(cx, init);
 791                     }
 792                 }
 793             },
 794             Res::Def(DefKind::Const | DefKind::Static, def_id) => {
 795                 if let Some(Node::Item(item)) = cx.tcx.hir().get_if_local(def_id) {
 796                     if let ItemKind::Const(.., body_id) | ItemKind::Static(.., body_id) = item.kind {
 797                         let body = cx.tcx.hir().body(body_id);
 798                         return path_to_matched_type(cx, &body.value);
 799                     }
 800                 }
 801             },
 802             _ => {},
 803         },
 804         ExprKind::Array(exprs) => {
 805             let segments: Vec<SymbolStr> = exprs
 806                 .iter()
 807                 .filter_map(|expr| {
 808                     if let ExprKind::Lit(lit) = &expr.kind {
 809                         if let LitKind::Str(sym, _) = lit.node {
 810                             return Some(sym.as_str());
 811                         }
 812                     }
 813
 814                     None
 815                 })
 816                 .collect();
 817
 818             if segments.len() == exprs.len() {
 819                 return Some(segments);
 820             }
 821         },
 822         _ => {},
 823     }
 824
 825     None
 826 }
 827
 828 // This is not a complete resolver for paths. It works on all the paths currently used in the paths
 829 // module.  That's all it does and all it needs to do.
 830 pub fn check_path(cx: &LateContext<'_>, path: &[&str]) -> bool {
 831     if path_to_res(cx, path) != Res::Err {
 832         return true;
 833     }
 834
 835     // Some implementations can't be found by `path_to_res`, particularly inherent
 836     // implementations of native types. Check lang items.
 837     let path_syms: Vec<_> = path.iter().map(|p| Symbol::intern(p)).collect();
 838     let lang_items = cx.tcx.lang_items();
 839     for item_def_id in lang_items.items().iter().flatten() {
 840         let lang_item_path = cx.get_def_path(*item_def_id);
 841         if path_syms.starts_with(&lang_item_path) {
 842             if let [item] = &path_syms[lang_item_path.len()..] {
 843                 for child in cx.tcx.item_children(*item_def_id) {
 844                     if child.ident.name == *item {
 845                         return true;
 846                     }
 847                 }
 848             }
 849         }
 850     }
 851
 852     false
 853 }
 854
 855 declare_lint_pass!(InvalidPaths => [INVALID_PATHS]);
 856
 857 impl<'tcx> LateLintPass<'tcx> for InvalidPaths {
 858     fn check_item(&mut self, cx: &LateContext<'tcx>, item: &'tcx Item<'_>) {
 859         let local_def_id = &cx.tcx.parent_module(item.hir_id());
 860         let mod_name = &cx.tcx.item_name(local_def_id.to_def_id());
 861         if_chain! {
 862             if mod_name.as_str() == "paths";
 863             if let hir::ItemKind::Const(ty, body_id) = item.kind;
 864             let ty = hir_ty_to_ty(cx.tcx, ty);
 865             if let ty::Array(el_ty, _) = &ty.kind();
 866             if let ty::Ref(_, el_ty, _) = &el_ty.kind();
 867             if el_ty.is_str();
 868             let body = cx.tcx.hir().body(body_id);
 869             let typeck_results = cx.tcx.typeck_body(body_id);
 870             if let Some(Constant::Vec(path)) = constant_simple(cx, typeck_results, &body.value);
 871             let path: Vec<&str> = path.iter().map(|x| {
 872                     if let Constant::Str(s) = x {
 873                         s.as_str()
 874                     } else {
 875                         // We checked the type of the constant above
 876                         unreachable!()
 877                     }
 878                 }).collect();
 879             if !check_path(cx, &path[..]);
 880             then {
 881                 span_lint(cx, CLIPPY_LINTS_INTERNAL, item.span, "invalid path");
 882             }
 883         }
 884     }
 885 }
 886
 887 #[derive(Default)]
 888 pub struct InterningDefinedSymbol {
 889     // Maps the symbol value to the constant DefId.
