clippy_lints/src/utils/internal_lints.rs

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