 890     symbol_map: FxHashMap<u32, DefId>,
 891 }
 892
 893 impl_lint_pass!(InterningDefinedSymbol => [INTERNING_DEFINED_SYMBOL, UNNECESSARY_SYMBOL_STR]);
 894
 895 impl<'tcx> LateLintPass<'tcx> for InterningDefinedSymbol {
 896     fn check_crate(&mut self, cx: &LateContext<'_>, _: &Crate<'_>) {
 897         if !self.symbol_map.is_empty() {
 898             return;
 899         }
 900
 901         for &module in &[&paths::KW_MODULE, &paths::SYM_MODULE] {
 902             if let Some(def_id) = path_to_res(cx, module).opt_def_id() {
 903                 for item in cx.tcx.item_children(def_id).iter() {
 904                     if_chain! {
 905                         if let Res::Def(DefKind::Const, item_def_id) = item.res;
 906                         let ty = cx.tcx.type_of(item_def_id);
 907                         if match_type(cx, ty, &paths::SYMBOL);
 908                         if let Ok(ConstValue::Scalar(value)) = cx.tcx.const_eval_poly(item_def_id);
 909                         if let Ok(value) = value.to_u32();
 910                         then {
 911                             self.symbol_map.insert(value, item_def_id);
 912                         }
 913                     }
 914                 }
 915             }
 916         }
 917     }
 918
 919     fn check_expr(&mut self, cx: &LateContext<'tcx>, expr: &'tcx Expr<'_>) {
 920         if_chain! {
 921             if let ExprKind::Call(func, [arg]) = &expr.kind;
 922             if let ty::FnDef(def_id, _) = cx.typeck_results().expr_ty(func).kind();
 923             if match_def_path(cx, *def_id, &paths::SYMBOL_INTERN);
 924             if let Some(Constant::Str(arg)) = constant_simple(cx, cx.typeck_results(), arg);
 925             let value = Symbol::intern(&arg).as_u32();
 926             if let Some(&def_id) = self.symbol_map.get(&value);
 927             then {
 928                 span_lint_and_sugg(
 929                     cx,
 930                     INTERNING_DEFINED_SYMBOL,
 931                     is_expn_of(expr.span, "sym").unwrap_or(expr.span),
 932                     "interning a defined symbol",
 933                     "try",
 934                     cx.tcx.def_path_str(def_id),
 935                     Applicability::MachineApplicable,
 936                 );
 937             }
 938         }
 939         if let ExprKind::Binary(op, left, right) = expr.kind {
 940             if matches!(op.node, BinOpKind::Eq | BinOpKind::Ne) {
 941                 let data = [
 942                     (left, self.symbol_str_expr(left, cx)),
 943                     (right, self.symbol_str_expr(right, cx)),
 944                 ];
 945                 match data {
 946                     // both operands are a symbol string
 947                     [(_, Some(left)), (_, Some(right))] => {
 948                         span_lint_and_sugg(
 949                             cx,
 950                             UNNECESSARY_SYMBOL_STR,
 951                             expr.span,
 952                             "unnecessary `Symbol` to string conversion",
 953                             "try",
 954                             format!(
 955                                 "{} {} {}",
 956                                 left.as_symbol_snippet(cx),
 957                                 op.node.as_str(),
 958                                 right.as_symbol_snippet(cx),
 959                             ),
 960                             Applicability::MachineApplicable,
 961                         );
 962                     },
 963                     // one of the operands is a symbol string
 964                     [(expr, Some(symbol)), _] | [_, (expr, Some(symbol))] => {
 965                         // creating an owned string for comparison
 966                         if matches!(symbol, SymbolStrExpr::Expr { is_to_owned: true, .. }) {
 967                             span_lint_and_sugg(
 968                                 cx,
 969                                 UNNECESSARY_SYMBOL_STR,
 970                                 expr.span,
 971                                 "unnecessary string allocation",
 972                                 "try",
 973                                 format!("{}.as_str()", symbol.as_symbol_snippet(cx)),
 974                                 Applicability::MachineApplicable,
 975                             );
 976                         }
 977                     },
 978                     // nothing found
 979                     [(_, None), (_, None)] => {},
 980                 }
 981             }
 982         }
 983     }
 984 }
 985
 986 impl InterningDefinedSymbol {
 987     fn symbol_str_expr<'tcx>(&self, expr: &'tcx Expr<'tcx>, cx: &LateContext<'tcx>) -> Option<SymbolStrExpr<'tcx>> {
 988         static IDENT_STR_PATHS: &[&[&str]] = &[&paths::IDENT_AS_STR, &paths::TO_STRING_METHOD];
 989         static SYMBOL_STR_PATHS: &[&[&str]] = &[
 990             &paths::SYMBOL_AS_STR,
 991             &paths::SYMBOL_TO_IDENT_STRING,
 992             &paths::TO_STRING_METHOD,
 993         ];
 994         // SymbolStr might be de-referenced: `&*symbol.as_str()`
 995         let call = if_chain! {
 996             if let ExprKind::AddrOf(_, _, e) = expr.kind;
 997             if let ExprKind::Unary(UnOp::Deref, e) = e.kind;
 998             then { e } else { expr }
 999         };
1000         if_chain! {
1001             // is a method call
1002             if let ExprKind::MethodCall(_, _, [item], _) = call.kind;
1003             if let Some(did) = cx.typeck_results().type_dependent_def_id(call.hir_id);
1004             let ty = cx.typeck_results().expr_ty(item);
1005             // ...on either an Ident or a Symbol
1006             if let Some(is_ident) = if match_type(cx, ty, &paths::SYMBOL) {
1007                 Some(false)
1008             } else if match_type(cx, ty, &paths::IDENT) {
1009                 Some(true)
1010             } else {
1011                 None
1012             };
1013             // ...which converts it to a string
1014             let paths = if is_ident { IDENT_STR_PATHS } else { SYMBOL_STR_PATHS };
1015             if let Some(path) = paths.iter().find(|path| match_def_path(cx, did, path));
1016             then {
1017                 let is_to_owned = path.last().unwrap().ends_with("string");
1018                 return Some(SymbolStrExpr::Expr {
1019                     item,
1020                     is_ident,
1021                     is_to_owned,
1022                 });
1023             }
1024         }
1025         // is a string constant
1026         if let Some(Constant::Str(s)) = constant_simple(cx, cx.typeck_results(), expr) {
1027             let value = Symbol::intern(&s).as_u32();
1028             // ...which matches a symbol constant
1029             if let Some(&def_id) = self.symbol_map.get(&value) {
1030                 return Some(SymbolStrExpr::Const(def_id));
1031             }
1032         }
1033         None
1034     }
1035 }
1036
1037 enum SymbolStrExpr<'tcx> {
1038     /// a string constant with a corresponding symbol constant
1039     Const(DefId),
1040     /// a "symbol to string" expression like `symbol.as_str()`
1041     Expr {
1042         /// part that evaluates to `Symbol` or `Ident`
1043         item: &'tcx Expr<'tcx>,
1044         is_ident: bool,
1045         /// whether an owned `String` is created like `to_ident_string()`
1046         is_to_owned: bool,
1047     },
1048 }
1049
1050 impl<'tcx> SymbolStrExpr<'tcx> {
1051     /// Returns a snippet that evaluates to a `Symbol` and is const if possible
1052     fn as_symbol_snippet(&self, cx: &LateContext<'_>) -> Cow<'tcx, str> {
1053         match *self {
1054             Self::Const(def_id) => cx.tcx.def_path_str(def_id).into(),
1055             Self::Expr { item, is_ident, .. } => {
1056                 let mut snip = snippet(cx, item.span.source_callsite(), "..");
1057                 if is_ident {
1058                     // get `Ident.name`
1059                     snip.to_mut().push_str(".name");
1060                 }
1061                 snip
1062             },
1063         }
1064     }
1065 }